Dimensional Control of Highly Anisotropic and Transparent Conductive Coordination Polymers for Solution-Processable Large-Scale 2D Sheets.

Controlling the dimensional aspect of conductive coordination polymers is currently a key scientific interest. Herein, solution-based dimension control strategies are proposed for copper chloride thiourea (CuCl-TU) coordination polymers that enable centimeter-scale, 2D nanosheet formation for use as transparent electrodes. Despite the wide bandgap of CuCl-TU polymers (4.33 eV), through polaron-mediated electron transfer, the electrical conductivity of the 2D sheet at room temperature is able to reach 4.45 S cm-1 without intentional doping. This leads to a highly anisotropic electronic conductivity of up to the order of ≈103 differences, depending on the material orientation. Furthermore, by substituting alternative thiourea candidates, it is demonstrated that it is possible to predesign CuCl-TU structures with the desired functionality, stability, and porosity through dimensional control. These findings provide a blueprint to design next-generation transparent conducting materials that can operate at room temperature, thereby expanding their applicability to different fields.

Slippery, Water-Infused Membrane with Grooved Nanotrichomes for Lubricating-Induced Oil Repellency.

Water, abundant and ubiquitous in nature, is an easy yet powerful resource for the creatures to survive by putting together with their topologies interfacing their living environment. Here, a slippery, water-infusing surface (SWIS) that retains a thick and stable water layer on the membrane is presented, robustly maintaining the oil repellency against the pressure and friction of immiscible liquids. Inspired by the plant trichome structures and their function, grooved nanotrichome, formed on the fibrous membrane by the oxygen plasma etching, induces robust water lubrication on the SWIS. SWIS membrane repels and separates highly viscous and adhesive oils in air and underwater by preventing oils from adhering to the lubricating surface. Repeated tests both in air and underwater confirm the antiadhesion and self-cleaning properties of the SWIS. The SWIS oil scooper, fixed on a frame with a handle, successfully collects spilled oil on a pilot-scale oil spill site and a real ocean oil spill site by simply scooping and recovering the oil. In addition, SWIS membrane is expected to help protect environments with further applications such as oil-wastewater treatment and oil separation in food.

Respiratory Safety Evaluation in Mice and Inhibition of Adenoviral Amplification in Human Bronchial Endothelial Cells Using a Novel Type of Chlorine Dioxide Gas Reactor.

Since the onset of the COVID-19 pandemic, there has been a growing demand for effective and safe disinfectants. A novel use of chlorine dioxide (ClO2) gas, which can satisfy such demand, has been reported. However, its efficacy and safety remain unclear. For the safe use of this gas, the stable release of specific concentrations is a must. A new type of ClO2 generator called Dr.CLOTM has recently been introduced. This study aimed to investigate: (1) the effects of Dr.CLOTM on inhibiting adenoviral amplification on human bronchial epithelial (HBE) cells; and (2) the acute inhalation safety of using Dr.CLOTM in animal models. After infecting HBE cells with a recombinant adenovirus, the inhibitory power of Dr.CLOTM on the virus was expressed as IFU/mL in comparison with the control group. The safety of ClO2 gas was indirectly predicted using mice by measuring single-dose inhalation toxicity in specially designed chambers. Dr.CLOTM was found to evaporate in a very constant concentration range at 0-0.011 ppm/m3 for 42 days. In addition, 36-100% of adenoviral amplification was suppressed by Dr.CLOTM, depending on the conditions. The LC50 of ClO2 gas to mice was approximately 68 ppm for males and 141 ppm for females. Histopathological evaluation showed that the lungs of female mice were more resistant to the toxicity from higher ClO2 gas concentrations than those of male mice. Taken together, these results indicate that Dr.CLOTM can be used to provide a safe indoor environment due to its technology that maintains the stable concentration and release of ClO2 gas, which could suppress viral amplification and may prevent viral infections.

Single-step plasma-induced hierarchical structures for tunable water adhesion.

