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Membrane biofouling has long been a major obstacle to highly efficient water treatment. The modification of the membrane surface with hydrophilic materials can effectively enhance biofouling resistance. However, the water flux of the membranes is often compromised for the improvement of antifouling properties. In this work, a composite membrane composed of a zwitterionic hydrogel and electrospinning fibers was prepared by a spin-coating and UV cross-linking process. At the optimum conditions, the composite membrane could effectively resist the biofouling contaminations, as well as purify polluted water containing bacteria or diatoms with a high flux (1349.2 ± 85.5 L m-2 h-1 for 106 CFU mL-1 of an Escherichia coli solution). Moreover, compared with the commercial poly(ether sulfone) (PES) membrane, the membrane displayed an outstanding long-term filtration performance with a lower water flux decline. Therefore, findings in this work provide an effective antifouling modification strategy for microfiltration membranes and hold great potential for developing antifouling membranes for water treatment.

The term "zwitterionic polymers" refers to polymers that bear a pair of oppositely charged groups in their repeating units. When these oppositely charged groups are equally distributed at the molecular level, the molecules exhibit an overall neutral charge with a strong hydration effect via ionic solvation. The strong hydration effect constitutes the foundation of a series of exceptional properties of zwitterionic materials, including resistance to protein adsorption, lubrication at interfaces, promotion of protein stabilities, antifreezing in solutions, etc. As a result, zwitterionic materials have drawn great attention in biomedical and engineering applications in recent years. In this review, we give a comprehensive and panoramic overview of zwitterionic materials, covering the fundamentals of hydration and nonfouling behaviors, different types of zwitterionic surfaces and polymers, and their biomedical applications.

Biomimetic membrane materials have been widely explored and developed for drug loading and tissue engineering applications due to their excellent biocompatibility and abundant reaction sites. However, novel cytomembrane mimics have been lacking for a long time. In this study, black phosphorus (BP) was used as the foundation for a new generation of promising cytomembrane mimics due to its multiple similarities to cytomembranes. Inspired by the dual function of endotoxins on membranes, we prepared a BP-based cytomembrane mimic with controllable antibacterial ability via electrostatic interaction between BP and [1-pentyl-1-quaternary ammonium-3-vinyl-imidazole]Br ([PQVI]Br). The release of PQVI could be manipulated in different conditions by adjusting the electrostatic force, thereby achieving controllable antibacterial ability. This report confirms the possibility of using BP as a new material to mimic cytomembranes and provides a new concept of controllable antibacterial action based on endotoxins.

Iodine capture and reutilization have become one of the most pressing global challenges to public health. Herein, we synthesized novel antibacterial nano-povidones containing hydrophobic nitrile units and hydrophilic pyrrolidone units as two side chains via a radical copolymerization strategy. The pyrrolidone units functioned as an adsorbent to capture iodine and were capable of releasing iodine to attack pathogens. The particles’ morphology, size, and hydrophilicity/hydrophobicity balance were regulated facilely by introducing polyacrylonitrile into the povidone system. The final nano-povidone–iodines were found to be extremely potent against two selected pathogens Escherichia coli and Staphylococcus aureus, with low cytotoxicity. Remarkably, in comparison with their bulk counterparts, the nano-povidone–iodines showed unexpectedly enhanced antibacterial action because of their special morphology and nanoscale size, rough surfaces, and hydrophilicity/hydrophobicity balance. This proposed strategy may indicate a new direction for pollutant treatment and secondary utilization.

Designing antimicrobials with high efficiency and long-term antibacterial activity is an imperative issue. We found that the antimicrobial effect of Ti3C2Tx and Ag/Ti3C2Tx could be significantly strengthened upon near-infrared light exposure. The synergistic antibacterial mode of the photothermal bactericidal effect and intrinsic bacterial activity have been revealed, which confirms that the Ti3C2Tx MXene is an excellent near-infrared light-mediated nanoplatform for antibacterial applications. To further test the antibacterial effect in practical applications, Ag/Ti3C2Tx embedded hydrogels were used as wound dressings in a wound model experiment. They exhibit outstanding bacterial inhibition and wound healing performance with near-infrared light exposure. This work inspires us to explore the MXene-based photothermal platform in terms of antibacterial application.

