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.