George S Wilson

University of Kansas | KU · Department of Chemistry

Histamine dehydrogenase from the gram-negative bacterium Rhizobium sp. 4-9 (HaDHR) is a member of a small family of dehydrogenases containing a covalently attached FMN, and the only member so far identified to date that does not exhibit substrate inhibition. In this study, we present the 2.1 Å resolution crystal structure of HaDHR. This new structu...

A minireview provides insights into spectroelectrochemistry with the Kuwana group being a major driving force. The review then considers the further application of these these techniques to proteins. Initially developed using uv‐vis spectroscopy many additional techniques were developed including those providing insight into the reaction of protein...

Oxidation of Met affects the stability of proteins, and was identified as a step in the beta amyloid-dependent pathogenesis of Alzheimer's disease. One-electron oxidation of Met is facilitated through stabilization of sulfide radical cations with electron-rich heteroatoms. The formation of such 2-center-3-electron bonds, formed between sulfide radi...

The electrochemical oxidation of thioethers is shown to be facilitated by neighboring amide participation. (1)H NMR spectroscopic analysis in acetonitrile solution of two conformationally constrained compounds with such facilitation shows that two-electron participation by the amide π2 orbital can occur to stabilize the developing sulfur radical ca...

S-tert-Butyl m-terphenyl thioethers have been efficiently synthesized by Suzuki–Miyaura coupling reactions with 2,6-dibromo-S-tert-butylthio benzene. Selective monocoupling could be achieved with o-substituted boronic acids. This facilitated the synthesis of unsymmetrical S-tert-butyl m-terphenyl thioethers and bis(S-tert-butyl m-terphenyl thioethe...

In this work, a sensitive electrochemical aptasensor for thrombin (TB) based on synergetic catalysis of enzyme and porous Au@Pd core-shell nanostructure has been constructed. With the advantages of large surface area and outstanding catalytic performance, porous Au@Pd core-shell nanostructures were firstly employed as the nanocarrier for the immobi...

An ideal biomarker for sleep should change rapidly with sleep onset, remain at a detectably differential level throughout the sleep period, and exhibit a rapid change with waking. Currently, no molecular marker has been identified that exhibits all three properties. This study examined three substances (lactate, glucose, and glutamate) for suitabil...

Methionine residues have been shown to function as efficient "hopping" sites in long-range electron transfer in model polyprolyl peptides. We suggest that a key to this ability of methionine is stabilization of the transient sulfur radical cation by neighboring proline amide participation. That is, in a model system a neighboring pyrrolidine amide...

We report on electroencephalograph (EEG) and electromyograph (EMG) measurements concurrently with real-time changes in l-glutamate concentration. These data reveal a link between sleep state and extracellular neurotransmitter changes in a freely-moving (tethered) mouse. This study reveals, for the first time in mice, that the extracellular l-glutam...

There are now available a wide range of electrochemical techniques which can provide fundamental information about both energetics and kinetics of thioether redox chemistry. Before discussing the various techniques, it is first appropriate to consider the kinds of reactions which thioethers are known to undergo and the information one desires about...

The electrochemistry of m-terphenylthio-, seleno-, and telluroethers was studied using cyclic voltammetry in acetonitrile. All of the compounds studied showed irreversible oxidations. The first oxidation potentials for the thio- and selenoethers are less positive than expected. This facilitation in oxidation is ascribed to through-space S center do...

Artificial neural networks (ANNs) are trained using high-throughput screening (HTS) data to recover active compounds from a large data set. Improved classification performance was obtained on combining predictions made by multiple ANNs. The HTS data, acquired from a methionine aminopeptidases inhibition study, consisted of a library of 43,347 compo...

To investigate neighboring amide participation in thioether oxidation, which may be relevant to brain oxidative stress accompanying beta-amyloid peptide aggregation, conformationally constrained methylthionorbornyl derivatives with amido moieties were synthesized and characterized, including an X-ray crystallographic study of one of them. Electroch...

Second by second measurement of neurochemicals such as glutamate, glucose and lactate in the brain using electrochemical biosensors is a powerful tool that has been used to profile concentration changes due to pharmacological and behavioral interactions. Now this ability to measure metabolic changes in targeted regions of the brain has been integra...

