| 1. |
- Baldassarre, Maurizio, et al.
(författare)
-
Simultaneous acquisition of infrared, fluorescence and light scattering spectra of proteins : direct evidence for pre-fibrillar species in amyloid fibril formation
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:3, s. 963-973
-
Tidskriftsartikel (refereegranskat)abstract
- Different spectroscopic approaches are often used to probe specific aspects of amyloid fibril formation but are usually performed separately and under different conditions. This makes it problematic to relate different aspects of the aggregation process when these are monitored by different methods. We report on a multispectral approach for simultaneous acquisition of infrared, fluorescence and light scattering spectra of proteins undergoing aggregation. We have applied our approach to study beta-lactoglobulin, a milk protein known to form amyloid fibrils under well-established conditions. Our real-time multispectral measurements show that unfolding of this protein is followed by formation of early aggregates consisting of intermolecular beta-sheets with a typical infrared absorption at similar to 1619 cm(-1) in (H2O)-H-2. These aggregates, which lead to an increase in the light scattering signal, do not bind the amyloid-specific fluorophore ThT and therefore consist of oligomers or protofibrils. Fibril growth is then observed as a sigmoidal increase in ThT fluorescence. After similar to 25 h, a plateau is observed in the intensities of ThT emission and of the band at 1619 cm(-1), indicating that no new fibrils are forming. However, a second phase in the light scattering signal taking place after similar to 25 h suggests that the fibrils are assembling into larger structures, known as mature fibrils. This is associated with an upshift of the main beta-sheet band in the infrared spectrum. TEM analyses confirmed the existence of thick fibrils comprising 3-5 filaments.
|
|
| 2. |
- Bergman, Hilde-Marlene, et al.
(författare)
-
Profiling and quantifying endogenous molecules in single cells using nano-DESI MS
- 2017
-
Ingår i: The Analyst. - : ROYAL SOC CHEMISTRY. - 0003-2654 .- 1364-5528. ; 142:19, s. 3639-3647
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular profiling of single cells has the potential to significantly advance our understanding of cell function and cellular processes of importance to health and disease. In particular, small molecules with rapid turn-over rates can reveal activated metabolic pathways resulting from an altered chemical environment or cellular events such as differentiation. Consequently, techniques for quantitative metabolite detection acquired in a higher throughput manner are needed to characterize the biological variability between seemingly homogenous cells. Here, we show that nanospray desorption electrospray ionization (nano-DESI) mass spectrometry ( MS) enables sensitive molecular profiling and quantification of endogenous species in single cells in a higher throughput manner. Specifically, we show a large number of detected amino acids and phospholipids, including plasmalogens, readily detected from single cheek cells. Further, by incorporating a phosphatidylcholine ( PC) internal standard into the nano-DESI solvent, we determined the total amount of PC in one cell to be 1.2 pmoles. Finally, we describe a higher throughput approach where molecules in single cells are automatically profiled. These developments in single cell analysis provide a basis for future studies to understand cellular processes related to drug effects, cell differentiation and altered chemical microenvironments.
|
|
| 3. |
- Bergman, Hilde-Marléne, et al.
(författare)
-
Quantitative mass spectrometry imaging of small-molecule neurotransmitters in rat brain tissue sections using nanospray desorption electrospray ionization
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:12, s. 3686-3695
-
Tidskriftsartikel (refereegranskat)abstract
- Small molecule neurotransmitters are essential for the function of the nervous system, and neurotransmitter imbalances are often connected to neurological disorders. The ability to quantify such imbalances is important to provide insights into the biochemical mechanisms underlying the disorder. This proof-of-principle study presents online quantification of small molecule neurotransmitters, specifically acetylcholine, γ-aminobutyric acid (GABA) and glutamate, in rat brain tissue sections using nanospray desorption electrospray ionization (nano-DESI) mass spectrometry imaging. By incorporating deuterated internal standards in the nano-DESI solvent we show identification, accurate mapping, and quantification of these small neurotransmitters in rat brain tissue without introducing any additional sample preparation steps. We find that GABA is about twice as abundant in the medial septum-diagonal band complex (MSDB) as in the cortex, while glutamate is about twice as abundant in the cortex as compared to the MSDB. The study shows that nano-DESI is well suited for imaging of small molecule neurotransmitters in health and disease.
|
|
| 4. |
|
|
| 5. |
- Dahlin, Andreas, 1980
(författare)
-
Sensing applications based on plasmonic nanopores: The hole story
- 2015
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 140:14, s. 4748-4759
-
Forskningsöversikt (refereegranskat)abstract
- A review of sensing applications based on plasmonic nanopores is given. Many new types of plasmonic nanopores have recently been fabricated, including pores penetrating multilayers of thin films, using a great variety of fabrication techniques based on either serial nanolithography or self-assembly. One unique advantage with nanopores compared to other plasmonic sensors is that sample liquids can flow through the surface, which increases the rate of binding and improves the detection limit under certain conditions. Also, by utilizing the continuous metal films, electrical control can be implemented for electrochemistry, dielectrophoresis and resistive heating. Much effort is still spent on trying to improve sensor performance in various ways, but the literature uses inconsistent benchmark parameters. Recently plasmonic nanopores have been used to analyse targets of high clinical or academic interest. Although this is an important step forward, one should probably reflect upon whether the same results could have been achieved with another optical technique. Overall, this critical review suggests that the research field would benefit by focusing on applications where plasmonic nanopores truly can offer unique advantages over similar techniques.
|
|
| 6. |
- Duncan, Kyle D., et al.
