A sensitive and selective biosensor activated by tailor-designed platinum nanoparticles electrodeposited onto a gold microelectrode

A novel amperometric biosensor was fabricated for glucose sensing based on the precursor of a tailor-designed platinum nanoparticle (nano-Pt) modified polycrystalline gold disk-microelectrode (poly-Au DME). The platinum nanoparticles were electrodeposited onto poly-Au DME modified with a submonolayer (Au(sm)) of cysteine (nano-Pt/Au(sm)), and its resulting electrocatalytic activity was evaluated by chronoamperometry. By means of self-assembly technique, cysteamine was grafted on cysteine-modified nano-Pt/Au(sm) to introduce sulfhydryl groups for immobilization of gold nanoparticles (nano-Au) and adsorption of glucose oxidase (GOD, which acts as an enzyme template) at nano-Au. In order to improve the anti-interference ability, diethylenetriaminepentaacetic acid (DTPA), with negatively charged functional groups, was anchored on the modified microelectrode. This well-prepared biosensor shows remarkable electrocatalytic activity and selectivity towards hydrogen peroxide ejected from enzymatic activities, with a pronounced oxidation current at a low positive potential of 0.4 V (vs. Ag/AgCl). Glucose is chronoamperometrically determined, and the linear range is between 0.1 and 50 mu M, with a detection limit of 0.01 mu M. The response time is less than 5 s. In addition, it exhibits good reproducibility, strong stability, and less interference from other coexistent electroactive species.