David John Pritchard

Glutamate oxidase enzyme electrodes: microsensors for neurotransmitter determination using electrochemically polymerized permselective films

Abstract Enzyme entrapment in electrochemically polymerized membranes is an attractive method for the development of stable reproducible enzyme microsensors with fast response times. In this paper the development of a biosensor for the determination of glutamate, involving the entrapment of the enzyme glutamate oxidase in two different electropolymerization matrices, is described. Subsequently, the kinetics of the immobilized enzyme in the different matrices are compared, and the role of the polymers in providing a permselective barrier for the exclusion of potential electroactive interferents are characterized.

Simultaneous determination of follicle stimulating hormone and luteinising hormone using a multianalyte immunosensor

A technique is described for constructing a multianalyte immunosensor for the quantitative determination of the human gonadotrophin hormones follicle stimulating hormone (FSH) and luteinising hormone (LH). The assay is a based upon the electrochemical detection of two horseradish peroxidase labelled antibodies using a ferrocene mediated system. The detection limits (3σ) were 2.1 U l−1 FSH and 1.8 U l−1 LH. There was negligible cross reactivity. Results obtained with the biosensor showed a good correlation with those obtained using an established clinical diagnostic technique based upon dissociation-enhanced lanthanide fluorometric immunoassay. This is the first report of an electrochemical multianalyte immunosensor for high molecular weight analytes.

Photo-patterning of sensor surfaces with biomolecular structures: characterisation using AFM and fluorescence microscopy.

The miniaturisation of biosensors has resulted in the need to develop techniques for the high resolution patterning of different biological molecules onto surfaces. In this paper, we describe a procedure for the selective deposition of antibodies using biological self-assembly with photo-activation of a bound ligand, and we will detail methods which may subsequently be used to characterise the resultant biomolecular constructs.

Biomolecular sensors for neurotransmitter determination: electrochemical immobilization of glutamate oxidase at microelectrodes in a poly(o-phenylenediamine) film

The adsorption of glutamate oxidase onto 25 Μm and 10 Μm platinum microelectrodes followed by immobilization in an electrochemically polymerized non-conducting polymer, poly(o-phenylenediamine), is described as a method of fabricating an enzyme electrode for the amperometric determination of glutamate. The response of the enzyme electrodes were found to be highly reproducible with a linear dynamic range upto approximately 15 mmol dm−3. The response of the 25 Μm and 10 Μm enzyme electrodes to glutamate were analysed using an established kinetic model and the potential application of the sensor for the study of neurotransmitter dynamics was investigated. The sensor was stable over a period of 30 days and the polymeric film was found to reduce interference from the electroactive compounds, uric acid and ascorbic acid.