Highly sensitive photoelectrochemical biosensor for microRNA159c detection based on a Ti

Herein, an ultra-sensitive photoelectrochemical biosensor based on Ti3C2:CdS nanocomposite was established for the selective detection of microRNA159c. Ti3C2:CdS nanocomposites were used as optoelectronic materials because Ti3C2:CdS interaction effectively separates photogenerated electrons and holes, and significantly improves the high photoelectric conversion efficiency. Firstly, Ti3C2:CdS nanocomposite was deposited on the surface of the fluorine-doped tin oxide (FTO) electrode. After the chitosan (CS) was dropped, the SH-miRNA were bonded on the electrode surface via the S-Cd bond. Then 6-mercaptohexanol (MCH) blocked the unbound site, the DNA strand was introduced to hybridize with the target SH-miRNA. At this time, the obtained photocurrent gradually decreases. Subsequently, the photosensitizer TMPyP as signal amplification was modified, the photocurrent increased significantly. The target SH-miRNA was detected based upon the photocurrent change originated from quantities change of TMPyP. Working under the best experimental conditions, the sensing platform had good stability, selectivity, and high sensitivity. The detection range for miRNA159c was 1.0 × 10-6-1.0 × 10-13 mol·L-l, and the detection limit was approximately 33 fmol·L-l. The detection of miRNA159c in human serum provided a huge opportunity to explore the relationship between the abundance of this miRNA and the incidence of breast cancer (BC), and to further achieve effective detection of BC.