SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Björklund Sebastian) "

Sökning: WFRF:(Björklund Sebastian)

  • Resultat 1-50 av 56
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Albèr, Cathrine, et al. (författare)
  • Effects of water gradients and use of urea on skin ultrastructure evaluated by confocal Raman microspectroscopy
  • 2013
  • Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier. - 0005-2736 .- 1879-2642 .- 0006-3002. ; 1828:11, s. 2470-2478
  • Tidskriftsartikel (refereegranskat)abstract
    • The rather thin outermost layer of the mammalian skin, stratum corneum (SC), is a complex biomembrane which separates the water rich inside of the body from the dry outside. The skin surface can be exposed to rather extreme variations in ambient conditions (e.g. water activity, temperature and pH), with potential effects on the barrier function. Increased understanding of how the barrier is affected by such changes is highly relevant for regulation of transdermal uptake of exogenous chemicals. In the present study we investigate the effect of hydration and the use of a well-known humectant, urea, on skin barrier ultrastructure by means of confocal Raman microspectroscopy. We also perform dynamic vapor sorption (DVS) microbalance measurements to examine the water uptake capacity of SC pretreated with urea. Based on novel Raman images, constructed from 2D spectral maps, we can distinguish large water inclusions within the skin membrane exceeding the size of fully hydrated corneocytes. We show that these inclusions contain water with spectral properties similar to that of bulk water. The results furthermore show that the ambient water activity has an important impact on the formation of these water inclusions as well as on the hydration profile across the membrane. Urea significantly increases the water uptake when present in skin, as compared to skin without urea, and it promotes formation of larger water inclusions in the tissue. The results confirm that urea can be used as a humectant to increase skin hydration.
  •  
2.
  • Björklund, Sebastian, et al. (författare)
  • A calorimetric method to determine water activity
  • 2011
  • Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 82:11
  • Tidskriftsartikel (refereegranskat)abstract
    • A calorimetric method to determine water activity covering the full range of the water activity scale is presented. A dry stream of nitrogen gas is passed either over the solution whose activity should be determined or left dry before it is saturated by bubbling through water in an isothermal calorimeter. The unknown activity is in principle determined by comparing the thermal power of vaporization related to the gas stream with unknown activity to that with zero activity. Except for three minor corrections (for pressure drop, non-perfect humidification, and evaporative cooling) the unknown water activity is calculated solely based on the water activity end-points zero and unity. Thus, there is no need for calibration with references with known water activities. The method has been evaluated at 30 °C by measuring the water activity of seven aqueous sodium chloride solutions ranging from 0.1 mol kg−1 to 3 mol kg−1 and seven saturated aqueous salt solutions (LiCl, MgCl2, NaBr, NaCl, KCl, KNO3, and K2SO4) with known water activities. The performance of the method was adequate over the complete water activity scale. At high water activities the performance was excellent, which is encouraging as many other methods used for water activity determination have limited performance at high water activities.
  •  
3.
  • Björklund, Sebastian, et al. (författare)
  • A water gradient can be used to regulate drug transport across skin
  • 2010
  • Ingår i: Journal of Controlled Release. - : Elsevier. - 0168-3659 .- 1873-4995. ; 143:2, s. 191-200
  • Tidskriftsartikel (refereegranskat)abstract
    • At normal conditions there is a substantial water gradient over the skin as it separates the water-rich inside of the body from the dry outside. This leads to a variation in the degree of hydration from the inside to the outside of skin and changes in this gradient may affect its structure and function. In this study we raise the question: How do changes in the water gradient across skin affect its permeability? We approach this problem in novel diffusion experiments that permit strict control of the gradient in the chemical potential of water and hence well-defined boundary conditions. The results demonstrate that a water gradient can be used to regulate transport of drugs with different lipophilic characteristics across the skin barrier. It is shown that the transport of metronidazole (log Po/w=0.0) and methyl salicylate (log Po/w=2.5) across skin increases abruptly at low water gradients, corresponding to high degrees of skin hydration, and that this effect is reversible. This phenomenon is highly relevant to drug delivery applications due to its potential of temporarily open the skin barrier for transdermal drug delivery and subsequently close the barrier after treatment. Further, the results contribute to the understanding of the occlusion effect and indicate the boundary conditions of the water gradient needed to make use of this effect
  •  
4.
  • Björklund, Sebastian, et al. (författare)
  • Alcohols react with MCM-41 at room temperature and chemically modify mesoporous silica
  • 2017
  • Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
  • Tidskriftsartikel (refereegranskat)abstract
    • Mesoporous silica has received much attention due to its well-defined structural order, high surface area, and tunable pore diameter. To successfully employ mesoporous silica for nanotechnology applications it is important to consider how it is influenced by solvent molecules due to the fact that most preparation procedures involve treatment in various solvents. In the present work we contribute to this important topic with new results on how MCM-41 is affected by a simple treatment in alcohol at room temperature. The effects of alcohol treatment are characterized by TGA, FTIR, and sorption calorimetry. The results are clear and show that treatment of MCM-41 in methanol, ethanol, propanol, butanol, pentanol, or octanol at room temperature introduces alkoxy groups that are covalently bound to the silica surface. It is shown that alcohol treated MCM-41 becomes more hydrophobic and that this effect is sequentially more prominent going from methanol to octanol. Chemical formation of alkoxy groups onto MCM-41 occurs both for calcined and hydroxylated MCM-41 and the alkoxy groups are hydrolytically unstable and can be replaced by silanol groups after exposure to water. The results are highly relevant for mesoporous silica applications that involve contact or treatment in protic solvents, which is very common.
  •  
5.
  • Björklund, Sebastian, et al. (författare)
  • Characterization of stratum corneum molecular dynamics by natural-abundance (13)c solid-state NMR.
  • 2013
  • Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite the enormous potential for pharmaceutical applications, there is still a lack of understanding of the molecular details that can contribute to increased permeability of the stratum corneum (SC). To investigate the influence of hydration and heating on the SC, we record the natural-abundance (13)C signal of SC using polarization transfer solid-state NMR methods. Resonance lines from all major SC components are assigned. Comparison of the signal intensities obtained with the INEPT and CP pulse sequences gives information on the molecular dynamics of SC components. The majority of the lipids are rigid at 32°C, and those lipids co-exist with a small pool of mobile lipids. The ratio between mobile and rigid lipids increases with hydration. An abrupt change of keratin filament dynamics occurs at RH = 80-85%, from completely rigid to a structure with rigid backbone and mobile protruding terminals. Heating has a strong effect on the lipid mobility, but only a weak influence on the keratin filaments. The results provide novel molecular insight into how the SC constituents are affected by hydration and heating, and improve the understanding of enhanced SC permeability, which is associated with elevated temperatures and SC hydration.
  •  
6.
  • Björklund, Sebastian, et al. (författare)
  • Glycerol and urea can be used to increase skin permeability in reduced hydration conditions
  • 2013
  • Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 5:50, s. 638-645
  • Tidskriftsartikel (refereegranskat)abstract
    • The natural moisturizing factor (NMF) is a group of hygroscopic molecules that is naturally present in skin and protects from severe drying. Glycerol and urea are two examples of NMF components that are also used in skin care applications. In the present study, we investigate the influence of glycerol and urea on the permeability of a model drug (metronidazole, Mz) across excised pig skin membranes at different hydrating conditions. The degree of skin hydration is regulated by the gradient in water activity across the membrane, which in turn depends on the water activity of the formulation in contact with the skin membrane. Here, we determine the water activity of all formulations employed using an isothermal calorimetric method. Thus, the gradient in water activity is controlled by a novel experimental set-up with well-defined boundary conditions on both sides of the skin membrane. The results demonstrate that glycerol and urea can retain high steady state flux of Mz across skin membranes at dehydrating conditions, which otherwise would decrease the permeability due to dehydration. X-ray diffraction measurements are performed to give insight into the effects of glycerol and urea on SC molecular organization. The novel steady state flux results can be related to the observation that water, glycerol, and urea all affect the structural features of the SC molecular components in a similar manner.
  •  
7.
  • Björklund, Sebastian, et al. (författare)
  • Humidity scanning quartz crystal microbalance with dissipation monitoring setup for determination of sorption-desorption isotherms and rheological changes
  • 2015
  • Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 86:5
  • Tidskriftsartikel (refereegranskat)abstract
    • A new method to determine water sorption-desorption isotherms with high resolution in the complete range of water activities (relative humidities) is presented. The method is based on quartz crystal microbalance with dissipation monitoring (QCM-D). The QCM-D is equipped with a humidity module in which the sample film is kept in air with controlled humidity. The experimental setup allows for continuous scanning of the relative humidity from either dry to humid conditions or vice versa. The amount of water sorbed or desorbed from the sample is determined from the resonance frequencies of the coated quartz sensor, via analysis of the overtone dependence. In addition, the method allows for characterization of hydration induced changes of the rheological properties from the dissipation data, which is closely connected to the viscoelasticity of the film. The accuracy of the humidity scanning setup is confirmed in control experiments. Sorption-desorption isotherms of pig gastric mucin and lysozyme, obtained by the new method, show good agreement with previous results. Finally, we show that the deposition technique used to coat the quartz sensor influences the QCM-D data and how this issue can be used to obtain further information on the effect of hydration. In particular, we demonstrate that spin-coating represents an attractive alternative to obtain sorption-desorption isotherms, while drop-coating provides additional information on changes of the rheological properties during hydration.
  •  
8.
