A high performance glucose biosensor enhanced via nanosized SiO2

A series of monodispersed nano-SiO2 film enhanced glucose biosensors with different thickness were fabricated by using dip-coating method. The suitable thickness of nanosized SiO2 film provided optimal environment for glucose oxidase to retain its bioactivity. A key factor to fabricate high sensitivity glucose biosensor was to enlarge the enzyme loading on the surface. The high surface area of the small nanosized SiO2 particles in the thick film increased the surface enzyme loading, resulting in the high performance of the biosensor. But if the film is too thick, the performance of the sensor would decrease because the mass transfer of glucose and H2O2 became difficulty. The electrochemical response of glucose with the 800 nm SiO2-biosensor revealed a linear behavior in the range of 0.005-2.5 mM glucose in pH 7.2 phosphate buffer solution. Such a glucose biosensor held its sensitivity as high as 71.1 μA mM−1 cm−2 and its detection limit as low as 0.3 μM. The good sensor-to-sensor reproducibility also indicates the simpleness and practicability of this kind of biosensor.