ZnO-Nafion assisted optical fiber dual-SPR biosensor for simultaneous detection of urea and uric acid concentrations

A novel dual-parameter optical fiber biosensor based on surface plasmon resonance (SPR) for simultaneous measurement of urea and uric acid concentrations is proposed in this paper. Based on the principle of positive and negative electric combination, ZnO nanoparticles is selected as the matrix for immobilizing urease and uricase with selective recognition ability, which can also be used as a sensitizing material to increase the refractive index detection sensitivity of SPR by 22%. Then, Nafion ion exchange membrane was introduced to wrap the urea sensing area to avoid crosstalk caused by the overlap of adjacent sensing areas. The difference in the number of enzymes loaded on ZnO nanoparticles was used to meet the refractive index gap for forming dual SPR detection channels. Experiments indicate that the sensitivity of urea detection is 1.6 nm/mM in the range of 1–9 mM urea concentration. The detection sensitivity of uric acid is 36 nm/mM in the concentration range of 50–500 μM. The detection ability of the sensor to actual biological samples was verified by serum samples, which proved that the sensor has practical application potential and reliable selectivity. It can provide a new idea for the research and development of multi-parameter optical fiber biosensors.