  • Björklund, Sebastian, et al. (författare)
  • Hydration-Induced Phase Transitions in Surfactant and Lipid Films
  • 2016
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32:21, s. 5223-5232
  • Tidskriftsartikel (refereegranskat)abstract
    • For several surfactant and lipid systems, it is crucial to understand how hydration influences the physical and chemical properties. When humidity changes, it affects the degree of hydration by adding or removing water molecules. In many cases, this process induces transitions between liquid crystalline phases. This phenomenon is of general interest for numerous applications simply because of the fact that humidity variations are ubiquitous. Of particular interest are hydration-induced phase transitions in amphiphilic films, which in many cases appear as the frontier toward a vapor phase with changing humidity. Considering this, it is important to characterize the film thickness needed for the formation of 3D liquid crystalline phases and the lyotropic phase behavior of this kind of film. In this work, we study this issue by employing a recently developed method based on the humidity scanning quartz crystal microbalance with dissipation monitoring (HS QCM-D), which enables continuous scanning of the film hydration. We investigate five surfactants films (DDAO, DTAC, CTAC, SDS, and n-octyl beta-D-glucoside) and one lipid film (monoolein) and show that HS QCM-D enables the fast characterization of hydration-induced phase transitions with small samples. Film thicknesses range from tens to hundreds of nanometers, and clear phase transitions are observed in all cases. It is shown that phase transitions in films occur at the same water activities as for corresponding bulk samples. This allows us to conclude that surfactant and lipid films, with a thickness of as low as 50 nm, are in fact assembled as 3D-structured liquid crystalline phases. Furthermore, liquid crystalline phases of surfactant films show liquidlike behavior, which decreases the accuracy of the absorbed water mass measurement. On the other hand, the monoolein lipid forms more rigid liquid crystalline films, allowing for an accurate determination of the water sorption isotherm, which is also true for the sorption isotherms corresponding to the solid surfactant phases.
  •  
9.
  • Björklund, Sebastian (författare)
  • Skin hydration - How water and osmolytes influence biophysical properties of stratum corneum
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The outermost layer of skin (i.e., the stratum corneum, SC) is the interface that separates the water-rich inside of the body from the relatively dry external environment. SC forms an effective permeability barrier, which has to be overcome in transdermal drug delivery. Its function as a barrier for molecular diffusion depends on the SC molecular structure and phase behavior. Both structure and phase behavior may be altered, for example, by hydration or addition of other solutes, which affects the barrier properties. This thesis explores the interplay between molecular properties of SC components and the macroscopic properties of the SC membrane. We investigate the influence of hydration on SC permeability at steady state by using an in vitro set-up where the boundary conditions are controlled by the water activity in the solutions in contact with the skin membrane. Changes of macroscopic properties are rationalized by employing techniques that provide information on SC molecular organization and molecular dynamics. We show that SC hydration leads to increased SC permeability, which is attributed to a higher fraction of fluid SC molecular components with lower diffusional resistance. This can have implications, for example, in transdermal delivery applications where it is desirable to increase the amount of drug delivered across the skin barrier to reach therapeutic effect. We show that common so-called moisturizers, like glycerol and urea, can be used to retain high SC permeability under dehydrating conditions. This effect is ascribed to the capability of these small polar molecules to maintain the SC molecular properties in a state that is similar to a more hydrated SC membrane at reduced hydration conditions. This result provides a deeper understanding of the beneficial effect of moisturizers in treatment of dry skin conditions and challenges the view that moisturizers, like glycerol and urea, are beneficial for skin health by merely increasing the SC hydration.
  •  
10.
  • Björklund, Sebastian, et al. (författare)
  • Skin membrane electrical impedance properties under the influence of a varying water gradient
  • 2013
  • Ingår i: Biophysical Journal. - : Elsevier. - 0006-3495 .- 1542-0086. ; 104:12, s. 2639-2650
  • Tidskriftsartikel (refereegranskat)abstract
    • The stratum corneum (SC) is an effective permeability barrier. One strategy to increase drug delivery across skin is to increase the hydration. A detailed description of how hydration affects skin permeability requires characterization of both macroscopic and molecular properties and how they respond to hydration. We explore this issue by performing impedance experiments on excised skin membranes in the frequency range 1 Hz to 0.2 MHz under the influence of a varying gradient in water activity (aw). Hydration/dehydration induces reversible changes of membrane resistance and effective capacitance. On average, the membrane resistance is 14 times lower and the effective capacitance is 1.5 times higher when the outermost SC membrane is exposed to hydrating conditions (aw ¼ 0.992), as compared to the case of more dehydrating conditions (aw ¼ 0.826). Molecular insight into the hydration effects on the SC components is provided by natural-abundance 13C polarization transfer solidstate NMR and x-ray diffraction under similar hydration conditions. Hydration has a significant effect on the dynamics of the keratin filament terminals and increases the interchain spacing of the filaments. The SC lipids are organized into lamellar structures with ~ 12.6 nm spacing and hexagonal hydrocarbon chain packing with mainly all-trans configuration of the acyl chains, irrespective of hydration state. Subtle changes in the dynamics of the lipids due to mobilization and incorporation of cholesterol and long-chain lipid species into the fluid lipid fraction is suggested to occur upon hydration, which can explain the changes of the impedance response. The results presented here provide information that is useful in explaining the effect of hydration on skin permeability.
  •  
11.
  • Björklund, Sebastian, et al. (författare)
  • Stratum corneum molecular mobility in the presence of natural moisturizers.
  • 2014
  • Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 10:25, s. 4535-4546
  • Tidskriftsartikel (refereegranskat)abstract
    • The outermost layer of the skin, the stratum corneum (SC), is a lipid-protein membrane that experiences considerable osmotic stress from a dry and cold climate. The natural moisturizing factor (NMF) comprises small and polar substances, which like osmolytes can protect living systems from osmotic stress. NMF is commonly claimed to increase the water content in the SC and thereby protect the skin from dryness. In this work we challenge this proposed mechanism, and explore the influence of NMF on the lipid and protein components in the SC. We employ natural-abundance (13)C solid-state NMR methods to investigate how the SC molecular components are influenced by urea, glycerol, pyrrolidone carboxylic acid (PCA), and urocanic acid (UCA), all of which are naturally present in the SC as NMF compounds. Experiments are performed with intact SC, isolated corneocytes and model lipids. The combination of NMR experiments provides molecularly resolved qualitative information on the dynamics of different SC lipid and protein components. We obtain completely novel molecular information on the interaction of these NMF compounds with the SC lipids and proteins. We show that urea and glycerol, which are also common ingredients in skin care products, increase the molecular mobility of both SC lipids and proteins at moderate relative humidity where the SC components are considerably more rigid in the absence of these compounds. This effect cannot be attributed to increased SC water content. PCA has no detectable effect on SC molecular mobility under the conditions investigated. It is finally shown that the more apolar compound, UCA, specifically influences the mobility of the SC lipid regions. The present results show that the NMF components act to retain the fluidity of the SC molecular components under dehydrating conditions in such a way that the SC properties remain largely unchanged as compared to more hydrated SC. These findings provide a new molecular insight into how small polar molecules in NMF and skin care products act to protect the human skin from drying.
  •  
12.
  • Björklund, Sebastian, et al. (författare)
  • The effects of polar excipients transcutol and dexpanthenol on molecular mobility, permeability, and electrical impedance of the skin barrier
  • 2016
  • Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 479, s. 207-220
  • Tidskriftsartikel (refereegranskat)abstract
    • In the development of transdermal and topical products it is important to understand how formulation ingredients interact with the molecular components of the upper layer of the skin, the stratum corneum (SC), and thereby influence its macroscopic barrier properties. The aim here was to investigate the effect of two commonly used excipients, transcutol and dexpanthenol, on the molecular as well as the macroscopic properties of the skin membrane. Polarization transfer solid-state NMR methods were combined with steady-state flux and impedance spectroscopy measurements to investigate how these common excipients influence the molecular components of SC and its barrier function at strictly controlled hydration conditions in vitro with excised porcine skin. The NMR results provide completely new molecular insight into how transcutol and dexpanthenol affect specific molecular segments of both SC lipids and proteins. The presence of transcutol or dexpanthenol in the formulation at fixed water activity results in increased effective skin permeability of the model drug metronidazole. Finally, impedance spectroscopy data show clear changes of the effective skin capacitance after treatment with transcutol or dexpanthenol. Based on the complementary data, we are able to draw direct links between effects on the molecular properties and on the macroscopic barrier function of the skin barrier under treatment with formulations containing transcutol or dexpanthenol.
  •  
13.
  • Björklund, Sebastian, et al. (författare)
  • Water vapor sorption-desorption hysteresis in glassy surface films of mucins investigated by humidity scanning QCM-D
  • 2019
  • Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 545, s. 289-300
  • Tidskriftsartikel (refereegranskat)abstract
    • Hypothesis: Investigating the origin of water sorption-desorption hysteresis in glassy biopolymers is important for understanding the properties of biological barriers, such as the mucus epithelium. In general, hysteresis is a result of a complex interplay between diffusion of water and relaxation of the polymer matrix. Our hypothesis is that for thin films, typical for quartz crystal microbalance with dissipation monitoring (QCM-D) experiments performed in gas phase with defined relative humidity, the diffusion limitation is eliminated and hysteresis results only from relaxation of the polymer matrix. Experiments: We use a recently developed humidity scanning (HS) QCM-D method to obtain water sorption-desorption isotherms of mucin films under controlled conditions where water diffusion is not the limiting factor, neither in the vapor phase nor in the glassy mucin film. Findings: We present new results on the water sorption-desorption behavior of glassy mucin films with nanoscale thicknesses. Despite the fact that water diffusion is not the limiting factor, the sorption-desorption branches show clear hysteresis effects that are similar to those typically observed in bulk samples. The hydration-induced glass transition, resolved from monitoring the rheological behavior of the films, is shown to be in excellent agreement with the onset of the sorption-desorption hysteresis. We suggest that the hysteresis effect is related to a difference in dynamical and structural properties of the glassy materials depending on the hydration history of the films.
  •  
14.
  • Cancino-Montecinos, Sebastian, et al. (författare)
  • A General Model of Dissonance Reduction : Unifying Past Accounts via an Emotion Regulation Perspective
  • 2020
  • Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 11
  • Tidskriftsartikel (refereegranskat)abstract
    • Cognitive dissonance has been studied for more than 60 years and many insightful findings have come from this research. However, some important theoretical and methodological issues are yet to be resolved, particularly regarding dissonance reduction. In this paper, we place dissonance theory in the larger framework of appraisal theories of emotion, emotion regulation, and coping. The basic premise of dissonance theory is that people experience negative affect (to varying degrees) following the detection of cognitive conflict. The individual will be motivated to alleviate these emotional reactions and could do so by reducing dissonance in some manner. We argue that detection of dissonance will follow the same principles as when people interpret any other stimuli as emotionally significant. Thus, appraisal theory of emotion, which argues that emotions are generated via the cognitive evaluation of surrounding stimuli, should be applicable to the dissonance-detection process. In short, we argue that dissonance-reduction strategies (attitude change, trivialization, denial of responsibility, etc.) can be understood as emotion-regulation strategies. We further argue that this perspective contributes to reconciling fragmented (and sometimes contrary) viewpoints present in the literature on dissonance reduction. In addition to proposing the general model of dissonance reduction, we illustrate at the hand of empirical data how research on dissonance reduction can be performed without relying on experimental paradigms that focus on a specific reduction strategy.