Cell cryopreservation has evolved as an important technology required for supporting various cell-based applications, such as stem cell therapy, tissue engineering, and assisted reproduction. Recent times have witnessed an increase in the clinical demand of these applications, requiring urgent improvements in cell cryopreservation. However, cryopreservation technology suffers from the issues of low cryopreservation efficiency and cryoprotectant (CPA) toxicity. Application of advanced biotechnology tools can significantly improve post-thaw cell survival and reduce or even eliminate the use of organic solvent CPAs, thus promoting the development of cryopreservation. Herein, based on the different cryopreservation mechanisms available, we provide an overview of the applications and achievements of various biotechnology tools used in cell cryopreservation, including trehalose delivery, hydrogel-based cell encapsulation technique, droplet-based cell printing, and nanowarming, and also discuss the associated challenges and perspectives for future development.

Silk is an attractive natural fiber due to its excellent mechanical properties and biocompatibility. Xenobiotic modification of pristine silk is gaining significant attention to meet specific demands. The silk payload of xenobiotics is affected by their uptake efficiency, biodistribution, metabolism, and excretion. Herein, we systematically evaluated the effect of the nanoparticle size (20–100 nm) on the biodistribution and silk production by introducing silver nanoparticles (AgNPs) into the silkworm diet. Interestingly, the silk payload of AgNPs is highly dependent on their overall size, where 50 nm AgNPs are prone to accumulate in silk glands and reveal the highest content in the produced silk, qualifying silk antibacterial activity against both Gram-positive and Gram-negative bacteria. These findings provide new insights to understand how nanoparticle properties influence the incorporation of nanomaterials into silk and can help optimize the material design.

Resin hemoperfusion is a life-saving treatment for drug intoxication or hepatic failure of patients. However, current resin adsorbents exhibit a limited hemocompatibility or low adsorption efficiency, representing a major roadblock to successful clinical applications. In this work, we developed a hemocompatible and effective hemoadsorbent based on polystyrene resin (H103) microparticles encapsulated in anti-biofouling zwitterionic poly(carboxybetaine) (PCB) hydrogels. Apart from a strong mechanical stability, this PCB-based adsorbent (PCB-H103) exhibited excellent hemocompatibility (hemolysis ratio was ∼0.64%), which was attributed to the anti-biofouling property of PCB hydrogel. In addition, it can efficiently adsorb both small and middle molecular weight molecules in phosphate-buffered saline, and the efficiencies were significantly higher than poly(ethylene glycol) methacrylate-based and poly(2-hydroxyethyl methacrylate)-based adsorbent counterparts, indicating the favorable permeability of PCB hydrogel coating. More importantly, PCB-H103 could effectively remove protein-bound toxins including phenol red and bilirubin in bovine serum albumin solution or even in 100% fetal bovine serum (FBS). In 100% FBS, the adsorption capacity of PCB-H103 towards bilirubin was 8.3 times higher than that of pristine clinical-scale resin beads. Findings in this work may provide a new strategy for the development of modern resin hemoperfusion technology.