(författare)
-
A pneumatically assisted nanospray desorption electrospray ionization source for increased solvent versatility and enhanced metabolite detection from tissue
- 2017
-
Ingår i: The Analyst. - : ROYAL SOC CHEMISTRY. - 0003-2654 .- 1364-5528. ; 142:18, s. 3424-3431
-
Tidskriftsartikel (refereegranskat)abstract
- Nanospray desorption electrospray ionization (nano-DESI) has been established as a powerful technique for mass spectrometry imaging (MSI) of biomolecules from tissue samples. The direct liquid extraction of analytes from a surface at ambient pressure negates the need for significant sample preparation or matrix application. Although many recent studies have applied nano-DESI to new and exciting applications, there has not been much work in the development and improvement of the nano-DESI source. Here, we incorporate a nebulizer to replace the self-aspirating secondary capillary in the conventional nano-DESI setup, and characterize the device by use of rat kidney tissue sections. We find that the pneumatically assisted nano-DESI device offers improved sensitivity for metabolite species by 1-3 orders of magnitude through more complete desolvation and reduced ionization suppression. Further, the pneumatically assisted nano-DESI device reduces the dependence on probe-to-surface distance and enables sampling and imaging using pure water as the nano-DESI solvent. This provides exclusive detection and imaging of many highly polar endogenous species. Overall, the developed pneumatically assisted nano-DESI device provides more versatile solvent selection and an increased sensitivity for metabolites, which generates ion images of higher contrast - allowing for more intricate studies of metabolite distribution.
|
|
| 7. |
- Duncan, Kyle D., et al.
(författare)
-
Advances in mass spectrometry based single-cell metabolomics
- 2019
-
Ingår i: The Analyst. - : ROYAL SOC CHEMISTRY. - 0003-2654 .- 1364-5528. ; 144:3, s. 782-793
-
Forskningsöversikt (refereegranskat)abstract
- Metabolomics has grown into a prominent field contributing to the molecular understanding of complex biological processes in both health and disease. Furthermore, single-cells are known to display metabolic differences between seemingly homogeneous populations of cells. Single-cell metabolomics attempts to analyze many cellular metabolites from single cells to understand phenotypic heterogeneity, which is a significant challenge due to the low analyte abundances and limited sample volumes. Label-free metabolite detection can be achieved with mass spectrometry, which is capable of simultaneously analyzing hundreds of metabolites. Herein, we review the recent advances in mass spectrometry based single-cell metabolomics, highlighting the current state-of-the-art within the last three years, and identify the challenges to move the field forward.
|
|
| 8. |
- Duner, Gunnar, et al.
(författare)
-
Signal Enhancement in Ligand-Receptor Interactions using Dynamic Polymers at Quartz Crystal Microbalance Surfaces
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:13, s. 3993-3996
-
Tidskriftsartikel (refereegranskat)abstract
- The potential for signal amplification on QCM sensors by use of in situ polymerized poly(acrylic acid) brushes has been studied. A biotin derivative was immobilized on these surfaces and the interaction with anti-biotin Fabs was evaluated. Interaction data was found to be specific for the studied binding events, and the level of non-specific binding was shown to be low. The surface was proven to be suitable for regeneration, of importance for biomolecular interaction analysis and repetitive immunoassays.For comparison, the same interaction system was tested using commercial sensor surfaces with carboxylated self-assembled monolayers. The poly(acrylic acid) surface showed a dramatic increase in signal response with more than ten times the signal of the carboxylated self-assembled monolayer surface. Thus, the present study shows that polymers can be successfully applied to amplify responses on QCM sensors, valuable for studies of interactions between receptors and low molecular weight compounds.
|
|
| 9. |
- Duong-Thi, Minh-Dao, et al.
(författare)
-
Lipodisks integrated with weak affinity chromatography enable fragment screening of integral membrane proteins
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:3, s. 981-988
-
Tidskriftsartikel (refereegranskat)abstract
- Membrane proteins constitute the largest class of drug targets but they present many challenges in drug discovery. Importantly, the discovery of potential drug candidates is hampered by the limited availability of efficient methods for screening drug-protein interactions. In this work we present a novel strategy for rapid identification of molecules capable of binding to a selected membrane protein. An integral membrane protein (human aquaporin-1) was incorporated into planar lipid bilayer disks (lipodisks), which were subsequently covalently coupled to porous derivatized silica and packed into HPLC columns. The obtained affinity columns were used in a typical protocol for fragment screening by weak affinity chromatography (WAC), in which one hit was identified out of a 200 compound collection. The lipodisk-based strategy, which ensures a stable and native-like lipid environment for the protein, is expected to work also with other membrane proteins and screening procedures.
|
|
| 10. |
- Duong-Thi, Minh-Dao, et al.
(författare)
-
Lipodisks integrated with weak affinity chromatography enable fragment screening of integral membrane proteins
- 2016
-
Ingår i: The Analyst. - 0003-2654 .- 1364-5528. ; 141:3, s. 981-988
-
Tidskriftsartikel (refereegranskat)abstract
- Membrane proteins constitute the largest class of drug targets but they present many challenges in drug discovery. Importantly, the discovery of potential drug candidates is hampered by the limited availability of efficient methods for screening drug-protein interactions. In this work we present a novel strategy for rapid identification of molecules capable of binding to a selected membrane protein. An integral membrane protein (human aquaporin-1) was incorporated into planar lipid bilayer disks (lipodisks), which were subsequently covalently coupled to porous derivatized silica and packed into HPLC columns. The obtained affinity columns were used in a typical protocol for fragment screening by weak affinity chromatography (WAC), in which one hit was identified out of a 200 compound collection. The lipodisk-based strategy, which ensures a stable and native-like lipid environment for the protein, is expected to work also with other membrane proteins and screening procedures.
|
|
| 11. |
- Eriksson, Anna, et al.
