Bacterial-Infection-Triggered Release of Antibacterial Aldehyde from Triblock Copolyether Hydrogels.

Bacterial infections pose a significant threat to public health worldwide. Hydrogel-based biomaterials have proven to be particularly useful in addressing persistent bacterial infections due to their stimuli-responsive degradability, high biocompatibility, ability to release antibacterial agents on demand, and long-lasting antibacterial activity. Herein, we fabricated ABA-type triblock copolyether hydrogels, wherein, hexanal, a bioactive aldehyde with antibacterial activity, was affixed to the hydrophobic micellar core via acetal linkage. The hydrogel exhibited degradation under acidic environment via the hydrolysis of acetal linkages, leading to the concomitant release of hexanal to exhibit highly potent bactericidal activity against both Escherichia coli and Staphylococcus aureus. Furthermore, a dual-mode release of the model therapeutic agent Nile Red from the hydrophobic micellar core of the hydrogel in conjunction with hexanal was demonstrated using this system. We anticipate that this study will provide a new platform for the development of hydrogels with tailorable release profiles for biologically active compounds that are activated by the acidification triggered by bacterial infection.

Inhalable Nitric Oxide Delivery Systems for Pulmonary Arterial Hypertension Treatment.

Pulmonary arterial hypertension (PAH) is a severe medical condition characterized by elevated blood pressure in the pulmonary arteries. Nitric oxide (NO) is a gaseous signaling molecule with potent vasodilator effects; however, inhaled NO is limited in clinical practice because of the need for tracheal intubation and the toxicity of high NO concentrations. In this study, inhalable NO-releasing microspheres (NO inhalers) are fabricated to deliver nanomolar NO through a nebulizer. Two NO inhalers with distinct porous structures are prepared depending on the molecular weights of NO donors. It is confirmed that pore formation can be controlled by regulating the migration of water molecules from the external aqueous phase to the internal aqueous phase. Notably, open porous NO inhalers (OPNIs) can deliver NO deep into the lungs through a nebulizer. Furthermore, OPNIs exhibit vasodilatory and anti-inflammatory effects via sustained NO release. In conclusion, the findings suggest that OPNIs with highly porous structures have the potential to serve as tools for PAH treatment.

Generation of zinc ion-rich surface via in situ growth of ZIF-8 particle: Microorganism immobilization onto fabric surface for prohibit hospital-acquired infection.

Viruses/bacteria outbreaks have motivated us to develop a fabric that will inhibit their transmission with high potency and long-term stability. By creating a metal-ion-rich surface onto polyester (PET) fabric, a method is found to inhibit hospital-acquired infections by immobilizing microorganisms on its surface. ZIF-8 and APTES are utilized to overcome the limitations associated with non-uniform distribution, weak biomolecule interaction, and ion leaching on surfaces. Modified surfaces employing APTES enhance ZIF-8 nucleation by generating a monolayer of self-assembled amine molecules. An in-situ growth approach is then used to produce evenly distributed ZIF-8 throughout it. In comparison with pristine fabric, this large amount of zinc obtained from the modification of the fabric has a higher affinity for interacting with membranes of microorganisms, leading to a 4.55-fold increase in coronavirus spike-glycoprotein immobilization. A series of binding ability stability tests on the surface demonstrate high efficiency of immobilization, >90%, of viruses and model proteins. The immobilization capacity of the modification fabric stayed unchanged after durability testing, demonstrating its durability and stability. It has also been found that this fabric surface modification approach has maintained air/vapor transmittance and air permeability levels comparable to pristine fabrics. These results strongly advocate this developed fabric has the potential for use as an outer layer of face masks or as a medical gown to prevent hospital-acquired infections.

Lightweight mobile stick-type water-based triboelectric nanogenerator with amplified current for portable safety devices.