The microdroplets in fog flow have been considered as an important resource for supplying fresh drinking water. Most of the reported works of fog collection focus on the water-collecting ability rather than the environmental reliability of selected materials. In this work, a beetle-inspired hierarchical fog-collecting interface based on the antibacterial needle-array (ABN) and hydrophilic/hydrophobic cooperative structure is displayed. The hydrophilic ABN is coated with zwitterionic carboxybetaine (CB) brushes that endow the fog collector with a long-term cleaning in harsh environment. Due to its strong affinity to water molecules, the tilted needles with a CB coating can facilitate the capture of fog and the rapid delivery of condensed water driven by gravity. After being transported to the connected hydrophobic sheet, the collected droplets can be rapidly detached and stored in the container, achieving a high fog-harvesting rate. Furthermore, CB-patterned channels are integrated on the hydrophobic sheet for the pathway-controlled water delivery. The CB coating is able to efficiently resist bacterial adhesion and contamination during fog harvesting, protecting the device from microbiological corrosion. The current design provides a promising method to incorporate antibacterial ability into fog collectors, which offer great opportunity to develop water harvesters for real-world applications.

Currently, the state-of-the-art cryoprotectants for cell cryopreservation have bottleneck problems (such as cytotoxicity), which place enormous logistical limitations to the development of regenerative medicine. In this work, a first alginate polymer-based approach for human chondrocyte cryopreservation is reported. Combined with zwitterionic betaine, a natural osmoprotectant to offer intracellular protection, this alginate polymer-based approach can achieve ∼90% cryopreservation efficiency. Because of the biocompatibility of alginate polymer and betaine, this approach can easily retrieve the post-thaw cells without traditional multistep cryoprotectant washing procedures, which is highly favorable to cell therapy. Meanwhile, because of the feasible and mild gelation process of alginate polymer, this approach can also directly encapsulate the post-thaw cells into hydrogels without cryoprotectant removal, which is highly useful to tissue engineering. Moreover, these hydrogels exhibit tunable mechanical properties and can form variable shapes and sizes of scaffolds to inject into the patient's defect sites. After encapsulating post-thaw cells, these hydrogels can maintain high cell viability (∼90%) and normal cellular functions for at least 14 days. This work provides a step-change in cryopreservation of cells to be directly used in cell-based applications and may realize promising cellular therapy products that can integrate preservation with clinical practice.

Chemotherapy is a key medical method for cancer treatment because a large amount of patients are not suitable for surgeries, and the multi-drug resistance (MDR) and drug toxicity are still the major obstacles for clinical advancement. Here, we report the development of a nanoliposomal multi-drug delivery system with lapatinib and doxorubicin co-loaded in PEGylated nanoliposomes (Lip-LPT-DOX). Lip-LPT-DOX showed great chemosensitization of two human lung adenocarcinoma cell lines. LPT loaded in nanoliposomes could inhibit the function of ABC transporters, which could pump drugs out of cancer cells and lead to decreased intracellular drug accumulation. Lip-LPT-DOX showed a uniform size distribution and high loading efficiency with negligible drug leakage. Compared to clinical formulation, liposomal DOX (Lip-DOX), both intracellular DOX accumulation and therapeutic efficiency of Lip-LPT-DOX were significantly improved. Lip-LPT-DOX with half amount of DOX as Lip-DOX showed higher therapeutic efficiency, and it exhibited negligible toxicity to somatic cells, indicating the significantly reduced side effects. This novel nanoliposomal multi-drug delivery system provided a promising chemosensitization strategy that could likely overcome MDR and reduce the administration dose of DOX in cancer chemotherapy.

Cryopreservation of red blood cells (RBCs) is fundamentally important to modern transfusion medicine. Currently, organic solvent glycerol is utilized as the state-of-the-art cryoprotectant (CPA) for RBC cryopreservation. However, glycerol must be removed before RBC transfusion to avoid intravascular hemolysis via a time-consuming deglycerolization process with specialized equipment (e.g., ACP 215), thus limiting the clinical use of frozen RBCs. Herein, we report novel biocompatible CPA formulations combining betaine with membrane stabilizers (disaccharides or amino acids), which can achieve outstanding efficiency for RBC cryopreservation directly using whole blood without any separation process. Most importantly, because of the osmotic regulation capacity of betaine, a simple and fast one-step method can be used for CPA removal, which is significantly superior to the current multistep deglycerolization process. This work offers a promising solution for highly efficient and solvent-free RBC cryopreservation and holds great potential for improving the long-term storage and long-distance distribution of RBCs.

