Enzymatic electrochemiluminescence sensor based on a ternary luminol-H2O2-confined nanocatalyst system for sensitive determination of uric acid.

An enzymatic electrochemiluminescence (ECL) sensor based on a ternary luminol system is developed for highly sensitive detection of uric acid (UA). The platform integrates nanochannel-confined platinum nanoparticle (PtNPs) and nitrogen-doped graphene quantum dot (NGQDs) nanocomposites (PtNPs-NGQDs) as coreaction accelerators, with urate oxidase (Uox) covalently immobilized at the nanochannel entrances. In this design, an amino-functionalized vertically ordered mesoporous silica film (NH2-VMSF) confined the PtNPs-NGQDs within its nanochannels, while Uox is attached to the outer surface. The confined PtNPs-NGQDs exhibit a synergistic catalytic effect, amplifying the ECL signal of the luminol-H2O2 system by 16.1-fold. In the presence of UA, immobilized Uox catalyzes its oxidation to generate H2O2, which is subsequently decomposed by the PtNPs-NGQDs nanocomposite, leading to enhanced ECL emission. Under optimized conditions, the sensor exhibits two linear response ranges for UA (0.01-1 µM and 1-50 µM) and a low detection limit of 8.1 nM (S/N = 3). The sensor also demonstrates good selectivity and stability, enabling reliable UA quantification in complex urine samples. This work provides a simple and versatile strategy for constructing sensitive ECL enzymatic platforms suitable for the detection of metabolites.