Due to its abundance, mechanical energy is a promising ambient energy source. Triboelectric nanogenerators (TENGs) represent an effective mechanical energy harvesting method based on the use of contact electrification. The existing liquid-based TENGs can operate robustly without surface damage; however, the output of these TENGs is considerably smaller than that of solid-based TENGs. Notably, liquid-based TENGs in which the liquid directly contacts the conductive material can produce an electrical current of more than few mA. However, the liquid reservoir must have an adequate volume, and sufficient space must be provided for the liquid to move for generating the electrical output. To ensure a compact and lightweight design and produce electrical output in the low input frequency range, we introduce a mobile stick-type water-based TENG (MSW-TENG). The proposed MSW-TENG can generate an open-circuit voltage and closed-circuit current of up to 710 V and 2.9 mA, respectively, and be utilized as self-powered safety device. The findings of this study can promote the implementation of TENGs in everyday applications.

Investigation of the Structural Mechanism and Film Growth on Cytoprotective Type I Collagen-Based Nanocoating of Individual Cellular Surfaces.

Cell surface coating using the layer-by-layer assembly (LbL) method has many advantages for biomedical applications. Because the cell surface is a dynamic and highly complex structure, it is hypothesized that LbL multilayer films on cells have characteristics different from those observed in traditional film characterization results. Here, to demonstrate the mechanism of LbL-film formation on cells, LbL films are prepared on HeLa cells using collagen (Col) and hyaluronic acid (HA). The growth behavior of the film and the main driving forces inducing the formation of an LbL film on the cells are investigated. Col self-assembles via electrostatic and hydrophobic interactions; therefore, the Col-based film on the cells grows laterally rather than volumetrically. For the film construction conditions, the ionic density and chain conformation of the polymers change, resulting in mainly hydrophobic interactions. Additional interactions, such as hydrophobic interactions and biological recognition between the substrate and building blocks, also exist and tightly stabilize the films on the cells. The Col/HA film shows an even distribution on the cell surface as the extracellular matrix, and it activates proliferation and the cytoprotective signaling pathway under harsh conditions, resulting in the focal adhesion kinase signaling pathway and low lactate dehydrogenase release. Therefore, information for film construction on cells is beneficial to understand the effectiveness of an LbL film for cells.

Acceleration of Nitric Oxide Release in Multilayer Nanofilms through Cu(II) Ion Intercalation for Antibacterial Applications.

Implant-derived bacterial infection is a prevalent cause of diseases, and no antibacterial coating currently exists that is biocompatible and that does not induce multidrug resistance. To this end, nitric oxide (NO) has been emerging as an effective antimicrobial agent that acts on a broad range of bacteria and elicits no known resistance. Here, a method for accelerating NO release from multilayered nanofilms has been developed for facilitating antibacterial activity. A previously reported multilayered nanofilm (nbi film) was fabricated by alternative deposition of branched polyethyleneimine (BPEI) and alginate via the layer-by-layer assembly method. N-Diazeniumdiolate, a chemical NO donor, was synthesized at the secondary amine moiety of BPEI within the film (nbi/NO film). Cu(II) ions can be incorporated into the film by forming chelating compounds with unreacted amines that have not been converted to NO donors. The increase of the amine protonation state in the chelate caused destabilization of the NO donor by reducing hydrogen bonding between the deprotonated amine and the NO donor. Thus, the Cu(II) ion-embedding film presented accelerated NO release and was further subjected to antibacterial testing to demonstrate the correlation between the NO release rate and the antibacterial activity. This study aimed to establish a novel paradigm for NO-releasing material design based on multilayered nanofilms by presenting the correlation between the NO release rate and the antibacterial effect.

Mussel-Inspired Multiloop Polyethers for Antifouling Surfaces.

Despite the widespread use of polymers for antifouling coatings, the effect of the polymeric topology on the antifouling property has been largely underexplored. Unlike conventional brush polymers, a loop conformation often leads to strong steric stabilization of surfaces and antifouling and lubricating behavior owing to the large excluded volume and reduced chain ends. Herein, we present highly antifouling multiloop polyethers functionalized with a mussel-inspired catechol moiety with varying loop dimensions. Specifically, a series of polyethers with varying catechol contents were synthesized via anionic ring-opening polymerization by using triethylene glycol glycidyl ether (TEG) and catechol-acetonide glycidyl ether (CAG) to afford poly(TEG-co-CAG)n. The versatile adsorption and antifouling effects of multiloop polyethers were evaluated using atomic force microscopy and a quartz crystal microbalance with dissipation. Furthermore, the crucial role of the loop dimension in the antifouling properties was analyzed via a surface force apparatus and a cell attachment assay. This study provides a new platform for the development of versatile antifouling polymers with varying topologies.