Coronary stent implantation is an effective procedure for percutaneous coronary intervention treatment. However, its long-term safety and efficacy are still hindered by the in-stent restenosis and late thrombus formation. Herein, an anti-biofouling and endothelial cell selective zwitterionic hydrogel coating was developed to simultaneously enhance the nonspecific resistance and rapid re-endothelialization of the titanium surface. An endothelial cell selective peptide, REDV, could be simply conjugated on the zwitterionic carboxybetaine (CB) hydrogel to prepare the REDV/CB coating. It was found that the REDV/CB hydrogel layer maintained antifouling properties, which could inhibit the protein adsorption, bacterial adhesion, platelet activation and aggregation, and smooth muscle cell proliferation. More importantly, the co-culture study confirmed that the conjugated REVD peptide could specifically capture endothelial cells and promote their migration and proliferation, and simultaneously decrease the adhesion and proliferation of smooth muscle cells. Therefore, the antifouling and endothelial cell selective coating proposed in this work provides a promising strategy to develop an intravascular stent for promoted re-endothelialization and inhibited neointimal hyperplasia in clinical applications.

Designing antimicrobials with high efficiency and long-term antibacterial activity is an imperative issue. We found that the antimicrobial effect of Ti3C2Tx and Ag/Ti3C2Tx could be significantly strengthened upon near-infrared light exposure. The synergistic antibacterial mode of the photothermal bactericidal effect and intrinsic bacterial activity have been revealed, which confirms that the Ti3C2Tx MXene is an excellent near-infrared light-mediated nanoplatform for antibacterial applications. To further test the antibacterial effect in practical applications, Ag/Ti3C2Tx embedded hydrogels were used as wound dressings in a wound model experiment. They exhibit outstanding bacterial inhibition and wound healing performance with near-infrared light exposure. This work inspires us to explore the MXene-based photothermal platform in terms of antibacterial application.

A metal-organic framework (MOF)-based antibiofouling hemoadsorbent (PCB-MIL101) was developed through a facile encapsulation of MIL-101(Cr) in zwitterionic poly carboxybetaine (PCB) hydrogel. PCB-MIL101 possessed strong mechanical strength and superior hemocompatibility, ensuring its safety in hemoperfusion applications. In addition, it showed efficient and effective adsorption toward bilirubin (BR), and its maximum adsorption capacity was ∼583 mg g

Preventing bacterial contamination, treating wound infections and promoting wound healing have been major challenges in wound care management. In this work, a novel wound dressing based on a zwitterionic polycarboxybetaine (PCB) hydrogel and antibacterial silver nanoparticles (AgNPs) was developed via a one-step method for the efficient treatment of infected wounds. The PCB-AgNP hydrogel exhibits effective antibacterial ability against both Gram positive bacteria (Saphylococcus aureus) and Gram negative bacteria (Escherichia coli). Furthermore, in a murine model, the PCB-AgNP hydrogel is found to efficiently treat S. aureus infection and accelerate cutaneous wound healing. After a two-week healing process, histological tests indicate that it can promote the reconstruction of intact epidermis, which is much faster than those treated with a commercial wound dressing (Duoderm® film). This new bifunctional wound dressing provides new opportunities for highly efficient skin wound care and management.

