Carbon nanotube/cobalt hexacyanoferrate nanoparticle-biopolymer system for the fabrication of biosensors

Cobalt hexacyanoferrate nanoparticles (CoNP) can be easily prepared by mixing hexacyanoferrate and cobalt chloride solution at room temperature. The nanoparticles were solubilized in aqueous solution of a biopolymer chitosan (CHIT). With the introduction of carbon nanotubes (CNT), the CoNP–CNT–CHIT system formed shows synergy between CNT and CoNP with the significant improvement of redox activity of CoNP due to the excellent electron-transfer ability of CNT. The CoNP–CNT–CHIT film modified glassy carbon electrode allows low potential detection of hydrogen peroxide with high sensitivity and fast response time. In particular, with the introduction of CNT, it amplified the H2O2 sensitivity by ∼70 times compared to film of CoNP–CHIT. With the immobilization of glucose oxidase onto the electrode surface using glutaric dialdehyde, a biosensor that responds sensitively to glucose has been constructed. In pH 6.98 phosphate buffer, interference free determination of glucose has been realized at −0.2 V versus saturated calomel electrode (SCE) with a linear range from 0.01 to 10 mM and response time <10 s. The detection limit was 5 μM glucose (S/N = 3).