Quaternary Ammonium Chitosan Research Articles

Self-healing hydrogels loaded with Spatholobi Caulis alleviate disc degeneration by promoting autophagy in nucelus pulposus

Intervertebral disc degeneration (IDD) is a common degenerative disease of the spine that has a significant impact on both society and human health. Many studies have confirmed that there is a close relationship between IDD and senescence and apoptosis, and autophagy can combat apoptosis and senescence. Spatholobi caulis (SC) is an herb that contains various active compounds that are effective in tissue repair and regeneration, but it has not been explored in field of IDD. In this study, it was first found that SC can boost autophagy and reduce the apoptosis and senescence of Nucleus pulposus cell (NPCs). However, our animal studies revealed limited absorption of SC. To improve the bioavailability and efficacy of SC, we developed a hydrogel incorporating quaternary ammonium chitosan (QCS) and oxidized starch (OST) as carriers for SC. The QCS-OST/SC hydrogel exhibits excellent compatibility with cells, can be easily injected, and can release SC durably. At the cellular level, the QCS-OST/SC hydrogel enhances cell viability, initiates autophagy and release of the extracellular matrix (ECM), and inhibits cellular senescence and apoptosis. The injection of the QCS-OST/SC hydrogel via microneedles (MNs) into discs had successfully diminished disc degeneration in rats, which shows that this hydrogel has broad potential in the treatment of IDD.

Encapsulation of Antarctic krill peptide by polysaccharide-based nanoparticles: Preparation, characterization, evaluation of stability and hypoglycemic activity

The aim of this study was to construct a chitosan quaternary ammonium salt (HTCC)/sodium alginate (SA) nanoparticle delivery system for the encapsulation of Antarctic krill peptide (AKP), with the goal of enhancing its stability and post-digestive hypoglycemic activity. Additionally, the effect of the content and encapsulation sequence of HTCC/SA on the structure and properties of AKP-loaded nanoparticles (AKP-loaded NPs) was investigated. As the content of the outermost wall material (HTCC) increased, the particle size of nanoparticles initially increased and then decreased. Concurrently, the zeta potential showed a trend of increase, ranging from -38.77 to 46.07 mV. When SA was used as the outermost wall material, the nanoparticles exhibited a smaller particle size (240.1 nm) and better dispersibility. Electrostatic interaction and hydrogen bonding were the major forces involved in the formation of AKP-loaded NPs. X-ray diffraction revealed that AKP was successfully encapsulated in an amorphous state. Scanning electron microscopy showed that AKP-loaded NPs had an elliptical or blocky appearance. Moreover, AKP-loaded NPs demonstrated good storage and temperature stability, while nanoparticles with HTCC in the outermost layer (HTCC:SA=2:1) showed good pH and ionic stability. During simulated digestion, AKP-loaded NPs inhibited the release of AKP in gastric fluid. Consequently, the hypoglycemic activity of digested AKP-loaded NPs was remarkably higher than unencapsulated AKP. Notably, the nanoparticles with HTCC in the outermost layer provided superior hypoglycemic activity. In summary, the polysaccharide-based delivery system exhibited great potential to improve the stability and post-digestive hypoglycemic activity of AKP, broadening its applications in the food and pharmaceutical industries.

Promoting algae separation of forward osmosis by peracetic acid and chitosan quaternary ammonium salt: Purification efficiency, membrane fouling alleviation, and lipid production

Forward osmosis (FO) is a prospective technology for microalgae biomass recovery, whereas severe membrane fouling still limits its application. To improve the separation efficiency of FO, peracetic acid (PAA) oxidation followed by chitosan quaternary ammonium salt (HTCC) coagulation was proposed. The synergistic effect of PAA-HTCC on the characteristics of Chlorella vulgaris and the separation performance of FO were systematically studied, and the mechanism was revealed. With PAA-HTCC treatment, the harvesting efficiency of algal cells was increased to 88.5 %, and algal aggregates with sizes of 100-300 μm were formed while maintaining excellent cell viability. Membrane fouling caused by microalgae was mitigated, with the water flux increased from 15.0 to 19.2 L/(m2·h), and the recovery flux increased to 90.0 %. The lipid production capacity of microalgae was significantly promoted, with the lipid productivity increased from 10.5 to 27.9 mg·L−1·d−1. During PAA oxidation, •OH and •CH3 were the major reactive species, which could remove electronegative organics coated on algal cells, contributing to the aggregation of microalgae in the coagulation by HTCC. Moreover, PAA-HTCC could also provide carbon sources for microalgae growth, thus the water purification efficiency of FO and the lipid production of concentrated microalgae were simultaneously promoted. The proposed strategy has certain significance for water purification and resource utilization of algae.