Synthesis of 6-endo and 6-exomethylthio-2-endoarylbicyclo[2.2.1]heptanes was accomplished stereoselectively. The ionization energies, determined by photoelectron spectroscopy, and electrochemical oxidation potentials, determined by cyclic voltammetry, were lower for the 6-endomethylthio compounds than for their 6-exomethylthio analogues. Calculatio...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A discussion on electrochemically based devices that will be used for single cells, cell cultures, tissue slices, and in vivo measurements is given as well as the dynamic concentration changes in ions as the likes of Ca 2+, Na +, K +, and H + that are all coupled with various stimuli. One these devices are the enzyme-based sensors which have played...

During the last decade or so, the term bioelectrochemistry has been used to describe a variety of research endeavors involving electrochemical phenomena of biological systems. The phenomena grouped under this heading include such diverse areas as generation of potentials across membranes, the oxidation-reduction chemistry of macromolecules, and the...

This is a first attempt at a brief sketch of the history of biosensors. It is far from complete and rather unsystematic. Many names are still missing, and we apologize for this. But the authors hope to have laid a humble cornerstone for a future “Complete History of Biosensors”. We hope that many of our colleagues will contribute!

Detailed understanding of the dynamics of living systems requires a means to monitor, in real time, changes in the levels of key components in response to specific stimuli. Applications involving cultured cells, tissue slices and implantation in living systems are discussed.

This chapter will provide an overview of radio frequency (RF) telemetry systems by examining the design requirements of two contrasting systems: a wireless system designed to support Fast Scan Cyclic Voltammetry (FSCV) and a wireless system designed to support selective biosensors. Traditionally, RF design and analog circuit design were very compli...

Acute promyelocytic leukemia (AML-M3) is characterized by a translocation between chromosomes 15 and 17 [t(15;17)]. The detection of t(15;17) at the single cell level, is commonly done by fluorescence in situ hybridization (FISH) using recombinant locus specific genomic probes greater than 14 kilobases kb in length. To allow a more thorough study o...

Biofouling of in vivo glucose sensors has been indicated as the primary reason for sensitivity losses observed during the first 24 h after implant [Wisniewski N, Moussy F, Reichert WM. Characterization of implantable biosensor membrane biofouling. Fresen J Anal Chem 2000; 366(6-7): 611-621]. Identification of the biomolecules that contribute to the...

Acute promyelocytic leukemia (AML-M3) is characterized by a translocation between chromosomes 15 and 17 [t(15:17)]. The detection of t(15;17) at the single cell level, is commonly done by fluorescence in situ hybridization (FISH) using recombinant locus specific genomic probes greater than 14 kilobases kb in length. To allow a more thorough study o...

The two main shortcomings of the state-of-the-art method of sorting chromosomes, specificity and the efficiency of fractionating a significant amount of chromosomes, are addressed by this work in the design of a massively parallel approach using magnetic beads binding to a chromosome-specific DNA probe. In an attempt to isolate human chromosome 15...

In vivo glucose sensor nitric oxide (NO) release is a means of mediating the inflammatory response that may cause sensor/tissue interactions and degraded sensor performance. The NO release (NOr) sensors were prepared by doping the outer polymeric membrane coating of previously reported needle-type electrochemical sensors with suitable lipophilic di...

The current status of sensors capable of continuous measurement of analytes in biological media is reviewed. This review containing 173 references deals with devices whose use in single cells, tissue slices, animal models and humans has been demonstrated. In addition to sensors specific for glucose, lactate, glutamate, pyruvate, choline and acetylc...

We report the picosecond and nanosecond timescale rotational dynamics of a dye-labeled DNA oligonucleotide or "aptamer" designed to bind specifically to immunoglobulin E. Rotational dynamics in combination with fluorescence lifetime measurements provide information about dye-DNA interactions. Comparison of Texas Red (TR), fluorescein, and tetrameth...

A rapid, homogeneous aptamer-based bioanalysis is reported for the sensitive detection of immunoglobulin E (IgE) using fluorescence polarization (FP). 5'-End-labeled D17.4 DNA aptamer was used for IgE detection based on the anisotropy differences of the labeled ligand. Two different fluorophores, fluorescein and Texas Red, were used to analyze IgE...

We report the picosecond time-scale fluorescence dynamics of a dye-labeled DNA oligonucleotide or "aptamer" designed to bind specifically to Immunoglobulin E. Comparison of the photophysics of Texas Red (TR), fluorescein and 5'-carboxytetramethylrhodamine (TAMRA)-labeled aptamers reveals surprising differences with significant implications for meas...

