CdSe quantum dots-decorated ZnIn2S4 nanosheets for “signal-on” photoelectrochemical aptasensing of ATP by integrating exciton energy transfer with exciton-plasmon coupling

Herein, we report CdSe quantum dots (QDs)-decorated ZnIn2S4 nanosheets for “signal-on” photoelectrochemical (PEC) aptasensing of adenosine triphosphate (ATP) by integrating exciton energy transfer with exciton-plasmon coupling. Under visible light irradiation, the CdSe/ZnIn2S4 shows higher PEC activity than ZnIn2S4 nanosheets and CdSe QDs resulting from the formation of n-n type heterojunction. To construct a PEC aptasensor, Au nanoparticle (AuNP)-labeled short DNA strand (denoted as c-DNA) is immobilized on the CdSe/ZnIn2S4 modified indium tin oxide (ITO) electrode and then hybridized with an aptamer to yield a double-stranded DNA. Before ATP incubation, AuNPs are kept away from the CdSe/ZnIn2S4/ITO, so the exciton energy transfer between CdSe QDs and AuNPs greatly quenches the photocurrent (“signal-off” state). After ATP incubation, AuNPs labeled on the c-DNA are in close contact with the CdSe/ZnIn2S4/ITO, and an increased photocurrent can be obtained due to the great exciton-plasmon coupling effect (“signal-on” state). This distance-triggered signaling “off–on” strategy enables sensitive aptasensing of ATP, with a broad linear range from 0.2 pM to 1 μM and a detection limit of 0.1 pM.