Skin traumas are among the most common health problems in the world, and are routinely treated with wound dressings such as bandages and gauze. Traditional dressings are typically made of dry cotton, which tends to adhere to the wound, causing scab formation and bacterial infections. Ideally, a dressing should accelerate wound healing while avoiding any side effects or complications. Recent studies have found that wet dressings, especially hydrogels, can provide a moist environment for wounds that mimics the in vivo environment, thus facilitating debridement of necrotic tissue, enhancing tissue regeneration, and avoiding scab formation. Zwitterionic hydrogels exhibit strong hydration, are biomimetic in nature, and show excellent anti-fouling properties; their resulting high water content, excellent biocompatibility, and negligible interactions with proteins and cells make them ideal wet wound dressings. In this work, we demonstrated that zwitterionic hydrogels, especially poly-carboxybetaine (PCB) hydrogels, can efficiently promote skin wound healing. Skin wounds treated with zwitterionic hydrogels healed significantly better than those treated with PHEMA hydrogels and the commercial product DuoDerm. Moreover, these zwitterionic hydrogels can be easily coated on cotton gauze or bandage pads for easy handling and application. The findings in this work hold great promise for the development of next-generation wound dressings to improve healthcare.

Biofouling from nonspecific protein adsorption and microorganism adhesion is a continuous challenge in numerous biomedical applications such as implants, biosensors, and tissue-engineered scaffolds. The bacteria attached to the biomaterial surface can encapsulate themselves within a protective extracellular polymeric layer, leading to the formation of biofilm that is difficult to combat or eliminate. A promising strategy to prevent device-related infections is the development of new biomaterials that are anti-biofouling and/or antimicrobial. In general, anti-biofouling materials exhibit low adhesion or resistance properties towards a variety of bacteria, while antimicrobial ones can kill microorganisms approaching the surfaces or in the surrounding areas. In this chapter, we briefly introduce the recent strategies in the design and applications of anti-biofouling and antimicrobial materials.

Zwitterionic materials have been attracting significant attentions due to their excellent non-fouling and biocompatible properties and thus have been widely used in many biomedical applications. However, differences among different types of zwitterionic materials have rarely been investigated and compared. In this work, four types of zwitterionic monomers were systematically studied and compared by testing the properties of the hydrogels. Their hydration, diffusion coefficient of water and mechanical properties were evaluated and analyzed. It was found that poly(carboxybetaine methacrylate) (PCBMA) hydrogel possessed the strongest compressive modulus, while poly(carboxybetaine acrylamide) (PCBAA) hydrogel showed the highest diffusion coefficient of water and highest hydration of water. Compared with other hydrogels, the mesh size of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) hydrogel was the largest. Furthermore, poly(sulfobetaine methacrylate) (PSBMA) hydrogel with disulfide crosslinker degraded faster than the others. Findings in this work provided insights and guidance for the selection of different zwitterionic polymers to suit different applications.

Foreign-body reaction (FBR) has been a long-term obstacle for implantable biomedical devices and materials, especially to those that require mass/signal transport between the implants and the body. However, currently, very limited biomaterials can mitigate FBR. In this work, we develop a balanced charged polyelectrolyte hydrogel that can efficiently resist FBR and collagenous capsule formation in a mouse model. Using this new strategy, we can easily tune the antifouling properties of the polyelectrolyte hydrogels by changing the ratio of negatively charged alginate and positively charged poly(ethylene imine). We find that at the optimum ratio where the net charge of hydrogel is neutral, the adhesion of proteins, cells, bacteria, and fresh blood on its surface can be significantly inhibited, indicating its excellent antifouling properties. In vivo studies show that after being implanted subcutaneously, this balanced charged hydrogel can prevent the capsule formation for at least 3 months. Furthermore, immunofluorescent staining results indicate that this balanced charged hydrogel elicits negligible inflammation, significantly reducing macrophage migration to the tissue-implant interface. This flexible and versatile approach holds a great promise for designing a wide spread of new antifouling hydrogels and using as immunoisolation materials for biomedical applications.

