Gold nanoclusters-incorporated nanogels as hybrid nanozymes for sensitive chemiluminescence immunoassays

Nanomaterials with excellent biocompatibility hold significant potential in chemiluminescence (CL) immunoassays. However, achieving green synthesis and maintaining the structural stability of such nanomaterials remain challenging. In this study, gold nanoclusters (Au NCs) were synthesized via the reduction of bovine serum albumin (BSA). These Au NCs were electrostatically combined with horseradish peroxidase (HRP) and chemically cross-linked to form Au NCs@BSA/HRP nanogels (ABH nanogels) with enhanced structural stability. The internal honeycomb architecture of the nanogels effectively prolongs the CL reaction. Within the nanogel, the dual catalytic system, composed of the Au NCs' mimetic peroxidase activity and the enzymatic activity of HRP, demonstrated high catalytic efficiency and stability. The nanogels also enhanced the luminol-H 2 O 2 system, producing sustained glow-type luminescence. Leveraging these properties, a sensitive and convenient CL immunoassay for CA15–3 detection was developed, with ABH nanogels serving as the signal detector. The sensor exhibited a broad linear detection range from 0.005 to 100 U/mL and a detection limit of 0.0015 U/mL (S/N = 3).