Design And Construction Of Novel DNA Nanomachines And The Application In MicroRNAs Imaging In Living Cells

The construction of engineered systems spans orders of magnitude in length-scale,ranging from traditional macroscopic machineries to more recent microscopic mechanical systems.The miniaturization of systems puts new demand on their constituent materials and corresponding engineering approaches.DNA nanomachines consisting of DNA or DNA composite nanostructure with other nanomaterial using DNA as the main component,can simulate the function of machine to complete specific biological functions in nanometer scale by converting some free energy into mechanical energy.To date,many versatile DNA nanomachines have been explored.Such devices include DNA tweezers,DNA gear,DNA logics,DNA walkers,DNA nanosensors and so on.In this paper,we explored two novel entropy-driven DNA walker nanomachines via autonomous walking along the DNA-AuNP track,and applied them for specific microRNAs imaging in living cells.The operation of these two DNA walker nanomachines was powered by the entropy-driven catalytic reaction,with a higher operation efficiency due to the intramolecular reaction induced by target.To the best of our knowledge,it is the first example of applying dynamic,nonenzymatic AuNP-based machines to image specific microRNAs inside living cells.Our nanomachines not only possess the merits of conventional AuNP conjugates of powerful versatility with high cellular transfection efficiency,stability,low immunogenicity,and fluorescence superquenching,but also have the superior sensitivity(pM concentration)almost three orders of magnitude lower than the conventional static AuNP conjugates model(nanoflare,nM concentration).This is due to accelerated intramolecular reaction speed resulting from motion components co-anchored on a single AuNP.Importantly,our nanomachine displays a high signal-to-noise ratio ascribing to the special design in walking leg.We believe that it offers a new insight on rational design of AuNP-based machine and expands the application fields.