(författare)
-
Cooperative adsorption behavior of phosphopeptides on TiO2 leads to biased enrichment, detection and quantification
- 2015
-
Ingår i: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 140:1, s. 303-312
-
Tidskriftsartikel (refereegranskat)abstract
- The adsorption behavior of phosphopeptides onto TiO2 surfaces was studied using the quartz crystal microbalance with dissipation monitoring (QCM-D) as the main experimental technique. The main focus is the characterization of the emergence of positive cooperativity under conditions where the peptides have a positively charged C-term. It is shown that when carrying no net charge, small water-soluble peptides as a rule develop positive cooperativity. The impact of the adsorption mechanism on the outcome of TiO2 based enrichment methods was investigated with the help of matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS). The data presented illustrate how the phosphopeptide profile in the enriched material may deviate from that in the native sample, as cooperative phosphopeptides are overrepresented in the former. Furthermore, commonly employed washing and elution solutions may facilitate preferential release of certain peptides, leading to further bias in the recovered sample. Taken together, the results of the present study demonstrate that thorough understanding of the mechanisms behind the adsorption of phosphopeptides on the enrichment material is necessary in order to develop reliable qualitative and quantitative methods for phosphoproteomics.
|
|
| 12. |
- Fernandes, Daniel L. A., et al.
(författare)
-
A 3D printed microliquid jet with an adjustable nozzle diameter
- 2015
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 140:18, s. 6234-6238
-
Tidskriftsartikel (refereegranskat)abstract
- Microliquid jets have many applications, in particular in the fields of spectroscopy/analysis of samples susceptible to beam damage. Herein, we report a microliquid jet, manufactured with 3D printing technology, with a tuneable nozzle diameter output. This strategy increases the breadth of techniques that can be covered with a single microliquid jet.
|
|
| 13. |
- Fuentes, Catalina, et al.
(författare)
-
Comparison between conventional and frit-inlet channels in separation of biopolymers by asymmetric flow field-flow fractionation
- 2019
-
Ingår i: Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654. ; 144:15, s. 4559-4568
-
Tidskriftsartikel (refereegranskat)abstract
- Asymmetric flow field-flow fractionation (AF4) is a separation technique in which a focusing/relaxation step is used after the sample is injected onto the separation channel. During the focusing/relaxation step, the sample is focused by two counter-directed flows. This allows sample components to establish a diffusion-dependent equilibrium concentration profile. The focusing step may, in some cases, cause a loss of sample due to adsorption into the accumulation wall (i.e. the membrane) or due to aggregation of the sample. In addition, the increase in sample concentration during the focusing step may prevent complete relaxation and cause overloading effects. In this study, a modified AF4 channel equipped with a frit inlet (FI-AF4) is utilized, where the sample is relaxed hydrodynamically as it enters to the channel through the frit. The main advantage of the FI-AF4 channel is to omit the focusing step. The FI-AF4 channel could also allow higher injection mass than in a conventional channel while still avoiding overloading. The purpose of the present study is to compare two channels (conventional and FI-AF4 channels) in terms of the plate height (H), resolution (Rs) and the mass recovery for analysis of a mixture of glycogen and pullulan. In addition, waxy maize (WM) starch was used to compare the mass overloading of the two channels. The results show that the type of relaxation method (i.e. focusing or hydrodynamic relaxation) had no significant effect on mass recovery. The resolution (Rs), was higher in the conventional AF4 channel than in the FI-AF4 channel for the separation of glycogen and pullulan. The results also show that it was possible to inject a higher mass of WM starch (i.e. twice the mass) onto the FI-AF4 channel, compared to a conventional AF4 channel, without observing an overloading effect.
|
|
| 14. |
- Haas, Julian, et al.
(författare)
-
Infrared Spectroscopy Based on Broadly Tunable Quantum Cascade Lasers and Polycrystalline Diamond Waveguides
- 2018
-
Ingår i: The Analyst. - 0003-2654 .- 1364-5528. ; 143:21, s. 5112-5119
-
Tidskriftsartikel (refereegranskat)abstract
- Recently emerging broadly tunable quantum cascade lasers (tQCL) emitting in the mid-infrared (MIR) are a versatile alternative to well established thermal emitters in combination with interferometers as applied in Fourier transform infrared (FTIR) spectroscopy. The wide and highly spectrally resolved wavelength tuning characteristics along with superior spectral energy density renders laser-based vibrational spectroscopy methods an efficient alternative vs. conventional molecular spectroscopies. Using diamond in attenuated total reflection (ATR) sensing formats benefits from the physical robustness and chemical resistivity of the internal reflective element (IRE) material. While inherent material absorption frequently limits the optical path length within diamond ATR elements, the herein presented design combining bright tQCLs with a multi-reflection polycrystalline diamond (PCD) ATR element enables an optical beam path length of approximately 5 cm. Thereby, sensitive spectroscopic measurements in the MIR are enabled. As an example, non-invasive glucose monitoring in human saliva is examined, highlighting the potential benefits of the proposed analytical concept with regards to exquisite sensitivity and selectivity in combination with a robust sensing interface, i.e., diamond. This approach paves the way towards directly analyzing molecular constituents in complex and potentially corrosive biomedical and biochemical matrices.
|
|
| 15. |
- Herr, Amy E., et al.
(författare)
-
Next wave advances in single-cell analyses
- 2019
-
Ingår i: The Analyst. - : ROYAL SOC CHEMISTRY. - 0003-2654 .- 1364-5528. ; 144:3, s. 735-737
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Welcome to this Analyst themed issue highlighting next wave advances in single cell analyses, Guest Edited by Amy Herr (University of California, Berkeley, USA) Takehiko Kitamori (University of Tokyo, Japan), Ulf Landegren (Uppsala University, Sweden) and Masood Kamali-Moghaddam (Uppsala University, Sweden).
|
|
| 16. |
- Kanje, Sara, et al.
