A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability

Molybdoenzymes-emulating bio-heterojunction hydrogel with rapid disinfection and macrophage reprogramming for wound regeneration

Developing hydrogel dressings with the capabilities to accommodate irregular wounds and provide a cascade disinfective-regenerative microenvironment for wound repair is of great importance to combating pathogenic bacteria-infected wounds but remains an ongoing challenge. To address the conundrum, we devise a molybdoenzymes-emulating bio-heterojunction (M-bioHJ) doped double network (DN) hydrogel dressing for bacterial-infected wound healing. The near-infrared (NIR) photothermal effect of the M-bioHJ facilitates the exchange of multiple dynamic crosslinking sites in the hydrogel, endowing the hydrogel with photo-remote reprocessing capabilities to completely accommodate the encountered irregular wounds and ultimately accomplish the admirable therapeutic effect. Meanwhile, the introduced M-bioHJ shows NIR light-enhanced photodynamic activity to induce a massive engendering of reactive oxygen species (ROS), allowing rapid sterilization without reliance on exogenous hydrogen peroxide. Furthermore, the Mo ions released from the M-bioHJ-encapsulated hydrogel can play a crucial role in reprogramming the macrophage phenotype and determining tissue regeneration. Both in vitro and in vivo evidences authenticate the accelerated healing potential of infected wounds through the synergistic effects of photo-reprocessing, disinfection, and macrophage-reprogramming facilitated by the hydrogel. These findings highlight the promising application prospects of such neoteric M-bioHJ-encapsulated hydrogel dressings for wound disinfection and tissue regeneration.

A comprehensive review on nanochitosan and its diverse applications in various industries

Nanochitosan, a nanostructured form of chitosan produced from chitin, has become a widely used material with a wide range of applications in a variety of industries. This review summarizes the study on nanochitosan, including its synthesis techniques, distinct physicochemical characteristics, and uses in medicine, agriculture, cosmetics, and cleaning up the environment. The review also emphasizes the impact of synthesis methods such as nanoprecipitation, electrospinning, and chemical modifications on the material's properties and applications. In agriculture, nanochitosan can be used as a long-lasting biopolymer to support crop growth and health. Because it is mucoadhesive and compatible with living things, it can also enhance the effectiveness of medication. The potential of nanochitosan to enhance skin permeability and encapsulate active chemicals in cosmetics presents exciting opportunities for innovation. Furthermore, nanochitosan effectiveness as a biosorbent and antibacterial agent in wastewater treatment highlights its potential to tackle environmental issues. The present study offers valuable perspectives on the present status of nanochitosan research, highlights significant obstacles, and suggests future avenues for optimizing its industrial applications.

Decoupling of Bonding Strength and Water Retention in Aqueous Wood Adhesive Inspired by Plant Cell

Aqueous wood adhesives with both water retention and strong bonding strength are essential for wood industrial applications. However, the enhanced water retention of adhesive often suffers from low water resistance and bonding strength due to its increased hydrophilicity. Inspired by the water retention and mechanical support in plant cell, we develop a multifunctional biomass soybean meal (SM) adhesive by combining the rigid internal boron-nitrogen coordinated boronic esters structure for reinforcement with the flexible zwitterionic polymer for water retention. Such a design provides good dry (2.03 MPa) and wet shear (1.14 MPa) strengths and demonstrates durable adhesion in various harsh environments for up to 80 days. The adhesive exhibits the anticipated water retention property, extending the plywood shaping manufacturing time to 60 min due to the ability of the water-retaining polymer to convert free water into a bound state and suppress water evaporation. Additionally, the adhesive demonstrates a 10-fold increase in mildew resistance compared with the SM adhesive and exhibits good flame retardancy. This study presents a versatile and efficient approach for developing durable, water-retaining, and sustainable aqueous adhesives for various bonding techniques and shaping materials.

An effective approach to obtain functional poly-β-peptides for combating drug-resistant bacterial infections

The high mortality of drug-resistant bacterial infections, especially those caused by multidrug-resistant Gram-negative pathogens, highlights an urgent demand for promising antimicrobial strategies. Host defense peptide (HDP)-mimicking poly-β-peptides have demonstrated significant potential in combating drug-resistant bacterial infections, with their antimicrobial activity closely dependent on their side-chain structures. However, the restricted structural diversity of poly-β-peptides necessitates efficient synthetic methods to expand their diversity, particularly positively charged side-chain structures. This study presents a water-tolerant approach that facilitates the controllable synthesis of poly-β-peptides with different chain lengths and structurally diverse side chains, including primary amines, tertiary amines, as well as alkyl, aryl, and methoxy groups. This approach serves as an HDP-mimicking discovery platform to obtain the optimal poly-β-peptide, AOc0.8HNL0.2, which exhibits broad-spectrum antibacterial activity and high selectivity against drug-resistant bacteria. The antibacterial mechanism studies reveal that AOc0.8HNL0.2 disrupts the membrane of Gram-negative bacteria. In vivo evaluations substantiate the therapeutic potential of AOc0.8HNL0.2 in treating drug-resistant bacterial infections with no observable toxicity. This study underscores the potential of this convenient synthetic strategy as a promising platform for developing antimicrobial poly-β-peptides to combat the growing threat of drug-resistant bacterial infections.

Bioactive hemostatic materials: a new strategy for promoting wound healing and tissue regeneration

Wound healing remains a critical global healthcare challenge, with an annual treatment cost exceeding $50 billion worldwide. Over the past decade, significant advances in wound care have focused on developing sophisticated biomaterials that promote tissue regeneration and prevent complications. Despite these developments, there remains a crucial need for multifunctional wound healing materials that can effectively address the complex, multiphase nature of wound repair while being cost effective and easily applicable in various clinical settings. This review systematically analyzes the latest developments in wound healing materials, examining their chemical composition, structural design, and therapeutic mechanisms. We comprehensively evaluate various bioactive components, including natural polymers, synthetic matrices, and hybrid composites, along with their different forms, such as hydrogels, powders, and smart dressings. Special attention is given to emerging strategies in material design that integrate multiple therapeutic functions, including sustained drug delivery, infection prevention, and tissue regeneration promotion. The insights provided in this review illuminate the path toward next-generation wound healing materials, highlighting opportunities for developing more effective therapeutic solutions that can significantly improve patient outcomes and reduce healthcare burden.

Enhanced antibacterial and antibiofilm activities of quaternized ultra-highly deacetylated chitosan against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacterial infections pose a severe threat to global public health and present significant challenges in the treatment of bacterial keratitis. The escalation of antimicrobial resistance (AMR) underscores the urgent need for alternative therapeutic strategies. In this study, we report the homogeneous synthesis of quaternized ultra-highly deacetylated chitosan (QUDCS) using a sequential acid-base combination approach. The optimized QUDCS-2 exhibits broad-spectrum antibacterial activity through a membrane-disruption mechanism driven by electrostatic, hydrogen bonding, and hydrophobic interactions, while maintaining low cytotoxicity and high selectivity. Compared to less deacetylated counterparts, QUDCS-2 demonstrates superior stability in enzyme-rich environments and effectively inhibits and eradicates mature biofilms of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Furthermore, QUDCS-2 exhibits a remarkable ability to prevent the development of antimicrobial resistance. In a mouse keratitis model, QUDCS-2 shows excellent biocompatibility and significant antibacterial efficacy, providing strong support for its potential as a long-term, effective antimicrobial agent.

