Enhanced photoelectrochemical sensing for MUC1 detection based on TiO2/CdS:Eu/CdS cosensitized structure

A novel ultrasensitive photoelectrochemical aptasensing was developed to detect mucin 1 (MUC1) based on TiO2/CdS:Eu nanocomposite. The TiO2/CdS:Eu nanocomposite modified fluorine-doped tin oxide (FTO) electrode was prepared by successive ionic layer adsorption and reaction technique (SILAR) and then was employed as matrix for immobilization of SH-DNA (DNA1). After 6-mercaptohexanol (MCH) blocked unbound sites of the electrode surface, the MUC1 aptamer(DNA2) was introduced, allowing MUC1 aptamer to hybridize with DNA1. Subsequently, CdS-COOH QDs as signal amplification elements were successively labeled on the terminal of MUC1 aptamer. In this case, the target MUC1 detection was based upon the photocurrent change originated from quantities change of the signal amplification elements CdS. In the presence of MUC1, the MUC1 aptamer was specifically bound with MUC1, and meanwhile MUC1/DNA2/CdS was released from the electrode surface, resulting in significantly decreased photocurrent intensity. The novel ultrasensitive photoelectrochemical aptasensing presented a highly selective, sensitive and reproductive detection of MUC1 from 1 nM to 5 μM with a lower detection limit of 0.3 nM. At the same time, it also provided a good specificity, reproducibility, stability and promising strategy to detect a variety of other protein targets for early clinical diagnosis of different diseases.