Enzyme-coupled fluorescence sensor for sensitive determination of uric acid and uricase inhibitor

In this study, an enzyme-coupled fluorescence sensor was developed successfully for the sensitive detection of uric acid (UA) and uricase inhibitor based on graphene quantum dots (GQDs). UA was first oxidized using uricase and produced hydrogen peroxide (H₂ O₂ ), which could oxidize phenol to benzoquinone in the presence of horseradish peroxidase (HRP) as the catalysis. Benzoquinone is an efficient quencher and can cause fluorescence quenching of GQDs. The degree of quenching was proportional to UA concentration and was linear for the UA concentration in the ranges 0.2-14 μmol/L. The detection limit was 0.06 μmol/L for UA. In addition, the proposed sensor was further utilized for UA detection in human serum samples with satisfactory reproducibility and accuracy. The proposed strategy provided may be widely utilized to sense H₂ O₂ or H₂ O₂ generating processes in related biological environment.