University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Michael Thompson

Abbrev:
Thompson, M.
Other Names:
Address:
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, Canada M5S 3H6
Phone:
+1-416-978-3575
Fax:
+1-416-978-3575

Citations 7

"Interfacial Properties Of Biotin Conjugate-avidin Complexes Studied By Acoustic Wave Sensor"
Langmuir 1999 Volume 15, Issue 2 Pages 564-572
Shakour Ghafouri and Michael Thompson

Abstract: The adsorption of avidin, neutravidin, and biotin-labeled dextran 10,000, dextran 70,000, bovine albumin, and insulin to the gold electrodes of thickness-shear-mode acoustic wave devices was studied in a flow injection analysis configuration. Electrodes with different surface rugosity and free energy were also examined Changes in series resonance frequency for the various molecules as a result of electrode adsorption cannot be explained in terms of the conventional mass-response effect. Perturbation of the properties of the protein and polysaccharide layers, such as their viscosity, and acoustic coupling phenomena offer a more reasonable basis to evaluate the results. In an analogous fashion, the acoustic wave sensor signals obtained for the formation of the various avidin-and neutravidin-biotin conjugate samples do not correspond to the additional mass deposited on the device surface. The responses for the binding of biotinylated insulin to avidin and to the nonglycosylated form of the parent mol. were completely different. This result is ascribed to a difference of surface free energy associated with the two protein-based interfaces. The acoustic wave sensor was also employed to investigate the formation of avidin-biotin conjugate multilayer structures on the surface of the device. Multilayer buildup is detectable for several pairs of avidin-biotin interactions, but the corresponding shifts in series resonance frequency gradually diminish in magnitude. Finally, the introduction of biotin itself appears to result in structural changes in the multilayer deposit, causing alterations in viscoelastic properties.
Adsorption

"Acoustic Waves And The Real-time Study Of Biochemical Macromolecules At The Liquid/solid Interface"
Faraday Discuss. 1997 Volume 107, Issue 1 Pages 159-176
B. A. Cavic, F. L. Chu, L. M. Furtado, S. Ghafouri, G. L. Hayward, D. P. Mack, M. E. McGovern, H. Su and M. Thompson

Abstract: The adsorption of the proteins, bovine serum albumin, fibrinogen, avidin and neutravidin (non-glycosylated form of avidin) to a variety of surfaces imposed on thickness shear mode sensors in examined in a flow injection analysis format. In all cases, adsorption of these moieties was essentially irreversible, although the magnitude of adsorption was dependent on surface free energy and functional group chemistry. Also described is the direct, real-time detection of the binding of peptides to HIV-1 TAR RNA bound on a thickness-shear mode (TSM) sensor surface. The results clearly indicate that responses are discriminatory for two different peptides. In order to provide a theoretical backcloth for the experimental measurements, a new model for the operation of the TSM in liquids is presented.
Proteins Albumin Fibrinogen Avidin Neutravidin Cow Serum Sensor Solid liquid interface

"Signaling Of Transcriptional Chemistry In The On-line Detection Format"
Biosens. Bioelectron. 2002 Volume 17, Issue 3 Pages 159-171
Christine N. Jayarajah and Michael Thompson

Abstract: A critical analysis of optical and acoustic wave instrumentation for examining the transcription apparatus and its regulation is given in the present review. The physico-chemical parameters derived from such in vitro experiments are important from a biophysical standpoint. The overall mechanism of transcription is composed of several mechanisms such as DNA-binding and promoter selection, closed and open polymerase complex formation, initiation of RNA synthesis, elongation and termination. Surface plasmon resonance (SPR) and fluorescence spectroscopy are widely employed techniques for investigating these mechanisms in real time. Although the binding of nucleotides, transcription factors (TFs) and inhibitors to RNA polymerase (RNAP) and the DNA template have been studied extensively, the synthesis of mRNA has not been investigated in detail except by methods based on electrophoresis. The use of acoustic wave physics for investigating transcriptional chemistry offers not only a time-course analysis but also the potential to gain insight into structural changes that occur during the process.

"Kinetic Characterization Of TAR RNA-Tat Peptide And Neomycin Interactions By Acoustic Wave Biosensor"
Biophys. Chem. 2003 Volume 106, Issue 3 Pages 241-252
Nardos Tassew and Michael Thompson

Abstract: The kinetics of binding of short Tat peptides and an aminoglycoside molecule to the human immunodeficiency virus-type 1(HIV-1) TAR RNA and to a bulge mutant analogue (MTAR) is studied in a biosensor format by monitoring the time course of the response in a series resonance frequency, using an acoustic wave biosensor. Association and dissociation rate constants are evaluated by fitting the experimental data to a simple 1:1 (Langmuir) model. Kinetic rate and equilibrium dissociation constants show that MTAR-peptide complexes are subject to a higher dissociation rate and are less stable compared to the corresponding TAR-peptide complexes. In addition, longer peptides display enhanced discrimination ability than a shorter peptide according to the equilibrium dissociation constants evaluated using this technique. KD values for TAR-Tat vs. MTAR-Tat complexes are 2.6 vs. 3.8 µM for Tat-12, 0.87 vs. 4.3 µM for Tat-18 and 0.93 vs. 1.6 µM for Tat-20. The equilibrium dissociation constant for TAR-neomycin complex is 12.4 µM and it is comparable to the values obtained from non-biosensor type assays. These findings are in parallel with those cited in the literature and the results from this study underline the potential of the acoustic wave sensor for detailed biophysical analysis of nucleic acid-ligand binding.

