Platinum nanoparticles-doped sol–gel/carbon nanotubes composite electrochemical sensors and biosensors

Platinum nanoparticle-doped sol–gel solution is prepared and used as a binder for multi-walled carbon nanotubes (CNT) for the fabrication of electrochemical sensors. Amine group containing sol–gel solution is selected to utilize the affinity of –NH2 groups toward metal nanoparticles for stabilization the nanoparticles in solution. The resulting CNT-silicate material brings new capabilities for electrochemical devices by using the synergistic action of the electrocatalytic activity of Pt nanoparticles and CNT. The combined electrocatalytic activity permits low-potential detection of hydrogen peroxide with remarkably improved sensitivity. With the incorporation of glucose oxidase within the Pt-CNT-silicate matrix, a Pt-CNT paste-based biosensor has been constructed that responds more sensitively to glucose than CNT-based biosensor. The influences of the composite of the sol–gel solution, the quantity of the solution and the Pt nanoparticles loading are examined. In pH 6.98 phosphate buffer, almost interference free determination of glucose is realized at 0.1 V versus SCE with a linear range from 1 to 25 mM, a response time <15 s, and the sensitivity is 0.98 μA mM−1 cm−2. The sensitivity of the Pt-CNT paste-based biosensor is almost four times larger than that of the CNT-based biosensor (0.27 μA mM−1 cm−2 at 0.1 V). The improved electrocatalytic activity and surface renewability made the Pt-CNT-silicate system a potential platform to immobilize different enzymes for other bioelectrochemical applications.