Preparation of N-(2-hydroxypropyltrimonium chloride)-O-dodecylylpyridine chitosan quaternary ammonium salt and its antibacterial activities

Chitosan derivatives, including O-carboxymethyl chitosan (CMC), N-(2-hydroxypropyltrimonium chloride)-O-carboxymethyl chitosan (QCMC), and N-(2-hydroxypropyltrimonium chloride)-O-dodecylylpyridine chitosan quaternary ammonium salt (DQCMC), were synthesized and characterized using Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (1H NMR) spectroscopy, Ultraviolet-visible (UV-vis) spectroscopy, and element analysis (EA). The antibacterial activities of chitosan and chitosan derivatives against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated through the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibacterial rate assays. Results demonstrated that DQCMC exhibited significantly higher antibacterial efficacy compared to chitosan, CMC, and QCMC. The MIC of DQCMC against E. coli and S. aureus were 31 μg/mL and 7 μg/mL, respectively, with a 100% antibacterial rate at a concentration of 0.5 mg/mL. Furthermore, assessment of mouse fibroblast (L929) cell viability using cell counting kit-8 (CCK-8) methods revealed no toxicity associated with the material.

Sludge dewaterability improvement in microbial fuel cell powered electro-Fenton system (MFCⓅEFs) coupled with chitosan quaternary ammonium salt

As improved and expanded wastewater treatment facilities, sludge dewatering is the essential process and major challenge due to the complex and abundant organic matter. Microbial fuel cell powered electro-Fenton system (MFCⓅEFs) has been demonstrated to generate •OH and destroy hydrophilic extracellular polymeric substances (EPS) as an improved method of high efficiency and low energy consumption. Nevertheless, the smaller particle size of the treated sludge and the release of partial organic matter into the supernatant can affect the sludge-water separation process. Chitosan quaternary ammonium salt (CQAS) as a renewable and biodegradability cationic coagulant can be involved in the follow-up treatment. The sludge after combined treatment exhibited better dewaterability, where the water content of sludge cake (WCSC), capillary suction time (CST), and specific resistance filtration (SRF) were 61.21%, 15.6 s, and 1.02×1012 m/kg (26.47%, 80.72% and 84.28% reduction), respectively. The oxidation of the MFCⓅEFs destroyed the cellular and EPS structure and the bridging flocculation and charge neutralization of CQAS caused the fine particles to squeeze each other. The combined treatment fully reduced the content of negative charge and hydrophilic substances on the surface, which affected the intensity change of N-H bond and altered the protein secondary structure to make it looser, thus releasing more bound water while improving aggregation characteristics. Overall, combined treatment can significantly improve sludge dewaterability and owns operational advantages of high efficiency, low energy and consumption, safety, and non-toxicity.

Adsorption characteristics and mechanism of novel ink melanin composite modified chitosan for Cd(II) in water

In this study, chitosan (CS), carboxymethyl chitosan (CMCS), and chitosan quaternary ammonium salt (HACC) were successfully loaded with ink melanin (ME) as efficient adsorbents for Cd(II) removal. The results of batch adsorption experiments and structural characterization showed that the modified CS loaded with ME improved the adsorption capacity of the composites for Cd(II). The pseudo-second-order kinetic and Langmuir equations were better suited to describe the batch adsorption experiments. The adsorption of Cd(II) was chemisorption with desirable adsorption effect when the concentration of the three composites was 0.5 mg/mL and the pH value was neutral. Among them, HACC-ME demonstrated remarkable Cd(II) adsorption performance (107.18 mg/g) and sustained an 85 % efficiency in Cd(II) removal over five adsorption-desorption cycles. Ion exchange, complexation, electrostatic attraction, and hydrophobic interaction were the primary mechanisms for Cd(II) removal. Overall, HACC-ME could be employed as a low-cost and highly efficient new natural adsorbent material for the removal of Cd(II) ions from wastewater. These findings illuminate pathways for the development of efficient and novel natural adsorbent materials for environmental cleanup purposes.

