| 1. |
- Aastrup, Teodor
(author)
-
In situ investigations of the metal/atmophere interface
- 1999
-
Doctoral thesis (other academic/artistic)abstract
- This thesis presents a new experimental setup for surfaceanalysis studies, incorporating chemical information frominfrared reflection absorption spectroscopy (IRAS) andquantitative information from quartz crystal microbalance(QCM). The integrated IRAS/QCM surface analysis system enablesin situstudies to be conducted of the metal/atmosphereinteraction on a sub-monolayer level. In combination withtopographical information from tapping mode atomic forcemicroscopy (TM-AFM), it was possible to follow the formation ofcorrosion products providing information about chemicalidentity, quantity and lateral distribution. The newlydeveloped system was used to study the influence of relativehumidity (RH) and levels of sulfur dioxide (SO2), ozone (O3)and nitrogen dioxide (NO2) down to concentrations of subparts-per-million (ppm), on the initial stages of atmosphericcorrosion of copper.Exposure to RH led to the formation of small grains ofcuprous oxide (Cu2O), with an average diameter of approximately40 nm. The grain nucleation rate increased with increasing RHdue to the increasing amount of physisorbed water on thesurface.Exposure to RH and SO2 led to the formation of coppersulfite (CuSO3•xH2O) species as well as reduction in therate of Cu2O formation. The formation of CuSO3•xH2Ooccurred through the dissolution and consecutive precipitationof surface-bound copper sulfite complexes.The roles of O3 and NO2 in the SO2-induced atmosphericcorrosion of copper was also investigated. O3 was found to havea two-fold effect, resulting in the oxidation of the coppersulfite species to copper sulfate and the enhancement of Cu2Oformation. NO2 promoted the oxidation of copper sulfitespecies, though less efficiently than O3, and reduced Cu2Oformation. In addition, copper nitrate formation wasobserved.IRAS was also used to investigate the interaction betweenSO2 and surfaces made of platinum and palladium. Sulfuric acidformation was observed on both metals, showing the importanceof the surface on the formation of the metal/atmospherereaction products.Keywords:Atmospheric corrosion, IR-spectroscopy, IRAS,QCM, AFM, SO2, O3, NO2, Cu.
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| 2. |
- Abellan-Flos, Marta, et al.
(author)
-
QCM sensing of multivalent interactions between lectins and well-defined glycosylated nanoplatforms
- 2019
-
In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 139
-
Journal article (peer-reviewed)abstract
- Quartz crystal microbalance (QCM) methodology has been adopted to unravel important factors contributing to the "cluster glycoside effect" observed in carbohydrate-lectin interactions. Well-defined, glycosylated nanostructures of precise sizes, geometries and functionalization patterns were designed and synthesized, and applied to analysis of the interaction kinetics and thermodynamics with immobilized lectins. The nanostructures were based on Borromean rings, dodecaamine cages, and fullerenes, each of which carrying a defined number of carbohydrate ligands at precise locations. The synthesis of the Borromeates and dodecaamine cages was easily adjustable due to the modular assembly of the structures, resulting in variations in presentation mode. The binding properties of the glycosylated nanoplatforms were evaluated using flow-through QCM technology, as well as hemagglutination inhibition assays, and compared with dodecaglycosylated fullerenes and a monovalent reference. With the QCM setup, the association and dissociation rate constants and the associated equilibrium constants of the interactions could be estimated, and the results used to delineate the multivalency effects of the lectin-nanostructure interactions.
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| 3. |
- Anderson, Henrik, et al.
(author)
-
Quartz crystal microbalance sensor design : I. Experimental study of sensor response and performance
- 2007
-
In: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 123:1, s. 27-34
-
Journal article (peer-reviewed)abstract
- This paper investigates a novel quartz crystal microbalance (QCM) biosensor with a small and rectangular flow cell along with a correspondingly shaped crystal electrode. The sensor was evaluated with impedance analysis and compared to standard circular sensor crystals and sensor crystals with small circular electrodes. Comparative QCM measurements on an antibody–antigen interaction system were carried out on the rectangular and standard circular sensor systems. Impedance analysis and subsequent data extraction of the three different sensor crystals showed that the smaller sensors had significantly higher Q-values in air, but that liquid load on the electrodes lowered the Q-values radically for all crystals. Under liquid load, Q-values for the standard circular and the rectangular sensors were similar whereas the Q-value for the small circular sensor was 50% higher. QCM experiments showed that the QCM system with rectangular crystal electrodes was fully functional in a liquid environment. The rectangular system showed higher and more rapid responses for series of antibody injections, albeit at a higher noise level than the standard system. The study elucidates a significant potential for improvement of sensor performance by optimising the sensor electrode size and shape together with the flow cell geometry.