  •  
15.
  • Cancino-Montecinos, Sebastian, et al. (författare)
  • Cognitive dissonance leads to an abstract mindset
  • 2016
  • Ingår i: Book of abstract. ; , s. 38-38
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • This study investigated the effects of cognitive dissonance on abstract thinking. According to action-identification theory, whenever people try to understand a situation in a new way, they activate an abstract mindset. Based on this premise, dissonance was hypothesized to put people in an abstract mindset. The induced compliance paradigm, in which participants are asked to write a counter-attitudinal essay under either low choice (producing little dissonance) or high choice (producing more dissonance), was employed. Results showed that dissonance did in fact activate a more abstract mindset, and this effect was more pronounced for participants having a more concrete mindset to begin with. This suggests that increasing abstraction, as a reaction to cognitive conflict, is a way for people to resolve inconsistencies.
  •  
16.
  • Cancino-Montecinos, Sebastian, et al. (författare)
  • Dissonance and abstraction : Cognitive conflict leads to higher level of construal
  • 2018
  • Ingår i: European Journal of Social Psychology. - : Wiley. - 0046-2772 .- 1099-0992. ; 48:1, s. 100-107
  • Tidskriftsartikel (refereegranskat)abstract
    • This study investigated the effects of cognitive conflict on abstract thinking. According to action-identification theory, an ambiguous and unfamiliar situation might propel an individual to a more abstract mindset. Based on this premise, cognitive conflict was hypothesized to put people in an abstract mindset. The induced compliance paradigm, in which participants are asked to write a counter-attitudinal essay under either low choice (producing little dissonance) or high choice (producing more dissonance), was employed. Results showed that an abstract mindset was in fact activated in the induced compliance paradigm, and this effect was more pronounced for participants having a more concrete mindset to begin with. The results suggest that the experience of cognitive conflict is closely related to increased abstraction.
  •  
17.
  • Cancino-Montecinos, Sebastian, et al. (författare)
  • Dissonance reduction as emotion regulation: Attitude change is related to positive emotions in the induced compliance paradigm.
  • 2018
  • Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203.
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to clarify how positive and negative emotions are related to the common attitude-change effect in cognitive dissonance research. Drawing on appraisal theories of emotion, and emotion-regulation research, we predicted that negative emotions would be inversely related to attitude change, whereas positive emotions would be positively related to attitude change in the induced compliance paradigm. In two studies, participants (N = 44; N = 106) wrote a counter-attitudinal essay under the perception of high choice, and were later asked to state their emotions in relation to writing this essay, as well as to state their attitude. Results confirmed the predictions, even when controlling for baseline emotions. These findings untangled a previously unresolved issue in dissonance research, which in turn shows how important emotion theories are for the understanding of cognitive dissonance processes.
  •  
18.
  • Cancino Montecinos, Sebastian, 1983- (författare)
  • New perspectives on cognitive dissonance theory
  • 2020
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Cognitive consistency is generally considered a fundamental aspect of the human mind, and cognitive dissonance theory is the most famous and studies theory within this framework. Dissonance theory holds that when related cognitions are in conflict (e.g. when behaving counter to one’s attitudes), people will experience negative affect. This affective reaction motivates people to engage in various dissonance-reduction strategies (e.g. attitude change). The aim of this thesis was to investigate some novel, and unanswered questions within dissonance research, and to relate dissonance theory to neighboring theories.In Study I, it was predicted (and supported) that cognitive dissonance (writing a counter-attitudinal essay in the induced-compliance paradigm) would lead to people exhibiting an abstract mindset. The rationale for this prediction (based on action-identification theory) was that unfamiliar and difficult situations, were action is usually impeded (much like dissonant situations), lead to individuals adopting more concrete representations of the situation – for the sake action execution. However, since people usually want to find meaning in their actions, they will quickly, after the action is executed, adopt an abstract representation of the situation – which might also lead to spillover effects were people’s mental representation of their actions in general become more abstract.In Study II, the aim was to investigate to what extent, and how, emotions relate to the attitude-change effect in the induced-compliance paradigm. Past researchers usually predict that negative emotions should be positively related to this effect. Based on the notion of emotion regulation, however, attitude change (a form of reappraisal) implies that people are positively (and less negatively) tuned to the situation – and should therefore feel more positive (and less negative) emotions towards the situation. Thus, contrary to past research, it was predicted that negative emotions would be inversely related to attitude change, and positive emotions would be positively related to attitude change. Result across two experiments supported these predictions.Lastly, in Study III, the aim was to provide a general theoretical model of dissonance reduction. Based on a cognitive-emotion perspective (including appraisal theories of emotion, emotion regulation, and coping), it was suggested that reduction processes are influenced by the intensity of the initial affective reaction. This affective reaction is in turn influenced by the magnitude of the dissonance and the novelty-familiarity dimension of the situation. When the dissonance magnitude is too big, and the situation novel, people might disengage rather quickly (leaving the situation or distracting themselves). If, however, people have enough motivation and cognitive capacity, they might engage more in the reduction processes. The advantage of this model is that it can be applied to any dissonant situation.Taken together, these studies suggest that there is still much to discover in dissonance research, and much can be gained by conceptualizing dissonance processes within a cognitive-emotion framework. Future research should focus more on how the social context (e.g. influence of other people) might affect these dissonance processes. More emphasis should also be put on the prevalence of different dissonant situations, and the accompanied reduction attempts, in real-life settings.
  •  
19.
  • Cancino-Montecinos, Sebastian, et al. (författare)
  • The effects of cognitive dissonance on abstract thinking : Dissonance leads to an abstract mindset
  • 2016
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • In this study, we investigated how individuals’ abstract thinking increases when experiencing dissonance. Dissonance theory holds that people reduce dissonance by accommodating their attitudes in order to fit their most recent behavior. This process resembles the reasoning of action-identification theory (AIT), which postulates that people usually try to understand their actions in a meaningful and coherent way, and also that actions can take on new meanings when people move from a low-level to a high-level understanding of the action. Thus, acting inconsistently threatens the coherent understanding of ones action; and in order to regain a sense of consonance, people will try to find a new meaning of their action (e.g., via attitude change). However, this occurs when moving to a high-level understanding (i.e., thinking more abstractly) of ones action. However, the effect of dissonance on abstraction should be stronger for individuals with low level of abstraction to begin with – since AIT holds that people who naturally tend to think abstractly already have high-level understandings of their actions. We predicted that: (1) dissonance puts people in a more abstract mindset, and (2) this effect will be more apparent for individuals low in abstraction. First, we established participants’ natural tendencies to abstract thinking with the Gestalt Completion Test (GCT). This variable was later split into low and high GCT. Several days later, we employed the induced compliance paradigm, in which participants were asked to write a counter-attitudinal essay under either low choice or high choice. High-choice participants usually experience more dissonance. We also created a neutral condition (to serve as a comparison to the other conditions) in which individuals were asked to write a pro-attitudinal essay. After the induced compliance manipulation, the Behavior Identification Form (BIF) was used to measure abstraction. The sample consisted of 125 non-psychology students. A 3 (condition: high-choice vs. low-choice vs. neutral) ˙ 2 (GCT: low vs. high) between subjects factorial ANOVA showed that participants in the high-choice condition (who experienced more dissonance) did exhibit a more abstract mindset, and level of GCT moderated this effect. The following simple effects analysis showed a significant effect for the low-GCT groups: (F(2, 119) = 6.607, p = .002, η2 = .100) and the pairwise comparisons revealed that high-choice participants exhibited a significantly more abstract mindset (M = 16.65, SD = 4.54) compared to both the low-choice participants (M = 13.18, SD = 4.45) p = .013, d = .77 and the neutral participants (M = 12.25, SD = 4.71) p < .001, d = .95. No significant effects were found when comparing the high-GCT groups (p = .398). The present study demonstrated that dissonance activates abstract thinking, which is thought to facilitate people’s understanding their recent actions. This finding has important implication for the future study of consequences of cognitive conflicts, and also the study of how abstraction enables people to find new meanings of their own actions. Hence, investigation on these mechanisms could shed more light on how people regulate their thoughts, emotions and behavior in real time.
  •  
20.
  • Clifton, Luke A, et al. (författare)
  • Design and use of model membranes to study biomolecular interactions using complementary surface-sensitive techniques.
  • 2020
  • Ingår i: Advances in Colloid and Interface Science. - : Elsevier. - 0001-8686 .- 1873-3727. ; 277
  • Tidskriftsartikel (refereegranskat)abstract
    • Cellular membranes are complex structures and simplified analogues in the form of model membranes or biomembranes are used as platforms to understand fundamental properties of the membrane itself as well as interactions with various biomolecules such as drugs, peptides and proteins. Model membranes at the air-liquid and solid-liquid interfaces can be studied using a range of complementary surface-sensitive techniques to give a detailed picture of both the structure and physicochemical properties of the membrane and its resulting interactions. In this review, we will present the main planar model membranes used in the field to date with a focus on monolayers at the air-liquid interface, supported lipid bilayers at the solid-liquid interface and advanced membrane models such as tethered and floating membranes. We will then briefly present the principles as well as the main type of information on molecular interactions at model membranes accessible using a Langmuir trough, quartz crystal microbalance with dissipation monitoring, ellipsometry, atomic force microscopy, Brewster angle microscopy, Infrared spectroscopy, and neutron and X-ray reflectometry. A consistent example for following biomolecular interactions at model membranes is used across many of the techniques in terms of the well-studied antimicrobial peptide Melittin. The overall objective is to establish an understanding of the information accessible from each technique, their respective advantages and limitations, and their complementarity.
  •  
21.