Silver Nanoparticle-Based Finishing for Leather Antimicrobial and UV Protection

This study focuses on preparing and characterizing functionalized silver nanoparticle-based (Ag-F NPs) finishing agents for leather treatment. Ag-F NPs were synthesized and functionalized through a ligand exchange process with citric acid, enhancing their dispersion stability in aqueous media. The nanoparticles were incorporated into polyurethane- and nitroemulsion-based finishing formulations and applied to ovine and bovine leather via a spray coating process. Morphological (SEM, TEM), structural (XRD), thermal (TGA), and spectroscopic (FT-IR) analyses confirmed successful functionalization and uniform dispersion within the finishing layer. Leather samples treated with Ag-F NPs exhibited a significant improvement in antibacterial properties, with microbial growth reduction of up to 90% after 72 h. Additionally, accelerated aging tests demonstrated enhanced UV resistance, with a 30% lower color change (∆E) compared to control samples. The Ag-F NPs-based finishing layers also exhibited superior abrasion and micro-scratch resistance, maintaining a stable coefficient of friction over time. These findings demonstrate the potential of Ag-F NPs as multifunctional leather-finishing agents, making them highly suitable for applications in the automotive, footwear, and leather goods industries.

Dual-Functional Antimicrobial and Low-Fouling Cellulose Coatings

Surfaces contaminated with pathogens raise significant concerns due to their potential role in increasing the risk of disease transmission and subsequent infection. Existing surface coatings face several challenges that undermine their effectiveness and their broader applicability. These include the impact of surface topography on pathogen adhesion, which leads to biofouling, high production costs, scalability issues, as well as environmental concerns stemming from the utilization of toxic antifoulants and biocides. Here, we report dual-functional surface coatings with intrinsic antimicrobial and low fouling properties that are synergistic. The coatings are a porous reactive cellulose fibers network with dialdehyde functionality that demonstrates high antibacterial and antiviral performance against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli, and influenza A/H1N1 virus. Furthermore, we showed that the wettability of the coating significantly reduces the adhesion and colony formation of bacteria and their dead debris after inactivation by dialdehyde groups. The reactive cellulose fibers did not demonstrate any acute toxicity on L929 cells, which can meet the safe use of coating on the contact surfaces. The cellulose fibers coating derived from agricultural waste is cost-effective, eco-friendly, and highly scalable and is promising for use in packaging, household products, public facilities, and medical settings surfaces.

Gadolinium doped carbon dots for anti-gram-negative bacteria and visible light photodynamic enhancement of antibacterial effect

Infection with gram-negative bacteria is the main source of the most serious infectious pathogens. Developing new antibacterial materials that break through their external membranes and stay in the bacterial body to result in an antibacterial effect is the key to achieving high efficiency against Gram-negative bacteria. A Gd-doped carbon dot (GRCD) was prepared using the approved therapeutic diagnostic agents Rose Bengal (RB) and gadolinium ions (Gd3+), which was used to resist Gram-negative bacteria (e.g. E. coli, Escherichia coli). GRCD not only showed strong antibacterial activity by destroying the external membranes of E. coli (inhibition rate against E. coli was 92.0 % at 20 μg/mL) but also bound to E. coli DNA and generated single oxygen (1O2) (quantum yield was 0.50) through visible light-driven catalysis, thus decomposing the DNA of E. coli and further enhancing the antibacterial performance of GRCD. Under visible light conditions, the inhibition rate against E. coli reached 95.8 % at a low concentration of 2.5 μg/mL, without obvious cytotoxicity to NIH3T3 cells. The use of GRCD in treating wound infections in mice caused by E. coli was quite good, without side reactions on the mice's essential organs. In this study, a new approach has been provided to the design and synthesis of carbon dot nanocomposites for use against Gram-negative bacteria.

Antibacterial and safe chitosan-graphene hydrogel films: a promising nanotherapeutic for Staphylococcus aureus wound infections

Pathogenic bacterial growth at wound sites, particularly Staphylococcus aureus, poses a serious threat during trauma. Delayed treatment can lead to increased inflammation and severe tissue damage. In this study, a chitosan cross-linked polycationic peptide-conjugated graphene-silver (CGrAP) nanocomposite hydrogel film was developed as an antibacterial wound dressing to treat S. aureus infections. The CGrAP hydrogel was synthesized via a Schiff-base reaction between the ε-poly-L-lysine functionalized graphene-silver nanocomposite and chitosan, and then cast into a film. Its antibacterial action is due to electrostatic interactions and ROS generation, finally disrupting the bacterial cells. In vivo studies on Wistar rat model demonstrated superior bacterial eradication and wound healing compared to antibiotic treatment. The CGrAP hydrogel also showed excellent physicochemical properties, including porosity, water uptake and cytocompatibility with L929 fibroblast cells along with no skin irritation or acute dermal toxicity. These results suggest that, CGrAP nanocomposite hydrogel films have strong potential for antibacterial wound dressing development in chronic wound care.

Insight into Iron(III)-Tannate Biosorbent for Adsorption Desalination and Tertiary Treatment of Water Resources

An innovative biosorbent-based water remediation unit could reduce the demand for freshwater while protecting the surface and groundwater sources by using saline water resources, such as brine, brackish water, and seawater for irrigation. Herein, for the first time, we introduce a simple, rapid, and cost-effective iron(III)-tannate biosorbent-based technology, which functions as a stand-alone fixed-bed filter system for the treatment of salinity, heavy-metal contaminants, and pathogens present in a variety of water resources. Our approach presents a streamlined, cost-efficient, energy-saving, and sustainable avenue for water treatment, distinct from current adsorption desalination or conventional membrane techniques supplemented with chemical and UV treatments for disinfection. The proof of feasibility for effective treatment of heavy metals, adsorption desalination, and cleansing of pathogens is demonstrated using synthetic water, brine, and field-collected seawater. The adsorption equilibrium and adsorption kinetic isotherm models, and mass transfer diffusion models confirmed the sorbent's function for sieving heavy-metal ions-silver (Ag+), cadmium (Cd2+), and lead (Pb2+)-from water. The maximum adsorption capacities (q m) of the sorbent for Ag+, Cd2+, and Pb2+ reach 96.25, 66.54, and 133.83 mg/g at neutral pH. The sorbent's affinity for heavy-metal-ion adsorption significantly increased, yielding q m of 116.57 mg/g for Ag+, 104.04 mg/g for Cd2+, and 165.66 mg/g for Pb2+, at pH 9, respectively, due to the sorbent's amphoteric nature. The pristine sorbents exhibit exceptional adsorption desalination efficacy (>70%) for removing salinity from brine and seawater, promoting heterogeneous adsorption. Fe(III)-TA's ability to disinfect seawater, with 67% efficacy over a very short contact time (∼15 min), confirms its remarkable antimicrobial properties for contact active mode pathogens cleansing. By preventing the release of salts, heavy-metal contaminants, and pathogens into the environment, our results proved that this novel multiplex biobased sorbent approach directly contributes to the water quality of surface and groundwater resources.