Smart surfaces in nature have been extensively studied to identify their hierarchical structures in micro-/nanoscale to elucidate their superhydrophobicity with varying water adhesion. However, mimicking hybrid features in multiscale requires complex, multi-step processes. Here, we proposed a one-step process for the fabrication of hierarchical structures composed in micro-/nanoscales for superhydrophobic surfaces with tunable water adhesion. Hierarchical patterns were fabricated using a plasma-based selective etching process assisted by a dual scale etching mask. As the metallic mesh is placed above the substrate, it serves the role of dual scale etching masks on the substrate: microscale masks to form the micro-wall network and nanoscale masks to form high-aspect-ratio nanostructures. The micro-walls and nanostructures can be selectively hybridized by adjusting the gap distance between the mesh and the target surface: single nanostructures on a large area for a larger gap distance and hybrid/hierarchical structures with nanostructures nested on micro-walls for a shorter gap distance. The hierarchically nanostructured surface shows superhydrophobicity with low water adhesion, while the hybrid structured surface becomes become superhydrophobic with high adhesion. These water adhesion tunable surfaces were explored for water transport and evaporation. Additionally, we demonstrated a robust superhydrophobic surface with anti-reflectance over a large area.

Subwavelength Hollow-Nanopillared Glass with Gradient Refractive Index for Ultralow Diffuse Reflectance and Antifogging.

Nanostructured glass with subwavelength hollow nanopillars of diameters of sub-65 nm was fabricated, showing high optical transmittance and ultralow diffuse reflectance. A simple process involving single-step plasma etching was used on a glass slide coated with a SiO2 sacrificial film. First, SiO2 nanodot structures were formed using plasma-induced anisotropic etching with CF4 plasma. The SiO2 nanodot array then became a secondary etching mask to form hollow nanopillars on the glass. The hollow structures formed at the upper part reaching up to the apex of the nanopillar had a lower solid fraction, while the lower part had a higher fraction. The refractive index (RI) gradually increased from 1.09 (near the value for air) to 1.42 (near the value for glass). Geometry-induced RI gradient enhanced light transmi, while it significantly reduced diffuse reflectance, particularly in the shorter wavelengths, thus suppressing the haziness or milky appearance of the nanostructured glass. Superhydrophilic and antifogging properties of nanostructured glasses and dental mirrored glasses were also demonstrated with water spraying and exhaled breath tests. Results showed that the wettability was enhanced in hydrophilicity and antifogging property by both the hydrophilic nature of the glass and the newly formed nanostructures. The nanostructured, superhydrophilic glass was also found to have easy cleaning nature against fine sand dust adhesion by simply blowing air or spraying water. Results of this study showed that such a hollow-pillared glass surface with gradient RI and special wettability could be applied in a variety of optical and optoelectronic applications requiring superwetting, such as optical windows for solar cell panels, display panels, light-emitting diodes, and medical devices even with curved surfaces.

Plasma-Based Nanostructuring of Polymers: A Review.

There are various fabrication methods for synthesizing nanostructures, among which plasma-based technology is strongly competitive in terms of its flexibility and friendly uses, economy, and safety. This review systematically discusses plasma techniques and the detailed interactions of charged particles, radicals, and electrons with substrate materials of, in particular, polymers for their nanostructuring. Applications employing a plasma-based nanostructuring process are explored to show the advantages and benefits that plasma treatment brings to many topical and traditional issues, and are specifically related to wettability, healthcare, or energy researches. A short perspective is also presented on strategic plans for overcoming the limitations in dimension from surface to bulk, lifetime of surface functions, and selectivity for interactions.

Targeted delivery of a phosphopeptide prodrug inhibits the proliferation of a human glioma cell line.

