Dual enzyme-mimetic activity of graphene oxide framework encapsulated copper-palladium bimetallic nanoparticles for uricase-free colorimetric detection of uric acid.

A novel CuPd@GOF nanocomposite is introduced, where copper and palladium nanoparticles (∼2 nm) are encapsulated within a three-dimensional graphene oxide framework (GOF), enabling superior catalytic performance. The rigid GOF structure ensures high nanoparticle dispersion, Maximizing atom utilization and catalytic efficiency. Additionally, Cu incorporation enhances activity through Fenton-like catalysis while reducing Material costs. The nanocomposite possesses a 2.72 eV bandgap, facilitating light harvesting ability for photocatalysis. CuPd@GOF exhibits dual enzyme-mimetic activities: a superior peroxidase-mimic activity, surpassing monometallic Cu@GOF and Pd@GOF, and an oxidase-mimic activity under external light irradiation. The peroxidase-mimic activity of this novel nanocomposite was exploited for uricase-free colorimetric detection of uric acid (UA), a key biomarker for gout and kidney disorders. The colorimetric assay utilizes Cu-mediated urate complexation and π-π interactions for enzyme-free detection, achieving a detection Limit of 12.62 µM with a broad linear range (5-100 µM) within 10 min. The method exhibits good selectivity against biological interferents and was successfully validated using fetal bovine serum, demonstrating its potential for biomedical applications.