Flexible coatings based on hydrogel to enhance the biointerface of biomedical implants

The use of biomedical implants in surgical techniques promotes the restoration of lost tissue or organ physiological functions in the body. The interface between different materials determines their interactions and ultimately affects the physicochemical properties of biomedical implants. After implantation, the biointerface plays a crucial role in determining the biocompatibility and functionality of biomedical implants. Surface modification of biomaterials by developing novel biomaterials like various flexible coatings to meet the requirements of biointerfaces, such as mechanical performance, compatibility safety, and biological activities, can improve material-biological interactions by maintaining its original volumetric characteristics. Hydrogels possess excellent plasticity, biodegradability, biocompatibility, and extracellular-matrix-like properties, making them widely used in the biomedical field. Moreover, due to their unique three-dimensional crosslinked hydrophilic network, hydrogels can encapsulate a variety of materials, such as small molecules, polymers, and particle. In recent years, it has been proved that coating biomedical implant materials with flexible hydrogels can optimize the biointerface and holds vast potential for implant surface modification. In this review, we first discussed the potential requirements of the biointerface on the surface of implantable materials in both in vitro and in vivo biological microenvironments. Based on these comprehensive reviews, we also introduced the potential applications of hydrogels in both in vitro and in vivo settings. Finally, this review focused on the challenges faced by the biointerface of implantable materials constructed based on hydrogels and proposed future approaches to inspire researchers with new ideas.

Native and cationic cellulose nanofibril films enriched with avocado seed compounds as a green alternative for potential wound care applications

Cellulose nanofibrils (CNF) show great potential for skin wound care and healing due to their biocompatibility, non-cytotoxicity, and high swelling with good mechanical stability. In the presented study, for the first time native and cationized cellulose nanofibrils were used in combination with avocado seeds extracts obtained with different extraction methods (ASE), as an alternative to a well-known antibiotic, Clindamycin, to produce films with high and long-lasting antimicrobial efficacy. The swelling capacity of prepared films and extracts/antibiotic release kinetics were studied at different pH values to evaluate pH response behavior. All developed films exhibited high bacteriostatic and bactericidal activity against Gram-negative Escherichia coli and G-positive Staphylococcus aureus, resulting in up to 100 % bacterial reduction with the log reduction factor up to 5.64 or 6.50, at 14.2 mg of avocado seed extract or clindamycin integrated in the 1 cm2 of CNF film. The high swelling capacity (up to 65.67 %) and stability of avocado seed extracts-enriched CNF films provide a suitable moisture environment and a sustainable release (up to 40.98 % in 48 h) of bioactive compounds. The prepared antibacterial films' chemical and morphological characteristics and pH-responsive behavior proved the potential applications in the cosmetics, biomedicine, and pharmaceutical industry.

Multi-functional Gleditsia sinensis galactomannan-based hydrogel with highly stretchable, adhesive, and antibacterial properties as wound dressing for accelerating wound healing

Design and development of a multifunctional wound dressing with self-healing, adhesive, and antibacterial properties to attain optimal wound closure efficiency are highly desirable in clinical applications. Nevertheless, conventional hydrogels face significant barriers in their mechanical strength, adhesive performance, and antibacterial properties. Herein, a tough hydrogel based on aldehyde-grafted galactomannan was synthesized through radical copolymerization and Schiff base reaction, incorporating hyaluronic acid, acrylamide, and the zwitterionic monomer to create a multi-crosslinked structure. The multiple crosslink structure pattern consisting of multiple hydrogen bonding, ionic interactions, reversible Schiff bases bonds, and molecular chain entanglement endowed this hydrogel with multiple functionalities, including high tensile strength (25 kPa), tensile strain (2200 %), toughness (391.59 kJ/m3), and Young's modulus (9.77 kPa). The presence of catechol groups and zwitterionic groups endow hydrogels with outstanding adhesion strength (42.21 kPa), which satisfied the adhesive demand for the ample motion of specific areas. The zwitterionic monomer provided long-lasting antibacterial properties and promoted migration and growth of negatively charged cells, capable of establishing efficient antibacterial barriers and serving as wound dressing. The in vivo and vitro experiments manifested that the optimized hydrogel demonstrated an inconspicuous inflammatory response, facilitating rapid healing of full-thickness skin wound in rat models. Therefore, this work provides a promising strategy and an ideal candidate for wound healing dressings in treating infected skin wounds.

An injectable carboxymethyl chitosan-based hydrogel with controlled release of BMP-2 for efficient treatment of bone defects

Although biological scaffolds containing bone morphogenetic protein-2 (BMP-2) have been widely used for osteogenic therapy, achieving stable and controlled release of BMP-2 remains a challenge. Herein, a novel BMP-2 sustained-release system composed of carboxymethyl chitosan (CMCS)/polyethylene glycol (PEG)/heparin sulfate (HS) (CMCS/PEG/HS) was constructed with a Schiff base reaction, yielding an injectable hydrogel for the release of BMP-2 in a controlled manner. For the CMCS/PEG/HS/BMP-2 hydrogel, the HS component had a negatively charged structure, which can bind to positively charged growth factors and prevent early hydrolytic metabolism of growth factors, thus achieving sustainable release of BMP-2. Notably, the release of BMP-2 in hydrogels was dependent mainly on degradation of the hydrogel matrix rather than simple diffusion. Generally, the CMCS/PEG/HS/BMP-2 hydrogel scaffold demonstrated excellent recoverability, good injectability, excellent biocompatibility and high adaptability, as well as efficient self-healing features to occupy irregularly shaped bone marrow cavities. The in vitro results revealed that the CMCS/PEG/HS/BMP-2 hydrogel promoted the osteogenic differentiation of MC3T3-E1 cells. Furthermore, the in vivo results suggest that the hydrogel has promising osteogenic effects that promote bone regeneration in a skull bone defect model. The injectable hydrogel scaffold shows great promise for bone treatment in the future.

Multifunctional coating with hydrophobicity, antibacterial and flame-retardant properties on cotton fabrics by layer-by-layer self-assembly curing of phytic acid and a tyrosine-derived hyperbranched benzoxazine

The inherent hydrophilicity and biocompatibility of cotton fabrics facilitated bacterial proliferation and safety concerns, limiting their applications. To address these issues, tyrosine-derived polyetherimide, bis(3-aminopropyl)-terminated poly(dimethylsiloxane), and paraformaldehyde were used to synthesize hyperbranched benzoxazine THB-BOZs-PDMS with potent antibacterial and antibiofilm activity. The protonated amino groups of benzoxazine facilitated electrostatic interactions with negatively charged bacteria, and hydrophobic interactions disrupted the cell membrane, leading to bacteria death. Notably, phytic acid interacts with benzoxazines through intermolecular forces, with its phosphoric acid groups facilitating the curing of benzoxazines, thereby imparting flame-retardant properties to the material. Consequently, a multifunctional coating was developed via LBL self-assembly and in-situ curing of benzoxazines and phytic acid on the fabric surfaces. The successful deposition of the coating was confirmed through compositional analysis and morphological characterization. After 4 cycles of LBL modification, the fabrics TBP + PA-CF-4 displayed outstanding antibacterial efficacy, bacterial anti-adhesion properties, and heat resistance. Furthermore, TBP + PA-CF-4 exhibited notable washing and mechanical durability, attributed to the stability conferred by in-situ cured of layers. Compared with other reported modified fabrics, TBP + PA-CF-4 displayed more comprehensive overall performances. These multifunctional fabrics provided a sustainable approach for advancing personal protective materials and public decoration, particularly suited for use in high-humidity environments or military settings.

