Fiber Optic SPR-Based Uric Acid Biosensor Using Uricase Entrapped Polyacrylamide Gel

In this letter, we report a fiber optic biosensor based on surface plasmon resonance (SPR) for the detection of uric acid in aqueous samples. The sensing probe is prepared by successive coatings of silver and silicon layers over a small unclad length of the plastic clad silica optical fiber in the middle. Thereafter, the probe is dipped in a polyacrylamide gel containing enzyme uricase to immobilize it using a gel entrapment method. The sensor is characterized using a wavelength interrogation method. The SPR spectra corresponding to different concentrations of uric acid in the range of 0-0.9 mM are recorded. A red shift in the resonance wavelength is observed with an increase in the concentration of uric acid around the probe. In addition, the sensitivity of the proposed biosensor is studied in relation to parameters, such as concentration and pH of the uric acid solution. Finally, the sensor is highly selective and possesses better limit of detection and limit of quantification.