  • Ericson, Petter, 1986- (författare)
  • Order-preserving graph grammars
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The field of semantic modelling concerns formal models for semantics, that is, formal structures for the computational and algorithmic processing of meaning. This thesis concerns formal graph languages motivated by this field. In particular, we investigate two formalisms: Order-Preserving DAG Grammars (OPDG) and Order-Preserving Hyperedge Replacement Grammars (OPHG), where OPHG generalise OPDG.Graph parsing is the practise of, given a graph grammar and a graph, to determine if, and in which way, the grammar could have generated the graph. If the grammar is considered fixed, it is the non-uniform graph parsing problem, while if the grammars is considered part of the input, it is named the uniform graph parsing problem. Most graph grammars have parsing problems known to be NP-complete, or even exponential, even in the non-uniform case. We show both OPDG and OPHG to have polynomial uniform parsing problems, under certain assumptions.We also show these parsing algorithms to be suitable, not just for determining membership in graph languages, but for computing weights of graphs in graph series.Additionally, OPDG is shown to have several properties common to regular languages, such as MSO definability and MAT learnability. We moreover show a direct corresponcence between OPDG and the regular tree grammars.Finally, we present some limited practical experiments showing that real-world semantic graphs appear to mostly conform to the requirements set by OPDG, after minimal, reversible processing.
  •  
22.
  • Genevskiy, Vladislav, et al. (författare)
  • Water sorption properties and nanostructures of airway mucus in patients with COPD and cystic fibrosis
  • 2022
  • Ingår i: European Respiratory Journal. - : EUROPEAN RESPIRATORY SOC JOURNALS LTD. - 0903-1936 .- 1399-3003. ; 60:Suppl 66
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Background: Muco-obstructive diseases lead to hypersecretion, changing the airway mucus properties, and impairing mucociliary transport, resulting in mucostasis, and increasing infection likelihood. Mucin structure may determine the water sorption properties of mucus and play a role in chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF).Objectives: Investigate the sorption properties and mucin nanostructures in mucus collected from healthy, COPD and CF airways.Methods: To investigate mucin nanostructures, small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) were used. Sorption properties were determined by quartz crystal microbalance with dissipation (QCM-D). Cell-culture (cc) samples from healthy airway mucus (HAM), COPD and CF cultures, and patient HAM from endotracheal tubes and COPD from bronchoscopy were used. Patient mucus was oven-dried at 80°C for the solids content.Results: SAXS and AFM revealed mucin monomers with typical dumbbell structures and varying chain lengths, CF mucins having the shortest chain lengths. Dry-weight solids reached 11wt% in COPD mucus. From QCM-D analysis, cc-COPD and COPD mucus had the highest water content (67 and 75%) during sorption at 99% humidity compared with cc-HAM and HAM (63 and 56%). The overall sorption isotherm for cc-CF mucus was notably lower than HAM and COPD. In low-humidity environments, no hydration-induced glass transition was observed, suggesting mucus remains in a rubbery state.Conclusions: Mucin nanostructures observed in disease could explain the sorption properties where mucin chains affect water content in high humidity environments, which may play a role in protecting the epithelium.
  •  
23.
  • Gidvall, Sanna, et al. (författare)
  • A novel versatile flow-donor chamber as biorelevant ex-vivo test assessing oral mucoadhesive formulations
  • 2021
  • Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 166
  • Tidskriftsartikel (refereegranskat)abstract
    • Oral transmucosal drug delivery is a non-invasive administration route for rapid therapeutic onset and greater bioavailability avoiding the first-pass metabolism. Mucoadhesive formulations are advantageous as they may retain the drug at the administration site. Proper equipment to assess mucoadhesive properties and corresponding drug absorption is fundamental for the development of novel drug delivery systems. Here we developed a new flow-through donor chamber for well-established diffusion cells, and we tested the effects on drug and formulation retention in situ of adding mucoadhesive polymers or mesoporous silica particles to a reference formulation. Mesoporous silica particles are of particular interest as they may be used to encapsulate and retain drug molecules. Compared to other ex-vivo methods described in literature for assessing mucoadhesive performance and transmucosal drug delivery, this new donor chamber provides several advantages: i) it reflects physiological conditions better as a realistic saliva flow can be provided over the administration site, ii) it is versatile since it can be mounted on any kind of vertical diffusion cell allowing simultaneous detection of drug retention at the administration site and drug permeation through the tissue, and iii) it enables optical quantification of formulations residence time aided by image processing. This new flow-through donor diffusion cell set-up proved sensitive to differentiate a reference formulation from one where 20 %(w/w) Carbomer was added (to further improve the mucoadhesive properties), with respect to both drug and formulation residence times. We also found that mesoporous silica particles, investigated as particles only and mixed together with the reference formulation, gave very similar drug and formulation retention to what we observed with the mucoadhesive Carbomer. However, after some time (>30 min) it became obvious that the tablet excipients in the reference formulation promote particle retention on the mucosa. This work provides a new simple and versatile biorelevant test for the evaluation of oral mucoadhesive formulations and paves the way for further studies on mesoporous silica particles as valuable excipients for enhancing oral mucoadhesion.
  •  
24.
  • Glaros, Vassilis, et al. (författare)
  • Limited access to antigen drives generation of early B cell memory while restraining the plasmablast response
  • 2021
  • Ingår i: Immunity. - : Elsevier. - 1074-7613 .- 1097-4180. ; 54:9, s. 2005-
  • Tidskriftsartikel (refereegranskat)abstract
    • Cell fate decisions during early B cell activation determine the outcome of responses to pathogens and vaccines. We examined the early B cell response to T-dependent antigen in mice by single-cell RNA sequencing. Early after immunization, a homogeneous population of activated precursors (APs) gave rise to a transient wave of plasmablasts (PBs), followed a day later by the emergence of germinal center B cells (GCBCs). Most APs rapidly exited the cell cycle, giving rise to non-GC-derived early memory B cells (eMBCs) that retained an AP-like transcriptional profile. Rapid decline of antigen availability controlled these events; provision of excess antigen precluded cell cycle exit and induced a new wave of PBs. Fate mapping revealed a prominent contribution of eMBCs to the MBC pool. Quiescent cells with an MBC phenotype dominated the early response to immunization in primates. A reservoir of APs/eMBCs may enable rapid readjustment of the immune response when failure to contain a threat is manifested by increased antigen availability.
  •  
25.
  • Gonzalez-Martinez, Juan Francisco, et al. (författare)
  • Humidity-induced phase transitions of surfactants embedded in latex coatings can drastically alter their water barrier and mechanical properties
  • 2018
  • Ingår i: Polymers. - : MDPI. - 2073-4360. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Latex coatings are environmentally friendly i.e., they are formed from aqueous polymer dispersions, are cheap to produce and provide exceptional mechanical properties. Therefore, they are ubiquitous and can be found in a wide range of different applications such as paints and varnishes, pressure-sensitive adhesives, textiles, construction materials, paper coatings and inks. However, they also have weaknesses and their surfactant content is among them. Surfactants are often needed to stabilize polymer particles in the aqueous latex dispersions. These surfactants also form part of the coatings formed from these dispersions, and it is well-known that they can lower their performance. This work further explores this aspect and focuses on the role that embedded surfactant domains play in the response of latex coatings to humid environments. For this purpose, we made use of several experimental techniques where humidity control was implemented: quartz crystal microbalance with dissipation, atomic force microscopy and differential scanning calorimetry. By means of this multimethodological approach, we report that surfactants embedded in latex coatings can undergo humidity-induced transitions towards more hydrated and softer phases, and that this results in a drastic decrease of the mechanical and water barrier properties of the whole coatings. Subsequently, this work highlights the potential of taking into account the phase behavior of surfactants when choosing which ones to use in the synthesis of latex dispersions as this would help in predicting their performance under different environmental conditions.
  •  
26.
  • Hallan, Supandeep Singh, et al. (författare)
  • The Potential of Caffeic Acid Lipid Nanoparticulate Systems for Skin Application : In Vitro Assays to Assess Delivery and Antioxidant Effect
  • 2021
  • Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The object of this study is a comparison between solid lipid nanoparticles and ethosomes for caffeic acid delivery through the skin. Caffeic acid is a potent antioxidant molecule whose cutaneous administration is hampered by its low solubility and scarce stability. In order to improve its therapeutic potential, caffeic acid has been encapsulated within solid lipid nanoparticles and ethosomes. The effect of lipid matrix has been evaluated on the morphology and size distribution of solid lipid nanoparticles and ethosomes loaded with caffeic acid. Particularly, morphology has been investigated by cryogenic transmission electron microscopy and small angle X-ray scattering, while mean diameters have been evaluated by photon correlation spectroscopy. The antioxidant power has been evaluated by the 2,2-diphenyl-1-picrylhydrazyl methodology. The influence of the type of nanoparticulate system on caffeic acid diffusion has been evaluated by Franz cells associated to the nylon membrane, while to evaluate caffeic acid permeation through the skin, an amperometric study has been conducted, which was based on a porcine skin-covered oxygen electrode. This apparatus allows measuring the O2 concentration changes in the membrane induced by polyphenols and H2O2 reaction in the skin. The antioxidative reactions in the skin induced by caffeic acid administered by solid lipid nanoparticles or ethosomes have been evaluated. Franz cell results indicated that caffeic acid diffusion from ethosomes was 18-fold slower with respect to solid lipid nanoparticles. The amperometric method evidenced the transdermal delivery effect of ethosome, indicating an intense antioxidant activity of caffeic acid and a very low response in the case of SLN. Finally, an irritation patch test conducted on 20 human volunteers demonstrated that both ethosomes and solid lipid nanoparticles can be safely applied on the skin.
  •  
27.
  • Hering, Kathrin, et al. (författare)
  • Inkjet printing of surfactants, proteins and enzymes for biomedical applications
  • 2016
  • Konferensbidrag (refereegranskat)abstract
    • Ink solutions relevant for biomedical applications have been printed using a commercial inkjet printer. Specifically, water-based inks containing surfactant, protein and enzyme have been evaluated. Printability of surfactant ink was theoretically estimated from practically determined surface tension and viscosity of the solution. Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to estimate the mass of inkjet printed surfactant. The effect of printing patterns and hydration on the QCM-D data was evaluated. Finally, horseradish peroxidase ink was printed on skin and an enzymatic reaction on skin was observed. Taken together, the results from this study provide a promising starting point from which inkjet printing of protein-enzyme mixtures on skin can be evaluated.
  •  
28.
