Reconfiguration of DNA nanostructures induced by enzymatic ligation treatment.

Enzymatic ligation is a popular method in DNA nanotechnology for structural enforcement. When employed as stability switch for chosen components, ligation can be applied to induce DNA nanostructure reconfiguration. In this study, we investigate the reinforcement effect of ligation on addressable DNA nanostructures assembled entirely from short synthetic strands as the basis of structural reconfiguration. A careful calibration of ligation efficiency is performed on structures with programmable nicks. Systematic investigation using comparative agarose gel electrophoresis enables quantitative assessment of enhanced survivability with ligation treatment on a number of unique structures. The solid ligation performance sets up the foundation for the ligation-based structural reconfiguration. With the capability of switching base pairing status between permanent and transient (ON and OFF) by a simple round of enzymatic treatment, ligation induced reconfiguration can be engineered for DNA nanostructures accordingly.

A Biostable l-DNA Hydrogel with Improved Stability for Biomedical Applications.

DNA hydrogels have attracted increasing attention owing to their excellent permeability and high mechanical strength, together with thixotropy, versatile programmability and good biocompatibility. However, the moderate biostability and immune stimulation of DNA have arisen as big concerns for future potential clinical applications. Herein, we report the self-assembly of a novel l-DNA hydrogel, which inherited the extraordinary physical properties of a d-DNA hydrogel. With the mirror-isomer deoxyribose, this hydrogel exhibited improved biostability, withstanding fetal bovine serum (FBS) for at least 1 month without evident decay of its mechanical properties. The low inflammatory response of the l-DNA hydrogel has been verified both in vitro and in vivo. Hence, this l-DNA hydrogel with outstanding biostability and biocompatibility can be anticipated to serve as an ideal 3D cell-culture matrix and implanted bio-scaffold for long-term biomedical applications.

Kinetically Interlocking Multiple-Units Polymerization of DNA Double Crossover and Its Application in Hydrogel Formation.

A novel kinetically interlocking multiple-units (KIMU) supramolecular polymerization system with DNA double crossover backbone is designed. The rigidity of DX endows the polymer with high molecular weight and stability. The observed concentration of the formed polymers is insensitive and stable under ultralow monomer concentration owing to the KIMU interactions, in which multiple noncovalent interactions are connected by the phosphodiester bonds. Furthermore, a pH-responsive DNA supramolecular hydrogel is constructed by introducing a half i-motif domain into the DNA monomer. The rigidity of DNA polymer endows the hydrogel with high mechanical strength and low gelation concentration. This study enriches the KIMU strategy and offers a simple but effective way to fabricate long and stable supramolecular polymers by balancing the reversibility and stability. It also shows great potentials to construct next generation of smart materials, such as DNA nanostructures, DNA motors, and DNA hydrogels.

Reshaping the Landscape of the Genome: Toolkits for Precise DNA Methylation Manipulation and Beyond.

DNA methylation plays a pivotal role in various biological processes and is highly related to multiple diseases. The exact functions of DNA methylation are still puzzling due to its uneven distribution, dynamic conversion, and complex interactions with other substances. Current methods such as chemical- and enzyme-based sequencing techniques have enabled us to pinpoint DNA methylation at single-base resolution, which necessitated the manipulation of DNA methylation at comparable resolution to precisely illustrate the correlations and causal relationships between the functions of DNA methylation and its spatiotemporal patterns. Here a perspective on the past, recent process, and future of precise DNA methylation tools is provided. Specifically, genome-wide and site-specific manipulation of DNA methylation methods is discussed, with an emphasis on their principles, limitations, applications, and future developmental directions.

Preparing liposomes through frame guided assembly with high-loading functional nucleic acids.

Recently, a frame guided assembly (FGA) has been demonstrated as a robust tool to prepare liposomes with customized morphologies. However, the potential application of FGA liposomes in delivering nucleic acid drugs is still limited by the low payload. In this study, by systemically investigating the correlation between the leading hydrophobic group (LHG) density and the initial detergent concentration, it has been demonstrated that frames with a low LHG density, which may facilitate the increase of the load of the nucleic acid drug, could be guided to form liposomes at low initial detergent concentrations. By capitalizing on this phenomenon, FGA liposomes with a high loading of ASO/siRNA have been successfully prepared and applied to treat pathogenic genes.

Inducing Favorable Cation Antisite by Doping Halogen in Ni-Rich Layered Cathode with Ultrahigh Stability.

The cation antisite is the most recognizable intrinsic defect type in nickel-rich layered and olivine-type cathode materials for lithium-ion batteries, and important for electrochemical/thermal performance. While how to generate the favorable antisite has not been put forward, herein, by combining first-principles calculation with neutron powder diffraction (NPD) study, a defect inducing the favorable antisite mechanism is proposed to improve cathode stability, that is, halogen substitution facilitates the neighboring Li and Ni atoms to exchange their sites, forming a more stable local octahedron of halide (LOSH). According to the mechanism, it is demonstrated by NPD that F-doping not only induces the antisite formation in layered LiNi0.85Co0.075Mn0.075O2 (LNCM), but also increases the antisite concentration linearly. F substitution (1%) induces 5.7% antisite, and it displays an excellent capacity retention of 94% at 1 C for 200 cycles under 25 °C, outstanding high temperature cyclability (153.4 mAh·g-1 at 1 C for 120 cycles under 55 °C). The onset decomposition temperature increases by 48 °C. The ultrahigh cycling/thermal stability is attributed to the stronger LOSH, and it keeps the structural integrity after long cycling and develops an electrostatic repulsion force between oxygen layers to increase the lattice parameter c, which benefits Li-ion migration.