Selective and sensitive electrochemical detection of glucose in neutral solution using platinum-lead alloy nanoparticle/carbon nanotube nanocomposites

Electrodeposition of Pt-Pb nanoparticles (PtPbNPs) to multi-walled carbon nanotubes (MWCNTs) resulted in a stable PtPbNP/MWCNT nanocomposite with high electrocatalytic activity to glucose oxidation in either neutral or alkaline medium. More importantly, the nanocomposite electrode with a slight modification exhibited high sensitivity, high selectivity, and low detection limit in amperometric glucose sensing at physiological neutral pH (poised at a negative potential). At +0.30 V in neutral solution, the nanocomposite electrode exhibited linearity up to 11mM of glucose with a sensitivity of 17.8 mu RA cm(-2) mM(-1) and a detection limit of 1.8 mu M (S/N = 3). Electroactive ascorbic acid (0. 1 mM), uric acid (0. 1 mM) and fructose (0.3 mM) invoked only 23%, 14% and 9%, respectively, of the current response obtained for 3 mM glucose. At -0. 15 V in neutral solution, the electrode responded linearly to glucose up to 5 mM with a detection limit of 0. 16 mM (S/N = 3) and detection sensitivity of similar to 18 mu A cm(-2) mM(-1). At this negative potential, ascorbic acid, uric acid, and fructose were not electroactive, therefore, not interfering with glucose sensing. Modification of the nanocomposite electrode with Nation coating followed by electrodeposition of a second layer of PtPbNPs on the Nation coated PtPbNP/MWCNT nanocomposite produced a glucose sensor (poised at -0. 15 V) with a lower detection limit (7.0 mu M at S/N = 3) and comparable sensitivity, selectivity and linearity compared to the PtPbNP/MWCNT nanocomposite. The Nation coating lowered the detection limit by reducing the background noise, while the second layer of PtPbNPs restored the sensitivity to the level before Nafion coating. (C) 2007 Elsevier B.V. All rights reserved.