(författare)
-
Next generation of labeling reagents for quantitative and multiplexing immunoassays by the use of LA-ICP-MS
- 2016
-
Ingår i: ANALYST. - : Royal Society of Chemistry. - 0003-2654. ; 141:23, s. 6374-6380
-
Tidskriftsartikel (refereegranskat)abstract
- Immuno imaging by the use of Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICP-MS) is a growing research field in life sciences such as biology and biomedicine. Various element labeling strategies for antibodies have been developed for the application of multiplex immunoassays analyzed by the use of LA-ICP-MS. High multiplexing capabilities, a wide linear dynamic range and the possibility of absolute quantification are the main advantages of ICP-MS. But in the context of immuno imaging by the use of LA-ICP-MS, quantification of analytes is limited due to non-controllable antibody labeling chemistry. In the presented proof-of-principle a novel antibody labeling technique has been investigated which results in a controlled labeling degree. A small affinity protein based on the C2 domain of protein G was modified with conventional metal coded tags (MeCAT) after introducing a cysteine into the C-terminus of the protein. The modified C2 domain photo-crosslinks to the Fc or Fab region of the IgG and allows specific and covalent labeling of antibodies for multiplex immunoassay analysis by the use of LA-ICP-MS. In combination with a house-made calibration membrane the amount of labeled antibody-antigen complexes in a multiplex western blot immuno-assay was determined by LA-ICP-MS.
|
|
| 17. |
- Kumar, Keshav, et al.
(författare)
-
Constraint randomised non-negative factor analysis (CRNNFA) : an alternate chemometrics approach for analysing the biochemical data sets
- 2017
-
Ingår i: The Analyst. - : ROYAL SOC CHEMISTRY. - 0003-2654 .- 1364-5528. ; 142:11, s. 1916-1928
-
Tidskriftsartikel (refereegranskat)abstract
- The present work introduces an alternate chemometrics approach constraint randomised non-negative factor analysis (CRNNFA) for analysing the bioanalytical data sets. The CRNNFA algorithm provides the outputs that are easy to interpret and correlate with the real chromatograms. The CRNNFA algorithm achieves termination when the iteration limit is reached circumventing the premature convergence. Theoretical and computational aspects of the proposed method are also described. The analytical and computational potential of CRNNFA are successfully tested by analysing the complex chromatograms of the peptidoglycan samples belonging to the Alphaproteobacterium members. The obtained results clearly show that CRNNFA can easily trace the compositional variability of the peptidoglycan samples. In summary, the proposed method in general can be a potential alternate approach for analysing the data sets obtained from different analytical and clinical fields.
|
|
| 18. |
- Kumar, Saroj, et al.
(författare)
-
Sensing protein antigen and microvesicle analytes using high-capacity biopolymer nano-carriers
- 2016
-
Ingår i: The Analyst. - 0003-2654 .- 1364-5528. ; 141:3, s. 836-846
-
Tidskriftsartikel (refereegranskat)abstract
- Lab-on-a-chip systems with molecular motor driven transport of analytes attached to cytoskeletal filament shuttles (actin filaments, microtubules) circumvent challenges with nanoscale liquid transport. However, the filaments have limited cargo-carrying capacity and limitations either in transportation speed (microtubules) or control over motility direction (actin). To overcome these constraints we here report incorporation of covalently attached antibodies into self-propelled actin bundles (nanocarriers) formed by cross-linking antibody conjugated actin filaments viafascin, a natural actin-bundling protein. We demonstrate high maximum antigen binding activity and propulsion by surface adsorbed myosin motors. Analyte transport capacity is tested using both protein antigens and microvesicles, a novel class of diagnostic markers. Increased incubation concentration with protein antigen in the 0.1–100 nM range (1 min) reduces the fraction of motile bundles and their velocity but maximum transportation capacity of >1 antigen per nm of bundle length is feasible. At sub-nanomolar protein analyte concentration, motility is very well preserved opening for orders of magnitude improved limit of detection using motor driven concentration on nanoscale sensors. Microvesicle-complexing to monoclonal antibodies on the nanocarriers compromises motility but nanocarrier aggregation via microvesicles shows unique potential in label-free detection with the aggregates themselves as non-toxic reporter elements.
|
|
| 19. |
- Källsten, Malin, et al.
(författare)
-
Qualitative analysis of antibody-drug conjugates (ADCs) : an experimental comparison of analytical techniques of cysteine-linked ADCs.
- 2018
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 143:22, s. 5487-5496
-
Tidskriftsartikel (refereegranskat)abstract
- Antibody-drug conjugates (ADCs) are an emerging type of biotherapeutics that utilize multiple tissue-specific antibodies combined with a range of linker designs to enable the transportation and selective release of cytotoxic drugs in close proximity to tumours. Consisting of antibodies conjugated to small drug molecules through a variety of linkers, ADCs are chemically complex analytes. Here we present a unique experimental comparison of four techniques for ADC analysis: hydrophobic interaction chromatography (HIC-UV/Vis), reversed phase liquid chromatography mass spectrometry (RPLC-MS), using either a QToF or an Orbitrap analyser, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Four different ADCs consisting of Trastuzumab, monomethyl auristatin E (MMAE) and a peptidic linker moiety differing in their respective stoichiometric ratios in regard to drug-to-antibody ratio (DAR) were used for the comparison. We found that the determined DAR from all techniques was comparable, while the accuracy of the molecular weights for the conjugated light and heavy chain differed more extensively. This indicates that the choice of a mass analyser is more crucial for determining the accurate weights of the light and heavy chains than to evaluate the DAR of a given batch. However, ambiguous DAR assignment in HIC-UV/Vis or bias for either the light or heavy chain fragments in the mass spectrometry-based techniques can influence the obtained average DAR value and the use of complementary techniques is advisable. Out of the four techniques evaluated, HIC-UV/Vis and MALDI required less time to obtain an average DAR value and would therefore be good for initial screenings in the early stages of the discovery phase of new ADCs.
|
|
| 20. |
|
|
| 21. |
- Majdi, Soodabeh, 1980, et al.
