Issue 1, 2006
From the journal:

Analyst

The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity

Colm P. McMahon,a   Gaia Rocchitta,ab   Pier A. Serra,ab   Sarah M. Kirwan,a   John P. Lowryb  and  Robert D. O'Neill*a  

* Corresponding authors

a UCD School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
E-mail: Robert.ONeill@UCD.ie
Fax: +353-1-7162127
Tel: +353-1-7162314

b UCD School of Biomolecular and Biomedical Sciences, University College Dublin, Belfield, Dublin 4, Ireland

Abstract

The apparent Michaelis constant, KM, for glutamate oxidase (GluOx) immobilised on Pt electrodes increased systematically with enzyme loading. The effect was due, at least in part, to electrostatic repulsion between neighbouring oxidase molecules and the anionic substrate, glutamate (Glu). This understanding has allowed us to increase the Glu sensitivity of GluOx-based amperometric biosensors in the linear response region (100 ± 11 nA cm−2 µM−1 at pH 7.4; SD, n = 23) by incorporating a polycation (polyethyleneimine, PEI) to counterbalance the polyanionic protein. Differences in the behaviour of glucose biosensors of a similar configuration highlight a limitation of using glucose oxidase as a model enzyme in biosensor design.

Graphical abstract: The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity

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Article information

DOI
https://doi.org/10.1039/B511643K
Article type
Paper
Submitted
15 Aug 2005
Accepted
17 Oct 2005
First published
09 Nov 2005

Analyst, 2006,131, 68-72

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The efficiency of immobilised glutamate oxidase decreases with surface enzyme loading: an electrostatic effect, and reversal by a polycation significantly enhances biosensor sensitivity

C. P. McMahon, G. Rocchitta, P. A. Serra, S. M. Kirwan, J. P. Lowry and R. D. O'Neill, Analyst, 2006, 131, 68 DOI: 10.1039/B511643K

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