An Ag+-stabilized triplex DNA molecular switch controlled hybridization chain reaction

Abstract

We described a new strategy to combine hybridization chain reaction (HCR) process and triplex DNA through Ag+/cysteine, thus to pursue the controllable process of HCR. H1, a specially-designed triplex DNA, with homopyrimidines which can bind to dsDNA through Hoogsteen bonding, forming a cap-like triplex DNA. The presence of Ag+ can play the role as a H1 locker to stop initiator from triggering HCR process, forming Ag+-stabilized triplex DNA molecular switch (denoted as Ag+-STDMS). However, the strong binding ability of cysteine towards Ag+ forming stable Ag+-cysteine can release the locking tail of H1 and realize the retriggering of HCR. This study presented a promising tool to regulate the self-assembly processes of DNA-based nanostructures in neutral environment. Under the optimum conditions, fluorescence intensity (peaking at 582 nm) of HCR is proportional to the concentration of Ag+ in the 0.2–4.0 μM range. Within the presence of Ag+, the fluorescence intensity is also proportional to the concentration of cysteine in the 0.2–3.0 μM range. The method can successfully manipulate the assembly and disassembly of DNA in HCR.