Oxygen tolerance of an implantable polymer/enzyme composite glutamate biosensor displaying polycation-enhanced substrate sensitivity.
Biosensors were fabricated at neutral pH by sequentially depositing the polycation polyethyleneimine (PEI), the stereoselective enzyme L-glutamate oxidase (GluOx) and the permselective barrier poly-ortho-phenylenediamine (PPD) onto 125-microm diameter Pt wire electrodes (Pt/PEI/GluOx/PPD). These devices were calibrated amperometrically at 0.7 V versus SCE to determine the Michaelis-Menten parameters for enzyme substrate, l-glutamate (Glu) and co-substrate, dioxygen. The presence of PEI produced a 10-fold enhancement in the detection limit for Glu (approximately 20 nM) compared with the corresponding PEI-free configurations (Pt/GluOx/PPD), without undermining their fast response time (approximately 2 s). Most remarkable was the finding that, although some designs of PEI-containing biosensors showed a 10-fold increase in linear region sensitivity to Glu, their oxygen dependence remained low.
McMahon
Colm P
CP
UCD School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
Rocchitta
Gaia
G
Kirwan
Sarah M
SM
Killoran
Sarah J
SJ
Serra
Pier A
PA
Lowry
John P
JP
O'Neill
Robert D
RD
D000594:Amino Acid Oxidoreductases; D015374:Biosensing Techniques / Q000295:instrumentation*; D018698:Glutamic Acid / Q000032:analysis*; D007700:Kinetics; D010100:Oxygen; D011073:Polyamines; D000071228:Polyelectrolytes; D013379:Substrate Specificity
D000594:Amino Acid Oxidoreductases; D018698:Glutamic Acid; D010100:Oxygen; D011073:Polyamines; D000071228:Polyelectrolytes; C023061:L-glutamate oxidase