(3-Mercaptopropyl)trimethoxysilane (MTS) forms a unique film on a platinum substrate by self-assembly and sol-gel cross-linking. The gelating and drying states of the self-assembled MTS sol-gel films were probed by use of electrochemical and spectroscopic methods. The thiol moiety was the only active group within the sol-gel network. Gold nanoparti...

The metal-catalyzed oxidation (MCO) of proteins represents an important pathway for protein degradation. Although many mechanistic details of MCO are currently unknown, such mechanistic information would greatly benefit formulation scientists in the rational design and analysis of protein formulations. Here, we describe the Fenton oxidation (by Fe(...

The complexation between a triamide ligand derived from tris-2-(aminoethyl)amine: N-{2-[bis-(2-(4-tert-butylbenzoyl)-aminoethyl)-amino]-ethyl}4-tert-butylbenzamide, L, and the three adenosine-containing nucleotides, ATP, ADP, and AMP, was investigated by facilitated ion transfer processes through a microhole array film. Differential pulse voltammet...

The widespread use of miniaturized chemical sensors to monitor clinically important analytes such as PO2, PCO2, pH, electrolytes, glucose and lactate in a continuous, real-time manner has been seriously hindered by the erratic analytical results often obtained when such devices are implanted in vivo. One major factor that has influenced the analyti...

Due to the lag between sugar intake and the beginning of recovery from hypoglycemia, it is necessary to intervene in an anticipatory way if one wants to prevent, not only detect, hypoglycemia. This article presents the principle of a hypoglycemia prevention system based on risk assessment. The risk situation can be defined as the moment when the sy...

A procedure is described that provides co-immobilization of enzyme and bovine serum albumin (BSA) within an alumina sol-gel matrix and a polyphenol layer permselective for endogenous electroactive species. BSA has first been employed for the immobilization of glucose oxidase (GOx) on a Pt electrode in a sol-gel to produce a uniform, thin and compac...

The calibration of a continuous glucose monitoring system, i.e. the transformation of the signal I(t) generated by the glucose sensor at time (t) into an estimation of glucose concentration G(t), represents a key issue. The two-point calibration procedure consists of the determination of a sensor sensitivity S and of a background current I(o) by pl...

Calibration, i.e. the transformation in real time of the signal I(t) generated by the glucose sensor at time t into an estimation of glucose concentration G(t), represents a key issue for the development of a continuous glucose monitoring system. To compare two calibration procedures. In the one-point calibration, which assumes that I(o) is negligi...

For biosensor fabrication, it is important to optimize materials and methods in order to create predictable function in vitro and in vivo. For this reason, we designed a new glucose sensor ('revised protocol') that utilized an outer permselective membrane made of amphiphobic polyurethane which allows glucose passage through hydrophilic segments. An...

The direct electrodeposition of glucose oxidase (EC 1.1.3.4) on a platinum electrode was investigated as a means for controlled immobilization. The presence of a nonionic detergent, Triton X-100, was found essential to produce a multilayered deposit. Moreover, to work properly, the detergent must be present above its critical micelle concentration....

A procedure is described that provides for electrochemically mediated deposition of enzyme and a polymer layer permselective for endogenous electroactive species. Electrodeposition was first employed for the direct immobilization of glucose oxidase to produce a uniform, thin, and compact film on a Pt electrode. Electropolymerization of phenol was t...

The definition of a "primary method of measurement" [1] has permitted a full consideration of the definition of primary standards for pH, determined by a primary method (cell without transference, Harried cell), of the definition of secondary standards by secondary methods, and of the question whether pH, as a conventional quantity, can be incorpor...

The definition of a "primary method of measurement" [1] has permitted a full consideration of the definition of primary standards for pH, determined by a primary method (cell without transference, Harried cell), of the definition of secondary standards by secondary methods, and of the question whether pH, as a conventional quantity, can be incorpor...

A microITIES array, created by laser photoablation of a 12-microm polyester film, was used to investigate electroassisted anion transfer between two immiscible electrolyte solutions. Besides measuring directly the transfer of nitrate to the organic phase, the enhancement of transfer of the cation (K+) by facilitated anion (counterion) transfer was...

Two Divisions of the International Union of Pure and Applied Chemistry (IUPAC), namely Physical Chemistry (Commission I.7 on Biophysical Chemistry formerly Steering Committee on Biophysical Chemistry) and Analytical Chemistry (Commission V.5 on Electroanalytical Chemistry) have prepared recommendations on the definition, classification and nomencla...

