Using small circular DNA molecules of different lengths as scaffolds, we successfully synthesised DNA nanotubes consisting of Mao's DNA tensegrity triangle tiles with four-arm junctions (Holliday junctions) at all vertices. Due to the intrinsic curvature of the triangle tile and the consecutive tile alignment, the 2D arrays are organised in the form of nanotubes. Two sized triangle tiles with equilateral side lengths of 1.5 and 2.5 full helical turns are connected by the sticky ended cohesion of a duplex with a length of 2.5 helical turns respectively, and their parallel lozenge tiling lattices were demonstrated by high resolution AFM images, where the former lozenge unit cell has a lattice constant of 13.6 nm, and the latter has a larger lattice constant of 17.0 nm. Modification of the triangle tile with infinitesimal disturbance on side lengths and insertion of one thymine single stranded loop at every vertex resulted in comparably similar nanotubes.
DNA as a life's information carrier can be modified into geometrically fine nanostructures via self-assembly of designed nucleotides with specified length. In this work, three DNA minicircles with designed lengths of 48-nt, 50-nt, and 52-nt, are directed to self-assemble into nanotubes after hybridization with staple strands, following the folding strategy with each double crossover (DX) at 2.5 turns. Much smaller DNA minicircles such as the 32-nt ring are highly rigid once they form double helices, therefore they lack the flexibility to form finely ordered nanotubes. In the case of nanotubes comprising of 52-nt minicircles, most nanotubes were 800 nm long and 20% were up to 2 µm, whereas the nanotubes composed of 50 base pair subunits and 48 base pair subunits with the DX at frustrated 2.5 turns showed relatively shorter nanotubes at 700 and 600 (or 500) nm, respectively.
Poly(A-T)-rich sequences as stems of DNA dumbbell tiles have been evidenced to be more rigid than randomly-sequenced stems for construction of single crystalline 2D lattice arrays with sub-tiles resolved by AFM in slightly acidic solutions.
Highly efficient transmembrane transport of exogenous reagents into cells is of vital importance for developing drugdelivery systems. Conventionally, transmembrane transport of exogenous reagents was accomplished with the assistance of transfection agents or other artificial means. However, the high toxicity and low transport efficiency of current delivery techniques still remain to be solved. In this work, by anchoring artificial receptors onto cell membranes with a mild chemical reaction, we demonstrated that the exogenous reagent framework nucleic acids, namely tetrahedral DNA nanostructures (TDN) can bind onto cell membranes effectively by the hybridization between single-stranded DNA (ssDNA) and pendant ssDNA of TDN. The transport rate was greatly enhanced, with the endocytosis time could be as fast as 0.5 h. Furthermore, the transport quantity was prominently improved, with around 30 % of TDN endocytosed within 4 h. Owing to its rapid transmembrane transport speed and improved endocytosis quantity, this artificial-receptor-mediated transmembrane transport is a promising tool for achieving rapid and highly efficient transmembrane transport of exogenous reagents.[a] Dr.
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