A Refractometric Uric Acid Biosensor Based on Immobilized Uricase and PVA plus PEG Composite Hydrogels

A mechanically stable, high-sensitivity, high-selectivity, optical uric acid sensitive membrane (UASM) was prepared by immobilizing uricase in a mixture of SiO2 mesocellular foams (SiMCFs) and nanoparticles (SiNPs), then embedding it in a composite gel of polyvinyl alcohol (PVA) and polyethylene glycol (PEG). The UASM was spin-coated onto a gold-glass sheet to create a surface plasmon resonance (SPR) biosensor without electromagnetic and light-intensity disturbances. A series of prism-based SPR sensing experiments showed that, for a UASM consisting of SiMCFs and SiNPs at a mass ratio of 6:4, PVA and PEG at a mass ratio of 4:1, the resonance angle of the sensor decreased by about 2.610 degrees and the average sensitivity was 2.175 degrees/mM within a UA concentration range of 0 - 1.2 mM. Young's moduli of four dry UASM strips (670 - 1050 MPa) were obtained, demonstrating that UASMs have good biomechanical stability. Langmuir adsorption isotherm could explain the adsorption law of the UASMs for UA molecules in the concentration range of 0.2 - 1.2 mM.

Automated summary

A mechanically stable and high-sensitivity optical uric acid sensitive membrane (UASM) was successfully prepared and verified for its effectiveness and stability within the uric acid concentration range through experiments.