Triple-Helix Molecular Switch Electrochemiluminescence Nanoamplifier Based on a S-Doped Lu₂O₃/Ag₂S Pair for Sensitive MicroRNA Detection

Development of sensitive detection methods for microRNAs has realistic application value for early clinical analysis and accurate diagnosis. In this study, a triple-helix molecular switch electrochemiluminescence resonance energy transfer (ECL-RET) nanoamplifier was designed to construct an electrochemiluminescence (ECL) biosensor for microRNA determination. The newly synthesized S-doped Lu₂O₃, which shows a 3 times better ECL performance than Lu₂O₃, was chosen as the donor in this ECL-RET system. Accordingly, Ag₂S quantum dots (QDs) were used as the matched acceptor. They exhibited overlapping spectra and efficient energy transfer between each other. Furthermore, using a triple-helix switch structure with an improved quenching effect for signal amplification and a nano-DNA walker transformational system as a powerful method for target amplification, a supernanoamplifier was achieved. As a consequence, the proposed ECL biosensor for microRNA-141 detection exhibited good analytical performance with a low detection limit (16 aM). The sensor not only led to the development of a novel ECL-RET pair but also provided a strong nanoamplifier for biosensing platform construction, which may offer some new considerations regarding material design, signal amplification, and show promising application value in biomedical and clinical diagnosis.