Co-existing "spear-and-shield" air filter: Anchoring proteinaceous pathogen and self-sterilized nanocoating for combating viral pandemic.

Infectious pollutants bioaerosols can threaten human public health. In particular, the indoor environment provides a unique exposure situation to induce infection through airborne transmission like SARS-CoV-2. To prevent the infection from spreading, personal protective equipment or indoor air purification is necessary. However, it has been discovered that the conventional filter can become contaminated by pathogen-containing aerosols, meaning that advanced filtering and self-sterilization systems are required. Here, we fabricate a multilayered nanocoating around the fabric using laponite (LAP) with Cu2+ ions (LAP-Cu2+ nanocoating) two contradictory functions in one system: trapping proteinaceous pathogens and antibacterial effect. Due to the strong LAP-protein interaction, albumin and spike protein (S-protein) are trapped into the fabric when proteins are sprayed using a nebulizer. The protein-blocking performance of the nanocoated fabric is 9.55-fold higher than bare fabric. These trapping capacities are retained after rinsing and repeated adsorption cycles, showing reproducibility for air filtration. Even though the protein-binding occurred, the LAP-Cu2+ fabric indicates antibacterial effect. LAP-Cu2+ fabric has an equivalent air and water transmittance rate to that of bare fabric with a stability under physiological environment. Therefore, given its excellent "Spear-and-shield" functions, the proposed LAP-Cu2+ fabric shows great potential for use in filter and masks during the viral pandemic.

Transmission and regulation of biochemical stimulus via a nanoshell directly adsorbed on the cell membrane to enhance chondrogenic differentiation of mesenchymal stem cell.

A nanoscale artificial extracellular matrix (nanoshell) formed by layer-by-layer adsorption can enhance and modulate the function of stem cells by transferring biochemical stimulus to the cell directly. Here, the nanoshell composed of fibronectin (FN) and chondroitin sulfate (CS) is demonstrated to promote chondrogenic differentiation of mesenchymal stem cells (MSCs). The multilayer structure of nanoshell is formed by repeating self-assembly of FN and CS, and its thickness can be controlled through the number of layers. The expression of chondrogenic markers in MSCs coated with the FN/CS nanoshell was increased as the number of bilayers in the nanoshell increased until four, but when it exceeds five bilayers, the effect began to decrease. Finally, the MSCs coated with optimized four bilayers of FN/CS nanoshell have high chondrogenic differentiation efficiency and showed the potential to increase formation of cartilage tissue when it is transplanted into mouse kidney. So, the precise regulation of stem cell fate at single cell level can be possible through the cellular surface modification by self-assembled polymeric film.

Sustained Nitric Oxide-Providing Small Molecule and Precise Release Behavior Study for Glaucoma Treatment.

Incidence ofglaucoma, a severe disease leading to irreversible loss of vision, is increasing with global aging populations. Lowering intraocular pressure (IOP) is the only proven treatment method for glaucoma. Nitric oxide (NO) is an emerging material targeting the conventional outflow pathway by relaxing the trabecular meshwork (TM). However, there is little understanding on the NO level effective in IOP lowering without toxicity. Here, we report a novel long-term NO-releasing polydiazeniumdiolate (NOP) that enables lowering IOP via the conventional outflow pathway. NOP is composed of carbon-bound polydiazeniumdiolate, a stable NO donor moiety. NO release was monitored with accurate parameters by real-time detection of gas and analysis of the accumulated release profile. Based on the NO release information, the selected safe level of NOP exhibited effective TM relaxation and a potential IOP lowering effect in vivo without side effects. This work provides new insights into nitric oxide release behavior that should be considered for glaucoma treatment.