  • Hernández, Aura Rocio, et al. (författare)
  • New concepts for transdermal delivery of oxygen based on catalase biochemical reactions studied by oxygen electrode amperometry
  • 2019
  • Ingår i: Journal of Controlled Release. - : Elsevier. - 0168-3659 .- 1873-4995. ; 306, s. 121-129
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of formulation concepts for improved skin tissue oxygenation, including methods for measuring oxygen (O) transport across biological barriers, are important research topics with respect to all processes that are affected by the O concentration, such as radiation therapy in oncology treatments, wound healing, and the general health status of skin. In this work we approach this topic by a novel strategy based on the antioxidative enzyme catalase, which is naturally present in the skin organ where it enables conversion of the reactive oxygen species hydrogen peroxide (HO) into O. We introduce various applications of the skin covered oxygen electrode (SCOE) as an in-vitro tool for studies of catalase activity and function. The SCOE is constructed by placing an excised skin membrane directly on an O electrode and the methodology is based on measurements of the electrical current generated by reduction of O as a function of time (i.e. chronoamperometry). The results confirm that a high amount of native catalase is present in the skin organ, even in the outermost stratum corneum (SC) barrier, and we conclude that excised pig skin (irrespective of freeze-thaw treatment) represents a valid model for ex vivo human skin for studying catalase function by the SCOE setup. The activity of native catalase in skin is sufficient to generate considerable amounts of O by conversion from HO and proof-of-concept is presented for catalase-based transdermal O delivery from topical formulations containing HO. In addition, we show that this concept can be further improved by topical application of external catalase on the skin surface, which enables transdermal O delivery from 50 times lower concentrations of HO. These important results are promising for development of novel topical or transdermal formulations containing low and safe concentrations of HO for skin tissue oxygenation. Further, our results indicate that the O production by catalase, derived from topically applied S. epidermidis (a simple model for skin microbiota) is relatively low as compared to the O produced by the catalase naturally present in skin. Still, the catalase activity derived from S. epidermidis is measurable. Taken together, this work illustrates the benefits and versatility of the SCOE as an in vitro skin research tool and introduces new and promising strategies for transdermal oxygen delivery, with simultaneous detoxification of HO, based on native or topically applied catalase.
  •  
29.
  • Hernández, Aura Rocio, et al. (författare)
  • The Effect of UVB Irradiation and Oxidative Stress on the Skin Barrier : A New Method to Evaluate Sun Protection Factor Based on Electrical Impedance Spectroscopy
  • 2019
  • Ingår i: Sensors. - : MDPI. - 1424-8220. ; 19:10
  • Tidskriftsartikel (refereegranskat)abstract
    • Sunlight is vital for several biochemical processes of the skin organ. However, acute or chronic exposure to ultraviolet radiation (UVR) has several harmful effects on the skin structure and function, especially in the case of the failing function of antioxidative enzymes, which may lead to substantial tissue damage due to the increased presence of reactive oxygen species (ROS). The aim of this work was to investigate the combined effect of ultraviolet B (UVB) irradiation and oxidative stress on the skin barrier integrity. For this, we employed electrical impedance spectroscopy (EIS) to characterize changes of the electrical properties of excised pig skin membranes after various exposure conditions of UVB irradiation, oxidative stress, and the inhibition of antioxidative enzymatic processes. The oxidative stress was regulated by adding hydrogen peroxide (HO) as a source of ROS, while sodium azide (NaN) was used as an inhibitor of the antioxidative enzyme catalase, which is naturally present throughout the epidermis. By screening for the combined effect of UVB and oxidative stress on the skin membrane electrical properties, we developed a new protocol for evaluating these parameters in a simple in vitro setup. Strikingly, the results show that exposure to extreme UVB irradiation does not affect the skin membrane resistance, implying that the skin barrier remains macroscopically intact. Likewise, exposure to only oxidative stress conditions, without UVB irradiation, does not affect the skin membrane resistance. In contrast to these observations, the combination of UVB irradiation and oxidative stress conditions results in a drastic decrease of the skin membrane resistance, indicating that the integrity of the skin barrier is compromised. Further, the skin membrane effective capacitance remained more or less unaffected by UVB exposure, irrespective of simultaneous exposure of oxidative stress. The EIS results were concluded to be associated with clear signs of macroscopic tissue damage of the epidermis as visualized with microscopy after exposure to UVB irradiation under oxidative stress conditions. Finally, the novel methodology was tested by performing an assessment of cosmetic sunscreen formulations with varying sun protection factor (SPF), with an overall successful outcome, showing good correlation between SPF value and protection capacity in terms of skin resistance change. The results from this study allow for the development of new skin sensors based on EIS for the detection of skin tissue damage from exposure to UVB irradiation and oxidative stress and provide a new, more comprehensive methodology, taking into account both the influence of UVB irradiation and oxidative stress, for in vitro determination of SPF in cosmetic formulations.
  •  
30.
  • Jankovskaja, Skaidre, et al. (författare)
  • Non-invasive skin sampling of tryptophan/kynurenine ratio in vitro towards a skin cancer biomarker
  • 2021
  • Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The tryptophan to kynurenine ratio (Trp/Kyn) has been proposed as a cancer biomarker. Non-invasive topical sampling of Trp/Kyn can therefore serve as a promising concept for skin cancer diagnostics. By performing in vitro pig skin permeability studies, we conclude that non-invasive topical sampling of Trp and Kyn is feasible. We explore the influence of different experimental conditions, which are relevant for the clinical in vivo setting, such as pH variations, sampling time, and microbial degradation of Trp and Kyn. The permeabilities of Trp and Kyn are overall similar. However, the permeated Trp/Kyn ratio is generally higher than unity due to endogenous Trp, which should be taken into account to obtain a non-biased Trp/Kyn ratio accurately reflecting systemic concentrations. Additionally, prolonged sampling time is associated with bacterial Trp and Kyn degradation and should be considered in a clinical setting. Finally, the experimental results are supported by the four permeation pathways model, predicting that the hydrophilic Trp and Kyn molecules mainly permeate through lipid defects (i.e., the porous pathway). However, the hydrophobic indole ring of Trp is suggested to result in a small but noticeable relative increase of Trp diffusion via pathways across the SC lipid lamellae, while the shunt pathway is proposed to slightly favor permeation of Kyn relative to Trp.
  •  
31.
  • Jankovskaja, Skaidre, et al. (författare)
  • Non-Invasive, Topical Sampling of Potential, Low-Molecular Weight, Skin Cancer Biomarkers : A Study on Healthy Volunteers
  • 2022
  • Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 94:15, s. 5856-5865
  • Tidskriftsartikel (refereegranskat)abstract
    • Monitoring of low-molecular weight cancer biomarkers, suchas tryptophan (Trp) and its derivative kynurenine (Kyn), might beadvantageous to non-invasive skin cancer detection. Thus, we assessedseveral approaches of topical sampling of Trp and Kyn, in relation tophenylalanine (Phe) and tyrosine (Tyr), on the volar forearm of six healthyvolunteers. The sampling was performed with three hydrogels (made ofagarose or/and chitosan), hydrated starchfilms, cotton swabs, and tapestripping. The biomarkers were successfully sampled by all approaches, butthe amount of collected Kyn was low, 20 +/- 10 pmol/cm2.Kynquantification was below LOQ, and thus, it was detected only in 20% oftopical samples. To mitigate variability problems of absolute amounts ofsampled amino acids, Tyr/Trp, Phe/Trp, and Phe/Tyr ratios were assessed,proving reduced inter-individual variation from 79 to 45% and intra-individual variation from 42 to 21%. Strong positive correlation was foundbetween Phe and Trp, pointing to the Phe/Trp ratio (being in the 1.0-2.0 range, at 95% confidence) being least dependent onsampling materials, approaches, and sweating. This study leads to conclusion that due to the difficulty in quantifying less abundantKyn, and thus the Trp/Kyn ratio, the Phe/Trp ratio might be a possible, alternative biomarker for detecting skin cancers.
  •  
32.
  • Kelly, Susyn J, et al. (författare)
  • Water Sorption and Structural Properties of Human Airway Mucus in Health and Muco-Obstructive Diseases.
  • 2024
  • Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 25:3, s. 1578-1591
  • Tidskriftsartikel (refereegranskat)abstract
    • Muco-obstructive diseases change airway mucus properties, impairing mucociliary transport and increasing the likelihood of infections. To investigate the sorption properties and nanostructures of mucus in health and disease, we investigated mucus samples from patients and cell cultures (cc) from healthy, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF) airways. Atomic force microscopy (AFM) revealed mucin monomers with typical barbell structures, where the globule to spacer volume ratio was the highest for CF mucin. Accordingly, synchrotron small-angle X-ray scattering (SAXS) revealed more pronounced scattering from CF mucin globules and suggested shorter carbohydrate side chains in CF mucin and longer side chains in COPD mucin. Quartz crystal microbalance with dissipation (QCM-D) analysis presented water sorption isotherms of the three types of human airway mucus, where, at high relative humidity, COPD mucus had the highest water content compared to cc-CF and healthy airway mucus (HAM). The higher hydration of the COPD mucus is consistent with the observation of longer side chains of the COPD mucins. At low humidity, no dehydration-induced glass transition was observed in healthy and diseased mucus, suggesting mucus remained in a rubbery state. However, in dialyzed cc-HAM, a sorption-desorption hysteresis (typically observed in the glassy state) appeared, suggesting that small molecules present in mucus suppress the glass transition.
  •  
33.
  • Krikstolaityte, Vida, et al. (författare)
  • Characterization of nano-layered solid-contact ion selective electrodes by simultaneous potentiometry and quartz crystal microbalance with dissipation.
