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, H2O2, 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.