Cytocompatible Hydrogels with Tunable Mechanical Strength and Adjustable Swelling Properties through Photo-Cross-Linking of Poly(vinylphosphonates)

Herein, the synthesis, characterization, and application of a novel synthetic hydrogel based on the photoinitiated cross-linking of poly(vinylphosphonates) is presented. First, statistical copolymers with adjustable ratios of the monomers diallyl vinylphosphonate (DAlVP) and diethyl vinylphosphonate (DEVP), as well as different molecular weights, were obtained via rare earth metal-mediated group-transfer polymerization (REM-GTP) while maintaining narrow polydispersities. The copolymers were cross-linked by applying photoinitiated thiol-ene click chemistry (λ = 365 nm). The network formation was monitored via oscillatory rheology coupled with UV-irradiation, revealing the high spatiotemporal control of the reaction. Moreover, the equilibrium storage moduli of poly(vinylphosphonate)-based hydrogels increased with a growing number of DAlVP units and upon application of a different cross-linker, which was additionally confirmed by nanoindentation experiments. In contrast, the water uptake of hydrogels decreased with higher DAlVP amounts in the corresponding hydrogels due to lower chain mobility and an overall increase in the hydrophobicity of the samples. Upon successful functionalization of P(DEVP-stat-DAlVP) copolymers with sodium 3-mercaptopropane-1-sulfonate, as indicated via 1H DOSY NMR, the respective cross-linked materials displayed a remarkable increase in the water uptake; thus, presenting highly hydrophilic gels with an apparent interplay between water uptake, cross-linking density, and functionalization degree. Finally, the purified hydrogels showed cytocompatibility and enabled cell adhesion of human umbilical artery smooth muscle cells (HUASMCs) after direct seeding. The materials further allowed the adhesion and growth of an endothelial layer, triggered no pro-inflammatory response as evidenced by cytokine release of M0 macrophages, and exhibited antibacterial properties toward S. aureus and E. coli.

Enhancing Performance of Silicone Hydrogel Contact Lenses with Hydrophilic Polyphenolic Coatings

This study explores the application of a dopamine-assisted co-deposition strategy to modify the surface of daily disposable silicone hydrogel contact lenses. Aiming to enhance the hydrophilicity of these typically hydrophobic lenses, we developed an industry-friendly process using simple dip coating in aqueous solutions. By co-depositing tannic acid, dopamine and chitosan derivative and employing periodate oxidation, we achieved a rapid and efficient coating process. High-molecular-weight branched polyethylene imine was introduced to promote surface reactions. The resulting lenses exhibited extreme hydrophilicity and lipid repellency without compromising their intrinsic properties or causing cytotoxicity. While the coating demonstrated partial antimicrobial activity against Gram-positive Staphylococcus aureus, it offers a foundation for the further development of broad-spectrum antimicrobial coatings. This versatile and efficient process, capable of transforming hydrophobic contact lenses into hydrophilic ones in just 15 min, shows significant potential for improving comfort and performance in daily disposable contact lenses.

Emerging strategies for treating medical device and wound-associated biofilm infections

Bacterial infections represent a significant global threat to human health, leading to considerable economic losses through increased healthcare costs and reduced productivity. One major challenge in treating these infections is the presence of biofilms - structured bacterial communities that form protective barriers, making traditional treatments less effective. Additionally, the rise of antibiotic-resistant bacteria has exacerbated treatment difficulties. To address these challenges, researchers are developing and exploring innovative approaches to combat biofilm-related infections. This mini-review highlights recent advancements in the following key areas: surface anti-adhesion technologies, electricity, photo/acoustic-active materials, endogenous mimicking agents, and innovative drug delivery systems. These strategies aim to prevent biofilm formation, disrupt existing biofilms, and enhance the efficacy of antimicrobial treatments. Currently, these approaches show great potential for applications in medical fields such as medical device and wound - associated biofilm infections. By summarizing these developments, this mini-review provides a comprehensive resource for researchers seeking to advance the management and treatment of biofilm-associated infections.

Guanidine-modified polysaccharide conditioning layer designed for regulating bacterial attachment behaviors

Biofouling has been persisting as a global problem due to the difficulties in finding efficient and environmentally friendly antifouling coatings for long-term applications. Initial attachment of bacteria on material surface and subsequent formation of biofilm are the predominate phenomena accounting for subsequent occurrence of biofouling. Among the various factors influencing the bacterial attachment, conditioning layer formed by organic macromolecules usually plays the key role in mediating bacterial attachment through altering physicochemical properties of substrate surface. In this study, a guanidine-modified polysaccharide conditioning layer with the capability of tuning the bacterial attachment is constructed and characterized. Dextran, a polysaccharide widespread in bacteria extracellular polymeric substances (EPS), is oxidized by sodium periodate, and cationic polymer polyhexamethylene guanidine hydrochloride (PHMG) is anchored to oxidized dextran (ODEX) by Schiff base reaction. AFM characterization reveals morphological changes of the polysaccharide conditioning layer from tangled chain to island conformation after the PHMG modification. The guanidine-based dextran conditioning layer promotes attachment of both P. aeruginosa and S. aureus and disrupted bacterial cytomembranes are seen for the attached bacteria due to electrostatic interaction of the electropositive guanidine group with the electronegative bacteria. The guanidine-based dextran conditioning layer shows a low survival ratio of 22 %-34 % and 1 %-4 % for P. aeruginosa and S. aureus respectively after incubation in the bacterial suspension for 72 hours. The results would give insight into further exploring the potential applications of the newly designed polysaccharides conditioning layer for combating occurrence of biofouling.

Antifouling Asymmetric Block Copolymer Nanofilms via Freestanding Interfacial Polymerization for Efficient and Sustainable Water Purification

Membrane materials that resist nonspecific or specific adsorption are urgently required in widespread practical applications, such as water purification, food processing, and life sciences. In water purification, inevitable membrane fouling not only limits membrane separation performance, leading to a decline in both permeance and selectivity, but also remarkably increases operation requirements, and augments extra maintenance costs and higher energy consumption. In this work, we report a freestanding interfacial polymerization (IP) fabrication strategy for in situ creation of asymmetric block copolymer (BCP) nanofilms with antifouling properties, greatly outperforming the conventional surface post-modification approaches. The resultant free-standing asymmetric BCP nanofilms with highly-dense, highly-hydrophilic polyethylene glycol (PEG) brushes on one side, can be readily formed via a typical IP process of a well-defined double-hydrophilic BCP composed of a highly-efficient antifouling PEG block and a membrane-forming multiamine block. The asymmetric BCP nanofilms have been applied for efficient and sustainable natural water purification, demonstrating extraordinary antifouling capabilities accompanied with superior separation performance far beyond commercial polyamide nanofiltration membranes. The antifouling behaviors of asymmetric BCP nanofilms derived from the combined effect of the hydration layer, electrostatic repulsion and steric hindrance were further elucidated by water flux and fouling resistance in combination with all-atom molecular dynamics (MD) simulation. This work opens up a new avenue for the large-scale and low-cost creation of broad-spectrum, asymmetric membrane materials with diverse functional "defect-free" surfaces in real-world applications.

