Chain-based precision amplification biosensor for microRNA detection based on dCas13a system and iridium complex

Abstract

Considering the close association between the abnormal expression of multiple microRNAs (miRNAs) and various diseases, multi-channel detection of miRNAs holds significant importance for disease diagnosis. However, traditional miRNA detection methods fall short of simultaneously achieving the required specificity, sensitivity, and multi-channel capability. To address this challenge, we developed a chain-based precision amplification photoelectrochemical biosensor for the simultaneous detection of multiple miRNAs, based on dCas13a system and iridium complex. The precise recognition of miRNA is achieved by the dCas13a-crRNA complex and then converted into a significant photocurrent response from iridium nanocomposite attached to a long double-stranded nucleic acid chain, thereby enabling signal amplification, namely chain-based precision amplification. The dCas13a-crRNA complex is modified onto a multi-channel electrode to simultaneously recognize and bind multiple target miRNAs. The iridium complex is modified on the surface of energy-level-matched quantum dots to suppress carrier recombination, and Au nanoparticles are further modified on the surface of the quantum dots, thereby constructing a nanocomposite for efficient photoelectric conversion. A double-stranded sequence is constructed at the 3' end of the miRNA to increase the attachment sites for the nanocomposite. The biosensor demonstrates exceptional specificity and sensitivity, capable of distinguishing single-base differences with a detection limit as low as the aM level, benefiting from the chain-based precision amplification. Furthermore, clinical sample testing underscores the practical applicability of the biosensor in clinical diagnostics. This multi-channel chain-based precision amplification biosensor offers a highly valuable and innovative approach for the simultaneous detection of multiple miRNAs, with considerable potential for clinical diagnostic applications.