Organic small molecule catalytic PET-RAFT electrochemical signal amplification strategy for miRNA-21 detection

Quantitative detection of the cancer -associated biomarker miRNA-21 is essential for the prevention and treatment of early -stage cancer patients. In the early diagnosis of cancer, due to the low concentration of miRNA in the organism, it is necessary to develop a fast, simple, highly sensitive and specific method using signal amplification techniques. Herein, a photo -induced electron/energy transfer reversible addition -fragmentation chain transfer polymerization signal amplification electrochemical biosensor was developed. Peptide nucleic acid was used as the recognition probe for miRNA-21 and the chain transfer agent (4-cyano-4-(dodecylsulfonylsulfanylthiocarbonyl)sulfonylpentanoic acid) bearing a carboxylic acid group was successfully conjugated with a phosphate group in the presence of ZrOCl 2 to form the phosphate-Zr(IV)-carboxylic acid complex. Subsequently, the polymerization of the monomer (ferrocenylmethyl methacrylate) was achieved by blue light irradiation in the presence of erythrosin B (higher triple quantum yield) and triethanolamine (increases electron transfer rate). With this sophisticated signal amplification biosensing platform, low detection limit of 12.4 aM was achieved for miRNA-21. The biosensor reduces costs and simplifies experimentation while ensuring high sensitivity and selectivity. Meanwhile, the biosensor exhibits excellent anti -interference ability in serum samples and has great potential for practical applications in the early prevention of cancer.