Peptides are ideal candidates for developing therapeutics. Polo-like kinase 1 is an important regulatory protein in the cell cycle and contains a C-terminal polo-box domain, which is the hallmark of this protein family. We developed a peptide inhibitor of polo-like kinase 1 that targets its polo-box domain. This new phosphopeptide, cRGDyK-S-S-CPLHSpT, preferentially penetrates the cancer cell membrane mediated by the integrin receptor, which is expressed at high levels by cancer cells. In the present study, using high performance liquid chromatography and mass spectroscopy, we determined the stability of cRGDyK-S-S-CPLHSpT and its cleavage by glutathione under typical conditions for cell culture. We further assessed the ability of the peptide to inhibit the proliferation of the U87MG glioma cell line. The phosphorylated peptide was stable, and the disulfide bond of cRGDyK-S-S-CPLHSpT was cleaved in 50 mM glutathione. This peptide inhibited the growth of cancer cells and changed their morphology. Therefore, we conclude that the phosphopeptide shows promise as a prodrug and has a high potential to act as an anticancer agent by inhibiting polo-like kinase 1 by binding its polo-box domain. These findings indicate the therapeutic potential of PLHSpT and peptides similarly targeted to surface receptors of cancer cells and to the functional domains of regulatory proteins.

Nano self-assembly of recombinant human gelatin conjugated with α-tocopheryl succinate for Hsp90 inhibitor, 17-AAG, delivery.

A wide variety of drug delivery systems have been developed for the delivery of anticancer agents. One of the most frequently used natural biomaterials in drug delivery systems is polysaccharides; however, they are difficult to digest and to eliminate from the body after systemic administration due to their high molecular weight natures and the absence of degrading enzymes. Therefore, the development of degradable and eliminable natural biomaterials is critical for successful in vivo applications. In the present study, we report the development of self-assembled biodegradable nanoparticles based on recombinant human gelatin (rHG) modified with alpha-tocopheryl succinate (TOS). The rHG-TOS nanoparticles efficiently encapsulated 17-AAG (17-allylamino-17-demethoxygeldanamycin), a small molecular anticancer drug targeting heat shock protein 90. The formation of 17-AAG-loaded nanoparticles was confirmed using TEM and dynamic light scattering analysis and found to be within the size of 90-220 nm. The loading efficiency, sustained release pattern, and stability of 17-AAG from the rHG-TOS nanoparticles were determined using HPLC. Furthermore, the passive targeting of rHG-TOS nanoparticles to the tumor area via enhanced permeability and retention effect was examined by noninvasive live animal imaging in a tumor mouse model. Finally, the 17-AAG-loaded nanoparticles were nonimmunogenic and more efficient than free 17-AAG in manifesting an anticancer effect in the tumor model. Overall, our data demonstrate rHG-TOS as a promising tool for the delivery of 17-AAG featuring therapeutic efficacy and biocompatibility.

Poly(oligo-D-arginine) with internal disulfide linkages as a cytoplasm-sensitive carrier for siRNA delivery.

Small interfering RNA (siRNA) has emerged as a therapeutic strategy for various diseases due to its target-specific gene silencing; however, its relatively high molecular weight, negative charge, and low stability hamper in vitro and in vivo applications. Approaches to overcome those drawbacks have relied on nonviral siRNA carriers based on cationic polymers or peptides. Nevertheless, cationic polymer-based siRNA carriers have yet to resolve intrinsic problems such as cytotoxicity and immunogenicity. An environment-sensitive carrier was recently proposed to enhance siRNA bioactivity and to reduce the carrier safety issues. Only a few studies, however, have shown cytoplasm-sensitive dissociation of the polyplex. In the present study, we clearly demonstrated decondensation of siRNA/poly(oligo-D-arginine) polyplex in the cytoplasm in response to intracellular glutathione (GSH) and the enhanced bioactivity of siRNA against VEGF (siVEGF) used as a model both in vitro and in an animal model. Reducible poly(oligo-D-arginine) (rPOA) rapidly dissociated in the cytoplasm, resulting in fast siRNA release to its target location while maintaining siRNA bioactivity both in vitro and in vivo.