Amperometric flow injection analysis of glucose using immobilized glucose oxidase on nano-composite carbon nanotubes-platinum nanoparticles carbon paste electrode

We report a novel amperometric glucose biosensor based on glucose oxidase (GOx) immobilized on a carbon nanotube (CNTs)-poly(diallyldimethyl-ammonium chloride) (PDDA)-platinum nanoparticle (PtNPs) modified carbon-paste electrode (CNTs-PDDA-PtNPs/CPE). The CNTs-PDDA-PtNPs composite materials were characterized by TEM and electrochemical techniques. Cyclic voltammetric results reveal direct electron transfer of the immobilized GOx, indicated by two quasi-reversible redox peaks at a potential of 0.37 V (vs. Ag/AgCl) in phosphate buffered solution (PBS) (0.10 M, pH 7). The biosensor provides good glucose oxidation activity and retention of GOx electrocatalytic activity due to CNTs-PDDA-PtNPs enhancement of the redox response. The carbon paste electrode was installed as working electrode in a flow through electrochemical cell of a flow injection (FI) system. Glucose was quantified using amperometric measurements at 0.5 V vs. Ag/AgCl and PBS carrier (0.10 M, pH 7.0) at a flow rate of 1.0 mL min(-1). The linear working ranges for glucose measurements were 0.1-3 mM (r(2)=0.995) and 5100 mM (r(2)=0.997), with corresponding sensitivities of 0.127 and 0.060 (mu A s) mM(-1), respectively. The system provides good precision of 2.8% R.S.D with a calculated detection limit (3 S/N) of 15 mu M. The proposed method was successfully applied to determination of glucose in food and pharmaceutical samples with throughput of 200 samples h(-1). (C) 2015 Elsevier B.V. All rights reserved.