Mesoporous silica hollow sphere (MSHS) for the bioelectrochemistry of horseradish peroxidase

In this work, novel mesoporous silica hollow spheres (MSHS) were chosen as an immobilization matrix, to construct a mediator-free third-generation HRP biosensor. UV–vis spectroscopy revealed that horseradish peroxidase (HRP) entrapped in MSHS could retain its native structure. FTIR spectroscopy and nitrogen adsorption–desorption isotherms indicated that HRP are intercalated into the mesopores. The direct electron transfer of HRP entrapped in MSHS was observed. A pair of stable and well-defined redox peaks of HRP with a formal potential of about −0.150 V (vs. Ag/AgCl) in 0.1 M pH 7.0 phosphate-buffered solution (PBS) were obtained. The biosensor exhibited a fast amperometric response to H2O2 with a linear range of 3.9 × 10−6 to 1.4 × 10−4 M (R = 0.997, N = 20). The detection limit was 1.2 × 10−6 M based S/N = 3.