Intelligent microneedle patch based on functionalized alginate and chitosan for long-term self-regulated insulin delivery

Severely diabetic patients need insulin input to maintain the body's glycemic balance. However, traditional injection methods are often associated with poor adherence and an increased risk of hypoglycemia. Microneedle technology offers a promising solution by minimizing pain and trauma during insulin administration. Nonetheless, achieving prolonged glycemic control by microneedle with high insulin loading remains a significant challenge. Herein, we introduce an innovative microneedle patch that draws inspiration from the elegant light-induced blooming of water lily petals. The patch features a glucose-responsive hydrogel network crafted from two modified polysaccharide polymers, which enables the delivery of long-acting insulin without depending on glucose oxidase. By incorporating phenylboronic acid-modified sodium alginate, quaternary ammonium chitosan, and polyvinyl alcohol into a hydrogel matrix, we have created a microneedle system that harbors dynamic borate ester linkages and electrostatic attractions, resulting in heightened sensitivity to blood glucose levels. The electrostatic interaction acts as a relatively stable crosslinking point, balancing the dynamic reproducibility response based on the borate ester bond. This self-adaptive hydrogel can regulate insulin-controlled release by responding to changes in glucose concentration. Herein, we achieved massive insulin loading (20 IU) with long lasting glycaemic control (48 h) in a single treatment of diabetic SD rats.

Porous chitosan quaternary ammonium salt hydrogel embedded with Cu, Ni and Pd nanoparticles for efficient coupled adsorption-catalytic reduction of methylene blue and 4-nitrophenol

Anthropogenic wastewater generation and water pollution can have negative impacts on public health and ecosystems. However, most materials do not have both adsorptive and catalytic properties, so the design and development of sustainable and multifunctional materials is essential for wastewater treatment. Herein, composite hydrogel (PHG) containing [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) and chitosan quaternary ammonium salts (HACC) were prepared for wastewater treatment. The adsorption capacities of the PHG hydrogels for nickel (NiII), copper (CuII), and palladium (PdII) ions were 158.68, 182.99, and 229.78 mg/g, respectively. The adsorption process is consistent with the Langmuir adsorption model and quasi-secondary kinetics. For further application of adsorbed metal ions, NaBH4 was selected for in situ reduction to prepare hydrogel-based catalysts cemented with metal nanoparticles (Ni-, Cu- and Pd-NPs), respectively. The PHG-Pd catalysts demonstrated significant catalytic efficiency in reducing 4-nitrophenol and methylene blue, and Kapp were 0.307 and 0.365 min−1, respectively. Among them, the activation parameters for the reduction of 4-NP over PHG-Pd catalyst were calculated as Ea = 36.27 kJ/mol, ΔH# = 33.72 kJ/mol and ΔS# = −259.68 J/(mol·K). This study is expected to provide insights into the design of multifunctional adsorption catalysts for the removal of dyes and nitro compounds from wastewater.

Fabrication of injectable, adhesive, self-healing, superabsorbent hydrogels based on quaternary ammonium chitosan and oxidized pullulan

Injectable hydrogels, which are polymeric materials that are characterized by their ability to be injected in a liquid form into cavities and subsequently undergo in situ solidification, have garnered significant attention. These materials are extensively used in a range of biomedical applications. This study synthesized several injectable composite hydrogels through the mild Schiff base reaction while imposing different concentrations of quaternary ammonium chitosan and oxidized pullulan. Subsequent characterizations revealed a consistent and coherent porous structure within the hydrogels with smooth inner walls. The hydrogels were also determined to possess good adhesion, mechanical properties, self-healing ability, and injectability. Furthermore, antimicrobial tests against Escherichia coli and Staphylococcus aureus demonstrated antibacterial properties, which improved with increasing concentrations of quaternary ammonium chitosan. Co-culturing with skin fibroblasts demonstrated that the injectable hydrogels exhibited favourable biocompatibility and the capacity to boost cellular activity, thus underscoring its potential for use in biomedical applications.

