A Mechanically Stable and High-Sensitivity Glucose-Sensitive Membrane Based on the Entrapping of Immobilized GODs in PVA+PEG Composite Hydrogels

A mechanically stable and high-sensitivity optical glucose sensitive membrane (OGSM) is prepared by immobilizing glucose oxidases (GODs) onto a mixture of SiO2 mesocellular foams (SiMCFs) and nanoparticles (SiNPs) and embedding ImGODs in the composite gel of polyvinyl alcohol (PVA) and polyethylene glycol (PEG). The OGSM is coated onto a gold-glass sheet to create a surface plasmon resonance (SPR) sensor. For the OGSM consisting of SiMCFs and SiNPs with a mass ratio of 7:3, PVA and PEG with a mass ratio of 4:1, resonance angle of the sensor decreases from about 77.19° to 71.45°, and the average sensitivity is 0.029°/(mg/dL) in a glucose concentration range of 0-200 mg/dL. It was found that the volume fraction of glucose in the OGSM is linear approximately with the concentration of glucose when the concentration of glucose is lower than about 80 mg/dL, as described by the Freundlich isotherm model. The Langmuir isotherm model is suitable for describing the adsorption process of the OGSM for the glucose molecules in a concentration range of 80-200 mg/dL. In addition, Young's modulus of three strips of OGSMs, 0.573 MPa, 0.642 MPa, and 0.649 MPa were obtained, show that the OGSMs have good biomechanical stability.