Chitosan microflower-embedded gelatin sponges for advanced wound management and hemostatic applications

The study explored the antimicrobial, antibiofilm, and hemostatic properties of chitosan microflowers (CMF) in sponge form. The main objective was to enhance the preparation of CMF by employing varying quantities of calcium chloride (CaCl2) and tripolyphosphate (TPP). CMF was then combined with gelatin (GE) in different proportions to produce three sponge samples: CMF0@GE, CMF1@GE, and CMF2@GE. The CMF had a morphology like that of a flower and produced surfaces with a porous sponge-like structure. The antibacterial activity, as determined by the zone of inhibition (ZOI), increased with greater doses of CMF. Among the tested samples, CMF2@GE had the greatest activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecium. CMF2@GE successfully suppressed biofilm formation, decreased clotting time to an average of 212.67 s, and exhibited excellent biocompatibility by preserving over 90 % viability of human skin fibroblast cells at dosages below 100 μg/mL. The results indicated that gelatin sponges filled with CMF have considerable promise as flexible medical instruments for wound healing and infection control.

A Microenvironment-Responsive, Controlled Release Hydrogel Delivering Embelin to Promote Bone Repair of Periodontitis via Anti-Infection and Osteo-Immune Modulation

Periodontitis, a prevalent chronic inflammatory disease, poses significant challenges for effective treatment due to its complex etiology involving specific bacteria and the inflammatory immune microenvironment. Here, this study presents a novel approach for the targeted treatment of periodontitis utilizing the immunomodulatory and antibacterial properties of Embelin, a plant-derived compound, within an injectable hydrogel system. The developed Carboxymethyl Chitosan-Oxidized Dextran (CMCS-OD) hydrogel formed via dynamic chemical bonds exhibited self-healing capabilities and pH-responsive behavior, thereby facilitating the controlled release of Embelin and enhancing its efficacy in a dynamic oral periodontitis microenvironment. This study demonstrates that this hydrogel system effectively prevents bacterial invasion and mitigates excessive immune response activation. Moreover, it precisely modulates macrophage M1/M2 phenotypes and suppresses inflammatory cytokine expression, thereby fostering a conducive environment for bone regeneration and addressing periodontitis-induced bone loss. These findings highlight the potential of the approach as a promising strategy for the clinical management of periodontitis-induced bone destruction.

Hydroxypropyl chitosan/ε-poly-l-lysine based injectable and self-healing hydrogels with antimicrobial and hemostatic activity for wound repair

The biggest obstacle to treating wound healing continues to be the production of simple, inexpensive wound dressings that satisfy the demands associated with full process of repair at the same time. Herein, a series of injectable composite hydrogels were successfully prepared by a one-pot method by utilizing the Schiff base reaction as well as hydrogen bonding forces between hydroxypropyl chitosan (HCS), ε-poly-l-lysine (EPL), and 2,3,4-trihydroxybenzaldehyde (TBA), and multiple cross-links formed by the reversible coordination between iron (III) and pyrogallol moieties. Notably, hydrogel exhibits excellent physicochemical properties, including injectability, self-healing, water retention, and adhesion, which enable to fill irregular wounds for a long period, providing a suitable moist environment for wound healing. Interestingly, the excellent hemostatic properties of the hydrogel can quickly stop bleeding and avoid the serious sequelae of massive blood loss in acute trauma. Moreover, the powerful antimicrobial and antioxidant properties also protect against bacterial infections and reduce inflammation at the wound site, thus promoting healing at all stages of the wound. The study of biohydrogel with multifunctional integration of wound treatment and smart medical treatment is clarified by this line of research.

Antimicrobial Polymer Surfaces Containing Quaternary Ammonium Centers (QACs): Synthesis and Mechanism of Action

Synthetic polymer surfaces provide an excellent opportunity for developing materials with inherent antimicrobial and/or biocidal activity, therefore representing an answer to the increasing demand for antimicrobial active medical devices. So far, biologists and material scientists have identified a few features of bacterial cells that can be strategically exploited to make polymers inherently antimicrobial. One of these is represented by the introduction of cationic charges that act by killing or deactivating bacteria by interaction with the negatively charged parts of their cell envelope (lipopolysaccharides, peptidoglycan, and membrane lipids). Among the possible cationic functionalities, the antimicrobial activity of polymers with quaternary ammonium centers (QACs) has been widely used for both soluble macromolecules and non-soluble materials. Unfortunately, most information is still unknown on the biological mechanism of action of QACs, a fundamental requirement for designing polymers with higher antimicrobial efficiency and possibly very low toxicity. This mini-review focuses on surfaces based on synthetic polymers with inherently antimicrobial activity due to QACs. It will discuss their synthesis, their antimicrobial activity, and studies carried out so far on their mechanism of action.

A Hemoglobin Bionics-Based System for Combating Antibiotic Resistance in Chronic Diabetic Wounds via Iron Homeostasis Regulation

Owing to the increased tissue iron accumulation in patients with diabetes, microorganisms may activate high expression of iron-involved metabolic pathways, leading to the exacerbation of bacterial infections and disruption of systemic glucose metabolism. Therefore, an on-demand transdermal dosing approach that utilizes iron homeostasis regulation to combat antimicrobial resistance is a promising strategy to address the challenges associated with low administration bioavailability and high antibiotic resistance in treating infected diabetic wounds. Here, it is aimed to propose an effective therapy based on hemoglobin bionics to induce disturbances in bacterial iron homeostasis. The preferred "iron cargo" is synthesized by protoporphyrin IX chelated with dopamine and gallium (PDGa), and is delivered via a glucose/pH-responsive microneedle bandage (PDGa@GMB). The PDGa@GMB downregulates the expression levels of the iron uptake regulator (Fur) and the peroxide response regulator (perR) in Staphylococcus aureus, leading to iron nutrient starvation and oxidative stress, ultimately suppressing iron-dependent bacterial activities. Consequently, PDGa@GMB demonstrates insusceptibility to genetic resistance while maintaining sustainable antimicrobial effects (>90%) against resistant strains of both S. aureus and E. coli, and accelerates tissue recovery (<20 d). Overall, PDGa@GMB not only counteracts antibiotic resistance but also holds tremendous potential in mediating microbial-host crosstalk, synergistically attenuating pathogen virulence and pathogenicity.

Continuous and Controllable Preparation of Sodium Alginate Hydrogel Tubes Guided by the Soft Cap Inspired by the Apical Growth of the Plant

Hydrogel tubes made of sodium alginate (SA) have potential applications in drug delivery, soft robots, biomimetic blood vessels, tissue stents, and other fields. However, the continuous preparation of hollow SA hydrogel tubes with good stability and size control remains a huge challenge for chemists, material scientists, and medical practitioners. Inspired by the plant apical growth strategy, a new method named soft cap-guided growth was proposed to produce SA hydrogel tubes. Due to the introduction of inert low gravity substances, such as air and heptane, into the extrusion needle in front of calcium chloride solution to form a soft cap, the SA hydrogel tubes with controllable sizes were fabricated rapidly and continuously without using a template through a negative gravitropism mechanism. The SA hydrogel tubes had good tensile strength, high burst pressure, and good cell compatibility. In addition, hydrogel tubes with complex patterns were conveniently created by controlling the motion path of a soft cap, such as a rotating SA bath or magnetic force. Our research provided a simple innovative technique to steer the growth of hydrogel tubes, which made it possible to mass produce hydrogel tubes with controllable sizes and programmable patterns.