Laccase is an important oxidase for many applications such as bioremediation, chemical synthesis, and biosensors, due to its wide range of substrates and prominent capacity to degrade phenolic compounds. However, its unsatisfactory stability, activity, and reusability still remain a major challenge for practical applications. In this work, we found that when laccase was encapsulated in zwitterionic hydrogels, especially poly-carboxybetaine (PCB), its performance could be significantly enhanced. Compared with the free enzyme, PCB–laccase displayed a remarkably increased activity (∼20-fold higher Kcat/Km value). Meanwhile, its stability could also be effectively maintained even in an extensive range of temperatures, pH values and organic solvents. In addition, PCB–laccase demonstrated excellent storage stability, and retained 80% of its initial activity after an 8-week storage period. In a successive 6-cycle decoloration of acid orange 7, PCB–laccase could still retain 52% of its initial activity, demonstrating superior durability to the free laccase. Therefore, we have provided an efficient and stable support matrix for enzyme immobilization, which exhibits potential for practical applications even in harsh environments.

Skin injury caused by large doses of ionizing radiation is the common and severe side effect of radiotherapy. However, its therapeutic efficacy is always hindered by early reactive oxygen species generation, repetitive inflammatory microenvironment and bacterial infection risk. Herein, we report an anti-biofouling hydrogel with anti-inflammation and anti-oxidative properties for the treatment of irradiation-induced skin injury. The anti-biofouling hydrogel can be achieved by balancing oppositely charged alginate, hyaluronic acid (HA) and polylysine (PLL) at the optimal ratio, which effectively resist protein and bacterial adhesion, and evades immune response. Moreover, curcumin and epigallocatechin gallate (EGCG) can be facially encapsulated and substantially released from the hydrogel. Results showed that the resulting AHP-Cur/EGCG hydrogel can significantly weaken the development of skin injury and accelerate its healing process by alleviating inflammation, scavenging ROS and promoting angiogenesis. Therefore, the findings presented in this work provide an effective strategy for clinical management and treatment of ionizing radiation-induced skin injury.

Organic solvents, such as dimethyl sulfoxide (DMSO) and glycerol, have been commonly used as cryoprotectants (CPAs) in cell cryopreservation. However, their cytotoxicity and need of complex freezing protocols have impeded their applications especially in clinical cell therapy and regenerative medicine. Trehalose has been explored as a natural CPA to cryopreserve cells, but its poor cell permeability frequently results in low cryopreservation efficacy. In this work, we presented that a natural zwitterionic molecule-l-carnitine-could serve as a promising CPA for solvent-free cryopreservation. We demonstrated that l-carnitine possessed strong ability to depress water freezing point, and with ultrarapid freezing protocol, we studied the post-thaw survival efficiency of four cell lines (GLC-82 cells, MCF-7 cells, NIH-3T3 cells and Sheep Red Blood Cells) using l-carnitine without addition of any organic solvents. At the optimum l-carnitine concentration, all four cell lines could achieve above 80% survival efficiency, compared with the significantly lower efficiency using organic CPAs and trehalose. After cryopreservation, the recovered cell behaviors including cell attachment and proliferation were found to be similar to the normal cells, indicating that the cell functionalities were not affected. Moreover, l-carnitine showed no observable cytotoxicity, which was superior to the organic CPAs. This work offered an attractive alternative to traditional CPAs and held great promise to revolutionize current cryopreservation technologies, to benefit the patients in various cell-based clinical applications.

Alginate is one of the most favorable materials in many biomedical applications. The mechanical properties of alginate hydrogels can be easily tailored by adding different concentrations of divalent cations. In this work, we demonstrate that the method can also notably influence the biofouling behaviors of alginate hydrogels. A series of alginate hydrogels was prepared by tuning the concentrations of two types of divalent cation (Ca2+ or Ba2+). It was found that the biofouling behaviors of the hydrogels exhibited a 'U' curve tendency with the cation concentrations. Interestingly, we found that in optimal conditions ([Ca2+] = 0.9 mM or [Ba2+] = 0.54 mM), the resultant Ca0.9- and Ba0.54-alginate hydrogels were able to achieve negligible adhesion of the proteins and bacteria. Moreover, these two formulations were also able to prevent inflammatory responses at least 4 weeks after subcutaneous implantation in a mouse model. The findings in this work provide more insights into the design and development of appropriate alginate hydrogels for different applications.