  • 2020
  • Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 1128, s. 19-30
  • Tidskriftsartikel (refereegranskat)abstract
    • Nano-layered solid-contact potassium-selective electrodes (K+-ISEs) were explored as model ion-selective electrodes for their practical use in clinical analysis. The ultra-thin ISEs ought to be manufactured in a highly reproducible manner, potentially making them suitable for mass production. Thus, their development is pivotal towards miniaturised sensors with simplified conditioning/calibration protocols for point-of-care diagnostics. To study nano-layered ISEs, the ultra-thin nature of ISEs for the first time enabled to combine potentiometry-quartz crystal microbalance with dissipation (QCM-D) to obtain value-added information on the ISE potentiometric response regarding their physical state such as mass/thickness/viscoelastic properties/structural homogeneity. Specifically, the studies were focused on real-time observations of the ISE potentiometric response in relation to changes of their physicochemical properties during the ISE preparation (conditioning) and operation (including biofouling conditions) to identify the occurring processes that may accordingly be critical for potential instability of the ISEs, impeding their practical application. The K+-ISEs were prepared on a QCM-D gold sensor by electrodepositing poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) layer serving as an ion-to-electron transducer subsequently covered by a spin-coated poly(vinyl chloride) based K+-ion selective membrane (K+-ISM). The studies demonstrated that the performance of the nano-layered design of K+-ISEs is detrimentally affected by such processes as water layer formation accordingly causing the instability of the electrode potential. The changes in the ISE physical state such mass/viscoelastic properties associated with water layer formation and origin of the potential instability was already observed at the ISE conditioning stage. The potential instability of nano-layered ISEs limits their practical applicability, indicating the need of new solutions in designing ISEs, for instance, exploiting new water-resistant materials and modifying preparation protocols.
  •  
34.
  • Kristan, Matej, et al. (författare)
  • The first visual object tracking segmentation VOTS2023 challenge results
  • 2023
  • Ingår i: 2023 IEEE/CVF International conference on computer vision workshops (ICCVW). - : Institute of Electrical and Electronics Engineers Inc.. - 9798350307443 - 9798350307450 ; , s. 1788-1810
  • Konferensbidrag (refereegranskat)abstract
    • The Visual Object Tracking Segmentation VOTS2023 challenge is the eleventh annual tracker benchmarking activity of the VOT initiative. This challenge is the first to merge short-term and long-term as well as single-target and multiple-target tracking with segmentation masks as the only target location specification. A new dataset was created; the ground truth has been withheld to prevent overfitting. New performance measures and evaluation protocols have been created along with a new toolkit and an evaluation server. Results of the presented 47 trackers indicate that modern tracking frameworks are well-suited to deal with convergence of short-term and long-term tracking and that multiple and single target tracking can be considered a single problem. A leaderboard, with participating trackers details, the source code, the datasets, and the evaluation kit are publicly available at the challenge website1
  •  
35.
  • Kumlien, Christine, et al. (författare)
  • Research priorities to prevent and treat diabetic foot ulcers-A digital James Lind Alliance Priority Setting Partnership
  • 2022
  • Ingår i: Diabetic Medicine. - : John Wiley & Sons. - 0742-3071 .- 1464-5491. ; 39:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Aim To establish outcomes of a priority setting partnership between participants with diabetes mellitus and clinicians to identify the top 10 research priorities for preventing and treating diabetic foot ulcers (DFUs). Methods Due to the COVID-19 pandemic, the James Lind Alliance Priority Setting Partnership process was adapted into a digital format which involved a pilot survey to identify understandable uncertainties with high relevance for participants tested by calculating the content validity index; a main survey answered by 53 participants living with diabetes and 49 clinicians; and a final digital workshop to process and prioritise the final top 10 research priorities. Results The content validity index was satisfactory for 20 out of 25 uncertainties followed by minor changes and one additional uncertainty. After we processed the 26 uncertainties from the main survey and seven current guidelines, a list of 28 research uncertainties remained for review and discussion in the digital workshop. The final top 10 research priorities included the organisation of diabetes care; screening of diabetes, impaired blood circulation, neuropathy, and skin properties; vascular surgical treatment; importance of self-care; help from significant others; pressure relief; and prevention of infection. Conclusion The top 10 research priorities for preventing and treating DFUs represent consensus areas from persons living with diabetes and clinicians to guide future research. These research priorities can justify and inform strategic allocation of research funding. The digitalisation of James Lind Alliance methodology was feasible.
  •  
36.
  • Labecka, Nikol, et al. (författare)
  • Unraveling UVB effects : Catalase activity and molecular alterations in the stratum corneum
  • 2024
  • Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 666, s. 176-188
  • Tidskriftsartikel (refereegranskat)abstract
    • Aim: Ultraviolet B (UVB) radiation can compromise the functionality of the skin barrier through various mechanisms. We hypothesize that UVB induce photochemical alterations in the components of the outermost layer of the skin, known as the stratum corneum (SC), and modulate its antioxidative defense mechanisms. Catalase is a well-known antioxidative enzyme found in the SC where it acts to scavenge reactive oxygen species. However, a detailed characterization of acute UVB exposure on the activity of native catalase in the SC is lacking. Moreover, the effects of UVB irradiation on the molecular dynamics and organization of the SC keratin and lipid components remain unclear. Thus, the aim of this work is to characterize consequences of UVB exposure on the structural and antioxidative properties of catalase, as well as on the molecular and global properties of the SC matrix surrounding the enzyme. Experiments: The effect of UVB irradiation on the catalase function is investigated by chronoamperometry with a skin covered oxygen electrode, which probes the activity of native catalase in the SC matrix. Circular dichroism is used to explore changes of the catalase secondary structure, and gel electrophoresis is used to detect fragmentation of the enzyme following the UVB exposure. UVB induced alterations of the SC molecular dynamics and structural features of the SC barrier, as well as its water sorption behavior, are investigated by a complementary set of techniques, including natural abundance 13C polarization transfer solid-state NMR, wide-angle X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and dynamic vapor sorption microbalance. Findings: The findings show that UVB exposure impairs the antioxidative function of catalase by deactivating both native catalase in the SC matrix and lyophilized catalase. However, UVB radiation does not alter the secondary structure of the catalase nor induce any observable enzyme fragmentation, which otherwise could explain deactivation of its function. NMR measurements on SC samples show a subtle increase in the molecular mobility of the terminal segments of the SC lipids, accompanied by a decrease in the mobility of lipid chain trans-gauche conformers after high doses of UVB exposure. At the same time, the NMR data suggest increased rigidity of the polypeptide backbone of the keratin filaments, while the molecular mobility of amino acid residues in random coil domains of keratin remain unaffected by UVB irradiation. The FTIR data show a consistent decrease in absorbance associated with lipid bond vibrations, relative to the main protein bands. Collectively, the NMR and FTIR data suggest a small modification in the composition of fluid and solid phases of the SC lipid and protein components after UVB exposure, unrelated to the hydration capacity of the SC tissue. To conclude, UVB deactivation of catalase is anticipated to elevate oxidative stress of the SC, which, when coupled with subtle changes in the molecular characteristics of the SC, may compromise the overall skin health and elevate the likelihood of developing skin disorders.
  •  
37.
  • Morin, Maxim, et al. (författare)
  • Bicontinuous Cubic Liquid Crystals as Potential Matrices for Non-Invasive Topical Sampling of Low-Molecular-Weight Biomarkers
  • 2023
  • Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 15:8
  • Tidskriftsartikel (refereegranskat)abstract
    • Many skin disorders, including cancer, have inflammatory components. The non-invasive detection of related biomarkers could therefore be highly valuable for both diagnosis and follow up on the effect of treatment. This study targets the extraction of tryptophan (Trp) and its metabolite kynurenine (Kyn), two compounds associated with several inflammatory skin disorders. We furthermore hypothesize that lipid-based bicontinuous cubic liquid crystals could be efficient extraction matrices. They comprise a large interfacial area separating interconnected polar and apolar domains, allowing them to accommodate solutes with various properties. We concluded, using the extensively studied GMO-water system as test-platform, that the hydrophilic Kyn and Trp favored the cubic phase over water and revealed a preference for locating at the lipid-water interface. The interfacial area per unit volume of the matrix, as well as the incorporation of ionic molecules at the lipid-water interface, can be used to optimize the extraction of solutes with specific physicochemical characteristics. We also observed that the cubic phases formed at rather extreme water activities (>0.9) and that wearing them resulted in efficient hydration and increased permeability of the skin. Evidently, bicontinuous cubic liquid crystals constitute a promising and versatile platform for non-invasive extraction of biomarkers through skin, as well as for transdermal drug delivery.
  •  
38.
  • Morin, Maxim (författare)
  • Biophysical aspects of the skin barrier : towards increased non-invasive extraction and optimized biomarker sampling
  • 2021
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The skin provides a link to the body’s health via its rich variety of high and low molecular weight biomarkers, reflecting both systemic diseases (e.g., cancer, diabetes) and local skin disorders (e.g., atopic dermatitis, psoriasis). Non-invasive monitoring of disease-specific biomarkers on the skin surface provides a highly attractive diagnostic procedure as alternative to current practices that normally are biopsy-based and invasive. In order to succeed with non-invasive topical diagnostics, the sampling of biomarkers should proceed in a highly accurate and reproducible manner. Further, a major challenge to achieve this goal is to overcome the outermost skin layer (the stratum corneum, SC) that acts as a remarkable permeability barrier, restricting molecular diffusion in and out of our body, including diffusion of potential biomarkers.The primary aim of this thesis is to achieve an optimized and reproducible noninvasive sampling of endogenous biomarkers from the skin surface. Here, water plays a crucial role as the hydration degree of the SC has a strong influence on the diffusion of molecules across the skin barrier. In particular, fully hydrated skin is expected to be optimal for increased diffusion of biomarkers in the skin tissue, favoring efficient extraction.Considering this, to develop a suitable sampling matrix for non-invasive extraction, it is very important to optimize the matrix so that it has a good ability to hydrate the skin as well as a high capacity to absorb the biomarker and finally allow for analytic quantification. The main questions in this thesis are as follows. (i) How long time does it take to reach a stable level of skin hydration? (ii) How do the intrinsic properties of sampling matrices influence the extraction of biomarkers? (iii) What are the effects of the sampling matrices on the biophysical properties of the skin barrier?(iv) Are hydrogels and bicontinuous cubic liquid crystals suitable matrices for noninvasive sampling of endogenous biomarkers? (v) Is reverse iontophoresis a suitable technique to further enhance the extraction endogenous biomarkers?The hydration of the skin is investigated in vivo and in vitro in order to estimate the time to reach stable hydration level. We show that skin hydration proceeds in two distinct stages with different rates of change of the electrical impedance response and conclude that stable conditions are obtained approximately after 60 min of hydration. We explore the novel approach of using lipid-based bicontinuous cubic liquid crystalline phases as matrices for non-invasive sampling of biomarkers in vivo and invitro and compare them with hydrogel-based materials.From these investigations, we conclude that both kind of materials show promising capacity of hydrating the skin and collect skin-derived biomarkers. However, the cubic phases are shown to havea bout twice as high extraction capacity, as compared to hydrogels. Further, we show that reverse iontophoresis enhances extraction of a potential cancer biomarker in vitro by at least an order of magnitude, as compared to passive diffusion. Taken together, the results obtained in this thesis can serve as a point-of-departure for future applications based on non-invasive sampling of disease-related biomarkers from skinin clinical diagnostics.
