A novel photoelectrochemical biosensor for the sensitive detection of dual microRNAs using molybdenum carbide nanotubes as nanocarriers and energy transfer between CQDs and AuNPs

Herein, a novel photoelectrochemical (PEC) biosensor was developed for the ultrasensitive detection of dual microRNAs (miRNAs), with the detection being based on energy transfer (ET) between carbon quantum dots (CQDs) and gold nanoparticles (AuNPs). The PEC platform consisted of a CQDs@Mo2C nanotube modified ITO electrode. Two hairpin probes (H1 and H2) carrying the Au NPs were used switch off and switch on the PEC signal of the CQDs, with a close approach of the tagged AuNPs to the CQDs quenching the PEC signal. The introduction of different miRNAs (miRNA-159b and miRNA-166a) altered the interparticle distance between the AuNPs and CQDs, thereby affecting the intensity of the PEC response. This approach allowed the highly sensitive detection of both miRNA-159b and miRNA-166a. The linear range of the biosensor for miRNA-159b and miRNA-166a detection were 0.5-5000 fM, with low detection limits of 0.15 fM and 0.21 fM, respectively. To our knowledge, this is the first reported CQDs-based ET biosensor for the PEC detection of dual miRNAs. Results suggest that this approach offers a promising platform for the ultrasensitive detection of multiple miRNAs.