Discovery of the unique self-assembly behavior of terminal suckers-contained dsDNA onto GNP and novel "light-up" colorimetric assay of nucleic acids.

Noble metal nanoparticles are currently of great interest because of their unique optical properties and potential applications in disease diagnostics and cancer treatment. In the present work, a discovery was reported that dsDNA with terminal thiols at its two ends could lie easily flat onto the gold nanoparticle (GNP) surface rather than cross linked different GNPs, indicating an unique self-assembly behavior of newly-designed molecules on GNPs. This could intensively stabilize gold nanoparticles against aggregation even at a high salt concentration. On the basis of this discovery, a novel light-up colorimetric sensing strategy was developed for the detection of p53 gene by combining with the cyclical nucleic acid strand-displacement polymerization (CNDP). For the described colorimetric system, GNPs require no any surface functionalization, and target recognition reaction and CNDP amplification could be conducted under the optimized conditions to achieve a high efficiency. The high detection sensitivity and desirable selectivity are achieved, and the potential practical application was demonstrated. Besides, this sensing system can function in a wide range of salts, making it a suitable platform to cooperate with many biological processes.