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| 4. |
- Duner, Gunnar, et al.
(author)
-
Signal Enhancement in Ligand-Receptor Interactions using Dynamic Polymers at Quartz Crystal Microbalance Surfaces
- 2016
-
In: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 141:13, s. 3993-3996
-
Journal article (peer-reviewed)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.
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| 5. |
- Dunér, Gunnar, et al.
(author)
-
Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films
- 2008
-
In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:14, s. 7559-7564
-
Journal article (peer-reviewed)abstract
- Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be similar to 220 nm in a collapsed state and similar to 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.
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| 6. |
- Durall, Claudia, et al.
(author)
-
Robust QCM-Based Sensing and Assay Formats in Commercialized Systems
- 2023
-
In: Springer Series on Chemical Sensors and Biosensors. - : Springer.
-
Book chapter (peer-reviewed)abstract
- Attana’s Quartz Crystal Microbalance (QCM) analytical instruments have been developed to study in vitro biological interactions, mimicking the in vivo conditions. Attana’s superior technology for kinetic interaction studies allows to perform different assays, including biochemical, crude, sera, cell, and tissue-based, in vitro diagnostic and material chemistry assays, in real time and label free. With the focus to validate, select, and optimize drug candidates prior to clinical trials, Attana has helped pharmaceutical companies to increase their efficiency and profitability. In addition, the Attana instruments and services have been used in many other applications and research as described in this chapter.
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| 7. |
- Elmlund, Louise, et al.
(author)
-
Biotin selective polymer nano-films
- 2014
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In: Journal of Nanobiotechnology. - : Springer Science and Business Media LLC. - 1477-3155. ; 12
-
Journal article (peer-reviewed)abstract
- Background: The interaction between biotin and avidin is utilized in a wide range of assay and diagnostic systems. A robust material capable of binding biotin should offer scope in the development of reusable assay materials and biosensor recognition elements. Results: Biotin-selective thin (3-5 nm) films have been fabricated on hexadecanethiol self assembled monolayer (SAM) coated Au/quartz resonators. The films were prepared based upon a molecular imprinting strategy where N, N'-methylenebisacrylamide and 2-acrylamido-2-methylpropanesulfonic acid were copolymerized and grafted to the SAM-coated surface in the presence of biotin methyl ester using photoinitiation with physisorbed benzophenone. The biotinyl moiety selectivity of the resonators efficiently differentiated biotinylated peptidic or carbohydrate structures from their native counterparts. Conclusions: Molecularly imprinted ultra thin films can be used for the selective recognition of biotinylated structures in a quartz crystal microbalance sensing platform. These films are stable for periods of at least a month. This strategy should prove of interest for use in other sensing and assay systems.
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| 8. |
- Elmlund, Louise
(author)
-
QCM-based sensing using biological and biomimetic interfaces
- 2014
-
Doctoral thesis (other academic/artistic)abstract
- The objective of this thesis was to explore novel approaches for studying molecular recognition at biological and biomimetic surfaces using the quartz crystal microbalance (QCM) biosensor technique. The first two papers focused on the synthesis and study of biotin selective polymer films prepared using the molecularly imprinted polymer (MIP) technique. Control over polymer structure is of importance for sensor reproducibility and sensitivity, and was addressed in Paper I where a simple strategy for fabricating uniform thin biotin imprinted polymer films was employed. In Paper II the binding of biotin moieties to thin (3-5 nm) biomimetic polymer films was examined and consequences for sensor performance discussed. The potential for using QCM as a tool for assessing the binding of small peptides derived from phage display screening was presented Paper III. Here, screening of a phage peptide library against immobilized adenine resulted in candidate peptides that were studied using this technique. In Paper IV a whole cell-based biosensor was developed for studying interactions with cell membrane-incorporated targets. Epithelial cancer cells, SKOV3, were attached to QCM sensor chips and the binding of the monoclonal antibody HerceptinTM was studied. This approach demonstrates the potential of using QCM to study binding to membrane-incorporated targets, an alternative to assays based upon immobilized receptor structures lacking their natural context.
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| 9. |
- Elmlund, Louise, 1981-, et al.
