Temperature controlling fiber optic glucose sensor based on hydrogel-immobilized GOD complex

• PNIPAAm was combined with immobilized GOD to form PIGC.
• PIGC could have switching effect for catalysis to glucose oxidation.
• A temperature controllable glucose sensor based on PIGC was developed.
• This sensor has good properties and can detect glucose in real samples.

A novel fiber optic glucose biosensor based on Poly(N-isopropylacrylamide) (PNIPAAm)-immobilized glucose oxidase (GOD) complex (PIGC) was developed. PIGC was prepared by combining PNIPAAm with GOD immobilized on SiO2 nanoparticles using in-situ complex method. The catalyzation of oxidation of glucose could be controlled based on the feature that PNIPAAm exhibited swelling and shrinking response to the temperature below and above low critical solution temperature (LCST), respectively. The biosensor can perform the controllable detection of glucose by changing temperature. The optimal detection conditions for this biosensor were achieved at pH 6.5, 30 °C and 10 mg of GOD amount. There is a good linear relationship between the phase delay difference φ and the glucose concentration in the range of 50–700 mg/dL. This biosensor has good repeatability, selectivity and can be used for the detection of practical samples.