Green fabrication of biomass-derived carbon dots and bio-based coatings: Potential of enhancing postharvest quality on Chinese flowering cabbage

The objective of this study was to develop a bio-nanocomposite coating (CQSC) by combining chitosan quaternary ammonium salt (CQAS) and sericin (SC) with biomass-derived carbon dots (CDs) to extend the shelf life of Chinese flowering cabbage (CFC). The effects of different concentrations of CDs (0.2, 0.4, 0.6, 0.8, and 1.0 mg/mL) on the physicochemical, structural, and functional activity of nanocomposite particles were evaluated. CQAS exhibited strong inhibitory effects against Escherichia coli and Bacillus subtilis. Moreover, the application of CQSC on CFC significantly reduced mass losses, slowed the increase in lignin content, maintained ascorbic acid and chlorophyll levels, inhibited the growth of microorganisms, and preserved the unique texture and aroma of CFC during storage at 10 °C compared with uncoated CFC. The results will contribute to the further development of CDs coatings to improve the postharvest preservation effect of fruits and vegetables.

Battery-Free and Multifunctional Microfluidic Janus Wound Dressing with Biofluid Management, Multi-Indicator Monitoring, and Antibacterial Properties.

The sophisticated environment of chronic wounds, characterized by prolonged exudation and recurrent bacterial infections, poses significant challenges to wound recovery. Recent advancements in multifunctional wound dressings fall short of providing comprehensive, accurate, and comfortable treatment. To address these issues, a battery-free and multifunctional microfluidic Janus wound dressing (MM-JWD) capable of three functions, including exudate management, antibacterial properties, and multiple indications of wound infection detection, has been developed. During the treatment, the fully soft microfluidic Janus membrane not only demonstrated stable unidirectional fluid transport capabilities under various skin deformations for a longer period but also provided antibacterial effects through surface treatment with chitosan quaternary ammonium salts and poly(vinyl alcohol). Furthermore, integrating multiple colorimetric sensors within the Janus membrane's microchannels and a dual-layer structure enabled simultaneous monitoring of the wound's pH, uric acid, and temperature. The monitoring was facilitated by smartphone recognition of color changes in the sensors. In vivo and in vitro tests confirmed the exudate management, antibacterial, and sensing capabilities of the MM-JWD, proving its efficacy in monitoring and promoting the healing of wounds. Overall, this study provides a valuable method for the design of multifunctional wound dressings for chronic wound care.

Preparation and characterization of pickering emulsions stabilized by zein/quercetin/quaternary ammonium chitosan composite nanoparticles with antibacterial effect

The role of nanoparticles in the stabilizing interface is very important in the preparation of stable Pickering emulsions. In this study, ternary composite nanoparticles (ZQ-HC) were synthesized by complexing zein-quercetin covalent complex (ZQ) with quaternary ammonium chitosan (HTCC) and subsequently stabilized Pickering emulsions (ZQ-HC) with antibacterial activity. Results revealed that HTCC covers the surface of ZQ nanoparticles successfully, which designates an effective improvement in the surface wettability of ZQ effectively. Among them, ZQ-HC2:1 possesses the closest three-phase contact angle of 90° and the highest emulsification activity and emulsion stability. The results of ultra-high resolution microscopy showed that ZQ-HC nanoparticles were adsorbed at the oil-water interface to prevent droplet aggregation and improved the pH, ionic strength, and storage stability of the prepared Pickering emulsions. ZQ-HC nanoparticles construct an antioxidant barrier at the oil-water interface, improving the lipid oxidation stability of the emulsion. The ZQ-HC2:1 stabilized Pickering emulsion exhibits the most superior stability and strongest antibacterial activity against other emulsions. The ZQ-HC stabilized Pickering emulsions prepared in this study exhibit potential for use as carriers of bioactive ingredients in food applications.