(author)
-
Study of the Interaction of Trastuzumab and SKOV3 Epithelial Cancer Cells Using a Quartz Crystal Microbalance Sensor
- 2015
-
In: Sensors. - : MDPI. - 1424-8220. ; 15:3, s. 5884-5894
-
Journal article (peer-reviewed)abstract
- Analytical methods founded upon whole cell-based assays are of importance in early stage drug development and in fundamental studies of biomolecular recognition. Here we have studied the binding of the monoclonal antibody trastuzumab to human epidermal growth factor receptor 2 (HER2) on human ovary adenocarcinoma epithelial cancer cells (SKOV3) using quartz crystal microbalance (QCM) technology. An optimized procedure for immobilizing the cells on the chip surface was established with respect to fixation procedure and seeding density. Trastuzumab binding to the cell decorated sensor surface was studied, revealing a mean dissociation constant, K-D, value of 7 +/- 1 nM (standard error of the mean). This study provides a new perspective on the affinity of the antibody-receptor complex presented a more natural context compared to purified receptors. These results demonstrate the potential for using whole cell-based QCM assay in drug development, the screening of HER2 selective antibody-based drug candidates, and for the study of biomolecular recognition. This real time, label free approach for studying interactions with target receptors present in their natural environment afforded sensitive and detailed kinetic information about the binding of the analyte to the target.
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| 10. |
- Forssén, Patrik, 1966-, et al.
(author)
-
Reliable Strategy for Analysis of Complex Biosensor Data
- 2018
-
In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 90:8, s. 5366-5374
-
Journal article (peer-reviewed)abstract
- When using biosensors, analyte biomolecules of several different concentrations are percolated over a chip with immobilized ligand molecules that form complexes with analytes. However, in many cases of biological interest, e.g., in antibody interactions, complex formation steady-state is not reached. The data measured are so-called sensorgram, one for each analyte concentration, with total complex concentration vs time. Here we present a new four-step strategy for more reliable processing of this complex kinetic binding data and compare it with the standard global fitting procedure. In our strategy, we first calculate a dissociation graph to reveal if there are any heterogeneous interactions. Thereafter, a new numerical algorithm, AIDA, is used to get the number of different complex formation reactions for each analyte concentration level. This information is then used to estimate the corresponding complex formation rate constants by fitting to the measured sensorgram one by one. Finally, all estimated rate constants are plotted and clustered, where each cluster represents a complex formation. Synthetic and experimental data obtained from three different QCM biosensor experimental systems having fast (close to steady-state), moderate, and slow kinetics (far from steady-state) were evaluated using the four-step strategy and standard global fitting. The new strategy allowed us to more reliably estimate the number of different complex formations, especially for cases of complex and slow dissociation kinetics. Moreover, the new strategy proved to be more robust as it enables one to handle system drift, i.e., data from biosensor chips that deteriorate over time.
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| 11. |
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| 12. |
- Hjalmarsson, Nicklas, et al.
(author)
-
Electro-Responsive Surface Composition and Kinetics of an Ionic Liquid in a Polar Oil
- 2019
-
In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 35:48, s. 15692-15700
-
Journal article (peer-reviewed)abstract
- The quartz crystal microbalance (QCM) has been used to study how the interfacial layer of an ionic liquid dissolved in a polar oil at low weight percentages responds to changes in applied potential. The changes in surface composition at the QCM gold surface depend on both the magnitude and sign of the applied potential. The time-resolved response indicates that the relaxation kinetics are limited by the diffusion of ions in the interfacial region and not in the bulk, since there is no concentration dependence. The measured mass changes cannot be explained only in terms of simple ion exchange; the relative molecular volumes of the ions and the density changes in response to ion exclusion must be considered. The relaxation behavior of the potential between the electrodes upon disconnecting the applied potential is more complex than that observed for pure ionic liquids, but a measure of the surface charge can be extracted from the exponential decay when the rapid initial potential drop is accounted for. The adsorbed film at the gold surface consists predominantly of ionic liquid despite the low concentration, which is unsurprising given the surtactant-like structures of (some of) the ionic liquid ions. Changes in response to potential correspond to changes in the relative numbers of cations and anions, rather than a change in the oil composition. No evidence for an electric field induced change in viscosity is observed. This work shows conclusively that electric potentials can be used to control the surface composition, even in an oil-based system, and paves the way for other ion solvent studies.
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| 13. |
- Hjalmarsson, Nicklas, et al.
(author)
-
Weighing the surface charge of an ionic liquid
- 2015
-
In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 7:38, s. 16039-16045
-
Journal article (peer-reviewed)abstract
- Electrochemical quartz crystal microbalance has been used to measure changes in the composition of the capacitive electrical double layer for 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)-trifluorophosphate, an ionic liquid, in contact with a gold electrode surface as a function of potential. The mass difference between the cation and anion means that the technique can effectively "weigh" the surface charge accurately with high temporal resolution. This reveals quantitatively how changing the potential alters the ratio of cations and anions associated with the electrode surface, and thus the charge per unit area, as well as the kinetics associated with these interfacial processes. The measurements reveal that it is diffusion of co-ions into the interfacial region rather than expulsion of counterions that controls the relaxation. The measured potential dependent double layer capacitance experimentally validates recent theoretical predictions for counterion overscreening (low potentials) and crowding (high potentials) at electrode surfaces. This new capacity to quantitatively measure ion composition is critical for ionic liquid applications ranging from batteries, capacitors and electrodeposition through to boundary layer structure in tribology, and more broadly provides new insight into interfacial processes in concentrated electrolyte solutions.
