Photoelectrochemical biosensing of disease marker on p-type Cu-doped Zn0.3Cd0.7S based on RCA and exonuclease III amplification

In this work, a new “signal-on” split-type photoelectrochemical (PEC) sensing platform for prostate-specific antigen (PSA) detection was successfully constructed using p-type Cu-doped Zn 0.3 Cd 0.7 S as the photosensitive semiconductor material and target-triggered rolling circle amplification (RCA) for signal amplification . The signal derived from Cu-doped Zn 0.3 Cd 0.7 S was amplified by hemin/G-quadruplex. Upon target PSA introduction, the aptamer-primer probe (apt-pri) was captured by capture antibody-conjugated magnetic bead (MB-mAb) to form the sandwiched MB-mAb/PSA/apt-pri. The complex could initiate the RCA reaction to produce a long single-stranded DNA that provided binding sites for G-rich DNA and to form long single-stranded DNA/G-quadruplex/hemin. Upon the addition of exonuclease III (Exo III), the hemin/G-quadruplex immobilized on the RCA long product could be released by the digestion of Exo III. The hemin/G-quadruplex complexes in this study were used as efficient electron acceptors to neutralize the photoelectrons generated from the semiconductor and hindered the recombination of charges, thus enhancing the photocurrent . Under the optimum conditions, the developed sensing system displayed a good analytical performance with a linear range of 0.05–40 ng mL −1 PSA and a detection limit of 16.3 pg mL −1 . Furthermore, good selectivity , high anti-interference ability, satisfactory reproducibility, and good accuracy were also achieved. These prominent analytical properties revealed that our strategy might be a potential and reliable tool for the detection of PSA.