Cartilage tissue engineering highly relies on the ability to store and transport chondrocytes in order to be clinically successful. Cryopreservation is a most reliable technology for chondrocyte storage, but it suffers from the intrinsic toxicity of current state-of-the-art cryoprotectant, dimethyl sulfoxide (DMSO). In this work, we used the first fully zwitterionic compound-based approach for effective chondrocyte cryopreservation. A zwitterionic molecule combined with zwitterionic polymers could balance intra/extracellular osmotic stress and prevent ice formation, which were the keys of successful cryopreservation. Moreover, this zwitterionic combination showed noncytotoxicity due to its high biocompatibility, superior to cytotoxic DMSO. On the basis of these performances, chondrocytes could be well cryopreserved (∼90% post-thaw survival efficiency) for a long time without any addition of DMSO, and the recovered cells could maintain their normal functionalities. In view of the association between polymer molecular weight and cryopreservation efficacy, further mechanism of cryoprotection provided by zwitterionic molecule/polymer was proposed. This work opens a new window of opportunity for DMSO-free cryopreservation using biocompatible zwitterionic materials.

Cartilage tissue engineering highly relies on the ability to store and transport chondrocytes in order to be clinically successful. Cryopreservation is a most reliable technology for chondrocyte storage, but it suffers from the intrinsic toxicity of current state-of-the-art cryoprotectant, dimethyl sulfoxide (DMSO). In this work, we used the first fully zwitterionic compound-based approach for effective chondrocyte cryopreservation. A zwitterionic molecule combined with zwitterionic polymers could balance intra/extracellular osmotic stress and prevent ice formation, which were the keys of successful cryopreservation. Moreover, this zwitterionic combination showed noncytotoxicity due to its high biocompatibility, superior to cytotoxic DMSO. On the basis of these performances, chondrocytes could be well cryopreserved (∼90% post-thaw survival efficiency) for a long time without any addition of DMSO, and the recovered cells could maintain their normal functionalities. In view of the association between polymer molecular weight and cryopreservation efficacy, further mechanism of cryoprotection provided by zwitterionic molecule/polymer was proposed. This work opens a new window of opportunity for DMSO-free cryopreservation using biocompatible zwitterionic materials.

PDMS-based materials have been extensively studied in oil–water separation. However, their successful application is commonly limited by low efficiency, vulnerability to acid/alkali, complex processing procedures, incapability for emulsion separation, etc. Here, a highly durable and robust separation material is developed by coating PDMS-based copolymers on cotton textiles with a facile sol–gel approach. Solely driven by gravity, this new material not only can enable effective separation of oil–water mixture with a flux as high as ∼7500 L m–2 h–1 but also can separate surfactant-stabilized water-in-oil emulsion. Moreover, it remains fully functional even in the environments with high concentrations of acid, alkali, or salt. This novel and versatile strategy holds great promise to be widely used in practical applications of oil–water separation, including oil/chemical spill accidents and industrial sewage emission.

Silver nanoparticles (AgNPs) have been widely used as catalysts in a variety of chemical reactions owing to their unique surface and electronic properties, but their practical applications have been hindered by severe aggregation. The immobilization of AgNPs is crucial to preventing their aggregation or precipitation as well as to improving their reusability. Herein, we developed a facile route for the reductant-free in situ synthesis of AgNPs in zwitterionic hydrogels. Via this method, the embedded AgNPs had a uniform distribution, high activity, and antibiofouling capability. The catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using polycarboxybetaine-AgNPs (PCB-AgNPs) could achieve >95% conversion efficiency within 5 min. Meanwhile, the normalized rate constant knor (10.617 s–1mmol–1) was higher than that of most of the reported immobilized nanocatalysts. More importantly, in a biofouling environment, PCB-AgNPs could still exhibit >97% initial catalytic activity while AgNPs in the P...

