Dual-mode SERS-ECL biosensor for robust detection of circulating miRNAs based on in-situ synthesized probes

A novel dual-mode biosensor integrating surface-enhanced Raman spectroscopy (SERS) and electrochemiluminescence (ECL) was developed for the reliable detection of acute myocardial infarction (AMI) related circulating miRNAs. The DNA walker nucleic acid amplification technique was employed for signal amplification and facilitated in-situ synthesis of ECL luminescent clusters and SERS probes. The alkynyl-modified silver nanocluster (AgNC) template strand and the azido-modified DNA probe on the electrode were connected through linker release facilitated by the continuous rolling and cutting action of the DNA walker on the spherical substrate. Under Cu+ catalysis, the alkynyl and azide groups at the junction undergo conversion into triazole molecules, which can serve as SERS probes. Subsequently, AgNCs were synthesized using a template method, with SERS signals emitted due to plasma resonance effects of triazole molecules situated between Au nanoparticles and AgNCs. The developed dual-mode analysis platform efficiently minimizes the potential for signal leakage, significantly corrects systematic errors, improves detection accuracy and sensitivity, and facilitates dependable identification of circulating miRNA. The detection of miRNA-133a exhibited a linear relationship within the concentration range of 100 aM to 1 nM, with detection limits of 32 aM and 0.17 fM in ECL and SERS modes, respectively. The SERS-ECL dual-mode detection platform may provide forward-looking ideas for the field of biosensing and clinical analysis.