Eco-friendly, pH-sensitive curcumin-loaded sodium alginate/hydroxyapatite/quaternary ammonium chitosan microspheres with enhanced antibacterial and antioxidant activities for fruit preservation

The development of intelligent responsive reactive packaging materials with natural polymers shows excellent potential in food preservation. In this study, eco-friendly, pH-sensitive sodium alginate (SA)/hydroxyapatite (HA)/quaternary ammonium chitosan (HACC) composite microspheres loading curcumin (CUR) with excellent antibacterial and antioxidant activities were successfully synthesized. Scanning electron microscopy (SEM) and nitrogen adsorption/desorption tests indicated that the doping of HA substantially increased the specific surface area and pore volume of the microspheres. The loading experiments showed that the efficiency of the microspheres was significantly increased by 49.47 % and 55.10 %, respectively, when HA and HACC were incorporated into the SA network. The release test results suggested that the release rate of SA/HA/HACC microspheres loading CUR (SA/HA/HACC@CUR) increased as the pH decreased, demonstrating notable pH-responsive release characteristics. DPPH free radical scavenging experiments demonstrated that the SA/HA/HACC@CUR had excellent and long-lasting antioxidant capacity. The antibacterial experiments revealed that the SA/HA/HACC@CUR had excellent antibacterial properties, with inhibition rates of 88.73 % and 92.52 % against E. coli and S. aureus, respectively. Making coatings out of microspheres could effectively slow down the rotting and deterioration of cherry tomatoes during storage, suggesting that microspheres with intelligent responses have a broad application prospect in fruit preservation.

A modified hyaluronic acid hydrogel with strong bacterial capture and killing capabilities for drug-resistant bacteria-infected diabetic wound healing

Management of diabetic wounds becomes increasingly challenging as bacterial infections intensify the inflammation. Employing polysaccharide hydrogels with inherent antibacterial qualities can significantly reduce the need for antibiotics to manage infections in diabetic wounds. The typical approach to achieving antibacterial outcomes with hydrogels relies on the penetration of bacteria into their porous architecture. Such penetration not only takes time but can also prolong inflammation, thus impeding the healing of wounds. Hence, the quick capture and eradication of bacteria are essential for optimizing the hydrogel's antibacterial performance. Herein, we introduce a multifunctional polysaccharide hydrogel dressing—designated as HAQ—created for managing bacterial infections in diabetic wounds. This dressing is based on hyaluronic acid, which is modified with methacrylic anhydride, and special functional groups are added to the modified hyaluronic acid matrix: phenylboronic acid for capturing bacteria and quaternary ammonium chitosan for bacterial destruction. As expected, the HAQ system exhibits robust antibacterial effectiveness against both methicillin-resistant Staphylococcus aureus and multidrug-resistant Pseudomonas aeruginosa in vitro and in vivo. Consequently, HAQ stands as a promising hydrogel dressing with intrinsic antibacterial capabilities and offers significant potential for managing diabetic wounds infected by drug-resistant bacteria.

Quaternary ammonium chitosan-based active packaging films incorporated with dialdehyde guar gum-proanthocyanidins conjugates: Characterization and application in the edible coating of pork

In this study, antioxidant and antibacterial proanthocyanidins (PA) were covalently conjugated with dialdehyde guar gum (DGG) to produce DGG-PA conjugates. Then DGG-PA conjugates were incorporated into quaternary ammonium chitosan (QAC)-based matrix to create QAC/DGG-PA films. The structure, physicochemical properties, and antioxidant and antibacterial effects of DGG-PA conjugates and QAC/DGG-PA films were analyzed. The active packaging potentials of QAC/DGG-PA film-forming solutions in the edible coating of pork loins were evaluated. Results showed DGG-PA conjugates had unique UV absorption peak (280 nm), infrared bands (1610 and 1521 cm−1) and proton nuclear magnetic resonance signals (6.82 ppm) of PA groups. DGG-PA conjugates showed amorphous state with sheet-like and fibrous morphology. DGG-PA conjugates had good biocompatibility and antioxidant and antibacterial effects. After adding DGG-PA conjugates, the surface of QAC-based films became smooth and the crystallographic nature of the films declined. DGG-PA conjugates elevated the light/water vapor/oxygen barrier performances, mechanical properties, and antioxidant and antibacterial effects of QAC-based films. QAC/DGG-PA edible coatings effectively prolonged the shelf life of pork loins from 4 days to 6−10 days. Results verified QAC/DGG-PA films and their film-forming solutions had good application potentials in active packaging.

