Amperometric biosensor with HRP immobilized on a sandwiched nano-Au polymerized m-phenylenediamine film and ferrocene mediator

An amperometric biosensor has been developed for the determination of H2O2 in plant samples. Horseradish peroxidase (HRP) is immobilized on a sandwiched nano-Au particle / m-phenylenediamine polymer film by glutaraldehyde cross-linking. The film is formulated on the carbon paste electrode (CPE) blended with ferrocene as an electron transfer mediator. On the low concentration range, the current response is related to the H2O2 concentration linearly from 0 to 8x10(-6) M with a detection limit of 1.3x10(-7) M. On a wider concentration range of 8x10(-6) to 1.4x10(-4) M, the reciprocal of current response is linearly related to the reciprocal of H2O2 concentration. The apparent Michaelis-Menten constant (K-m(app)) was calculated to be 0.0334 mM. The sensor has been tested by determining H2O2 concentration in plant leaf samples.