Two Divisions of the International Union of Pure and Applied Chemistry (IUPAC), namely Physical Chemistry (Commission I.7 on Biophysical Chemistry formerly Steering Committee on Biophysical Chemistry) and Analytical Chemistry (Commission V.5 on Electroanalytical Chemistry) have prepared recommendations on the definition, classification and nomencla...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A preliminary characterization of protein adsorption and immunosorption kinetics carried out in polymer microchannels is reported. A photoablated poly(ethylene terephthalate) (PET) surface and a PET/polyethylene sealing laminate were used for the channel microfabrication. The surface state of the PET channel substrate and PET/polyethylene laminatio...

The synthesis of bifunctional antibodies using the principle of solid-phase synthesis is described. Two Fab' fragments were chemically linked together via a bismaleimide crosslinking reagent. The F(ab')(2) fragments from intact immunoglobulin G (IgG) were prepared using an immobilized pepsin column. Goat, mouse, and human antibodies were digested c...

To date, significant progress has been made in the development of sensors capable of in vivo measurements. The results are a consequence of proliferating cross-disciplinary interactions involving electrochemistry, spectroscopy, materials science, bioengineering, and medicine. In this article, the significant advances in in vivo biosensing are revie...

Syntheses are presented of the 1,2-dichalcogenins:  1,2-dithiin, 1,2-diselenin, and 2-selenathiin, both substituted and unsubstituted. 1,2-Dithiin and 1,2-diselenin are prepared by reaction of PhCH2XNa (X = S or Se) with 1,4-bis(trimethylsilyl)-1,3-butadiyne followed by reductive cleavage and oxidation. 2-Selenathiin is similarly prepared using a m...

The changes in plasma glucose concentration and in interstitial glucose concentration, determined with a miniaturized subcutaneous glucose sensor, were investigated in anesthetized nondiabetic rats. Interstitial glucose was estimated through two different calibration procedures. First, after a glucose load, the magnitude of the increase in intersti...

Progress in the area of faradaic bioelectrochemistry over the last decade has been reviewed. Electrochemical and spectroscopic studies of the protein–electrode interface are discussed along with the use of electron transfer promoters, self-assembled monolayers (SAMs), and surfactant films. Voltammetric techniques are described that permit rapid, in...

A microdisc sensor array, prepared by thin film technology, has been used as a model for miniaturized multi-functional biosensors. It consists of a series of wells, 20 μm in diameter, possessing a 1000 Å Pt layer at the bottom that serves as the indicating electrode. The depth of the wells ranged from 2.3–24 μm, depending on the photoresist employe...

Success in generating catalytic antibodies as enzyme mimics lies in the strategic design of the transition-state analog (TSA) for the reaction of interest, and careful development of screening processes for the selection of antibodies that are catalysts. Typically, the choice of TSA structure is straightforward, and the criterion for selection in s...

What caused the fish kill? Why does the beer smell 'skunky'? Are there properties of car bumpers that can be the basis of forensic data? George S. Wilson, Marc R. Anderson, and Craig E. Lunte describe a course in which students work in teams to solve 'real-world' problems.

Students work in groups to solve real-world problems.

Taxol (paclitaxel)--the natural product isolated from Pacific yew (Taxus brevifolia)--is a novel agent with high activity in the treatment of patients with several malignant tumors including those resistant to other cytotoxic drugs. The therapeutic index of this promising anticancer drug could be further increased by the exploration of its pharmaco...

The effectiveness of the carrier protein in eliciting antigen-specific antibodies was investigated. The effect of the carrier protein was independent of the conjugation chemistry involved. Keyhole limpet hemocyanin (KLH), purified protein derivative (PPD), and ovalbumin (OVA) were used as carrier proteins in the immunization of mice. Three antigens...

Biomolecules and cells are critical components of biosensors and biomaterials, but in order to function in an artificial environment, they must be immobilized in a manner that does not affect their interaction with target analytes. Biosensors demonstrate that we can harness the incredible functions of living molecules and cells for our own purposes...

Two Divisions of the International Union of Pure and Applied Chemistry (IUPAC), namely Physical Chemistry (Commission I.7 on Biophysical Chemistry formerly Steering Committee on Biophysical Chemistry) and Analytical Chemistry (Commission V.5 on Electroanalytical Chemistry) have prepared recommendations on the definition, classification and nomencla...

