G-quadruplex formation enhancing energy transfer in self-assembled multilayers and fluorescence recognize for Pb2+ ions

Abstract

Here we demonstrate a novel strategy for the detection of Pb2+ ions and DNA based on the fluorescence resonance energy transfer in the self-assembled multilayers (SAMs). Quartz/GO/PDDA/G5/PDDA/GQDs@GSH SAMs were built by employing graphene oxide (GO) as the energy acceptor, glutathione-functionalized graphene quantum dots (GQDs@GSH) as the energy donor as well as poly(diallydimethylammonium) chloride (PDDA) and G5 (G-rich DNA) strand as the linker. In the presence of a certain amount of Pb2+ ions, G5 DNA could be folded into G-quadruplex, which was confirmed by Quartz Crystal Microbalance (QCM) experiments. The formation of G-quadruplex could lead to a change in the chain length and the shortening of the distance between GO and GQDs@GSH, thereby, the efficiency of energy transfer between GQDs@GSH and GO was enhanced with the quenching of fluorescence of GQDs@GSH. Meanwhile, Pb2+ ions could be recognized successfully.