Bioquímica e Bioquímica Analítica

Abstrato

Impedimetric Nanobiosensor Based on Biocatalysis of Catalase at CdTe Nafion Modified Glassy Carbon Electrode for Subnanomolar Detection of Hydrogen Peroxide

Mehdi Asgari1, Mojtaba Shamsipur

A robust and effective nano-composite film based on nafion-CdTe quantum dots modified glassy carbon electrode was prepared by droplet casting. The fabricated nano-composite was used to construct a novel catalase biosensor for the determination of hydrogen peroxide. Direct electron transfer and electrocatalysis of catalase were investigated. A pair of quasi-reversible redox peaks of catalase was observed in 0.20 M deaerated phosphate buffer solution of pH 7.0. The nano-composite film showed a pronounced promotion of the direct electron transfer among catalase and glassy carbon electrode. The immobilized catalase exhibited an excellent electrocatalytic activity towards the reduction of H2 O2 . Cyclic Voltammetry (CV), Chronoamperometry (CA) and Electrochemical Impedance Spectroscopy (EIS) were used to characterize the performance of the prepared nanobiosensor. The results showed that the prepared biosensor could be used as an amperometric biosensor for H2 O2 detection. The system was also found well suited for the use of impedimetry as an excellent biosensing system for hydrogen peroxide. The electrochemical impedance spectroscopy measurements revealed that the charge transfer resistance decreases significantly after enzymatic reaction with hydrogen peroxide concentration, so that the proposed modified electrode can be applied as an excellent nanobiosensor to the detection of ultra-traces of H2 O2 (2.0 × 10-10-2.0 × 10-9 M).