FeCuS multilayer nanoflowers loaded with N-CDs dual-mode method for the detection of uric acid and gout risk prediction with the aid of chemometrics.

Transition metal sulfides have attracted much attention due to their low cost, high stability, adjustable performance, diverse morphology and good catalytic activity. In this work, nitrogen-doped carbon dots (N-CDs) were loaded onto bimetallic sulfides (FeCuS) and FeCuS/N-CDs could act as catalyst and fluorescent probe, which applied to the detection of uric acid (UA) in human blood and urine using dual-model assay (colorimetry and ratiometric fluorescence). The nanozyme has excellent peroxidase-like activity and steady-state kinetic results showed that the material prepared under optimized conditions had better affinity (K_m = 0.42 mM) for the substrate and faster reaction rate (V_max = 14.1 × 10^-8 M s^-1). •OH and O₂^•- were involved in the catalytic process of o-phenylenediamine (OPD) by FeCuS/N-CDs nanozymes. A profound discussion and quantitative analysis about the sensing mechanism of UA and fluorescence quenching mechanism between FeCuS/N-CDs and diaminophenazine (DAP) was performed. According to Parker equation, the inhibition efficiency of DAP in FeCuS/N-CDs was as high as 83 % of the total inhibition efficiency, confirming that the inhibition efficiency mainly came from internal filtering effect (IFE). The detection limits of ratiometric fluorescence method and colorimetric method were as low as 0.13 μM and 0.27 μM, respectively. Finally, principal component analysis was used to successfully distinguish three groups of people (healthy people, potential people and gout patients) and the model has potential value in clinical applications.