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 0.37V (vs. Ag/AgCl) in phosphate buffered solution (PBS) (0.10M, 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 0.5V vs. Ag/AgCl and PBS carrier (0.10M, pH 7.0) at a flow rate of 1.0mLmin−1. The linear working ranges for glucose measurements were 0.1–3mM (r2=0.995) and 5–100mM (r2=0.997), with corresponding sensitivities of 0.127 and 0.060 (μAs) mM−1, respectively. The system provides good precision of 2.8% R.S.D with a calculated detection limit (3S/N) of 15μM. The proposed method was successfully applied to determination of glucose in food and pharmaceutical samples with throughput of 200 samplesh−1. [Display omitted] •Preparation and characterization of CNTs–PDDA–PtNPs nanocomposites.•Effective composites for immobilization of GOx and enhancement of electron transfer.•Fabrication of sensitive and selective amperometric glucose biosensor (CNTs–PDDA–PtNPs–GOx/CPE).•Analysis of glucose in food and pharmaceutical samples with throughput of 200 samplesh−1.