(författare)
-
Selected recent in vivo studies on chemical measurements in invertebrates
- 2015
-
Ingår i: Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 140:11, s. 3676-3686
-
Tidskriftsartikel (refereegranskat)abstract
- In vivo measurements of neurotransmitters and related compounds have provided a better understanding of the chemical interactions that are a major part in functioning of brains. In addition, a great deal of technology has been developed to measure chemical species in other areas of living organisms. A key part of this work has been sampling technologies as well as direct measurements in vivo. This is extremely important when sampling from the smallest animal systems. Yet, very small invertebrate systems are excellent models and often have better defined and more easily manipulated genetics. This review focuses on in vivo measurements, electrochemical methods, fluorescence techniques, and sampling and is further narrowed to work over approximately the last three years. Rapid developments of in vivo studies in these model systems should aid in finding solutions to biological and bioanalytical challenges related to human physiological functions and neurodegenerative diseases.
|
|
| 22. |
- Minero, Antonio S. Gabriel, et al.
(författare)
-
Sequence-specific validation of LAMP amplicons in real-time optomagnetic detection of Dengue serotype 2 synthetic DNA
- 2017
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 142:18, s. 3441-3450
-
Tidskriftsartikel (refereegranskat)abstract
- We report on an optomagnetic technique optimised for real-time molecular detection of Dengue fever virus under ideal as well as non-ideal laboratory conditions using two different detection approaches. The first approach is based on the detection of the hydrodynamic volume of streptavidin coated magnetic nanoparticles attached to biotinylated LAMP amplicons. We demonstrate detection of sub-femtomolar Dengue DNA target concentrations in the ideal contamination-free lab environment within 20 min. The second detection approach is based on sequence-specific binding of functionalised magnetic nanoparticles to loops of LAMP amplicons. Melting studies reveal that true positive and spurious amplicons have different melting points and this allows us to discriminate between them. This is found to be in a good agreement with subsequent studies on real-time sequence-specific discrimination of LAMP amplicons. The specific binding causes clustering of magnetic nanoparticles via binding to multiple sites (loops) emerging in the elongation phase of LAMP. Formation of nanoclusters is monitored via the depletion of the optomagnetic signal due to free nanoparticles. After sequence-specific validation, we claim detection of down to 100 fM of Dengue target after 20 min of LAMP with a contamination background.
|
|
| 23. |
- Moein, Mohammad Mahdi, et al.
(författare)
-
A new strategy for surface modification of polysulfone membrane by in situ imprinted sol-gel method for the selective separation and screening of L-Tyrosine as a lung cancer biomarker
- 2015
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 140:6, s. 1939-1946
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a novel method based on in situ molecularly imprinted sol-gel for the surface modification of a polysulfone membrane (PSM) was developed. A modified molecularly imprinted sol-gel polysulfone membrane (MSM) was placed in a homemade plastic tube and coupled on-line with LC/MS/MS for the selective extraction and screening of L-Tyrosine (Tyr) as a tentative lung cancer biomarker in human plasma samples. The existence of molecularly imprinted sol-gel layers on both sides of a PSM was examined using scanning electron microscopy (SEM). To evaluate the role of precursor in the extraction performance, repeatability, and selectivity of developed method, three precursors, 3-(propylmethacrylate) trimethoxysilane (P1), 3-(triethoxysilyl)-propylamine (P2), tetraethyl orthosilicate (P3), individually and together were used for treatment of PSM. Our investigation showed that a single precursor's route is more repeatable, straightforward, precise, accurate, and selective for the extraction of Tyr in plasma samples. Moreover, to achieve the best conditions and extraction efficiency, the effect of influential parameters, including the conditioning, washing, and elution of solvents, sample flow rate, loading time, desorption time, loading sample volume, salt effect, pH, and adsorption capacity for the most efficiently prepared membranes were truly investigated. The non-molecularly imprinted sol-gel polysulfone membrane (NSM) was prepared as a blank via the same process but in the absence of the Tyr. The LOD (S/N = 3/1) was 0.1 nmol L-1 and the LOQ (S/N = 10/1) was 0.34 nmol L-1 for Tyr in the plasma samples. The linearity for the Tyr was in the range of 0.34-2000 nmol L-1 in the plasma samples. The coefficients of determination values were >= 0.998 for all runs. The extraction recovery was between 80%-85% for Tyr in the plasma samples. In addition, MSM could be used for up to 50 extractions without a significant change in recovery percentage.
|
|
| 24. |
- Nordberg, Markus, et al.
(författare)
-
UV Raman chemical imaging using compressed sensing
- 2019
-
Ingår i: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 144:5, s. 1513-1518
-
Tidskriftsartikel (refereegranskat)abstract
- Different chemical (hyperspectral) imaging techniques have proven to be powerful tools to provide and illustrate insightful data within a broad range of research areas. The present communication includes proof-of-principle results of UV Raman hyperspectral imaging, achieved via compressed sensing measurements using coded apertures (CA) and a reconstruction algorithm. The simple and cheap CA set up, obtained by a 50% overall transmissive random binary mask (chromium on fused silica with 100 m x 100 m pixel size) positioned at the entrance plane of an imaging spectrograph, resulted in an overall high throughput for the UV region of interest. The mask was mounted on a translation stage, allowing reproducible switching to different CA, thus making possible for multi frame CA imaging. Results from a scene containing liquid droplets are shown as examples and, as expected, qualitative improvements in resolution and contrast could be observed in both the spatial and spectral domain as the number of CA frames was increased.
|
|
| 25. |
- Qie, Zhiwei, et al.