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| 14. |
- Jennbacken, Karin, et al.
(author)
-
Phenotypic Screen with the Human Secretome Identifies FGF16 as Inducing Proliferation of iPSC-Derived Cardiac Progenitor Cells
- 2019
-
In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 20:23
-
Journal article (peer-reviewed)abstract
- Paracrine factors can induce cardiac regeneration and repair post myocardial infarction by stimulating proliferation of cardiac cells and inducing the anti-fibrotic, antiapoptotic, and immunomodulatory effects of angiogenesis. Here, we screened a human secretome library, consisting of 923 growth factors, cytokines, and proteins with unknown function, in a phenotypic screen with human cardiac progenitor cells. The primary readout in the screen was proliferation measured by nuclear count. From this screen, we identified FGF1, FGF4, FGF9, FGF16, FGF18, and seven additional proteins that induce proliferation of cardiac progenitor cells. FGF9 and FGF16 belong to the same FGF subfamily, share high sequence identity, and are described to have similar receptor preferences. Interestingly, FGF16 was shown to be specific for proliferation of cardiac progenitor cells, whereas FGF9 also proliferated human cardiac fibroblasts. Biosensor analysis of receptor preferences and quantification of receptor abundances suggested that FGF16 and FGF9 bind to different FGF receptors on the cardiac progenitor cells and cardiac fibroblasts. FGF16 also proliferated naive cardiac progenitor cells isolated from mouse heart and human cardiomyocytes derived from induced pluripotent cells. Taken together, the data suggest that FGF16 could be a suitable paracrine factor to induce cardiac regeneration and repair.
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| 15. |
- Jönsson, Mats, et al.
(author)
-
Quartz crystal microbalance biosensor design: II. Simulation of sample transport
- 2007
-
In: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 123:1, s. 21-26
-
Journal article (peer-reviewed)abstract
- The influence of flow cell geometry on sample dispersion in a quartz crystal microbalance (QCM) biosensor system was investigated. A circular and a rectangular flow cell and corresponding sensor electrodes were studied experimentally and modelled using a coupled Navier-Stokes and convection-diffusion model. Finite element simulations showed that dispersion phenomena in a flow cell can be significantly reduced with the rectangular flow cell compared to a circular system. Experimental results from measurement of the time-dependent viscosity change of a model sample indicate that the sample delivery system has a predominant effect on the dispersion of the whole sensor system. Consequently, improvement of the sensor flow cell should be accompanied with improvement of the sample delivery system. With reference to kinetic studies of biological interactions, the current dispersion should have little effect on the results for studies of interaction pairs with relatively slow to normal binding rates such as antibody-antigen interactions. Incentive for further development of the flow cell and sample delivery system exists primarily for applications with high reaction rates such as for certain receptor ligand interactions.
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| 16. |
- Mahajan, Rashmi, et al.
(author)
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Oxytocin-Selective Nanogel Antibody Mimics
- 2022
-
In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 23:5
-
Journal article (peer-reviewed)abstract
- Oxytocin imprinted polymer nanoparticles were synthesized by glass bead supported solid phase synthesis, with NMR and molecular dynamics studies used to investigate monomer-template interactions. The nanoparticles were characterized by dynamic light scattering, scanning- and transmission electron microscopy and X-ray photoelectron spectroscopy. Investigation of nanoparticle-template recognition using quartz crystal microbalance-based studies revealed sub-nanomolar affinity, k(d) approximate to 0.3 +/- 0.02 nM (standard error of the mean), comparable to that of commercial polyclonal antibodies, k(d) approximate to 0.02-0.2 nM.
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| 17. |
- Myrskog, Annica, 1980-, et al.
