LSPR based uric acid sensor using graphene oxide and gold nanoparticles functionalized tapered fiber

In this work, two different tapered optical fiber sensor probes were developed to detect the Uric acid (UA) presents in human bodies. In first sensor probe, a uniform layer of graphene oxide (GO) was coated over the tapered fiber structure. In second probe, a layer of gold nanoparticles (AuNPs) was sandwiched between GO layer and fiber surface. The AuNPs ensures the generation of surface plasmons (SPs) and results in localized surface plasmon resonance (LSPR) phenomenon. Thereafter, LSPR phenomenon was used to sense the change in refractive index around the sensor head. The GO layer was used due to its inherent properties of binding the biomolecules. The AuNPs and GO solutions were characterized by transmission electron microscopy (TEM). The coating of AuNPs and GO over the sensing region was confirmed by scanning electron microscopy (SEM). The linearity test was performed by detecting the different concentration of UA solutions in the range of 10 mu M-800 mu M. The selectivity of sensor was enhanced by functionalization of nanomaterials-coated fiber with uricase enzyme. To verify the selectivity, several biomolecules present in human serum/urine were detected.