Natural Products with Potential Effects on Hemorrhoids: A Review

Hemorrhoid disease is a common anorectal disorder affecting populations worldwide, with high prevalence, treatment difficulties, and considerable treatment costs. Compared to other treatment options, medical therapy for hemorrhoids offers minimal harm, more dignity to patients, and is more economical. Unfortunately, there are few chemical hemorrhoid medications available clinically, which makes the search for efficacious, cost-effective, and environmentally friendly new medication classes a focal point of research. In this context, searching for available natural products to improve hemorrhoids exhibits tremendous potential. These products are derived from nature, predominantly from plants, with a minor portion coming from animals, fungi, and algae. They have excellent coagulation pathway regulation, anti-inflammatory, antibacterial, and tissue regeneration activities. Therefore, we take the view that they are a class of potential hemorrhoid drugs, prevention products, and medication add-on ingredients. This article first reviews the factors contributing to the development of hemorrhoids, types, primary symptoms, and the mechanisms of natural products for hemorrhoids. Building on this foundation, we screened natural products with potential hemorrhoid improvement activity, including polyphenols and flavonoids, terpenes, polysaccharides, and other types.

Biomaterial-based sponge for efficient and environmentally sound removal of bacteria from water

Designing materials capable of disinfecting water without releasing harmful by-products is an ongoing challenge. Here, we report a novel polycationic sponge material synthesized from chitosan derivatives and cellulose fibers, exhibiting antibacterial properties. The design of such material is based on three key principles. First, the formation of a highly porous structure through cryogelation for an extensive surface area. Second, the incorporation of cationic quaternary ammonium moieties onto chitosan to enhance bacterial adsorption and antibacterial activity. Lastly, the reinforcement of mechanical properties through integration of cellulose fibers. The presented sponge materials exhibit up to a 4-log (99.99%) reduction within 6 h against both gram-positive B. subtilis and gram-negative E. coli. Notably, QCHI90/Cell, with the highest surface charge, exhibits a 2-4.5 log reduction within 1 h of incubation time. The eco-friendly synthesis from water and readily available biomaterials, along with cost-effectiveness and simplicity, underscores its versatility and feasibility of upscaling. Together with its outstanding antibacterial activity, this macroporous biomaterial emerges as a promising candidate for water disinfection applications.

Comparison study of surface-initiated hydrogel coatings with distinct side-chains for improving biocompatibility of polymeric heart valves

Polymeric heart valves (PHVs) present a promising alternative for treating valvular heart diseases with satisfactory hydrodynamics and durability against structural degeneration. However, the cascaded coagulation, inflammatory responses, and calcification in the dynamic blood environment pose significant challenges to the surface design of current PHVs. In this study, we employed a surface-initiated polymerization method to modify polystyrene-block-isobutylene-block-styrene (SIBS) by creating three hydrogel coatings: poly(2-methacryloyloxy ethyl phosphorylcholine) (pMPC), poly(2-acrylamido-2-methylpropanesulfonic acid) (pAMPS), and poly(2-hydroxyethyl methacrylate) (pHEMA). These hydrogel coatings dramatically promoted SIBS's hydrophilicity and blood compatibility at the initial state. Notably, the pMPC and pAMPS coatings maintained a considerable platelet resistance performance after 12 h of sonication and 10 000 cycles of stretching and bending. However, the sonication process induced visible damage to the pHEMA coating and attenuated the anti-coagulation property. Furthermore, the in vivo subcutaneous implantation studies demonstrated that the amphiphilic pMPC coating showed superior anti-inflammatory and anti-calcification properties. Considering the remarkable stability and optimal biocompatibility, the amphiphilic pMPC coating constructed by surface-initiated polymerization holds promising potential for modifying PHVs.

Time-Resolved Killing of Individual Bacterial Cells by a Polycationic Antimicrobial Polymer

Polycationic polymers are widely studied antiseptics, and their efficacy is usually quantified by the solution concentration required to kill a fraction of a population of cells (e.g., by Minimum Bactericidal Concentration (MBC)). Here we describe how the response to a polycationic antimicrobial varies greatly among members of even a monoclonal population of bacteria bathed in a single common antimicrobial concentration. We use fluorescence microscopy to measure the adsorption of a labeled cationic polymer, polydiallyldimethylammmonium chloride (PDADMAC, Mw ≈ 4 × 105 g mol-1) and the time course of cell response via a cell permeability indicator for each member of an ensemble of either Escherichia coli, Staphylococcus aureus, or Pseudomonas aeruginosa cells. This is a departure from traditional methods of evaluating synthetic antimicrobials, which typically measure the overall response of a collection of cells at a particular time and therefore do not assess the diversity within a population. Cells typically die after they reach a threshold adsorption of PDADMAC, but not always. There is a substantial time lag of about 5-10 min between adsorption and death, and the time to die of an individual cell is well correlated with the rate of adsorption. The amount adsorbed and the time-to-die differ among species but follow a trend of more adsorption on more negatively charged species, as expected for a cationic polymer. The study of individual cells via time-lapse microscopy reveals additional details that are lost when measuring ensemble properties at a particular time.

Synthesis and characterization of thermosensitive 2-hydroxypropyl-trimethylammonium chitin and its antibacterial sponge for noncompressible hemostasis and tissue regeneration

Noncompressible hemorrhage is a leading cause of preventable death in battlefield/civilian trauma. The development of novel injectable and biodegradable hemostatic sponges, with rapid shape recovery and excellent antibacterial activity that can control hemorrhage in noncompressible bleeding sites and promote in situ tissue regeneration is still urgently needed. In this study, thermo/pH sensitive 2-hydroxypropyl-trimethylammonium chitins (QCHs) with low degree of quaternization substitution (DS: 0.07-0.23) and high degree of acetylation (DA: 0.91-0.94) were synthesized homogeneously for the first time. Their chemical compositions including DS and DA were characterized accurately by proton NMR for the first time. High strength QCH based sponges with good water/blood absorbency, rapid shape recovery and good antibacterial activity were prepared without using any crosslinkers but only due to their thermosensitive property, since they are soluble at low temperature but insoluble at high temperature. Compared with commercial products, the QCH sponges with cationic groups had the stronger pro-coagulant ability, better hemostatic effect in normal/heparinized liver perforation and femoral artery models in rats and porcine subclavian arteriovenous resection model. Moreover, the porous structure and biodegradability of the QCH sponges could promote in situ tissue regeneration. Overall, the QCH sponges show great clinical translational potential for noncompressible hemorrhage and tissue regeneration.

Photothermal Hydrogel Composites Featuring G4-Carbon Nanomaterial Networks for Staphylococcus aureus Inhibition

Microbial infections represent a significant health risk, often leading to severe complications and, in some cases, even fatalities. As a result, there is an urgent need to explore innovative drug delivery systems and alternative therapeutic techniques. The photothermal therapy has emerged as a promising antibacterial approach and is the focus of this study. Herein, we report the successful synthesis of two distinct supramolecular composite hydrogels by incorporating graphene oxide (GO) and single-walled carbon nanotubes (SWNTs) into guanosine quadruplex (G4) based hydrogels containing covalently bound β-cyclodextrin (β-CD). The G4 matrix was synthesized through a two-step process, establishing a robust network between G4 and β-CDs, followed by the encapsulation of either GO or SWNTs. Comprehensive characterization of these composite hydrogels were conducted using analytical techniques, including circular dichroism, Raman spectroscopy, rheological investigations, X-ray diffraction, and scanning electron microscopy. A notable discovery from the conducted research is the differential photothermal responses exhibited by the hydrogels when exposed to near-infrared laser irradiation. Specifically, SWNT-based hydrogels demonstrated superior photothermal performance, achieving a remarkable temperature increase of up to 52 °C, in contrast to GO-based hydrogels, which reached a maximum of 34 °C. These composite hydrogels showed good cytotoxicity evaluation results and displayed synergistic antibacterial activity against Staphylococcus aureus, positioning them as promising candidates for antibacterial photothermic platforms, particularly in the context of wound treatment. This study offers a valuable contribution to the development of advanced and combined therapeutic strategies for combating microbial infections and highlights the potential of carbon nanomaterial-enhanced supramolecular hydrogels in photothermal therapy applications.

