Increasing enzyme-like activity by: In situ anchoring of Ag₃PO₄ nanoparticles on keratin-inorganic hybrid nanoflowers

Herein, we propose a strategy of rapid assembly of Ag₃PO₄ nanoparticles (NPs) within three dimensional (3D) keratin-inorganic hybrid nanoflowers (keratin-NF@Ag₃PO₄) with a facile in situ ion sedimentation approach. The 3D porous networks greatly prevent polycondensation of Ag₃PO₄ NPs because of the porous and interconnected microstructures, which enhanced the catalytic activity in the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) into a blue colored product (oxTMB) in the presence of H₂O₂. However, the addition of uric acid (UA) could lead to the reduction of oxTMB, resulting in fast fading of the blue color. Inspired by this finding, a simple and sensitive colorimetric assay for uric acid (UA) has been developed with a detection limit (LOD) of 0.94 μM. Furthermore, this strategy has been successfully applied to the detection of UA in practical samples.