Glucose biosensor based on covalent immobilization of enzyme in sol–gel composite film combined with Prussian blue/carbon nanotubes hybrid

A novel electrochemical glucose biosensor was developed based on in situ covalent immobilization of glucose oxidase (GOx) by one-pot chitosan (CS)-incorporated sol–gel process in the presence of Prussian blue deposited multi-walled carbon nanotubes hybrids (PB/MWNTs) using 3-isocyanatopropyltriethoxysilane (ICPTES) as both a sol–gel precursor and a covalent coupling agent for GOx and CS. The electrode modified with the PB/MWNTs-GOx-CS-ICPTES sol–gel composite film showed good electrical conductivity and effective low-potential electron transfer mediation toward H2O2 reduction attributed to the incorporation of PB/MWNTs. The biosensor exhibited a linear response to glucose in the concentration range from 2.5 × 10−5 to 1.3 × 10−3 M with a correlation coefficient of 0.9998, a detection limit of 7.5 × 10−6 M, a low response time (10 s), good sensitivity and high anti-interference ability. Compared with the control biosensor based on the traditional tetraethoxysilane derived sol–gel composite film, the biosensor showed a similarly small apparent Michaelis–Menten constant of 3.67 mM but much higher electrochemical and biosensing stability.