Enhanced pH-sensitive anthocyanin film based on chitosan quaternary ammonium salt: A promising colorimetric indicator for visual pork freshness monitoring

An intelligent pH response indicator film is an easy-to-use device for the real-time monitoring of meat freshness during transport and storage. Therefore, a novel pH-sensitive anthocyanin indicator film composed of polyvinyl alcohol–blueberry anthocyanin (BA)–2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) called PAH-2.0 with 1.2 mg/mL HACC to monitor meat freshness using HACC as the colorimetric enhancer has been developed. BA and HACC were mixed and immobilized in the polyvinyl alcohol matrix by hydrogen bonds, as confirmed via Fourier-transform infrared spectroscopy and X-ray diffraction. The inclusion of HACC improved the color stability and antioxidant and antibacterial properties of the PAH-2.0 film. When applied to pork for freshness monitoring at 4 °C, three freshness stages, including fresh, sub-fresh, and spoiled, could be clearly distinguished based on the color variations of the PAH-2.0 film. The distinct hierarchical color change from purple to blue-violet and finally to grayish-blue was highly correlated with the indicators of pork freshness: pH values, total volatile basic nitrogen, and total viable count. This study provides a simple and promising approach for fabricating meat freshness indicator films with high color recognition accuracy, thereby offering new possibilities for visual meat freshness monitoring.

A Highly Sustainable Supramolecular Bioplastic Film with Superior Hydroplasticity and Biodegradability.

Massive accumulation of postconsumer plastic waste in eco-system has raised growing environmental concerns. Sustainable end-of-life managements of the indispensable plastic are highly demanding and challenging in modern society. To relieve the plastic menace, herein we present a full life cycle sustainable supramolecular bioplastic made from biomass-derived polyelectrolyte (chitosan quaternary ammonium salt, QCS) and natural sodium fatty acid (sodium laurate, SL) through solid-phase molecular self-assembly (SPMSA), by which the QCS-SL complexes, precipitated from mixing the aqueous solutions, self-assemble to form bioplastic film by mildly pressing at room temperature. The QCS-SL bioplastic films display superior hydroplasticity owing to the water-activated molecular rearrangement and electrostatic bond reconstruction, which allows facile self-healing and reprocessing at room temperature to significantly extend the service lifetime of both products and raw materials. With higher water content, the dynamic electrostatic interactions and precipitation-dissolution equilibrium endow the QCS-SL bioplastic films with considerable solubility in water, which is promising to mitigate the plastic accumulation in aquatic environment. Because both QCS and SL are biocompatible and biodegradable, the dissolved QCS-SL films are nontoxic and environmentally friendly. Thus, this novel supramolecular bioplastic is highly sustainable throughout the whole life cycle, which is expected to open a new vista in sustainable plastic materials.

Polydopamine-assisted smart bacteria-responsive hydrogel: Switchable antimicrobial and antifouling capabilities for accelerated wound healing