"Thickness-shear-mode Acoustic Wave Sensors And Flow Injection Analysis"
Anal. Chim. Acta 1992 Volume 269, Issue 2 Pages 167-175
Mengsu Yang and Michael Thompson*

Abstract: The feasibility of coupling a thickness-shear-mode (TSM) quartz-crystal sensor to a flow injection system was evaluated using network analysis. The flow injection analysis system (diagram given) consisted of a four-channel EVA-Pump Model 1000 peristaltic pump combined with a EVA-Valve Model 2000 injector valve. The PTFE tubing for the sample loop had an i.d. of 0.5 mm and all other tubing had an i.d. of 0.8 m. The 9 MHz AT-cut quartz piezoelectric crystals were coated with either Au or Ag electrodes. The quartz crystal was characterized using an HP 4195A Network/Spectrum Analyser. Flow injection analysis provided a method to relate the hydrodynamic response of the sensor to the concentration profile of the analyte produced by the dispersion behavior of sample zones. Network analysis of the thickness-shear mode sensor provided data on the bulk properties of the liquid sample and surface properties at the liquid - solid interface. A feasibility study of the combination of the flow injection analysis (FIA) technique with the piezoelec. acoustic wave sensor (thickness-shear mode, TSM) is described. Flow -injection systems provide a method to relate the hydrodynamic response of the sensor to the concentration.-time profile of the analyte produced by the dispersion behavior of sample zones. Network anal. of the TSM sensor generates multi-dimensional information on the bulk properties of the liquid sample and surface properties at the liquid/solid interface. The relationship between acoustic energy transmission and the interfacial structure, viscosity, density and dielectric constant of the analyte is discussed. The FIA-TSM system provides a rapid, reproducible detection method with enhanced sensitivity and scope.
Sensor Piezoelectric crystal Dispersion Detector Apparatus Viscosity

"Electromagnetic Excitation Of High Frequency Acoustic Waves And Detection In The Liquid Phase"
Analyst 2003 Volume 128, Issue 8 Pages 1048-1055
Michael Thompson, Scott M. Ballantyne, Larisa-Emilia Cheran, Adrian C. Stevenson and Christopher R. Lowe

Abstract: Excitation of acoustic waves in a quartz disk has been instigated by exposing the piezoelectric substrate to the electromagnetic field of a planar spiral coil placed in close proximity to the disk. It is argued that reciprocally induced magnetic and electric fields lead to secondary electric fields which couple with the piezoelectric tensor. A comparison of acoustic resonance envelopes recorded in air and in electrolyte demonstrates that spurious acoustic modes are damped in the liquid medium, and that the dielectric properties at the device-solution interface contribute to the exciting electric field. In agreement with previous acoustic device work, increased viscosity of the surrounding fluid leads to a rise in damping which manifests itself in changes in sensor frequency, amplitude and quality factor. With respect to work at high frequencies it is possible to operate the device at as high a harmonic as the 75th, although at this level of frequency resonance begins to break down because of a significant reduction in acoustic Q value. Finally, the use of the system in the flow-injection mode has also been demonstrated through the on-line detection of the adsorption of the protein, neutravidin, to the device surface. The glycosylated parent molecule is very widely employed as a linker for the immobilization of biological macromolecules in bioanalytical chemistry.

"Blood Platelet Adhesion To Protein Studied By On-line Acoustic Wave Sensor"
Analyst 2001 Volume 126, Issue 3 Pages 342-348
Biljana A. Cavic, John Freedman, Zeynep Morel, Meera Mody, Margaret L. Rand, David C. Stone and Michael Thompson

Abstract: The attachment of blood platelets to the surface of bare and protein-coated thickness-shear mode acoustic wave devices operating in a flow-through configuration has been studied. Platelets in washed from bind to the gold electrodes of such sensors, but the resulting frequency shifts are far less than predicted by the conventional mass-based model of device operation. Adherence to albumin and various types of collagen can be produced by on-line introduction of protein or by a pre-coating strategy. Differences in attachment of platelets to collagen types I and IV and the Horm variety can be detected. Platelets attached to collagen yield an interesting delayed, but reversible signal on exposure to a flowing medium of low pH. Scanning electron microscopy of sensor surfaces at various time points in this experiment reveals that originally intact platelets are eventually destroyed by the high acidity of the medium. The reversible frequency is attributed to the presence of removable platelet granular components at the sensor-liquid interface. [Journal Article; In English; England]