Immobilization of horseradish peroxidase in mesoporous silica/silver nanoparticle/chitosan composite material for biosensor application

Abstract

The ultimate aim of this research was to investigate the immobilization of Horseradish peroxidase in mesoporous silica/silver nanoparticle/chitosan composite material using electrochemical method with glassy carbon electrode. In this study, the experiments were divided into three parts. Firstly, mesoporous silica type MCF was synthesized and silver nanoparticles were attached on MCF. The synthesized MCF has average pore size of 23.7 nm and total surface area of 629.97 m²/g. Secondly, the effects of amount of mesoporous silica (0.1 – 1 % w/v), chitosan concentration (0.1 – 1 % w/v), and silver nanoparticle concentration (20 – 100 ppm) on electrochemical response were studied. It was revealed that additives such as MCF and Ag particles helped enzyme dispersion to a certain concentration, however, higher concentration of additives resulted in higher substrate/product mass transfer limitation. In addition, Ag particles were found to help enhancing electrical response. Optimal compositions of modified electrode were 20 ppm Ag solution, 0.5 %w/v chitosan, 0.7%w/v modified MCF and 10 mg/ml HRP. The optimal composition of enzyme immobilization was further applied to investigate the reusability of immobilized enzyme. The use of modified electrode was limited to only once. The main cause was probably enzyme leakage from chitosan matrix.