Controlled Nitric Oxide Release Using Poly(lactic-co-glycolic acid) Nanoparticles for Anti-Inflammatory Effects.

Nitric oxide (NO) plays a key role in several physiological functions such as inflammatory responses and immune regulation. However, despite its beneficial functions, the short half-life and diffusion radius limit NO availability in biomedical applications. Hence, controlled release is important to achieve the desired therapeutic effects with exogenous NO delivery. In this study, we fabricated a poly(lactic-co-glycolic acid) (PLGA)-based NO delivery system to release NO in a sustained manner under physiological conditions. To prevent an initial burst release, branched polyethylenimine diazeniumdiolate (BPEI/NONOate), a pH-responsive NO donor, was encapsulated into the hydrophilic core of PLGA nanoparticles. Furthermore, low concentrations of NO released at a consistent level via a stabilization effect obtained as amine groups of BPEI/NONOate interacted with the nearby NONOate. Using the controlled-release profiles, we successfully regulated the inflammatory response in lipopolysaccharide-stimulated peripheral blood mononuclear cells. This work demonstrates the potential of a NO delivery carrier in the regulation of inflammation.

Tuning the Structural Integrity and Mechanical Properties of Globular Protein Vesicles by Blending Crosslinkable and NonCrosslinkable Building Blocks.

Vesicles made from functionally folded, globular proteins that perform specific biological activities, such as catalysis, sensing, or therapeutics, show potential applications as artificial cells, microbioreactors, or protein drug delivery vehicles. The mechanical properties of vesicle membranes, including the elastic modulus and hardness, play a critical role in dictating the stability and shape transformation of the vesicles under external stimuli triggers. Herein, we have developed a strategy to tune the mechanical properties and integrity of globular protein vesicle (GPV) membranes of which building molecules are recombinant fusion protein complexes: a mCherry fused with an acidic leucine zipper (mCherry-ZE) and a basic leucine zipper fused with an elastin-like polypeptide (ZR-ELP). To control the mechanical properties of GPVs, we introduced a nonstandard amino acid (para-azidophenylalanine (pAzF)) into the ELP domains (ELP-X), which enabled the creation of crosslinked vesicles under ultraviolet (UV) irradiation. Crosslinked GPVs made from mCherry-ZE/ZR-ELP-X complexes presented higher stability than noncrosslinked GPVs under hypotonic osmotic stress. The degree of swelling of GPVs increased as less crosslinking was achieved in the vesicle membranes, which resulted in the disassembly of GPVs into membraneless coacervates. Nanoindentation by atomic force microscopy (AFM) confirmed that the stiffness and Young's elastic modulus of GPVs increase as the blending molar ratio of ZR-ELP-X to ZR-ELP increases to make vesicles. The results obtained in this study suggest a rational design to make GPVs with tunable mechanical properties for target applications by simply varying the blending ratio of ZR-ELP and ZR-ELP-X in the vesicle self-assembly.

Nanoclay-Polyamine Composite Hydrogel for Topical Delivery of Nitric Oxide Gas via Innate Gelation Characteristics of Laponite.

Because nitric oxide (NO) gas is an endogenously produced signaling molecule related to numerous physiological functions, manystudies have been conducted to develop NO delivery systems for potential biomedical applications. However, NO is a reactive radical gas molecule that has a very short life-time and readily transforms into nitrogen oxide species via reaction with oxygen species. Therefore, it is necessary to develop an NO delivery carrier that allows local release of the NO gas at the site of application. In this study, Laponite (LP) nanoclay was used to fabricate an NO delivery carrier through the formation of Laponite-polyamine (LP-PAn) composites. The Laponite clay and pentaethylenehexamine (PEHA) formed a macromolecular structure by electrostatic interaction and the nitric oxide donor, N-diazeniumdiolate (NONOates), was synthesized into the LP-PAn composite. We investigated the conformation of the LP-PAn composite structure and the NO donor formation by ζ potential, X-ray diffraction, and UV-vis and Fourier transform infrared (FT-IR) spectroscopies and also by analyzing the NO release profile. Additionally, we confirmed the applicability in biomedical applications via a cell viability and in vitro endothelial cell tube formation assay.

