Amperometric biosensor for hydrogen peroxide based on ferrocene-bovine serum albumin and multiwall carbon nanotube modified ormosil composite

A novel amperometric biosensor for hydrogen peroxide (H2O2) was developed by entrapping horseradish peroxidase (HRP) in a new ormosil composite doped with ferrocene monocarboxylic acid–bovine serum albumin conjugate and multiwall carbon nanotubes (MWNTs). The ormosil was prepared using 3-(aminopropyl)triethoxysilane and 2-(3,4 epoxycyclohexyl)-ethyltrimethoxy silane as monomers. The encapsulated conjugate showed excellent electrochemistry and acted as an electron transfer mediator. The presence of MWNTs improved the conductivity of the composite film. This matrix showed a biocompatible microenvironment for retaining the native activity of the entrapped HRP and a very low mass transport barrier to the substrate, which provided a fast amperometric response to H2O2. The proposed H2O2 biosensor exhibited a linear range of 0.02–4.0 mM with a detection limit of 5.0 μM (S/N = 3) and a KMapp value of 2.0 mM. It could be used for flow injection analysis of hydrogen peroxide with a liner range from 0.02 to 4.5 mM, sensitivity of 0.042 μA/mM and analytical time of 20 s per sample. This biosensor possessed good analytical performance and storage stability.