The aim of this work was to set up an experimental model of glycemic fluctuations for assessing in the conscious freely moving rat, the performance of a continuous glucose-monitoring system, using a pocket-calculator-size electronic control unit and a miniaturized subcutaneous glucose sensor. The well-known triphasic glycemic pattern following stre...

Miniature fluid pumps, measuring 15×4×1 mm, have been microfabricated with silicon, glass, and polyimide. Pumps have been tested with deionized water and 10% glycerol solutions as the working solutions. The pumps have been operated with a pneumatic drive or a piezoelectric drive. Flow rates from 0.1 to 110 μl min−1 have been achieved. The maximum p...

In this technical paper a summary of the available in situ spectroelectrochemical methods, their basic principles, their typical applications, and their limitations is given. With respect to the names of the methods and usual abbreviations, the paper follows the literature as far as possible, but tries to point out inconsistencies. An introductory...

Anion-exchange and immunoaffinity particle loaded membranes (PLMs) were investigated as a mechanism for the isolation of charged organic analytes from water. Kinetic properties determined theoretically included dynamic capacity, pressure drop (delta P), residence and diffusion times (Tr, Td), and total membrane porosity (epsilon T). These propertie...

'This project has as its focus the design and synthesis of polyammonium macrocyclic receptors for oxoanions of environmental importance. The basic research aspects of this project involve: (1) synthesis (and the search for improved synthetic methods); (2) solid state structure determination and thermodynamics studies (to ascertain structural criter...

This review covers the application of flow injection analysis to immunoassays (FIA-IA). The advantages and limitations of this approach are discussed. Future directions, particularly those involving microfluidic systems are highlighted.

A review of Biosensors: An Introduction

Tribological issues have received little attention in microfabricated system. Although work on miniature mechanical devices was initiated in the early 1970’s with the suspended beam and rotating electrostatic motor, issues of surface interactions in these structures has prevented their reliable operation. The application of the technology for the m...

A successfully developed enzyme-based lactate microsensor with rapid response time allows the direct and continuous in vivo measurement of lactic acid concentration with high temporal resolution in brain extracellular fluid. The fluctuations coupled to neuronal activity in extracellular lactate concentration were explored in the dentate gyrus of th...

Microfabrication technology has been successful in producing a wide range of miniature sensors and mechanical devices. Of particular interest is the application of this technology to biological systems. For instance an immunobiosensor for a bacterial food toxin with a sensitivity of 1 ng/mL and miniature reaction chambers have been fabricated for D...

A novel use of monoclonal antibodies to probe adsorbed protein conformation is described. Previous electrochemical studies (Zhang, D. B. et al. Anal. Chem. 1994, 66, 3873−3881) described the characteristics of the potential-dependent adsorption of Desulfovibrio vulgaris (Hildenborough) cytochrome c3 on a mercury electrode. Monoclonal antibodies wer...

A needle-type electrochemically based microsensor for glucose (110 microns o.d.) is described. This sensor, designed for monitoring transient glucose content changes in response to neural stimuli, has a response time of approximately 5 s and has been shown to be free of interference from endogenous electroactive species such as ascorbate, urate, an...

One-electron oxidation of copper(I) bis(1,4,7-trithiacyclononane), [CuI(TTCN-κ3)(TTCN-κ1)]+, 1, a coordination complex with a tetrahedral CuS4 core, to [CuII(TTCN-κ3)2]2+, 2, with an octahedral CuS6 core, has been studied by pulse radiolysis and electrochemistry in aqueous solution at various pH values. In addition to the geometry change about the...

A crucial step in developing a glucose monitoring system using a subcutaneous implanted glucose sensor is the transformation of the sensor signal (a current) into an estimation of a blood glucose concentration. We have developed an Electronic Control Unit (ECU) able to recognize, before and after a glucose load, that the sensor current presents a p...

The development of a hypoglycemic alarm system using a subcutaneous glucose sensor implies that a decrease in blood glucose is rapidly followed by a decrease in the signal generated by the sensor. In a first set of experiments the linearity and the kinetics of the response of sensors implanted in the subcutaneous tissue of normal rats were investig...

The mechanism of reducing the glucose sensitivity of sensors implanted into the subcutaneous tissue of the normal rat was evaluated (n = 10) by comparing sensitivities observed in vitro and in vivo. In vivo sensitivity was significantly lower than that observed in vitro before implantation (p < 0.005). Most interestingly, in vitro sensitivity immed...

An oxidase-based glucose sensor has been developed that uses a mercaptosilane-modified platinum electrode to achieve selectivity of electrochemical interferan