Photoelectrochemical biosensors without external irradiation: Probing enzyme activities and DNA sensing using Hemin/G-quadruplex-stimulated chemiluminescence resonance energy transfer (CRET) generation of photocurrents

A hemin/G-quadruplex nanostructure that is immobilized on CdS quantum dots (QDs) associated with an electrode leads, in the presence of luminol, H ₂O ₂, and triethanolamine as an electron donor, to the generation of photocurrents with no external irradiation of the QDs. The hemin/G-quadruplex-catalyzed generation of chemiluminescence leads to the chemiluminescence resonance energy transfer (CRET) to the QDs, resulting in the photoexcitation of the QDs and the generation of electron-hole pairs. The transfer of the conduction-band electrons to the electrode, and the concomitant scavenging of the valence-band holes by the triethanolamine electron donor result in the generation of photocurrents. The CRET-stimulated generation of photocurrents is applied to sense DNA by the labeling of the probe-analyte complex with a hemin/G-quadruple, and is also implemented to follow the activity of glucose oxidase and to sense glucose, by the labeling of the enzyme with the hemin/G-quadruplex catalyst.