The study aimed to achieve enhanced targeted cytotoxicity and cell-internalization of cisplatin-loaded deoxyribonucleic acid-nanothread (CPT-DNA-NT),mediated by scavenger receptors into HeLa cells.DNA-NT was developed with stiff-topology utilizing circular-scaffold to encapsulate CPT.Atomic force microscopy (AFM) characterization of the DNA-NT showed uniformity in the structure with a diameter of 50-150 nm and length of 300-600 nm.The successful fabrication of the DNA-NT was confirmed through native-polyacrylamide gel electrophoresis analysis,as large the molecular-weight (polymeric) DNA-NT did not split into constituting strands under applied current and voltage.The results of cell viability confirmed that blank DNA-NT had the least cytotoxicity at the highest concentration (512 nM) with a viability of 92％ as evidence of its biocompatibility for drug delivery.MTT assay showed superior cyto-toxicity of CPT-DNA-NT than that of the free CPT due to the depot release of CPT after DNA-NT inter-nalization.The DNA-NT exhibited targeted cell internalizations with the controlled intracellular release of CPT (from DNA-NT),as illustrated in confocal images.Therefore,in vitro cytotoxicity assessment through flow cytometry showed enhanced apoptosis (72.7％) with CPT-DNA-NT (compared to free CPT;64.4％).CPT-DNA-NT,being poly-anionic,showed enhanced endocytosis via scavenger receptors.

DNA-nanotechnology-based nano-architecture scaffolds based on circular strands were designed in the form of DNA-nanowires(DNA-NWs)as a polymer of DNA-triangles.Circularizing a scaffold strand(84-NT)was the critical step followed by annealing with various staple strands to make stiff DNA-triangles.Atomic force microcopy(AFM),native polyacrylamide gel electrophoresis(PAGE),UV-analysis,MTT-assay,flow cytometry,and confocal imaging were performed to assess the formulated DNA-NWs and cisplatin(CPT)loading.The AFM and confocal microscopy images revealed a uniform shape and size distribution of the DNA-NWs,with lengths ranging from 2 to 4 μm and diameters ranging from 150 to 300 nm.One sharp band at the top of the lane(500 bp level)with the loss of electrophoretic mobility during the PAGE(native)gel analysis revealed the successful fabrication of DNA-NWs.The loading efficiency of CPT ranged from 66.85％to 97.35％.MTT and flow cytometry results showed biocompatibility of the blank DNA-NWs even at 95％concentration compared with the CPT-loaded DNA-NWs.The CPT-loaded DNA-NWs exhibited enhanced apoptosis(22％)compared to the apoptosis(7％)induced by the blank DNA-NWs.The release of CPT from the DNA-NWs was sustained at＜75％for 6 h in the presence of serum,demonstrating suitability for systemic applications.The IC50 of CPT@DNA-NWs was reduced to 12.8 nM CPT,as compared with the free CPT solution exhibiting an IC50 of 51.2 nM.Confocal imaging revealed the targetability,surface binding,and slow internalization of the DNA-NWs in the scavenger-receptor-rich cancer cell line(HepG2)compared with the control cell line.