Facile Synthesis of Poly(ethylene oxide)-Based Self-Healable Dynamic Triblock Copolymer Hydrogels.

Stimuli-responsive smart hydrogels have garnered considerable interest for their potential in biomedical applications. While widely utilized, little is known about the rheological and mechanical properties of the hydrogels with respect to the type of cross-linker in a systematic manner. In this study, we present a facile synthetic route toward ABA triblock copolymer hydrogels based on poly(ethylene oxide) (PEO). Two classes of hydrogels were prepared by employing the functional allyl glycidyl ether (AGE) monomer during the polymerization followed by the subsequent post-polymerization modification of prepared PAGE-b-PEO-b-PAGE via respective hydrogenation or thiol-ene reaction: (1) chemically cross-linked hydrogels responsive to redox stimuli and (2) physically cross-linked hydrogels responsive to temperature. A series of dynamic mechanical analyses revealed the relaxation dynamics of the associative A block. Most interestingly, the redox-responsive hydrogels demonstrated a highly tunable nature by introducing reducing and oxidizing agents, which provided the self-healing property and injectability. Together with superior biocompatibility, these smart hydrogels offer the prospect of advancing biomedical applications.

Liquid-Repellent Metal Oxide Photocatalysts.

Metal oxide photocatalysts (MOPCs) decompose organic molecules under illumination. However, the application of MOPCs in industry and research is currently limited by their intrinsic hydrophilicity because MOPCs can be wetted by most liquids. To achieve liquid repellency, the surface needs to possess a low surface energy, but most organic molecules with low surface energy are degraded by photocatalytic activity. Herein, current methods to achieve liquid repellency on MOPCs, while preventing degradation of hydrophobic coatings, are reviewed. Classically, composite materials containing MOPCs and hydrophobic organic compounds possess good liquid repellency. However, composites normally form irregular coatings and are hard to prepare on surfaces such as those that are mesoporous or nanostructured. In addition, the adhesion of composites to substrates is often weak, resulting in delamination. Recent studies have shown that the direct grafting reaction of polydimethylsiloxane (PDMS) from silicone oil (methyl-terminated PDMS) under illumination results in a stable polymer brush. This easy and simple grafting method allows us to create stable liquid-repellent surfaces on MOPCs of various types, structures, and sizes. In particular, super-liquid-repellent drops with an underlying air layer can be created on PDMS-grafted nano-/microstructured MOPCs. Potential applications of surfaces combining liquid repellency and photocatalytic activity are also discussed; thus offering new ways of using MOPCs in a wider range of applications.

General and Facile Coating of Single Cells via Mild Reduction.

Cell surface modification has been extensively studied to enhance the efficacy of cell therapy. Still, general accessibility and versatility are remaining challenges to meet the increasing demand for cell-based therapy. Herein, we present a facile and universal cell surface modification method that involves mild reduction of disulfide bonds in cell membrane protein to thiol groups. The reduced cells are successfully coated with biomolecules, polymers, and nanoparticles for an assortment of applications, including rapid cell assembly, in vivo cell monitoring, and localized cell-based drug delivery. No adverse effect on cellular morphology, viability, proliferation, and metabolism is observed. Furthermore, simultaneous coating with polyethylene glycol and dexamethasone-loaded nanoparticles facilitates enhanced cellular activities in mice, overcoming immune rejection.

Structure of a Multilayer Nanofilm To Increase the Encapsulation Efficiency of Basic Fibroblast Growth Factor.