(author)
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Esterification of Self-Assembled Carboxylic-Acid-Terminated Thiol Monolayers in Acid Environment : A Time-Dependent Study
- 2010
-
In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 26:2, s. 821-829
-
Journal article (peer-reviewed)abstract
- This contribution reports on the influence of acids oil the quality of carboxylic-acid-terminated self-assembled monolayers (SAMs) on gold prepared from ethanolic solution of HS-(CH2)(15)-COOH and HS-(CH2)(11)CONH-(EG)(6)CH2-COOH. Null ellipsometry, contact angle goniometry, and infrared reflection-absorption spectroscopy are used to monitor the physical and chemical changes occurring within the SAMs upon acid post treatment; after incubation with acids present in the solution: and after incubation in aged acid containing solutions. The presence of acid has a positive effect oil the crystallinity, packing, and orientation Of the Supporting alkyl and ethylene glycol Subunits of the SAM. Our Studies also confirm previous findings stating that the carboxylic groups are rapidly converted into ethyl ester groups in the presence of hydrochloric acid in the incubation solution. It is also evident that the conversion occurs in the presence of the weaker acid, acetic acid, although at a much slower rate than that for hydrochloric acid. This is a new observation that has not been reported on before. The physical and chemical characterization is also complemented with a functional bioaffinity study. The functional evaluation revealed that the present model system was surprisingly insensitive to the degree of esterification of the carboxylic acid groups, but that 4 weeks of storage of the two investigated thiols in hydrochloric acid containing ethanol resulted in SAMs that were completely inactive with respect to immobilization and subsequent binding of the antigen. It was encouraging to note that the nonspecific binding of both antigen and antibody was extremely low oil the two SAMs, regardless of the relative amount of ethyl esters on the surface.
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| 18. |
- Myrskog, Annica, 1980-, et al.
(author)
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On the stability of carboxylic acid-terminated self-assembled monolayers : Influence of varying alkyl chain length
-
Other publication (other academic/artistic)abstract
- The physio-chemical properties and storage stability of three carboxyl-terminated selfassembled monolayers (SAMs), prepared from ethanolic and acidified ethanolic thiolssolutions of HS-(CH2)nCONH-EG6CH2-COOH, n=3, 11 or 15 on gold, have been correlated to their performance as potential biosensor surfaces. The SAMs of the two longer thiols (n=11, 15) prepared from acidified thiol solutions displayed highly organized and crystallinelike alkyl and ethylene glycol portions. The length of the supporting alkyl chain also influenced the storage stability of the SAMs in nitrogen gas, water and acidified water/ethanol solutions. The two long alkyl chain SAMs exhibited excellent storage characteristics, whereas the short chain thiol resulted in a less storage stable SAM as revealed by increased molecular decomposition and desorption, and a significantly reduced biofunctionality.
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| 19. |
- Nilsson, Per H., 1980-, et al.
(author)
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Quartz Crystal Microbalance Platform for SARS-CoV-2 Immuno-Diagnostics
- 2023
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In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 24:23
-
Journal article (peer-reviewed)abstract
- Rapid and accurate serological analysis of SARS-CoV-2 antibodies is important for assessing immune protection from vaccination or infection of individuals and for projecting virus spread within a population. The quartz crystal microbalance (QCM) is a label-free flow-based sensor platform that offers an opportunity to detect the binding of a fluid-phase ligand to an immobilized target molecule in real time. A QCM-based assay was developed for the detection of SARS-CoV-2 antibody binding and evaluated for assay reproducibility. The assay was cross-compared to the Roche electrochemiluminescence assay (ECLIA) Elecsys (R) Anti-SARS-CoV-2 serology test kit and YHLO's chemiluminescence immunoassay (CLIA). The day-to-day reproducibility of the assay had a correlation of r(2) = 0.99, p < 0.001. The assay linearity was r(2) = 0.96, p < 0.001, for dilution in both serum and buffer. In the cross-comparison analysis of 119 human serum samples, 59 were positive in the Roche, 52 in the YHLO, and 48 in the QCM immunoassay. Despite differences in the detection method and antigen used for antibody capture, there was good coherence between the assays, 80-100% for positive and 96-100% for negative test results. In summation, the QCM-based SARS-CoV-2 IgG immunoassay showed high reproducibility and linearity, along with good coherence with the ELISA-based assays. Still, factors including antibody titer and antigen-binding affinity may differentially affect the various assays' responses.
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| 20. |
- Norberg, Oscar, et al.
(author)
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Photo-Click Immobilization on Quartz Crystal Microbalance Sensors for Selective Carbohydrate-Protein Interaction Analyses
- 2011
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 83:3, s. 1000-1007
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Journal article (peer-reviewed)abstract
- A photoclick method based on azide photoligation and Cu-catalyzed azide-alkyne cycloaddition has been evaluated for the immobilization of carbohydrates to polymeric materials. The biomolecular recognition properties of the materials have been investigated with regard to applicable polymeric substrates and selectivity of protein binding. The method was used to functionalize a range of polymeric surfaces (polystyrene, polyacrylamide, poly(ethylene glycol), poly(2-ethyl-2-oxazoline), and polypropene) with various carbohydrate structures (based on alpha-D-mannose, beta-D-galactose, and N-acetyl-beta-D-glucosamine). The functionalized surfaces were evaluated in real-time studies of protein-carbohydrate interactions using a quartz crystal microbalance flow through system with a series of different carbohydrate-binding proteins (lectins). The method proved to be robust and versatile, resulting in a range of efficient sensors showing high and predictable protein selectivities.
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| 21. |
- Norberg, Oscar, 1982-, et al.
(author)
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Photogenerated lectin sensors produced by thiol-ene/yne photo-click chemistry in aqueous solution
- 2012
-
In: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 34:1, s. 51-56
-
Journal article (peer-reviewed)abstract
- The photoinitiated radical reactions between thiols and alkenes/alkynes (thiol-ene and thiol-yne chemistry) have been applied to a functionalization methodology to produce carbohydrate-presenting surfaces for analyses of biomolecular interactions. Polymer-coated quartz surfaces were functionalized with alkenes or alkynes in a straightforward photochemical procedure utilizing perfluorophenylazide (PFPA) chemistry. The alkene/alkyne surfaces were subsequently allowed to react with carbohydrate thiols in water under UV-irradiation. The reaction can be carried out in a drop of water directly on the surface without photoinitiator, and any disulfide side products were easily washed away after the functionalization process. The resulting carbohydrate-presenting surfaces were evaluated in real-time studies of protein-carbohydrate interactions using a quartz crystal microbalance (QCM) flow-through system with recurring injections of selected lectins, with intermediate regeneration steps using low pH buffer. The resulting methodology proved fast, efficient and scalable to high-throughput analysis formats, and the produced surfaces showed significant protein binding with expected selectivities of the lectins used in the study.
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| 22. |
- Norberg, Oscar, et al.
(author)
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Synthesis and binding affinity analysis of alpha 1-2-and alpha 1-6-O/S-linked dimannosides for the elucidation of sulfur in glycosidic bonds using quartz crystal microbalance sensors
- 2017
-
In: Carbohydrate Research. - : ELSEVIER SCI LTD. - 0008-6215 .- 1873-426X. ; 452, s. 35-42
-
Research review (peer-reviewed)abstract
- The role of sulfur in glycosidic bonds has been evaluated using quartz crystal microbalance methodology. Synthetic routes towards alpha 1-2- and alpha 1-6-linked dimannosides with S-or O-glycosidic bonds have been developed, and the recognition properties assessed in competition binding assays with the cognate lectin concanavalin A. Mannose-presenting QCM sensors were produced using photoinitiated, nitrenemediated immobilization methods, and the subsequent binding study was performed in an automated flow-through instrumentation, and correlated with data from isothermal titration calorimetry. The recorded Kd-values corresponded well with reported binding affinities for the O-linked dimannosides with affinities for the alpha 1-2-linked dimannosides in the lower micromolar range. The S-linked analogs showed slightly disparate effects, where the alpha 1-6-linked analog showed weaker affinity than the O-linked dimannoside, as well as positive apparent cooperativity, whereas the alpha 1-2-analog displayed very similar binding compared to the O-linked structure.
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| 23. |
- Norberg, Oscar, et al.
(author)
-
Synthesis and Binding Affinity Analysis of α1-2- and α1-6-O/S-linked Dimannosides for the Elucidation of Sulfur in Glycosidic Bonds using Quartz Crystal Microbalance Sensors
-
Journal article (other academic/artistic)abstract
- Synthetic routes towards α1-2- and α1-6-linked dimannosides with S- or O-glycosidic bonds are presented. A glycosylation method was developed in which a sulfhydryl glycosyl acceptor was coupled to a 1-O-acetyl-glycosyl donor under Lewis acid catalysis. Final debenzylation of the S-linked dimannosides were accomplished through Birch reduction in high yields. The protein recognition properties of the synthesized dimannosides were then evaluated in a competition binding assay with the model lectin Con A, to investigate the effect of sulfur in the glycosidic bonds. Mannose-presenting surfaces were produced according to a previously reported Photo-Click immobilization method and the subsequent binding study was performed in an automated QCM flow through instrumentation. The recorded EC50-values correlated well to previously reported binding affinities for the O-linked dimannosides. Results were in agreement with known binding affinities, where the S-analogs displayed slightly weaker binding and a positive apparent cooperativity.
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| 24. |
- Pei, Zhichao, et al.
