Preparation of Horseradish Peroxidase Modified Gold Nanoparticle/Coiled Carbon Nanotube Nanocomposite and its application for bromate and nitrite determination

In this paper gold nanoparticles (AuNPs) were electrodeposited on the coiled carbon nanotubes (CCNTs) modified carbon ionic liquid electrode (CILE), and horseradish peroxidase (HRP) was fixed on the modified electrode by using Nafion film to get the modified electrode. HRP immobilized with AuNPs-CCNTs composite still retained the biostructure and direct electrochemistry of Nafion/HRP/AuNPs-CCNTs/CILE showed a quasi-reversible electrochemical behavior. Electrocatalysis to KBrO3 and NaNO2 were further checked with the apparent heterogeneous electron transfer rate constant (ks), the charge transfer coefficient (a) and the Michaelis-Menten constants (KappM) calculated. The linear detection range for KBrO3 concentration was from 0.5 to 10.0 mmol.L-1 with a detection limit of 0.16 mmol.L-1. And for NaNO2, the current response showed two linear sections in the concentration range from 0.1 to 0.7 mmol.L-1 and 0.9 to 3.0 mmol.L(-)1 with low detection limit of 0.03 mmol.L-1. The sensor was used for the real water samples analysis with high recovery, demonstrating the practical applications.

Automated summary

This study electrochemically deposited gold nanoparticles (AuNPs) on the surface of coiled carbon nanotubes (CCNTs) modified carbon ionic liquid electrode (CILE) and used Nafion film to immobilize horseradish peroxidase (HRP), resulting in a modified electrode. The HRP immobilized on the AuNPs-CCNTs composite retained its biostructure and exhibited quasi-reversible electrochemical behavior on the Nafion/HRP/AuNPs-CCNTs/CILE. The electrocatalytic activities towards KBrO3 and NaNO2 were further investigated, and the apparent heterogeneous electron transfer rate constant (ks), charge transfer coefficient (a), and Michaelis-Menten constants (KappM) were calculated. The linear detection range for KBrO3 was 0.5 to 10.0 mmol.L-1 with a detection limit of 0.16 mmol.L-1, while for NaNO2, the current response showed two linear sections in the concentration range of 0.1 to 0.7 mmol.L-1 and 0.9 to 3.0 mmol.L(-)1 with a low detection limit of 0.03 mmol.L-1. The sensor was successfully used for the analysis of real water samples, demonstrating its practical application.