  •  
39.
  • Morin, Maxim, et al. (författare)
  • Effects of storage conditions on permeability and electrical impedance properties of the skin barrier.
  • 2023
  • Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 637, s. 122891-
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to investigate the effect of various skin preservation protocols on in vitro drug permeation, epidermal-dermal drug distribution, and electrical impedance properties of skin membranes. Acyclovir (AC) and methyl salicylate (MS) were selected as model drugs due to their different physicochemical properties and skin metabolic profiles. In particular, AC is relatively hydrophilic (logP -1.8) and not expected to be affected by skin metabolism, while MS is relatively lipophilic (logP 2.5) and susceptible to metabolism, being a substrate for esterase residing in skin. Skin from pig ears was used and freshly excised into split-thickness membranes, which were divided and immediately stored at five different storage conditions: a) 4 °C overnight (fresh control), b) 4 °C for 4 days, c) and d) -20 °C for 6 weeks and one year, respectively, and e) -80 °C for 6 weeks. Based on the combined results, general trends are observed showing that fresh skin is associated with lower permeation of both model drugs and higher skin membrane electrical resistance, as compared to the other storage conditions. Interestingly, in the case of fresh skin, significantly lower amounts of MS are detected in the epidermis and dermis compartments, implying higher levels of ester hydrolysis of MS (i.e., higher esterase activity). In line with this, the concentration of salicylic acid (SA) extracted from the dermis is significantly higher for fresh skin, as compared to the other storage conditions. Nevertheless, for all storage conditions, substantial amounts of SA are detected in the receptor medium, as well as in the epidermis and dermis, implying that esterase activity is maintained to some extent in all cases. For AC, which is not expected to be affected by skin metabolism, freeze storage (protocols c-e) is observed to result in higher accumulation of AC in the epidermis, as compared to the case of fresh skin, while the AC concentration in dermis is unaffected. These observations can be rationalized primarily by the observed lower permeability of fresh skin towards this hydrophilic substance. Finally, a strong correlation between AC permeation and electrical skin resistance is shown for individual skin membranes irrespective of storage condition, while the corresponding correlation for MS is inferior. On the other hand, a strong correlation is shown for individual membranes between MS permeation and electrical skin capacitance, while a similar correlation for AC is lower. The observed correlations between drug permeability and electrical impedance open up for standardizing in vitro data for improved analysis and comparisons between permeability results obtained with skin stored at different conditions.
  •  
40.
  • Morin, Maxim, et al. (författare)
  • Hydrogels and Cubic Liquid Crystals for Non-Invasive Sampling of Low-Molecular-Weight Biomarkers-An Explorative In Vivo Study
  • 2022
  • Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 14:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The molecular composition of human skin is altered due to diseases, which can be utilized for non-invasive sampling of biomarkers and disease diagnostics. For this to succeed, it is crucial to identify a sampling formulation with high extraction efficiency and reproducibility. Highly hydrated skin is expected to be optimal for increased diffusion of low-molecular-weight biomarkers, enabling efficient extraction as well as enhanced reproducibility as full hydration represents a well-defined endpoint. Here, the aim was to explore water-based formulations with high water activities, ensuring satisfactory skin hydration, for non-invasive sampling of four analytes that may serve as potential biomarkers, namely tryptophan, tyrosine, phenylalanine, and kynurenine. The included formulations consisted of two hydrogels (chitosan and agarose) and two different liquid crystalline cubic phases based on the polar lipid glycerol monooleate, which were all topically applied for 2 h on 35 healthy subjects in vivo. The skin status of all sampling sites was assessed by electrical impedance spectroscopy and transepidermal water loss, enabling explorative correlations between biophysical properties and analyte abundancies. Taken together, all formulations resulted in the successful and reproducible collection of the investigated biomarkers. Still, the cubic phases had an extraction capacity that was approximately two times higher compared to the hydrogels.
  •  
41.
  • Morin, Maxim, et al. (författare)
  • Reverse Iontophoretic Extraction of Skin Cancer-Related Biomarkers
  • 2022
  • Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 14:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Non-invasive methods for early diagnosis of skin cancer are highly valued. One possible approach is to monitor relevant biomarkers such as tryptophan (Trp) and kynurenine (Kyn), on the skin surface. The primary aim of this in vitro investigation was, therefore, to examine whether reverse iontophoresis (RI) can enhance the extraction of Trp and Kyn, and to demonstrate how the Trp/Kyn ratio acquired from the skin surface reflects that in the epidermal tissue. The study also explored whether the pH of the receiver medium impacted on extraction efficiency, and assessed the suitability of a bicontinuous cubic liquid crystal as an alternative to a simple buffer solution for this purpose. RI substantially enhanced the extraction of Trp and Kyn, in particular towards the cathode. The Trp/Kyn ratio obtained on the surface matched that in the viable skin. Increasing the receiver solution pH from 4 to 9 improved extraction of both analytes, but did not significantly change the Trp/Kyn ratio. RI extraction of Trp and Kyn into the cubic liquid crystal was comparable to that achieved with simple aqueous receiver solutions. We conclude that RI offers a potential for non-invasive sampling of low-molecular weight biomarkers and further investigations in vivo are therefore warranted.
  •  
42.
  • Morin, Maxim, et al. (författare)
  • Skin hydration dynamics investigated by electrical impedance techniques in vivo and in vitro
  • 2020
  • Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1, s. 17218-
  • Tidskriftsartikel (refereegranskat)abstract
    • Skin is easily accessible for transdermal drug delivery and also attractive for biomarker sampling. These applications are strongly influenced by hydration where elevated hydration generally leads to increased skin permeability. Thus, favorable transdermal delivery and extraction conditions can be easily obtained by exploiting elevated skin hydration. Here, we provide a detailed in vivo and in vitro investigation of the skin hydration dynamics using three techniques based on electrical impedance spectroscopy. Good correlation between in vivo and in vitro results is demonstrated, which implies that simple but realistic in vitro models can be used for further studies related to skin hydration (e.g., cosmetic testing). Importantly, the results show that hydration proceeds in two stages. Firstly, hydration between 5 and 10 min results in a drastic skin impedance change, which is interpreted as filling of superficial voids in skin with conducting electrolyte solution. Secondly, a subtle impedance change is observed over time, which is interpreted as leveling of the water gradient across skin leading to structural relaxation/changes of the macromolecular skin barrier components. With respect to transdermal drug delivery and extraction of biomarkers; 1 h of hydration is suggested to result in beneficial and stable conditions in terms of high skin permeability and extraction efficiency.
  •  
43.
  • Nocchi, Sarah, et al. (författare)
  • Electrochemical monitoring of native catalase activity in skin using skin covered oxygen electrode
  • 2017
  • Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 93, s. 9-13
  • Tidskriftsartikel (refereegranskat)abstract
    • A skin covered oxygen electrode, SCOE, was constructed with the aim to study the enzyme catalase, which is part of the biological antioxidative system present in skin. The electrode was exposed to different concentrations of H2O2 and the amperometric current response was recorded. The observed current is due to H2O2 penetration through the outermost skin barrier (referred to as the stratum corneum, SC) and subsequent catalytic generation of O2 by catalase present in the underlying viable epidermis and dermis. By tape-stripping the outermost skin layers we demonstrate that SC is a considerable diffusion barrier for H2O2 penetration. Our experiments also indicate that skin contains a substantial amount of catalase, which is sufficient to detoxify H2O2 that reaches the viable epidermis after exposure of skin to high concentrations of peroxide (0.5–1 mM H2O2). Further, we demonstrate that the catalase activity is reduced at acidic pH, as compared with the activity at pH 7.4. Finally, experiments with often used penetration enhancer thymol shows that this compound interferes with the catalase reaction. Health aspect of this is briefly discussed. Summarizing, the results of this work show that the SCOE can be utilized to study a broad spectrum of issues involving the function of skin catalase in particular, and the native biological antioxidative system in skin in general.
  •  
44.
  • Pham, Quoc Dat, et al. (författare)
  • Chemical penetration enhancers in stratum corneum : Relation between molecular effects and barrier function
  • 2016
  • Ingår i: Journal of Controlled Release. - : Elsevier. - 0168-3659 .- 1873-4995. ; 232, s. 175-187
  • Tidskriftsartikel (refereegranskat)abstract
    • Skin is attractive for drug therapy because it offers an easily accessible route without first-pass metabolism. Transdermal drug delivery is also associated with high patient compliance and through the site of application, the drug delivery can be locally directed. However, to succeed with transdermal drug delivery it is often required to overcome the low permeability of the upper layer of the skin, the stratum corneum (SC). One common strategy is to employ so-called penetration enhancers that supposedly act to increase the drug passage across SC. Still, there is a lack of understanding of the molecular effects of so-called penetration enhancers on the skin barrier membrane, the SC. In this study, we provide a molecular characterization of how different classes of compounds, suggested as penetration enhancers, influence lipid and protein components in SC. The compounds investigated include monoterpenes, fatty acids, osmolytes, surfactant, and Azone. We employ natural abundance C-13 polarization transfer solid-state nuclear magnetic resonance (NMR) on intact porcine SC. With this method it is possible to detect small changes in the mobility of the minor fluid lipid and protein SC components, and simultaneously obtain information on the major fraction of solid SC components. The balance between fluid and solid components in the SC is essential to determine macroscopic material properties of the SC, including barrier and mechanical properties. We study SC at different hydration levels corresponding to SC in ambient air and under occlusion. The NMR studies are complemented with diffusion cell experiments that provide quantitative data on skin permeability when treated with different compounds. By correlating the effects on SC molecular components and SC barrier function, we aim at deepened understanding of diffusional transport in SC, and how this can be controlled, which can be utilized for optimal design of transdermal drug delivery formulations. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.
  •  
45.
