Synergistic enhancement of fluorescein-K[Fe(CN)] CL by MoO NPs for sensitive and noninvasive detection of uric acid in saliva.

MoO NPs was rapidly synthesized at room temperature by an easy stirring method. It was interesting to find that MoO NPs induce OH to generate active free radicals (ROS), which is a highly promising property in chemiluminescence (CL). Benefiting from the abundant oxygen vacancy, MoO NPs adsorbs HO and turn it into ·OH. The oxidase activity of fluorescein under visible light had already been reported, which catalyzes dissolved oxygen to become O· and continue to convert to HO. By creating the synergy effect with fluorescein, MoO NPs strengthen the CL intensity of K[Fe(CN)]-fluorescein system significantly. Utilizing the quench effect of uric acid for the CL intensity, we developed a rapid, simple, and highly sensitive CL platform for uric acid detection. The linear range was 5-80 µM and the detection limit (LOD) for uric acid was 3.11 µM (S/N = 3). This work expanded the application of MoO NPs in the CL field and developed a simple and highly sensitive CL sensing system to detect UA in human saliva.