Complexing self-assembled DNA nanostructures with various functional guest species is the key to unlocking new and exciting biomedical applications. Cationic guest species not only induce magnesium-free DNA to self-assemble into defined structures but also endow the final complex nanomaterials with new properties. Herein, we propose a novel strategy that employs naturally occurring cationic amino acids to induce DNA self-assembly into defined nanostructures. Natural l -arginine and l -lysine can readily induce the assembly of tile-based DNA nanotubes and DNA origami sheets in a magnesium-free manner. The self-assembly processes are demonstrated to be pH- and concentration-dependent and are achieved at constant temperatures. Moreover, the assembled DNA/amino acid complex nanomaterials are stable at a physiological temperature of 37 °C. Substituting l -arginine with its D form enhances its serum stability. Further preliminary examination of this complex nanomaterial platform for biomedical applications indicates that DNA/amino acids exhibit distinct cellular uptake behaviors compared with their magnesium-assembled counterparts. The nanomaterial mainly clusters around the cell membrane and might be utilized to manipulate molecular events on the membrane. Our study suggests that the properties of DNA nanostructures can be tuned by complexing them with customized guest molecules for a designed application. The strategy proposed herein might be promising to advance the biomedical applications of DNA nanostructures.

Diclofenac sodium (DCF) is a nonsteroidal anti-inflammatory drug (NSAID) and is widely used as an analgesic and anti-inflammatory agent. Herein, we found that DCF could relax high K + (80 mM K + )-/ACh-precontracted tracheal rings (TRs) in mice. This study aimed to elucidate the underlying mechanisms of DCF-induced relaxations. The effects of DCF on airway smooth muscle (ASM) cells were explored using multiple biophysiological techniques, such as isometric tension measurement and patch-clamping experiments. Both high K + - and ACh-evoked contraction of TRs in mice were relaxed by DCF in a dose-dependent manner. The results of isometric tension and patch-clamping experiments demonstrated that DCF-induced relaxation in ASM cells was mediated by cytosolic free Ca 2+ , which was decreased via inhibition of voltage-dependent L-type Ca 2+ channels (VDLCCs), nonselective cation channels (NSCCs), and Na +/ Ca 2+ exchange. Meanwhile, DCF also enhanced large conductance Ca 2+ activated K + (BK) channels, which led to the relaxation of ASMs. Our data demonstrated that DCF relaxed ASMs by decreasing the intracellular Ca 2+ concentration via inhibition of Ca 2+ influx and Na + /Ca 2+ exchange. Meanwhile, the enhanced BK channels also played a role in DCF-induced relaxation in ASMs. These results suggest that DCF is a potential candidate for antibronchospasmic drugs used in treating respiratory diseases such as asthma and chronic obstructive pulmonary disease.

Nonsmall cell lung cancer (NSCLC), driven by KRAS gene mutations, is a highly malignant disease currently lacking targeted medicines, except for a specific G12C mutation. However, nanotechnology-based interventions and nanomedicines hold great promise as alternatives to traditional chemotherapy. In this study, we propose a reverse engineering strategy to design and assemble DNA and RNA hybrid origami nanostructures as nanomedicines for the therapy of KRAS-mutated NSCLC. Instead of using M13 DNA as a scaffold for origami design, whose scaffold sequence is constant, the proposed reverse engineering strategy uses a pool of staple sequences that are constant while the scaffold sequences are variable. We conducted a research study on concept verification by designing DNA and RNA hybrid origami nanotubular structures whose staple strands are antisense oligonucleotides (ASON) that are complementary to the full exon regions of KRAS mRNA. The scaffold RNA sequence is thus determined by the ASON sequences and the geometry of the origami design. Once inside the cancer cells, the structure degrades the RNA and releases ASON under the activation of RNase H to exert an antitumor effect. The results from cellular experiments and in vivo studies demonstrated that the hybrid origami structure, composed of DNA and RNA, effectively inhibited both cell proliferation and tumor progression. Remarkably, the proposed reverse engineering method is a universal strategy that can be extended to designing nanomedicines targeting other pathogenic genes and diseases and has good prospects.