  • Shafaat, Atefeh, et al. (författare)
  • A Rapidly Responsive Sensor for Wireless Detection of Early and Mature Microbial Biofilms.
  • 2023
  • Ingår i: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 62:40
  • Tidskriftsartikel (refereegranskat)abstract
    • Biofilm-associated infections, which are able to resist antibiotics, pose a significant challenge in clinical treatments. Such infections have been linked to various medical conditions, including chronic wounds and implant-associated infections, making them a major public-health concern. Early-detection of biofilm formation offers significant advantages in mitigating adverse effects caused by biofilms. In this work, we aim to explore the feasibility of employing a novel wireless sensor for tracking both early-stage and matured-biofilms formed by the medically relevant bacteria Staphylococcus aureus and Pseudomonas aeruginosa. The sensor utilizes electrochemical reduction of an AgCl layer bridging two silver legs made by inkjet-printing, forming a part of near-field-communication tag antenna. The antenna is interfaced with a carbon cloth designed to promote the growth of microorganisms, thereby serving as an electron source for reduction of the resistive AgCl into a highly-conductive Ag bridge. The AgCl-Ag transformation significantly alters the impedance of the antenna, facilitating wireless identification of an endpoint caused by microbial growth. To the best of our knowledge, this study for the first time presents the evidence showcasing that electrons released through the actions of bacteria can be harnessed to convert AgCl to Ag, thus enabling the wireless, battery-less, and chip-less early-detection of biofilm formation.
  •  
46.
  • Shafaat, Atefeh (författare)
  • Development of Wireless Biosensors Integrated into the Radio Frequency Antenna for Chipless and Battery-less Monitoring of Biological Reactions
  • 2023
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Development of wireless sensors and biosensors is currently experiencing a rapid progress with a substantial focus directed toward highlighting their potential applications as non-invasive wearables, implants, and highly mobile point-of-care devices. Integration of wireless biosensors into the Internet of Things (IoT) is widely acknowledged as a technological advancement with the potential to significantly change daily life. To maximize this potential, simple integration of biosensors with wireless communication elements would be advantageous. In this regard, systems functioning in chipless, and battery-less modes outperform integrated circuit (IC) based and battery-powered wireless biosensors. Nevertheless, the accessibility of these wireless designs is still limited. In this study, we present a novel approach where incorporating silver nanoparticles(AgNPs) as a part of the radio frequency (RF) tag antenna enables the realization of simple, chipless, and battery-less wireless sensing of biological oxidation and reduction reactions. We exemplified the mechanism of operation in such systems by electronic wiring of enzymes through direct electron transfer (DET) and microorganisms through mediated electron transfer (MET) to the redox conversion of Ag/AgCl. The wiring was designed to facilitate the transformation of metallic AgNPs into AgCl (Ag → AgCl) or the conversion of AgCl particles back into metallic AgNPs (AgCl → Ag) when the enzymatic/microorganism based electron transfer reactions were present. These reactions occurring on the biosensor RF tag antenna strongly changed the impedance of the tag, which was wirelessly monitored by a radio frequency identification (RFID) reader. The functionality of the proposed setup in direct electron transfer coupling of the enzymatic reactions to the redox conversion of the Ag/AgCl was demonstrated by wireless detection of glucose in whole blood samples and hydrogen peroxide penetrated through the skin membrane using the enzymes glucose dehydrogenase(GDH) and horseradish peroxidase (HRP). Additionally, the capability of the proposed configuration in mediated electron transfer wiring of microorganisms to the Ag/AgCl electrochemistry was shown by wireless monitoring of medically relevant microbial biofilms in simulated wound fluid. Generalizing, the results of this work, for the first time, demonstrated that exploiting Ag/AgCl as a part of the tag antenna allows simple, chipless, and battery-less wireless sensing of biological oxidation and reduction reactions.
  •  
47.
  • Shafaat, Atefeh, et al. (författare)
  • Glucose-to-Resistor Transduction Integrated into a Radio-Frequency Antenna for Chip-less and Battery-less Wireless Sensing
  • 2022
  • Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 7:4, s. 1222-1234
  • Tidskriftsartikel (refereegranskat)abstract
    • To maximize the potential of 5G infrastructure in healthcare, simple integration of biosensors with wireless tag antennas would be beneficial. This work introduces novel glucose-to-resistor transduction, which enables simple, wireless biosensor design. The biosensor was realized on a near-field communication tag antenna, where a sensing bioanode generated electrical current and electroreduced a nonconducting antenna material into an excellent conductor. For this, a part of the antenna was replaced by a Ag nanoparticle layer oxidized to high-resistance AgCl. The bioanode was based on Au nanoparticle-wired glucose dehydrogenase (GDH). The exposure of the cathode-bioanode to glucose solution resulted in GDH-catalyzed oxidation of glucose at the bioanode with a concomitant reduction of AgCl to highly conducting Ag on the cathode. The AgCl-to-Ag conversion strongly affected the impedance of the antenna circuit, allowing wireless detection of glucose. Mimicking the final application, the proposed wireless biosensor was ultimately evaluated through the measurement of glucose in whole blood, showing good agreement with the values obtained with a commercially available glucometer. This work, for the first time, demonstrates that making a part of the antenna from the AgCl layer allows achieving simple, chip-less, and battery-less wireless sensing of enzyme-catalyzed reduction reaction. 
  •  
48.
  • Sparr, Emma, et al. (författare)
  • A Water Gradient can be used to Regulate Drug Transport across Skin - A Responding Membrane
  • 2010
  • Ingår i: Biophysical Journal. - : Cell Press. - 0006-3495 .- 1542-0086. ; 98:3, suppl 1, s. 627a-627a
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • At normal conditions there is a substantial water gradient over the skin as it separates the water-rich inside of the body from the dry outside. This leads to a variation in the degree of hydration along the skin and changes in this gradient may affect the structure and function of skin. In this study we raise the question: How do changes in the water gradient across skin affect its permeability? We approach this problem in experiments that permit strict control of the gradient in the chemical potential of water. The results demonstrate that an external water gradient can be used to regulate transport of drugs across the skin. It is shown that the permeability of the skin barrier increases abruptly at low water gradients, corresponding to high degrees of skin hydration, and that this effect is reversible. This phenomenon is highly relevant to drug delivery applications due to its potential of temporarily opening the skin barrier for transdermal delivery of drugs and subsequently closing the barrier after treatment. The results are explained on basis that the skin is a responding membrane, for which small changes in the environment can lead to major changes in membrane structure, which in turn affect its transport properties. We have in parallel theoretical modeling and experimental studies in model systems shown how a water gradient across multilayer lipid membrane can be used as a regulating mechanism to control the barrier properties. These principles are here applied to the barrier of stratum corneum, the upper layer of the human skin, where it can provide an explanation for the experimental findings that a water gradient can be used to regulate drug transport across the skin.
  •  
49.
  • Sparr, Emma, et al. (författare)
  • Controlling water evaporation through self-assembly
  • 2018
  • Ingår i: Abstracts of Papers of the American Chemical Society. - : American Chemical Society (ACS). - 0065-7727. ; 255
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
  •  
50.
  • Sparr, Emma, et al. (författare)
  • The stratum corneum barrier - From molecular scale to macroscopic properties
  • 2023
  • Ingår i: Current Opinion in Colloid & Interface Science. - : Elsevier. - 1359-0294 .- 1879-0399. ; 67
  • Forskningsöversikt (refereegranskat)abstract
    • The upper layer of our skin, the stratum corneum (SC), is a versatile material that combines mechanical strength with efficient barrier function. In this paper, we discuss these macroscopic properties of SC in relation to recent findings on molecular responses and structural diversity in SC protein and lipids. We put particular focus on the intermediate (colloidal) length scale and how the different SC substructures are organized with respect to each other, including effects of nonequilibrium conditions in the skin with respect to the gradients in water and other components.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-50 av 56
Typ av publikation
tidskriftsartikel (45)
konferensbidrag (5)
doktorsavhandling (5)
forskningsöversikt (1)
Typ av innehåll
refereegranskat (46)
övrigt vetenskapligt/konstnärligt (10)
Författare/redaktör
Björklund, Sebastian (44)
Sparr, Emma (11)
Engblom, Johan, 1965 ... (11)
Engblom, Johan (9)
Kocherbitov, Vitaly (8)
Björklund, Fredrik (6)
visa fler...
Topgaard, Daniel (5)
Lindholm, Torun (5)
Valetti, Sabrina (2)
Feiler, Adam (2)
Marko-Varga, György (2)
Gustafsson, Anna (2)
Genevskiy, Vladislav (2)
Svensson, Birgitta (2)
Neilands, Jessica (2)
Fröbert, Ole, 1964- (1)
Roger, Kevin (1)
Wang, Fei (1)
Mayer, Christoph (1)
Wang, Dong (1)
Ollmar, S (1)
Redfors, Björn (1)
Acosta, Stefan (1)
Kumlien, Christine (1)
Kelly, S. (1)
Wadsö, Lars (1)
Rehnberg, Nicola (1)
Erlinge, David (1)
Chen, Yan (1)
Alfredsson, Viveka (1)
James, Stefan, 1964- (1)
Götberg, Matthias (1)
Li, Xin (1)
Björklund, Johanna, ... (1)
Jensen, Jens (1)
Vu, Xuan-Son, 1988- (1)
Cardenas, Marite (1)
Albèr, Cathrine (1)
Brandner, B D (1)
Billsten, P. (1)
Corkery, Robert (1)
Ericson, Petter, 198 ... (1)
Venetsanos, Dimitrio ... (1)
Dworeck, Christian (1)
Wennerström, Håkan (1)
Zhu, Xuefeng (1)
Lavant, Eva (1)
Lood, Rolf (1)
Gunnarsson, M (1)
Neilands, Jessica, A ... (1)
visa färre...
Lärosäte
Malmö universitet (41)
Lunds universitet (22)
Stockholms universitet (6)
Linköpings universitet (6)
Kungliga Tekniska Högskolan (3)
Karolinska Institutet (3)
visa fler...
Umeå universitet (2)
Uppsala universitet (2)
Göteborgs universitet (1)
Luleå tekniska universitet (1)
Örebro universitet (1)
RISE (1)
visa färre...
Språk
Engelska (56)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (22)
Medicin och hälsovetenskap (22)
Samhällsvetenskap (7)
Teknik (6)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy