The Experts below are selected from a list of 774 Experts worldwide ranked by ideXlab platform
David S. Hage - One of the best experts on this subject based on the ideXlab platform.
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Clinical and pharmaceutical applications of affinity ligands in capillary electrophoresis: A review.
Journal of pharmaceutical and biomedical analysis, 2019Co-Authors: Chenhua Zhang, Ashley G. Woolfork, Kyungah Suh, Susan T. Ovbude, Marawan Elzoeiry, David S. HageAbstract:Abstract Affinity capillary electrophoresis (ACE) is a separation technique that combines a biologically-related binding agent with the separating power and efficiency of capillary electrophoresis. This review will examine several classes of binding agents that have been used in ACE and applications that have been described for the resulting methods in clinical or pharmaceutical analysis. Binding agents that will be considered are antibodies, aptamers, lectins, serum proteins, carbohydrates, and enzymes. This review will also describe the various formats in which each type of binding agent has been used in CE, including both homogeneous and heterogeneous methods. Specific areas of applications that will be considered are CE-based immunoassays, glycoprotein/glycan separations, chiral separations, and biointeraction studies. The general principles and formats of ACE for each of these applications will be examined, along with the potential advantages or limitations of these methods.
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Biointeraction Analysis of Immobilized Antibodies and Related Agents by High-Performance Immunoaffinity Chromatography
Methods (San Diego Calif.), 2011Co-Authors: Erika L. Pfaunmiller, Annette C. Moser, David S. HageAbstract:Summary A method is described based on high-performance immunoaffinity chromatography for examining the interactions of immobilized antibodies or related binding agents with their targets. It is shown how this method can be used to obtain information on the binding, elution and regeneration kinetics of immobilized binding agents, such as those used with immunoaffinity supports. The theory behind this approach is briefly described and it is demonstrated how both the kinetic and thermodynamic properties of a biointeraction can be determined experimentally through this method. Several applications are used to illustrate this technique, including antibody-antigen interactions and the binding of aptamers with their targets in the presence of silica-based supports. The same approach can be adapted for use with other types of targets, binding agents and support materials.
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Biointeraction analysis by high-performance affinity chromatography: Kinetic studies of immobilized antibodies.
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2009Co-Authors: Mary Anne Nelson, Annette C. Moser, David S. HageAbstract:Abstract A system based on high-performance affinity chromatography was developed for characterizing the binding, elution and regeneration kinetics of immobilized antibodies and immunoaffinity supports. This information was provided by using a combination of frontal analysis, split-peak analysis and peak decay analysis to determine the rate constants for antibody–antigen interactions under typical sample application and elution conditions. This technique was tested using immunoaffinity supports that contained monoclonal antibodies for 2,4-dichlorophenoxyacetic acid (2,4-D). Association equilibrium constants measured by frontal analysis for 2,4-D and related compounds with the immobilized antibodies were 1.7–12 × 106 M−1 at pH 7.0 and 25 °C. Split-peak analysis gave association rate constants of 1.4–12 × 105 M−1 s−1 and calculated dissociation rate constants of 0.01–0.4 s−1 under the application conditions. Elution at pH 2.5 for the analytes from the antibodies was examined by peak decay analysis and gave dissociation rate constants of 0.056–0.17 s−1. A comparison of frontal analysis results after various periods of column regeneration allowed the rate of antibody regeneration to be examined, with the results giving a first-order regeneration rate constant of 2.4 × 10−4 s−1. This combined approach and the information it provides should be useful in the design and optimization of immunoaffinity chromatography and other analytical methods that employ immobilized antibodies. The methods described are not limited to the particular analytes and antibodies employed in this study but should be useful in characterizing other targets, ligands and supports.
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Kinetic studies of biological interactions by affinity chromatography.
Journal of separation science, 2009Co-Authors: John E. Schiel, David S. HageAbstract:The rates at which biological interactions occur can provide important information on the mechanism and behavior of such processes in living systems. This paper will discuss how affinity chromatography can be used as a tool to examine the kinetics of biological interactions. This approach, referred to here as biointeraction chromatography, uses a column with an immobilized binding agent to examine the association or dissociation of this agent with other compounds. The use of HPLC-based affinity columns in kinetic studies has received particular attention in recent years. Advantages of using HPLC with affinity chromatography for this purpose include the ability to reuse the same ligand within a column for a large number of experiments, and the good precision and accuracy of this approach. A number of techniques are available for kinetic studies through the use of affinity columns and biointeraction chromatography. These approaches include plate height measurements, peak profiling, peak fitting, split-peak measurements, and peak decay analysis. The general principles for each of these methods are discussed in this paper and some recent applications of these techniques are presented. The advantages and potential limitations of each approach are also considered.
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Chromatographic analysis of allosteric effects between ibuprofen and benzodiazepines on human serum albumin
Chirality, 2005Co-Authors: Jianzhong Chen, Ilona Fitos, David S. HageAbstract:The effects of (R)- and (S)-ibuprofen on the binding of benzodiazepines to human serum albumin (HSA) were examined by biointeraction chromatography. The displacement of benzodiazepines from HSA by (R)- and (S)-ibuprofen was found to involve negative allosteric interactions (or possible direct competition) for most (R)-benzodiazepines. However, (S)-benzodiazepines gave positive or negative allosteric effects and direct competition when displaced by (R)- or (S)-ibuprofen. Association equilibrium constants and coupling constants measured for these effects indicated that they involved two classes of ibuprofen binding regions (i.e., low- and high-affinity sites). Based on these results, a model was proposed to explain the binding of benzodiazepines to HSA and their interactions with ibuprofen. This model gave good agreement with previous reports examining the binding of benzodiazepines to HSA.
Alioscka A Sousa - One of the best experts on this subject based on the ideXlab platform.
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Biointeractions of ultrasmall glutathione-coated gold nanoparticles: effect of small size variations
Nanoscale, 2016Co-Authors: Alioscka A Sousa, Sergio A Hassan, Luiza L Knittel, Andrea Balbo, Maria A Aronova, Peter Schuck, Patrick H. Brown, Richard D LeapmanAbstract:Recent in vivo studies have established ultrasmall (
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Biointeractions of ultrasmall glutathione coated gold nanoparticles effect of small size variations
Nanoscale, 2016Co-Authors: Alioscka A Sousa, Sergio A Hassan, Luiza L Knittel, Andrea Balbo, Maria A Aronova, P Brown, Peter Schuck, Richard D LeapmanAbstract:Recent in vivo studies have established ultrasmall (<3 nm) gold nanoparticles coated with glutathione (AuGSH) as a promising platform for applications in nanomedicine. However, systematic in vitro investigations to gain a more fundamental understanding of the particles’ Biointeractions are still lacking. Herein we examined the behavior of ultrasmall AuGSH in vitro, focusing on their ability to resist aggregation and adsorption from serum proteins. Despite having net negative charge, AuGSH particles were colloidally stable in biological media and able to resist binding from serum proteins, in agreement with the favorable bioresponses reported for AuGSH in vivo. However, our results revealed disparate behaviors depending on nanoparticle size: particles between 2 and 3 nm in core diameter were found to readily aggregate in biological media, whereas those strictly under 2 nm were exceptionally stable. Molecular dynamics simulations provided microscopic insight into interparticle interactions leading to aggregation and their sensitivity to the solution composition and particle size. These results have important implications, in that seemingly small variations in size can impact the Biointeractions of ultrasmall AuGSH, and potentially of other ultrasmall nanoparticles as well.
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Biointeractions of Ultrasmall Gold Nanoparticles: Influence of Nanoparticle Size and Surface Chemistry
Biophysical Journal, 2016Co-Authors: Luiza L Knittel, Sergio A Hassan, Maria A Aronova, Peter Schuck, Richard D Leapman, Alioscka A SousaAbstract:Recent studies have shown that gold nanoparticles (AuNPs) in the ultrasmall size regime (< 3 nm in diameter) can present distinct advantages for applications in nanomedicine, such as an efficient renal clearance in vivo. Herein we perform a systematic investigation of the effects of size and surface chemistry on the in vitro Biointeractions of ultrasmall AuNPs. Nanoparticle surface chemistry was modulated using small peptides as passivating ligands; size and uniformity were carefully characterized with dark-field scanning transmission electron microscopy (STEM) and analytical ultracentrifugation; and nanoparticle aggregation and serum protein adsorption were evaluated both experimentally by analytical ultracentrifugation as well as computationally by molecular dynamics simulations. First, our results showed that the colloidal stability of ultrasmall AuNPs in biological media can depend on seemingly small variations in core diameter. Our investigations also established how the surface chemistry could be tuned to produce ultrasmall AuNPs highly resistant to aggregation and adsorption from serum proteins.
S. Umapathi - One of the best experts on this subject based on the ideXlab platform.
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PVA and BSA stabilized silver nanoparticles based surface-enhanced plasmon resonance probes for protein detection.
Colloids and surfaces. B Biointerfaces, 2011Co-Authors: A. Nimrodh Ananth, S.c.g. Kiruba Daniel, T. Anitha Sironmani, S. UmapathiAbstract:To perform biosensing using nanoparticles in solution, silver particles were coated with bovine serum albumin (BSA) and polyvinyl alcohol (PVA) as control stabilizer. The plasmon resonance (420 nm) of the silver nanoparticles in solution was shifted slightly to longer wavelength (443 nm) when they were coated with BSA. The Biointeractions of these engineered nanoparticles were studied using a mouse model. No significant changes in behavior or toxicity were observed. The nanoparticles were detected in all tissues including the brain. Antibody recognition was monitored via the change in light absorption which accompanied binding, indicating that the particles can be used as a biosensor to gain more insight into cellular mechanisms governing the function of organs in general, and the blood brain barrier (BBB) and brain in particular.
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PVA and BSA stabilized silver nanoparticles based surface–enhanced plasmon resonance probes for protein detection B Biointerfaces
Colloids and Surfaces, 2011Co-Authors: A. Nimrodh Ananth, S.c.g. Kiruba Daniel, T. Anitha Sironmani, S. UmapathiAbstract:To perform biosensing using nanoparticles in solution, silver particles were coated with bovine serum albumin (BSA) and polyvinyl alcohol (PVA) as control stabilizer. The plasmon resonance (420nm) of the silver nanoparticles in solution was shifted slightly to longer wavelength (443nm) when they were coated with BSA. The Biointeractions of these engineered nanoparticles were studied using a mouse model. No significant changes in behavior or toxicity were observed. The nanoparticles were detected in all tissues including the brain. Antibody recognition was monitored via the change in light absorption which accompanied binding, indicating that the particles can be used as a biosensor to gain more insight into cellular mechanisms governing the function of organs in general, and the blood brain barrier (BBB) and brain in particular.
Marie Urbanová - One of the best experts on this subject based on the ideXlab platform.
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Bioinspired interactions studied by vibrational circular dichroism.
Chirality, 2009Co-Authors: Marie UrbanováAbstract:Vibrational circular dichroism (VCD) spectra are reliable indicators of the spatial structure of chiral molecules. The specific and characteristic feature of vibrational spectroscopy, and therefore also of VCD, where the energy of some vibrational modes is predominantly focused to a specific part of the molecule, enables monitoring both the structure of the molecule dissolved in different solvents and under different physicochemical conditions and molecular interactions. This minireview deals with recent contributions covering structural information on the bioinspired interactions obtained by means of VCD, especially in the following areas: interaction of DNA with biomolecules and biogenic metals, guanine tetramers and quadruplexes, Biointeractions of bile pigments, and polypeptide and protein interactions with other biomolecules.
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Bioinspired interactions studied by vibrational circular dichroism
Chirality, 2009Co-Authors: Marie UrbanováAbstract:Vibrational circular dichroism (VCD) spectra are reliable indicators of the spatial structure of chiral molecules. The specific and characteristic feature of vibrational spectroscopy, and therefore also of VCD, where the energy of some vibrational modes is predominantly focused to a specific part of the molecule, enables monitoring both the structure of the molecule dissolved in different solvents and under different physicochemical conditions and molecular interactions. This minireview deals with recent contributions covering structural information on the bioinspired interactions obtained by means of VCD, especially in the following areas: interaction of DNA with biomolecules and biogenic metals, guanine tetramers and quadruplexes, Biointeractions of bile pigments, and polypeptide and protein interactions with other biomolecules. Chirality 21:E215–E230, 2009. © 2009 Wiley-Liss, Inc.
Luiza L Knittel - One of the best experts on this subject based on the ideXlab platform.
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Biointeractions of ultrasmall glutathione-coated gold nanoparticles: effect of small size variations
Nanoscale, 2016Co-Authors: Alioscka A Sousa, Sergio A Hassan, Luiza L Knittel, Andrea Balbo, Maria A Aronova, Peter Schuck, Patrick H. Brown, Richard D LeapmanAbstract:Recent in vivo studies have established ultrasmall (
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Biointeractions of ultrasmall glutathione coated gold nanoparticles effect of small size variations
Nanoscale, 2016Co-Authors: Alioscka A Sousa, Sergio A Hassan, Luiza L Knittel, Andrea Balbo, Maria A Aronova, P Brown, Peter Schuck, Richard D LeapmanAbstract:Recent in vivo studies have established ultrasmall (<3 nm) gold nanoparticles coated with glutathione (AuGSH) as a promising platform for applications in nanomedicine. However, systematic in vitro investigations to gain a more fundamental understanding of the particles’ Biointeractions are still lacking. Herein we examined the behavior of ultrasmall AuGSH in vitro, focusing on their ability to resist aggregation and adsorption from serum proteins. Despite having net negative charge, AuGSH particles were colloidally stable in biological media and able to resist binding from serum proteins, in agreement with the favorable bioresponses reported for AuGSH in vivo. However, our results revealed disparate behaviors depending on nanoparticle size: particles between 2 and 3 nm in core diameter were found to readily aggregate in biological media, whereas those strictly under 2 nm were exceptionally stable. Molecular dynamics simulations provided microscopic insight into interparticle interactions leading to aggregation and their sensitivity to the solution composition and particle size. These results have important implications, in that seemingly small variations in size can impact the Biointeractions of ultrasmall AuGSH, and potentially of other ultrasmall nanoparticles as well.
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Biointeractions of Ultrasmall Gold Nanoparticles: Influence of Nanoparticle Size and Surface Chemistry
Biophysical Journal, 2016Co-Authors: Luiza L Knittel, Sergio A Hassan, Maria A Aronova, Peter Schuck, Richard D Leapman, Alioscka A SousaAbstract:Recent studies have shown that gold nanoparticles (AuNPs) in the ultrasmall size regime (< 3 nm in diameter) can present distinct advantages for applications in nanomedicine, such as an efficient renal clearance in vivo. Herein we perform a systematic investigation of the effects of size and surface chemistry on the in vitro Biointeractions of ultrasmall AuNPs. Nanoparticle surface chemistry was modulated using small peptides as passivating ligands; size and uniformity were carefully characterized with dark-field scanning transmission electron microscopy (STEM) and analytical ultracentrifugation; and nanoparticle aggregation and serum protein adsorption were evaluated both experimentally by analytical ultracentrifugation as well as computationally by molecular dynamics simulations. First, our results showed that the colloidal stability of ultrasmall AuNPs in biological media can depend on seemingly small variations in core diameter. Our investigations also established how the surface chemistry could be tuned to produce ultrasmall AuNPs highly resistant to aggregation and adsorption from serum proteins.