Antimicrobial polyacrylic acid/tannic acid hydrogel wound dressing facilitating full-thickness skin healing

Polyphenolic compound-modified hydrogel wound dressings with excellent wet tissue adhesion, antimicrobial properties, stretchability, and full-thickness skin healing properties are still extremely rare so far. Polyphenolic compounds such as tannic acid or dopamine can improve the antibacterial and bioadhesive properties of hydrogels, and are also polymerization inhibitors for free radical polymerization. In this study, polyacrylic acid (PAA) aqueous solution was first synthesized, and then antibacterial PAA-TA hydrogel was prepared by mixing it with tannic acid (TA) and the crosslinker 1,6-hexanediol bis(2-methyl-1-propionic acid azide) (HBMAP). This method avoids the hindrance of the phenolic hydroxyl groups in TA on acrylic acid polymerization, and we were able to obtain a series of TA hydrogels (in the range of 0-15 wt.%. We applied these PAA-TA hydrogels to wound dressings and found that they had excellent adhesion to biological tissues, and the tensile strength and elongation at break of PAA-TA hydrogels with 15 wt.%TA content were as high as 1.72 MPa and 1446.3% in tensile strength evaluation. In addition, microbiological analysis showed that wound dressings had significant antimicrobial activity against Staphylococcus aureus and Escherichia coli. In vitro wound healing experiments confirmed that the wound dressing was biocompatible and could significantly promote the healing of full-thickness skin defects in the guinea pig model. Our work describes an injectable, self-healing, antimicrobial hydrogel that may have promising clinical applications as a wound dressing material.

Mussel‐Inspired Recombinant Adhesive Protein‐Based Functionalization for Consistent and Effective Antimicrobial Treatment in Chronic Inflammatory Skin Diseases

Chronic inflammatory skin diseases, characterized by a vicious cycle of infection and hyperinflammation, necessitate consistent and effective antimicrobial treatment of target lesions to achieve practical therapeutic outcomes. Antimicrobial dressing materials offer notable advantages over conventional therapeutic drugs, including ease of application, extended contact time, and targeted antimicrobial action, resulting in enhanced efficacy in breaking the vicious cycle. In line with these advantages, this study aims to develop a plug‐and‐playable recombinant adhesive protein (RAP) inspired by the adhesive properties of marine mussels, serving as a durable and effective surface functionalization strategy. By genetically recombining mussel foot protein with antimicrobial peptides, RAP effectively incorporates antimicrobial properties into biomaterials for treating chronic inflammatory skin diseases. The durable adhesion of RAP ensures long‐lasting antimicrobial functionality on target surfaces, MFP making it a promising approach to inhibit chronic inflammation. In addition, when dip‐coated onto cotton gauze, RAP can be utilized as an antimicrobial patch, effectively suppressing chronic inflammation through the inhibition of bacteria‐induced toll‐like receptor signaling. These findings underscore the potential of nature‐inspired protein‐based surface functionalization of biomaterials as a compelling approach to advance the treatment of chronic inflammatory skin diseases.

Optimizing magnetic, dielectric, and antimicrobial performance in chitosan-PEG-Fe2O3@NiO nanomagnetic composites

There is a growing interest in eco-friendly and cost-effective organic-inorganic nanocomposites due to their alignment with the principles of "green" chemistry, as well as their biocompatibility and non-toxicity. This study focused on producing Chitosan-PEG-Fe2O3@NiO nanomagnetic composites to improve the stability, dielectric properties, and antimicrobial effectiveness of these nanocomposite materials. The process involved synthesizing Fe2O3@NiO via sol-gel and polymerizing chitosan-PEG. The nanocomposites were characterized by XRD, TEM, FTIR, optical, dielectric, and VSM. Incorporating Fe2O3@NiO significantly improved stability, and the interaction with Fe2O3 during the sol-gel process facilitated the formation of NiFe2O4 with an increase in the crystallinity within the chitosan-PEG matrix. The study examined optical and dielectric properties, highlighting that the 3 NiO-doped chitosan-PEG-Fe2O3 composites had high electrical conductivity (1.8 ∗ 10-3 S/cm) and a significant dielectric constant (106 at low frequencies). As the ratio of NiO NPs within the chitosan-PEG-Fe2O3 increases, the energy band gap of chitosan-PEG-Fe2O3 films decreases up to 3.7 eV. This decrease is owing to the quantum confinement effect. These composites also demonstrated improved antimicrobial activity against E. coli and S. aureus and higher activity in the presence of nanomagnetic particles. The minimum inhibitory concentrations of CS-PEG-Fe2O3/NiO NPs against (Bacillus cereus, M. luteus, S. aureus and (S. enterica, H. pylori, E. coli) were (22-35 mm) and (21-34 mm), respectively.

Current status of development and biomedical applications of peptide-based antimicrobial hydrogels

Microbial contamination poses a serious threat to human life and health. Through the intersection of material science and modern medicine, advanced bionic hydrogels have shown great potential for biomedical applications due to their unique bioactivity and ability to mimic the extracellular matrix environment. In particular, as a promising antimicrobial material, the synthesis and practical biomedical applications of peptide-based antimicrobial hydrogels have drawn increasing research interest. The synergistic effect of peptides and hydrogels facilitate the controlled release of antimicrobial agents and mitigation of their biotoxicity while achieving antimicrobial effects and protecting the active agents from degradation. This review reports on the progress and trends of researches in the last five years and provides a brief outlook, aiming to provide theoretical background on peptide-based antimicrobial hydrogels and make suggestions for future related work.

Hyperbranched Poly-L-Lysine-Based Water-Insoluble Complexes as Antibacterial Agents with Efficient Antibacterial Activity And Cytocompatibility

Despite the advances in technology, bacterial infection associated with biomedical devices is still one of the most challenging issues in clinical practice. Incorporation of antimicrobial agents is regarded as an efficient way to combat medical device associated infectious. However, most of antimicrobial agents have high toxicity to host cells. Thus, fabrication of novel antimicrobial agents that simultaneously fulfill the requirements of antibacterial activity as well as biocompatibility is urgently needed. Herein, a series of water-insoluble antibacterial complexes based on hyperbranched poly-L-lysine (HBPL) and four different surfactants through non-covalent interactions are developed. Such kinds of surfactants have great effects on the antibacterial property of poly(ɛ-caprolactone) (PCL) films that incorporate with the HBPL-based complexes. The results reveal that the PCL films that doped with HBPL/phosphate ester surfactant complexes showed the highest bacterial killing efficiency. Moreover, the cytocompatibility of the composite films is also investigated. Hemolysis experiments indicate that all the films  had low hemolytic activities. Considering the excellent antimicrobial and cytocompatibility properties, this work believes that the optimized complexes have great potential to be used as antimicrobial agents in biomedical field.

