Fabrication and features of a Methylene Green-mediating sensor for hydrogen peroxide based on regenerated silk fibroin as immobilization matrix for peroxidase

Regenerated silk fibroin prepared from waste silk was employed as immobilization matrix for peroxidase and the structures of the blend membranes of regenerated silk fibroin and peroxidase were first investigated with IR and scanning electron microscopy. There was intermolecular interaction between peroxidase and regenerated silk fibroin in the immiscible state. Cyclic voltammetry and constant applied potential measurement showed that Methylene Green efficiently mediated electron transfer from oxidized horseradish peroxidase in regenerated silk fibroin membrane to a glassy carbon electrode. A sensor coupling immobilized peroxidase with Methylene Green responded rapidly to low H(2)O(2) concentration and achieved 95% of the steady-state current in less than 25 s with a detection limit of 1.0 x 10(-7) M H(2)O(2). The sensor was stable in continuous operation, indicating that peroxidase was entrapped in regenerated silk fibroin membrane and did not freely diffuse away from the sensor surface into solutions.