Cu-doped In2S3 based DNA nanocluster for ultrasensitive photoelectrochemical detection of VEGF165

In this work, defective Cu-doped In2S3 (Cu: In2S3) was explored as photoactive material to fabricate a novel "signal-off" photoelectrochemical (PEC) sensing platform for ultrasensitive vascular endothelial growth factor 165 (VEGF165) detection. The defective Cu: In2S3 generated approximately ten times higher photocurrent than the pristine In2S3, which was attributed to the enhanced visible light absorption and electron-hole separation caused by the negative-charged defects induced by Cu doping. Moreover, an aptamer bridged nanocluster consisting of Cu: In2S3 material and DNA strand was assembled on the electrode as an efficient PEC signal indicator. The immobilized photoactive Cu: In2S3 could be released by recognition of the target VEGF165 to achieve a "signal-off" biosensor. The proposed PEC sensor performs a desirable detection response in the range of 10 fM to 100 nM VEGF165 with a low detection limit of 3 fM. This strategy not only avoided difficult assembly of diverse signal indicator and quenchers, but also significantly improved the detection sensitivity and linear range of PEC biosensor, offering a new perspective for construction of PEC biosensors for accurate, sensitive, and convenient bioanalysis and disease diagnosis.