Versatile Au nanoclusters/Au-MnO2 nanoflowers electrochemiluminescence energy transfer platform coupled with rolling circle amplification for dual-targets biosensing of PSA and Let-7a

Abstract

In this work, a versatile electrochemiluminescence (ECL) biosensor based on Au nanoclusters (AuNCs)/Au-MnO2 nanoflowers resonant energy transfer (RET) system coupled with rolling circle amplification (RCA) was designed for “OFF-ON” detection of prostate specificantigen (PSA) and Let-7a microRNA (miRNA). The biocompatible Au nanoclusters (Au NCs) displayed dramatically enhanced ECL intensitity and stability on 3,4-thiophene dicarboxylic acid (TDA) modified-electrode. Efficient ECL-RET system between AuNCs donors and Au-MnO2 nanoflowers (NFs) acceptors was constructed, which was used to develop a sandwich ECL immunosensor for signal “OFF” detection of PSA. Furthermore, Let-7a miRNA (target II) triggered RCA reaction to produce long DNA nanowires, which can bridge a large number of biotin-streptavidin to label alkaline phosphatase (ALP), catalyzing L-ascorbic acid-2-trisodium phosphate (AAP) to produce abundant ascorbic acid (AA). Then AA in-situ reduced MnO2 NFs to Mn2+, which inhibited ECL quenching, thus ECL was significantly recovered for “ON” detection of Let-7a. This versatile ECL platform combines 3,4-TDA-enhanced ECL of AuNCs, high quenching and oxidizing ability of Au-MnO2 NFs, and target-initiated RCA reaction for multi-target assay. The proposed multifunctional biosensing system is also suitable for highly sensitive detection of other disease-related proteins with promising actual and clinical applications.