Functionalizable poly-terthiophene/CuO heterojunction constructed for sensitive photoelectrochemical detection of long non-coding RNA markers.

A photoelectrochemical (PEC) sensor based on the poly-2,2,5,2-terthiophene (pTTh)/CuO heterojunction was constructed and applied for the detection of long non-coding RNA (lncRNA) TROJAN, a biomarker of triple-negative breast cancer. CuO and pTTh were electrodeposited and sequentially onto an indium tin oxide substrate. The bandgap of the resultant type II heterojunction was measured spectroscopically and the morphology was found to effectively separate photogenerated holes from electrons. A photocurrent density as high as 250 μA cm was attained, which is about three times higher than those of only pTTh or CuO. Owing to the close contact between pTTh and CuO, this PEC sensor is highly stable. Oligonucleotide probes for lncRNA can be cross-linked to carboxyl moieties of mercaptopropionic acid molecules adsorbed on pTTh/CuO. The desirable band structure and the high density of probe molecules collectively yielded a linear range of 0.1-10 000 pM. Our PEC sensor has been demonstrated to be amenable for detection of lncRNA markers with excellent analytical performance.