IntroductionWound infections and formation of biofilms caused by multidrug-resistant bacteria have constituted a series of wound deteriorated and life-threatening problems. The in situ resisting bacterial adhesion, killing multidrug-resistance bacteria, and releasing dead bacteria is strongly required to supply a gap of existing sterilization strategies. ObjectivesThis study aims to present a facile approach to construct a bacteria-responsive hydrogel with switchable antimicrobial-antifouling properties through a “resisting-killing-releasing” method. MethodsThe smart bacteria-responsive hydrogel was constructed by two-step immersion strategy: a simple immersion-coating process to construct Polydopamine (pDA) coatings on the surface of a gelatin-chitosan composite hydrogel and followed by grafting of bactericidal quaternary ammonium chitosan (QCS) as well as pH-responsive PMAA to this pDA coating. The in vitro antimicrobial activity, biocompatibility and the in vivo wound healing effects in a mouse MRSA-infected full-thickness defect model of the hydrogel were further evaluated. ResultsAssisted by polydopamine coating, the pH-responsive PMAA and bactericidal QCS are successfully grafted onto a gelatin-chitosan composite hydrogel surface and hydrogels maintain the adequate mechanical properties. At physiological conditions, the PMAA hydration layer endows the hydrogel with resistance to initial bacterial attachment. Once bacteria colonize and acidize local environment, the swelling PMAA chains tend to collapse then expose the bactericidal QCS, realizing the on-demand kill bacteria. Moreover, the dead bacteria can be released and the hydrogel will resume the resistance due to hydrophilicity of PMAA at increased pH, endowing the surface renewable ability. In vitro and in vivo studies demonstrate the favorable biocompatibility and wound healing capacity of hydrogels that can inhibit infection and further facilitate granulation tissue, angiogenesis, and collagen synthesis. ConclusionThis strategy provides a novel methodology for the development and design of smart wound dressing to combat multidrug-resistant bacteria infections.

Gel polymer electrolytes based on compound cationic additives for environmentally adaptive flexible zinc-air batteries with a stable electrolyte/zinc anode interface

With the rapid development of flexible wearable technology, there is an urgent need for the exploitation of flexible and sustainable energy storage devices. Flexible zinc-air battery (ZABs) have attracted extensive attention from researchers due to their high theoretical energy density, abundant raw material and environmental friendliness. However, there is no more effective strategy to solve the problems of dendrite growth and by-products formation on the zinc anode surface of flexible ZABs in a strong alkaline environment. Herein, the PMA-HLx hydrogels based on chitosan quaternary ammonium salt (HACC) and La3+ as compound cationic additives are prepared as gel polymer electrolytes (GPEs) for flexible ZABs. The optimal PMA-HL0.02 GPE shows admirable interfacial adhesion and favorable ionic conductivity of 130.43 mS cm−1. Meanwhile, the assembled flexible ZAB exhibits excellent electrochemical performance and long cycle life, as well as a stable charge-discharge voltage gap at different bending angles, and still has favorable power densities of 113.2 mW cm−2 and 93.65 mW cm−2 at -20°C and 80°C, respectively. Therefore, this synthesis strategy of GPEs based on compound cationic additives provides a useful reference for the development of flexible ZABs with environmental adaptability and interfacial stability in alkaline electrolyte environment.

Preparation of photothermal alginate/chitosan derivative/CuS@polydopamine composite fibers and application in desalination

A polyelectrolyte system consisting of sodium alginate (SA) and quaternary ammonium chitosan (QAC) blended with polydopamine-coated copper sulfide particles (CuS@PDA) was chosen to investigate the function of CuS@PDA in the uniform binary blending of anionic and cationic polyelectrolytes in detail. A smart composite fiber SA/QAC/CuS@PDA was prepared via a dry-wet spinning technique. With the addition of CuS@PDA (about 4.3 % in fiber), the as-prepared SA/QAC/CuS@PDA-0.50 fibers (SQCuS@P-0.50 SCFs) showed notably enhanced intensity 359.2 MPa, excellent moisture response, and photothermal conversion performance, with the temperature increasing from 25.9 to 80.7 °C as irradiated under a 980 nm infrared lamp at distance 20 cm away for 120 s. The photothermal performance was maintained after 6 lighting on-and-off cycles. The tensile strength decreased ~23.8 % after 4 cycles, then remained fixed. The diameter increases to ~480 % in wet state but decreases to the original size in dry state for 10 cycles. When the fabric with 90 wt% SQCuS@P-0.50 SCFs was used as a water evaporator, the water evaporation rate and efficiency were 1.68 kg·m−2·h−1 and 102 % under 1 sun irradiation. This work provides a simple and ecofriendly strategy for fabricating photothermal fabrics by designing and preparing composite fibers.