In this study, we established the structure of a multilayer nanofilm that more efficiently encapsulates basic fibroblast growth factor (bFGF). First, a positively charged layer material was selected from biocompatible polymers such as collagen (Col), poly(beta-amino ester) (Poly2), and chitosan (Chi), while considering the film thickness. We then investigated the change in bFGF encapsulation efficiency when the multilayer structure was changed from a tetralayer to a trilayer. As a result, we obtained a highly improved bFGF encapsulation efficiency in the nanofilm using a positively charged layer formed by a blend of Col and Poly2 and a negatively charged poly(acrylic acid) (PAA) layer within a trilayered structure. In particular, we found that a significant amount of adsorbed bFGF was desorbed again during the film fabrication process of a tetralayered nanofilm. In the conventional nanofilm, bFGF was regarded as a polycation and formed a multilayer nanofilm that was composed of a tetralayered structure and was represented as (polycation/polyanion/bFGF/polyanion) n where n = number of repeated tetralayers. Here, we suggested that bFGF should not be considered a polycation, rather it should be considered as a small quantity of molecule that exists between the polyanion and polycation layers. In this case, the nanofilm is composed of repeating units of (polycation/polyanion/bFGF/polycation/polyanion), because the amount of adsorbed bFGF is considerably lower than that of other building blocks.

In Vitro Osteogenic Differentiation and Antibacterial Potentials of Chalcone Derivatives.

Chalcone derivatives have been investigated as therapeutic agents for the anticancer, antioxidant, and anti-inflammatory fields. In this study, we have synthesized four different types of chalcone derivatives and demonstrated in vitro bioactivities. We divided these derivatives into two groups of chalcones on the basis of similar substituents on the aromatic rings, and we tested cell viability and proliferation potentials, which indicated that the methoxy substituent on the A ring could enhance cytotoxicity and antiproliferation potential depending on the chalcone concentration. We also investigated osteogenic differentiation of C2C12 cells by ALP staining, the early marker for osteogenesis, which demonstrated that the chalcones could not only induce activity of BMP-2 but also inhibit the activity of noggin, a BMP antagonist. In addition, chalcone bearing hydroxyl groups at the 2-, 4-, and 6-position on the A ring inhibited treptococcus mutans growth, a major causative agent of dental caries. Therefore, we concluded that the chalcone derivatives synthesized in this research can be good candidates for therapeutic agents promoting bone differentiation, with an expectation of inhibiting S. mutans, in dentistry.

Multilayered Controlled Drug Release Silk Fibroin Nanofilm by Manipulating Secondary Structure.

Many studies of drug delivery nanoplatforms have explored drug loading affinity and controlled release. The nanoplatforms can be influenced by their inherent building blocks. Natural polypeptide silk fibroin (SF) is an excellent nanoplatform material because of its high biocompatibility and unique structural properties. SF secondary structures have different properties that can be changed by external stimuli. Thus, the characterization of SF-containing platforms is strongly affected by secondary structure transformations. Structural changes can occur spontaneously, which hinders the control of structural variation in aqueous conditions. Herein, we successfully prepared a controllable secondary structure composed of SF/heparin (HEP) layer-by-layer assembled nanofilms using simple solvents (glycerol and methanol). SF in the SF/HEP nanofilms takes up than 90%, which means configurations of SF have a strong effect on the character of the nanofilms. We investigated the degradation profiles of SF/HEP nanofilms depending on their ß-sheet contents and demonstrated an immediate correlation between the transformation of secondary structures inside the nanofilms and the degree of degradation of nanofilms. Finally, SF/HEP nanofilms were used as a delivery platform for incorporating the anticancer drug epirubicin (EPI). We could control the loading efficiency and release profile of EPI with various ß-sheet contents of the nanofilms.

Drug Loading and Release Behavior Depending on the Induced Porosity of Chitosan/Cellulose Multilayer Nanofilms.

The ability to control drug loading and release is the most important feature in the development of medical devices. In this research, we prepared a functional nanocoating technology to incorporate a drug-release layer onto a desired substrate. The multilayer films were prepared using chitosan (CHI) and carboxymethyl cellulose (CMC) polysaccharides by the layer-by-layer (LbL) method. By using chemical cross-linking to change the inner structure of the assembled multilayer, we could control the extent of drug loading and release. The cross-linked multilayer film had a porous structure and enhanced water wettability. Interestingly, more of the small-molecule drug was loaded into and released from the non-cross-linked multilayer film, whereas more of the macromolecular drug was loaded into and released from the cross-linked multilayer film. These results indicate that drug loading and release can be easily controlled according to the molecular weight of the desired drug by changing the structure of the film.