(författare)
-
Sensitive detection of atrazine in tap water using TELISA
- 2015
-
Ingår i: Analyst. - : Royal Society of Chemistry (RSC). - 1364-5528. ; 140:15, s. 5220-5226
-
Tidskriftsartikel (refereegranskat)abstract
- A highly sensitive flow injection analysis (FIA)-based thermal enzyme-linked immunoassay, TELISA, was developed for the rapid detection of atrazine (ATZ) in tap water. ATZ and beta-lactamase-labeled ATZ were employed in a competitive immunoassay using a monoclonal antibody (mAb). After the off-column liquid-phase competition, the mAb was captured on the Protein G Sepharose (TM) 4 Fast Flow (PGSFF) column support material. Injected beta-lactamase substrate ampicillin was degraded by the column-bound ATZ-beta-lactamase, generating a detectable heat signal. Several assay parameters were optimized, including substrate concentration, flow rates and regeneration conditions, as well as the mAb and ATZ-beta dilution ratios and concentrations. The assay linear range was 0.73-4.83 ng mL(-1) with a detection limit of 0.66 ng mL(-1). An entire heat signal requires 10 min for generation, and the cycle time is less than 40 min. The results were reproducible and stable. ATZ-spiked tap water samples exhibited a recovery rate of 103%-116%, which correlated with the UHPLC-MS/MS measurements. We attributed this significant increase in sensitivity over our previously published work to the following factors: (i) the capture of already-formed immune complexes on the column via immobilized Protein G, which eliminated chemical immobilization of the antibody; (ii) off-column preincubation allows the formation of immune complexes under nearly ideal conditions; and (iii) multiple buffers can be used to, in one case, enhance immune-complex formation and in the other to maximize enzymatic activity. Furthermore, the scheme creates a universal assay platform in which sensing is performed in the off-column incubation and detection after capture in the enzyme thermistor (ET) detector, which opens up the possibility of detecting any antigen for which antibodies were available.
|
|
| 26. |
- Reuterswärd, Philippa, et al.
(författare)
-
An 8 minute colorimetric paper-based reverse phase vertical flow serum microarray for screening of hyper IgE syndrome
- 2015
-
Ingår i: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 140:21, s. 7327-7334
-
Tidskriftsartikel (refereegranskat)abstract
- Reverse phase microarrays are useful tools for affinity-based detection in hundreds of samples simultaneously. However, current methods typically require long assay times and fluorescent detection. Here we describe a paper-based Vertical Flow Microarray (VFM) assay as a rapid 8-minute colorimetric alternative for reverse phase microarray analysis. The VFM platform was optimized for detection of IgE with a detection limit of 1.9 μg mL-1 in whole serum. Optimized conditions were then used to screen 113 serum samples simultaneously for hyper IgE syndrome (hIgE), a rare primary immunodeficiency characterized by elevated levels of IgE. The same set of samples were then analysed with a conventional planar microarray with fluorescent detection for head-to-head testing. Both assays found elevated levels in three out of four hIgE patient samples, whereas no control samples displayed elevated levels in either method. The comparison experiments showed a good correlation between the two assays, as determined from a linear correlation study (Pearson's r = 0.76). Further, the assay-time reduction and reproducibility (intra assay CV = 12.4 ± 4.11%) demonstrate the applicability of the VFM platform for high throughput reverse phase screening.
|
|
| 27. |
- Sa, Jacinto, et al.
(författare)
-
Resonant X-ray emission spectroscopy of platinum(II) anticancer complexes
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:4, s. 1226-1232
-
Tidskriftsartikel (refereegranskat)abstract
- Platinum-based drugs are commonly used in cancer treatment. The biological activity of a metallodrug is obviously closely related to its chemical and stereochemical characteristics. An overlooked aspect is the effect of the ligand to the electronic structure of the metal atom (coordinated atom). We report herein a Resonant X-ray Emission Spectroscopy (RXES) study on the chemical speciation of chiral platinum complexes in which diastereomers are distinguished on the basis of their metal electronic configuration. This demonstrates RXES high chemical speciation capabilities, a necessary property to further investigate the reactivity of the Pt atom towards nucleophiles or bionucleophiles, and an important complement the previously reported RXES abilities, namely that it can be employed for in situ studies at physiological concentrations.
|
|
| 28. |
- Shi, Leilei, et al.
(författare)
-
An arylboronate locked fluorescent probe for hypochlorite
- 2017
-
Ingår i: The Analyst. - : ROYAL SOC CHEMISTRY. - 0003-2654 .- 1364-5528. ; 142:12, s. 2104-2108
-
Tidskriftsartikel (refereegranskat)abstract
- An unusual arylboronate based fluorescent probe R1 was synthesized for the selective and sensitive detection of ClO-. A detailed mechanistic study revealed that R1 reacted with ClO- through an oxidation to chlorination mechanism, and the arylboronate moiety in R1 acted as a "lock" to eliminate the effects of pH fluctuations. With this design strategy, R1 was successfully used to detect as low as 6.4 nM of ClO- over other ROS species in a wide pH range from 4.5 to 9.0.
|
|
| 29. |
- Ubhayasekera, Kumari, et al.
