Target-induced photocurrent-polarity-switching photoelectrochemical aptasensor with gold nanoparticle-ZnIn2S4 nanohybrids for the quantification of 8-hydroxy-2′-deoxyguanosine

This work reports on an ultrasensitive photoelectrochemical (PEC) aptasensor for the detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG) by using target-triggered hemin/G-quadruplex photocurrent polarity switching on ultrathin ZnIn2S4 nanosheets (ZISNS). Hemin/G-quadruplexes were assembled on indium tin oxide (ITO) electrodes coated with gold nanoparticle-modified ZISNS (AuNPs-ZISNS) as signaling labels for the polarity inversion mechanism in PEC aptasensors. Benefiting from the excellent photoelectronic properties of AuNPs-ZISNS and the photocurrent polarity switching reliability of hemin, the proposed aptasensor for 8-OHdG detection was in a broad range from 1.0 pM to 10,000 pM with a detection limit of 0.3 pM. Moreover, this assay has shown sufficient sensitivity, favorable stability, and high selectivity in the detection of complex biological matrices. The recoveries were in the range of 92–108%, and the relative standard derivations (RSD) were ranged from 2.1% to 5.1%, indicating the good accuracy and high precision of this approach. Impressively, the concept of photocurrent-polarity-switching mode provides an alternative for constructing accurate and plausible PEC bioanalysis and inspires more interest in the design of advanced PEC bioanalysis through readout signal regulation.