An integrated sensing system for detection of DNA using new parallel-motif DNA triplex system and graphene–mesoporous silica–gold nanoparticle hybrids

In this article, we demonstrate the use of graphene–mesoporous silica–gold NP hybrids (GSGHs) as an enhanced element of the integrated sensing platform for the ultra-sensitive and selective detection of DNA by using strand-displacement DNA polymerization and parallel-motif DNA triplex system as dual amplifications. We find that the present new sensing strategy based on GSGHs is able to detect target DNA with a fairly high detection sensitivity of 10 fm through the hybridization of duplex DNA to the acceptor DNA for the formation of parallel-motif DNA triplex on the multilayer film (containing GSGHs and redox probe) modified functional interface, and even has a good capability to investigate the single nucleotide polymorphisms (SNPs). The detection limit for target DNA is about two orders of magnitude lower than that of graphene-based DNA electrochemical impedance spectroscopy (EIS) sensor (6.6 pm), four orders of magnitude lower than those of graphene-based DNA sensors coupled with fluorescent assay (100 pm and 1 nm) and five orders of magnitude lower than those of field effect transistor (FET)-based assays (1 nm and 2 nm). Most importantly, our present sensing system can also be facilely achieved in the ITO electrode array, which is of paramount importance for possible multiplex analysis in lab-on-chip.