Currently, it is highly desirable to develop a stable and effective antifouling coating in maritime industries. In this work, a novel surface-active copolymer basing on hydrophilic polyvinylpyrrolidone (PVP) and hydrophobic poly(dimethylsiloxane) (PDMS) was designed and incorporated into a crosslinked PDMS matrix to form a surface-renewable antifouling coating. In the copolymer, PVP segments possessed a chemical stability and could prevent the settlement of fouling organisms attributable to its strong hydrophilicity; PDMS endowed the copolymer with compatibility to PDMS matrix and could efficiently reduce the fouling adhesion strength attributable to the low surface energy. Based on the surface-active copolymer, the coating could be reconstructed underwater in response to the environment forming a renewable surface to promote the fouling-release property. In addition, a set of controllable composition coatings were prepared to investigate the effects of surface chemistry on antifouling and fouling-release performance. Laboratory bioassays against marine unicellular diatom adhesion (∼99 % reduction) and mimetic barnacle attachment (∼81 % reduction) demonstrated an outstanding antifouling and fouling-release property of the copolymer-based coating compared to pristine PDMS, and the coating with a higher PVP content exhibited a better performance. Moreover, a long-term antifouling capability in marine field test (∼4 months) was also demonstrated. This work may offer a promising solution to the problems induced by marine biofouling.

Ice accretion on airplane surfaces, power lines, or wind turbines can cause operational difficulties and disastrous events. Great efforts have been made to develop environmentally-friendly anti-icing or deicing surfaces over the last several decades, but a high-efficient, robust, and energy-saving surface for both anti-icing and deicing still remains a challenge. Herein, a sunlight-responsive and robust anti-icing/deicing coating is designed by integrating photothermogenic nanocarbon fibers with an amphiphilic material, which is based on hydrophobic polydimethylsiloxane (PDMS) and hydrophilic polyvinylpyrrolidone (PVP) segments. The resultant coating represents an excellent and energy-saving anti-icing/deicing performance: a 34-fold increase of freezing delay time compared with control steel and ~18 KPa of ice adhesion strength enabling easy removal by a natural wind action, attributable to the intrinsic material properties (the ability of PVP to depress water freezing point and the low surface energy of PDMS). Moreover, nanocarbon fibers can further reduce the ice adhesion strength and endow the coating with a rapidly sunlight-sensitive photothermal deicing performance (up to 10 °C/min), presenting the superiority of outdoor applications especially for high-altitude equipment and vehicles. After 30 icing-deicing cycle, simulated acid rain (pH = 0) scouring, sand dropping, and 200 abrasion cycle tests, this coating also exhibits an extraordinary durability and robustness. This work makes a promising anti-icing and deicing coating for a large-scale operation and practical applications in particular outdoors.

Endowing hydrogel with antibacterial capability is promising for tissue repair, but most strategies in the synthesis of antibacterial hydrogel is high-cost and low-yield, suffering from many tedious multi-step reaction procedures to obtain antibacterial function. Taking hyaluronic acid-based hydrogel as an example, we herein report a super-convenient and broad-spectrum effective strategy based on a simple N-halogenation reaction allowing a scalable production of N-halamine-based hydrogel capable of bacteria-killing for infected skin defect therapy. This N-halogenation-based strategy in building antibacterial hydrogel is available to most N–H bond-containing hydrogel, and the specific synthesis is regulatable on-demand by tuning N-halogenation conditions. After a biological systematic evaluation, the hydrogel shows good antibacterial function against bacteria, as well as a low toxicity. Meanwhile, in vivo wound healing test reveals that the hydrogel can resist wound bacterial infection, accelerate the healing process, and promote epithelial regeneration. This contribution demonstrates for the first time that benefiting from its integrated advantages of super-convenience, universality, and scalable producibility, the N-halamine-based hydrogel would be very promising in practical biomedical applications.