(författare)
-
A novel, fast and sensitive supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) method for analysis of arachidonic acid metabolites
- 2018
-
Ingår i: The Analyst. - : ROYAL SOC CHEMISTRY. - 0003-2654 .- 1364-5528. ; 143:15, s. 3661-3669
-
Tidskriftsartikel (refereegranskat)abstract
- The development of a rapid, sensitive and reliable method for the quantification of bioactive arachidonic acid metabolites (AA-metabolites) in biological samples is quite challenging due to the minute concentration, short half-life and their structural complexity arising from different isomers. In this study, a simple, fast and environmentally friendly supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) method was developed and validated for simultaneous measurement of five (PGD(2), PGE(2), PGF(2), 6KetoPGF(1) and LTB4) AA-metabolites in biological samples. These analytes were extracted by protein precipitation followed by separation and quantification. The analysis was completed within 3 minutes. The matrix matched linear calibration ranged from 0.5-100 ng mL(-1) (r(2) 0.995), whilst, the limit of quantification of PGD(2), PGE(2), PGF(2), and LTB4 was 0.5 ng mL(-1) and was 2.5 ng mL(-1) for 6KetoPGF(1). The interday and intraday precisions of the method were less than 15% while the accuracy of most of the analytes varied between 83 and 109%. Finally, as a proof of concept, the method was successfully applied for the determination of eicosanoids in human samples, which expands the possibility to explore physiological states, disease phenotypes, and novel biomarkers.
|
|
| 30. |
- Undin, Torgny, 1975-, et al.
(författare)
-
Mechanistic investigation of the on surface enzymatic digestion (oSED) protein adsorption detection method using targeted mass spectrometry
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:5, s. 1714-1720
-
Tidskriftsartikel (refereegranskat)abstract
- This study describes our efforts to study some of the mechanistic aspects of the earlier established onsurface enzymatic digestion (oSED) method. In a multitude of application areas, it has become important to be able to fully characterize and understand selective protein adsorption to biomaterial surfaces for various applications, including biomedicine (implants), nanotechnology (microchip surfaces and sensors) and materials sciences. Herein, the investigation of the mechanistic aspects was based on microdialysis catheter tubes that were flushed with controlled protein solutions mimicking the extracellular fluid of the brain. The protein adsorption properties were monitored using high-resolution liquid chromatography tandem mass spectrometry (LC-MS/MS) with a targeted method. The temporally resolved results show that most proteins stay adsorbed onto the surface during the entire digestion process and are only cut away piece by piece, whereas smaller proteins and peptides seem to desorb rather easily from the surface. This information will simplify the interpretation of data generated using the oSED method and can also be used for the characterization of the physicochemical properties controlling the adsorption of individual proteins to specific surfaces.
|
|
| 31. |
- Urbanczyk, M., et al.
(författare)
-
Monitoring polydispersity by NMR diffusometry with tailored norm regularisation and moving-frame processing
- 2016
-
Ingår i: Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:5, s. 1745-1752
-
Tidskriftsartikel (refereegranskat)abstract
- Nuclear magnetic resonance (NMR) is currently one of the main analytical techniques applied in numerous branches of chemistry. Furthermore, NMR has been proven to be useful to follow in situ reactions occurring on a time scale of hours and days. For complicated mixtures, NMR experiments providing diffusion coefficients are particularly advantageous. However, the inverse Laplace transform (ILT) that is used to extract the distribution of diffusion coefficients from an NMR signal is known to be unstable and vulnerable to noise. Numerous regularisation techniques to circumvent this problem have been proposed. In our recent study, we proposed a method based on sparsity-enforcing l(1)-norm minimisation. This approach, which is referred to as ITAMeD, has been successful but limited to samples with a 'discrete' distribution of diffusion coefficients. In this paper, we propose a generalisation of ITAMeD using a tailored l(p)-norm (1 <= p <= 2) to process, in particular, signals arising from 'polydisperse' samples. The performance of our method was tested on simulations and experimental datasets of polyethylene oxides with varying polydispersity indices. Finally, we applied our new method to monitor diffusion coefficient and polydispersity changes of heparin undergoing enzymatic degradation in real time.
|
|
| 32. |
- Venzac, B., et al.
(författare)
-
On-chip conductometric detection of short DNA sequences via electro-hydrodynamic aggregation
- 2018
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 143:1, s. 190-199
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorescence measurement is the main technology for post-amplification DNA detection in automated systems. Direct electrical reading of DNA concentration in solution could be an interesting alternative to go toward more miniaturized or less expensive devices, in particular in the pathogen detection field. Here we present the detection of short bacterial biomarkers with a direct impedancemetric measurement, within solutions of amplified and elongated DNA sequences in a microchannel. This technology relies on the electrohydrodynamic instability occurring in solutions of long charged macromolecules in a strong electric field. This instability specifically induces the aggregation of long DNAs and triggers conductivity variations that can be monitored by on-contact conductometry. An innovative isothermal amplification and elongation strategy was developed, combining SDA and HRCA reactions, in order to yield long DNAs suitable to be detected by the above principle, from a dilute initial DNA target. In contrast with previous label-free detection methods, this new strategy is very robust to matrix effects, thanks to the unique molecular weight dependence of the instability, coupled with this specific DNA amplification strategy. We demonstrate the detection of a 1 pM gene sequence specific to Staphylococcus aureus, in a portable system.
|
|
| 33. |
- Volpati, D., et al.
(författare)
-
Exploring copper nanostructures as highly uniform and reproducible substrates for plasmon-enhanced fluorescence
- 2015
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 140:2, s. 476-482
-
Tidskriftsartikel (refereegranskat)abstract
- The unique properties of metallic nanostructures of coinage metals that can sustain localized surface plasmon resonances (LSPR) put them at the centre of plasmon-enhanced phenomena. The theory of plasmonic phenomena based on LSPR is well-established. However, the fabrication of plasmonic substrates, reproducibly, is still challenging for applications in surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF). In this work we describe well-ordered copper nanostructures (CuNSs), produced by electrodeposition and nanosphere lithography, as active substrates for SEF. After a detailed spectroscopic and microscopic characterization, CuNSs are successfully applied as SEF-active substrates using a well-known perylene derivative as a target molecule. The signal reproducibility from CuNS substrates was established by comparing the results against those obtained from a simply roughened Cu substrate. Under optimal conditions, signal variability is around 4%.
|
|
| 34. |
- Weiss, Victor U., et al.
