Gold Nanoparticles and Uricase Functionalized Tapered Fiber Sensor for Uric Acid Detection

In this paper, a tapered optical fiber-based sensor is developed for the detection of uric acid (UA) in human serum. The fiber probes were fabricated using single-mode fiber (SMF) with taper diameter of 40 μm. The diameter of taper section has culminated on the basis of excretion of evanescent waves and their handling capacity. To enhance the sensitivity, taper section (sensing region) was immobilized with synthesized gold nanoparticles (AuNPs). The AuNPs were used to initiate the excitation of surface plasmons (SP) at the fiber surface and ultimately leads to the localized surface plasmon resonance (LSPR) phenomenon. The comparative studies were also done to analyze the effect of size of AuNPs by immobilizing the sensor probes with ~10 nm and ~30 nm size of AuNPs. The UV-Vis spectrophotometry, high resolution-transmission electron microscopy (HR-TEM) and scanning electron microscopy (SEM) were used for the characterization of AuNPs solution and developed sensor probes. The sensing ability of sensors was authenticated by recording the transmitted intensity of LSPR spectrum for a wide range of UA from 10 μM to 800 μM. The detected range of UA completely covers its concentration available in human serum that is from 150 μM to 420 μM. Thereafter, the wavelength shift in LSPR spectrums was evaluated to determine the sensitivity and detection limit of sensors. The selectivity of the sensor probe was enhanced by functionalizing it with uricase enzyme (0.672 U/ml). The specificity of uricase functionalized sensor probes were also analyzed in the presence of other biomolecules found in human-serum.