Ultrasensitive electrochemiluminescent immunosensing based on trimetallic Au–Pd–Pt/MoS2 nanosheet as coreaction accelerator and self-enhanced ABEI-centric complex

In this work, an ultrasensitive electrochemiluminescence (ECL) immunosensor for the determination of cystatin C (CYSC) was developed based on the combination of coreaction accelerator amplification and self-enhanced ECL luminophores. Trimetallic Au–Pd–Pt nanoflowers functionalized MoS2 nanosheet (Au–Pd–Pt/MoS2) was used as an efficient coreaction accelerator of ABEI/O2 ECL system. Besides, the coreactant l-cysteine (L-Cys) was also cross-linked with ABEI to obtain self-enhanced ABEI-centric complex (ABEI-Cys) which was further immobilized onto the surface of Au–Pd–Pt/MoS2 nanosheet, thereby achieving an outstanding signal tagging. Benefiting from the coreaction accelerator amplification of Au–Pd–Pt/MoS2 nanosheet towards ABEI/O2 ECL system and efficient self-enhanced ABEI-Cys complex, this developed ECL immunosensor for CYSC detection exhibited a wide linear range from 1.0 fg/mL to 5.0 ng/mL with low limit of detection down to 0.35 fg/mL. More importantly, this proposed ECL immunosensing system could remain excellent feasibility in human serum, showing great potential application in clinical diagnosis for proteins monitoring.