(författare)
-
Nano electrospray gas-phase electrophoretic mobility molecular analysis (nES GEMMA) of liposomes : Applicability of the technique for nano vesicle batch control
- 2016
-
Ingår i: Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654. ; 141:21, s. 6042-6050
-
Tidskriftsartikel (refereegranskat)abstract
- Liposomes are biodegradable nanoparticle vesicles consisting of a lipid bilayer encapsulating an aqueous core. Entrapped cargo material is shielded from the extra-vesicular medium and sustained release of encapsulated material can be achieved. However, application of liposomes as nano-carriers demands their characterization concerning size and size distribution, particle-number concentration, occurrence of vesicle building blocks in solution and determination of the resulting vesicle encapsulation capacity. These questions can be targeted via gas-phase electrophoretic mobility molecular analysis (GEMMA) based on a nano electrospray (nES) charge-reduction source. This instrument separates single-charged nanoparticles in the gas-phase according to size in a high-laminar sheath-flow by means of an orthogonal, tunable electric field. nES GEMMA analysis enables to confirm liposome integrity after passage through the instrument (in combination with atomic force microscopy) as well as to exclude vesicle aggregation. Additionally, nanoparticle diameters at peak apexes and size distribution data are obtained. Differences of hydrodynamic and dry particle diameter values, as well as the effect of number- and mass-based concentration data analysis on obtained liposome diameters are shown. Furthermore, the repeatability of liposome preparation is studied, especially upon incorporation of PEGylated lipids in the bilayer. Finally, the instruments applicability to monitor mechanical stress applied to vesicles is demonstrated.
|
|
| 35. |
- Witos, Joanna, et al.
(författare)
-
Partial filling affinity capillary electrophoresis including adsorption energy distribution calculations : towards reliable and feasible biomolecular interaction studies
- 2015
-
Ingår i: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 140:9, s. 3175-3182
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, a method to study and analyze the interaction data in free solution by exploiting partial filling affinity capillary electrophoresis (PF-ACE) followed by adsorption energy distribution calculations (AED) prior model fit to adsorption isotherms will be demonstrated. PF-ACE-AED approach allowed the possibility to distinguish weak and strong interactions of the binding processes between the most common apolipoprotein E protein isoforms (apoE2, apoE3, apoE4) of high density lipoprotein (HDL) and apoE-containing HDL2 with major glycosaminoglycan (GAG) chain of proteoglycans (PGs), chondroitin-6-sulfate (C6S). The AED analysis clearly revealed the heterogeneity of the binding processes. The major difference was that they were heterogeneous with two different adsorption sites for apoE2 and apoE4 isoforms, whereas interestingly for apoE3 and apoE-containing HDL2, the binding was homogeneous (one site) adsorption process. Moreover, our results allowed the evaluation of differences in the binding process strengths giving the following order with C6S: apoE-containing HDL2 > apoE2 > apoE4 > apoE3. In addition, the affinity constant values determined could be compared with those obtained in our previous studies for the interactions between apoE isoforms and another important GAG chain of PGs - dermatan sulfate (DS). The success of the combination of AED calculations prior to non-linear adsorption isotherm model fit with PF-ACE when the concentration range was extended, confirmed the power of the system in the clarification of the heterogeneity of biological processes studied.
|
|
| 36. |
- Xiong, Kunli, 1987, et al.
(författare)
-
Biosensing using plasmonic nanohole arrays with small, homogenous and tunable aperture diameters
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:12, s. 3803-3810
-
Tidskriftsartikel (refereegranskat)abstract
- Plasmonic nanohole arrays are widely used for optical label-free molecular detection. An important factor for many applications is the diameter of the apertures. So far nanohole arrays with controllable diameters below 100 nm have not been demonstrated and it has not been systematically investigated how the diameter influences the optical properties. In this work we fine-tune the diameter in short range ordered nanohole arrays down to 50 nm. The experimental far field spectra show how the wavelength of maximum extinction remains unaffected while the transmission maximum blue shifts with smaller diameters. The near field is visualized by numerical simulations, showing a homogenous enhancement throughout the cylindrical void at the transmission maximum for diameters between 50 and 100 nm. For diameters below 50 nm plasmon excitation is no longer possible experimentally or by simulations. Further, we investigate the refractive index sensing capabilities of the smaller holes. As the diameter was reduced, the sensitivity in terms of resonance shift with bulk liquid refractive index was found to be unaltered. However, for the transmission maximum the sensitivity becomes more strongly localized to the hole interior. By directing molecular binding to the bottom of the holes we demonstrate how smaller holes enhance the sensitivity in terms of signal per molecule. A real-time detection limit well below one protein per nanohole is demonstrated. The smaller plasmonic nanoholes should be suitable for studies of molecules confined in small volumes and as mimics of biological nanopores.
|
|
| 37. |
- Özalp, V Cengiz, et al.
(författare)
-
Small molecule detection by lateral flow strips via aptamer-gated silica nanoprobes.
- 2016
-
Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:8, s. 2595-9
-
Tidskriftsartikel (refereegranskat)abstract
- A fast, sensitive and ratiometric biosensor strategy for small molecule detection was developed through nanopore actuation. The new platform engineers together, a highly selective molecular recognition element, aptamers, and a novel signal amplification mechanism, gated nanopores. As a proof of concept, aptamer gated silica nanoparticles have been successfully used as a sensing platform for the detection of ATP concentrations at a wide linear range from 100 μM up to 2 mM.
|
|
