SnS2 Quantum Dots as New Emitters with Strong Electrochemiluminescence for Ultrasensitive Antibody Detection

Herein, we designed an electrochemiluminescence (ECL) biosensor with SnS₂ quantum dots (SnS₂ QDs) as novel emitters for the ultrasensitive assay of cytomegalovirus pp65 antibody (anti-CMV pp65) via smart circular peptide-DNA nanomachine amplification. First, the novel ECL biosensing platform was constructed by self-assembly of water-soluble, nontoxic, and earth-abundant SnS₂ QDs on the 3D hierarchical silver nanoflowers (Ag NFs) surface, where the Ag NFs, as coreaction accelerator in the ECL ternary (SnS₂ QDs/S₂O₈^2-/Ag NFs) system, could efficiently boost the ECL intensity of SnS₂ QDs. Furthermore, we designed a specific nucleic acid sequence labeled antigenic peptide to act as multifunctionalized capture probe (CP), which could specifically recognize the target antibody assisting with two auxiliary DNA strands via the proximity hybridization of DNA motifs to form a smart circular peptide-DNA nanomachine. Then, with the aid of nuclease, the resultant circular peptide-DNA nanomachine could initiate the subsequent cascade recycling amplification to output massive DNA products as mimic target (MT). As a result, the proposed ECL biosensor for anti-CMV pp65 detection exhibited high sensitivity with a wide linear range from 1 fM to 100 nM and a low detection limit (0.33 fM). Importantly, this work not only first utilized SnS₂ QDs as promising ECL emitters for biosensing platform construction but also opened an efficient way for highly sensitive and selective detection of antibody in disease diagnosis and clinical analysis.