Photoelectrochemical platform with tailorable anode-cathode activities based on semiconductors coupling DNA walker for detection of miRNA

Herein, an anode-cathode cooperative paper photoelectrochemical (PEC) platform was fabricated by the mutual attraction mechanism of different conductive semiconductors to realize the ultrasensitive monitoring of miRNA-155. Concretely, n-type ZnCdS nanorods and p-type BiOI hollow microspheres were sensitized simultaneously by CdS quantum dots (QDs) to amplify the initial signals of photoanode and photocathode, respectively. After the anode and cathode were integrated through the paper chip device, the bipolar synergy realized the secondary promotion of photocurrent signal. With the participation of target miRNA-155 and T7 Exo, DNA walker amplification was triggered to promote CdS QDs away from the electrode surface to destroy the matched energy level structure, leading to obvious signal attenuation. Excitedly, the quenching effect of photocurrent signal was twofold due to the fact that both photoelectrodes were equipped with sensing and identification steps. On the basis of the multifold amplification mechanisms, the designed platform exhibited excellent sensitivity, while the electrode zoning and cathode detection improved its selectivity. As far as I know, there is no research of using two photoelectrodes for simultaneous sensing construct to accomplish cascade amplification and quenching of signals, so it provides a novel reference for the fabrication of PEC analysis device.