(author)
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Optimizing immobilization on two-dimensional carboxyl surface : pH dependence of antibody orientation and antigen binding capacity
- 2010
-
In: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 398:2, s. 161-168
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Journal article (peer-reviewed)abstract
- The performance of immunosensors is highly dependent on the amount of immobilized antibodies and their remaining antigen binding capacity. In this work, a method for immobilization of antibodies on a two dimensional carboxyl surface has been optimized using quartz crystal microbalance biosensors. We have shown that successful immobilization is highly dependent on surface pKa, antibody pI and pH of immobilization buffer. By use of EDC/sulfo-NHS activation reagents, the effect of the intrinsic surface pKa is avoided and immobilization also at very low pH has been made possible which is of importance for immobilization of acidic proteins. Generic immobilization conditions were demonstrated on a panel of antibodies which resulted in an average coefficient of variation of 4% for the immobilization of these antibodies. Antigen binding capacity as a function of immobilization pH was studied. In most cases the antigen binding capacity followed the immobilization response. However, the antigen to antibody binding ratio differed between the antibodies investigated, and for one of the antibodies, the antigen binding capacity was significantly lower than expected from immobilization in a certain pH range. Tests with anti-Fc and anti-Fab antibodies on different antibody surfaces showed that the orientation of the antibodies on the surface had a profound effect on the antigen binding capacity of the immobilized antibodies.
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| 25. |
- Pei, Zhichao, et al.
(author)
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Redox-Responsive and Calcium-Dependent Switching of Glycosyldisulfide Interactions with Concanavalin A
- 2005
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In: Bioorganic & Medicinal Chemistry Letters. - : Elsevier BV. - 0960-894X .- 1464-3405. ; 15, s. 2707-2710
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Journal article (peer-reviewed)abstract
- Glycosyldisulfides can interact efficiently with carbohydrate-binding entities. This has been shown for a range of thiosaccharide dimers when tested for their effects against the lectin Concanavalin A using a modified quartz crystal microbalance-technique. Contrary to the thiosaccharide monomers, showing no significant binding up to 10 mM, several of the dimers showed IC50-values in the low millimolar range. Three of the glycosyldisulfides tested also displayed very high positive apparent cooperativity effects that were found to be both calcium-dependent and redox-responsive.
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| 26. |
- Pei, Zhichao, et al.
(author)
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Study of Real-time Lectin–Carbohydrate Interactions on the Surface of a Quartz Crystal Microbalance
- 2005
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In: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 21:1, s. 60-66
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Journal article (peer-reviewed)abstract
- A quartz crystal microbalance (QCM) biosensor system for lectin-carbohydrate interactions has been developed. Yeast mannan was immobilised on polystyrene-coated quartz crystals, and interactions tested with the lectin concanavalin A (Con A). The biosensor could be easily operated, where mannan immobilisation and all binding analyses were performed in real-time using a flow-through system. The apparent binding constant for yeast mannan to Con A was estimated to be 0.4 μM, well in accordance to reported literature values. In addition, the effective concentration values (EC50-values) for a series of mannose/mannoside ligands, acting as competitors to the mannan/Con A interaction, were determined to range from 0.18 to 5.3 mM, in good correlation with a related enzyme-labelled lectin assay (ELLA) protocol
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| 27. |
- Persson Skare, Tor, et al.
(author)
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Quartz Crystal Microbalance Measurement of Histidine-Rich Glycoprotein and Stanniocalcin-2 Binding to Each Other and to Inflammatory Cells
- 2022
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In: Cells. - : MDPI. - 2073-4409. ; 11:17
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Journal article (peer-reviewed)abstract
- The plasma protein histidine-rich glycoprotein (HRG) is implicated in the polarization of macrophages to an M1 antitumoral phenotype. The broadly expressed secreted protein stanniocalcin 2 (STC2), also implicated in tumor inflammation, is an HRG interaction partner. With the aim to biochemically characterize the HRG and STC2 complex, binding of recombinant HRG and STC2 preparations to each other and to cells was explored using the quartz crystal microbalance (QCM) methodology. The functionality of recombinant proteins was tested in a phagocytosis assay, where HRG increased phagocytosis by monocytic U937 cells while STC2 suppressed HRG-induced phagocytosis. The binding of HRG to STC2, measured using QCM, showed an affinity between the proteins in the nanomolar range, and both HRG and STC2 bound individually and in combination to vitamin D3-treated, differentiated U937 monocytes. HRG, but not STC2, also bound to formaldehyde-fixed U937 cells irrespective of their differentiation stage in part through the interaction with heparan sulfate. These data show that HRG and STC2 bind to each other as well as to U937 monocytes with high affinity, supporting the relevance of these interactions in monocyte/macrophage polarity.
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| 28. |
- Suriyanarayanan, Subramanian, et al.
(author)
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Protein-resistant hyperbranched polyethyleneimine brush surfaces
- 2013
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In: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 396, s. 307-315
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Journal article (peer-reviewed)abstract
- A novel hyperbranched polyethyleneimine (PEI) modified gold surface has been designed, fabricated, and investigated with respect to its ability to resist non-specific adsorption of proteins. The facile synthesis strategy, based on self-assembly, involves immobilization of polyethyleneimine to gold surfaces modified with 11-mercaptoundecanoic acid (MuDA) monolayers using traditional carbodiimide chemistry. The hyperbranched polymer brushes were characterized by X-ray photoelectron spectroscopy (XPS). Reflection absorption infrared spectroscopy (RAIRS) and ellipsometry measurements showed the thickness of the PEI brushes increases with adsorption solution ionic strength. Polymer brush surface concentrations can be improved from 2560 to 3880 chains/mu m(2) by changing the ionic strength of the adsorption solution (PBS) by varying NaCl concentration from 0 to 650 mM. Protein adsorption (pH 7.4) was evaluated under flow injection analysis (FIA) conditions using a quartz crystal microbalance (QCM). The PEI brushes suppress protein adsorption, for example, cytochrome C, bovine serum albumin (BSA), and ribonuclease A, to less than 0.08 mu g/cm(2) and the protein resistance increases with increasing ionic strength of the carrier solution, performance comparable to that achieved with comparable PEG-coated surfaces. The PEI brushes were exceptionally stable, with adsorption characteristics maintained after 6 months storage in aqueous conditions (pH 7.4, 25 degrees C, PBS). The potential of hyperbranched PEI structures as protein-resistant surfaces is discussed.
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| 29. |
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| 30. |
- Tor, Persson Skare, et al.
(author)
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Histidine-rich glycoprotein and stanniocalcin-2 high affinity interactions with inflammatory cells
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Other publication (other academic/artistic)abstract
- AbstractThe plasma protein Histidine-rich protein (HRG), is implicated in macrophage polarization to an M1 antitumoral phenotype. The broadly expressed, secreted protein Stanniocalcin 2 (STC2), also implicated in tumor inflammation, is an HRG interaction partner. To assess the effects of HRG and STC2 on inflammation in a biologically relevant model, binding of recombinant HRG and STC2 preparations to each other and to cells was explored using quartz crystal microbalance (QCM) methodology. Protein functionality was tested in a phagocytosis assay. Stimulation with HRG increased phagocytosis in U937 cells while STC2 suppressed HRG-induced phagocytosis. Binding of HRG to STC2 measured using QCM showed an affinity in the nanomolar range and occurred in a conformation-dependent manner. Both HRG and STC2 bound individually and in combination to monocytic U937 cells with higher efficiency after vitamin D3-induced differentiation. HRG, but not STC2, also bound to formaldehyde-fixed U937 cells irrespective of differentiation stage, potentially through heparan sulphate. These data show that binding of HRG to STC2 is specific and conformation-dependent, and HRG and STC2 bind to separate sites on U937 cells, suggesting that they exert their effects through distinct cell surface entities.
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| 31. |
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| 32. |
- Wiklander, Jesper G., et al.
(author)
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A synthetic polymer with avidin-like binding properties
- 2010
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Conference paper (peer-reviewed)abstract
- A series of streptavidin mimicking molecularly imprinted polymers has been developed and evaluated for their biotin binding characteristics. A combination of molecular dynamics and NMR spectroscopy was used to examine potential polymer systems, in particular with the functional monomers methacrylic acid and 2-acrylamidopyridine. Synthesis of co-polymers of ethylene dimethacrylate and one or both of these functional monomers was performed. A combination of radioligand binding studies and surface area analyses (BET, SEM) demonstrated the presence of selectivity in polymers prepared using methacrylic acid as functional monomer. This correlated well with the molecular dynamics studies, showing the power of this methodology as a prognostic tool for predicting the behaviour of molecularly imprinted polymers.
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| 33. |
- Wiklander, Jesper G., 1974-, et al.
(author)
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Towards a synthetic avidin mimic
- 2011
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In: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 400:5, s. 1397-1404
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Journal article (peer-reviewed)abstract
- A series of streptavidin-mimicking molecularly imprinted polymers has been developed and evaluated for their biotin binding characteristics. A combination of molecular dynamics and NMR spectroscopy was used to examine potential polymer systems, in particular with the functional monomers methacrylic acid and 2-acrylamidopyridine. The synthesis of copolymers of ethylene dimethacrylate and one or both of these functional monomers was performed. A combination of radioligand binding studies and surface area analyses demonstrated the presence of selectivity in polymers prepared using methacrylic acid as the functional monomer. This was predicted by the molecular dynamics studies showing the power of this methodology as a prognostic tool for predicting the behavior of molecularly imprinted polymers.
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