Surface Plasmon Resonance Sensing Performance and Adsorption Law of Self-Assembly Glucose-Sensitive Membrane

A high-sensitive surface plasmon resonance (SPR) sensor was proposed using a self-assembly optical glucose-sensitive membrane (OGSM) and an osmoticprotection membrane on a glass/gold sheet. A prism and an OGSM were assembled to form a multilayer structure such as glass/gold/(PDDA/PSS)2/(PDDA/ImGODs)n/(PVA+PEG), where the ImGODs layer refers to immobilized glucose oxidases (ImGODs) on mixed nanoparticles consisting of SiO2 nanoparticles (SiNPs) and mesocellular foams (SiMCFs) and where polyvinyl alcohol and polyethylene glycol were used to form an osmotic-protection film. Many glucose-sensing experiments were performed to determine the optimal parameters of the OGSM proposed. For the OGSM with a mass ratio of SiMCFs:SiNPs = 7:3, the plasmon resonance angle of the glucose sensor reduced 2.60° and 0.26°/(mg/dL) of average sensitivity within the glucose concentration range from 0 to 10 mg/dL. The relationships among the resonance angle shift of the sensor, refractive index of the OGSM, and adsorption isotherm of the OGSM were established. The relationships showed that the Langmuir isotherm model was suitable for describing the adsorption process of the OGSM for glucose molecules in the concentration range of 0-80 mg/dL. For the SPR glucose sensor with three sensitive bilayers (PDDA/ImGODs)3, the dependence relationships of resonance angle shift and sensor sensitivity on glucose concentration, Δθres = -2.076C/ (1 + 0.707C) and S = 2.076/(1 + 0.707C)2, were obtained.