Self-Assembled DNA Nanocentipede as Multivalent Drug Carrier for Targeted Delivery

An idea drug carrier, with good binding affinity, selectivity, drug payload capacity, and cellular internalized capability, will greatly improve the efficiency of target delivery. Herein a self-assembled and multivalent DNA nanostructure was developed as drug carrier for efficient and targeted delivery. The DNA structure was similar to that of a centipede, composed of trunk and legs: The trunk was a self-assembled DNA scaffold via hybridization chain reaction (HCR) from two biotinylated hairpin monomers created upon initiation by a trigger DNA, and the legs were biotinylated aptamers conjugated to the trunk via streptavidin-biotin affinity interaction. The long trunk of the "DNA nanocentipede" was loaded with doxorubicin (Dox), and the legs were SMMC-7721 cell-binding aptamers (Zy1) which functioned as targeting moieties to firmly and selectively grasp target cells. The results of agarose gel electrophoresis and fluorescence anisotropy confirmed that Zy1-based DNA nanocentipedes (Zy1-Nces) were successfully constructed. Flow cytometric analyses demonstrated that Zy1-Nces were more effective than free Zy1 in binding affinity and selectivity due to a multivalent effect. Confocal microscopy studies demonstrated that the internalization was highly dependent on the higher valences of DNA nanocentipedes without the loss of selectivity. Meanwhile, Zy1-Nces exhibited high drug-loading capacity and selective drug transport. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed enhanced cellular cytotoxicity of the Dox-loaded Zy1-Nces (Zy1-Nces-Dox) to the target SMMC-7721 cells but not negative control L02 cells. This approach is applicable to prepare drug carriers for other targets by construction of the nanocentipedes with relevant nucleic acid fragments.