Biosynthesis of poly(β-L-malic acid) from rubberwood enzymatic hydrolysates in co-fermentation by Aureobasidium pullulans

Co-fermentation of multiple substrates has emerged as the most effective method to improve the yield of bioproducts. Herein, sustainable rubberwood enzymatic hydrolysates (RWH) were co-fermented by Aureobasidium pullulans to produce poly(β-L-malic acid) (PMA), and RWH + glucose/xylose was also investigated as co-substrates. Owing to low inhibitor concentration and abundant natural nitrogen source content of RWH, a high PMA yield of 0.45 g/g and a productivity of 0.32 g/L/h were obtained by RWH substrate fermentation. After optimization, PMA yields following the fermentation of RWH + glucose and RWH + xylose reached 59.92 g/L and 53.71 g/L, respectively, which were 52 % and 36 % higher than that after the fermentation of RWH. RWH + glucose more significantly affected the correlation between PMA yield and substrate concentration than RWH + xylose. The results demonstrated that the co-fermentation of RWH co-substrate is a promising method for the synthesis of bioproducts.

Hydrogel dressings with intrinsic antibiofilm and antioxidative dual functionalities accelerate infected diabetic wound healing

Chronic wounds are often infected with biofilm bacteria and characterized by high oxidative stress. Current dressings that promote chronic wound healing either require additional processes such as photothermal irradiation or leave behind gross amounts of undesirable residues. We report a dual-functionality hydrogel dressing with intrinsic antibiofilm and antioxidative properties that are synergistic and low-leaching. The hydrogel is a crosslinked network with tethered antibacterial cationic polyimidazolium and antioxidative N-acetylcysteine. In a murine diabetic wound model, the hydrogel accelerates the closure of wounds infected with methicillin-resistant Staphylococcus aureus or carbapenem-resistant Pseudomonas aeruginosa biofilm. Furthermore, a three-dimensional ex vivo human skin equivalent model shows that N-acetylcysteine promotes the keratinocyte differentiation and accelerates the re-epithelialization process. Our hydrogel dressing can be made into different formats for the healing of both flat and deep infected chronic wounds without contamination of the wound or needing other modalities such as photothermal irradiation.

Advances in reparative materials for infectious bone defects and their applications in maxillofacial regions

Infectious bone defects are characterized by the partial loss or destruction of bone tissue resulting from bacterial contaminations subsequent to diseases or external injuries. Traditional bone transplantation and clinical methods are insufficient in meeting the treatment demands for such diseases. As a result, researchers have increasingly focused on the development of more sophisticated biomaterials for improved therapeutic outcomes in recent years. This review endeavors to investigate specific reparative materials utilized for the treatment of infectious bone defects, particularly those present in the maxillofacial region, with a focus on biomaterials capable of releasing therapeutic substances, functional contact biomaterials, and novel physical therapy materials. These biomaterials operate via heightened antibacterial or osteogenic properties in order to eliminate bacteria and/or stimulate bone cells regeneration in the defect, ultimately fostering the reconstitution of maxillofacial bone tissue. Based upon some successful applications of new concept materials in bone repair of other parts, we also explore their future prospects and potential uses in maxillofacial bone repair later in this review. We highlight that the exploration of advanced biomaterials holds promise in establishing a solid foundation for the development of more biocompatible, effective, and personalized treatments for reconstructing infectious maxillofacial defects.

Tough and antibacterial poly(l-lactic acid) composites prepared via blending with the bifunctional macromolecular ionomer

In order to expand the application of PLLA in the packaging field, improving its toughness and antibacterial activity has been widely concerned. However, seldom researches can simultaneously efficiently improve the toughness and antibacterial activity of PLLA by adding one kind of additions. To address above problems, the bifunctional branched poly(butylene adipate) ionomer additive (b-PBAUi) was synthesized. For b-PBAUi, its branched structure not only increased the plasticizing effect of additive, but also acted as reaction sites to introduce more antibacterial ionic salt. Due to the special structure of b-PBAUi, PLLA/b-PBAUi blends achieved excellent toughness and antibacterial efficiency. The elongation of blend reached 125 % even by adding 5 wt% b-PBAUi, which was 10 times higher than that of PLLA. From the analysis of phase morphology, it could be found that the microvoids promoting tensile yielding was the main tensile toughening mechanism for PLLA/b-PBAUi blends. In addition, the antibacterial activity of PLLA was significantly improved by adding b-PBAUi. For PLLA/b-PBAUi10 and PLLA/b-PBAUi15, the antibacterial efficiency against E. coli and S. aureus bacteria exceeded 99.0 %. By comprehensive consideration, the optimal blend ratio was achieved by PLLA/b-PBAUi10 due to its excellent toughness and antibacterial efficiency.

Synthesis and characterization of novel chitosan derivatives (containing dipyridinium quaternary salts) with antimicrobial potential

Chitosan derivatives are versatile materials, biocompatible and biodegradable, that can be tailor-made to suit specific biomedical applications. In this study, two N-heterocyclic salts (N,N'-diphenacyl-[4,4'-dipyridinium] dibromide (DP) and N,N'-diphenacyl-1,2-bis-(4-pyridinium)ethane dibromide (DPE)) were used for chitosan functionalization to enhance its antimicrobial potential. Physico-chemical characterization of the newly synthesized derivatives (Ch-DP and Ch-DPE) was performed by elemental analysis, spectrometry (UV-Vis, FTIR), electrochemistry (OCP, CV), and electron microscopy (SEM) proving that the highest degree of functionalization was obtained for Ch-DP. The antimicrobial effect of chitosan functionalization was further tested in terms of its interaction with Listeria monocytogenes Scott A, and Staphylococcus aureus ATCC 25923, as Gram-positive bacteria and Escherichia coli ATCC 25922, as Gram-negative bacterium, respectively, showing that the Ch-DP had a good inhibitory activity compared with Ch-DPE.

Azithromycin-loaded liposomal hydrogel: a step forward for enhanced treatment of MRSA-related skin infections

Azithromycin (AZT) encapsulated into various types of liposomes (AZT-liposomes) displayed pronounced in vitro activity against methicillin-resistant Staphylococcus aureus (MRSA) (1). The present study represents a follow-up to this previous work, attempting to further explore the anti-MRSA potential of AZT-liposomes when incorporated into chitosan hydrogel (CHG). Incorporation of AZT-liposomes into CHG (liposomal CHGs) was intended to ensure proper viscosity and texture properties of the formulation, modification of antibiotic release, and enhanced antibacterial activity, aiming to upgrade the therapeutical potential of AZT-liposomes in localized treatment of MRSA-related skin infections. Four different liposomal CHGs were evaluated and compared on the grounds of antibacterial activity against MRSA, AZT release profiles, cytotoxicity, as well as texture, and rheological properties. To our knowledge, this study is the first to investigate the potential of liposomal CHGs for the topical localized treatment of MRSA-related skin infections. CHG ensured proper viscoelastic and texture properties to achieve prolonged retention and prolonged release of AZT at the application site, which resulted in a boosted anti-MRSA effect of the entrapped AZT-liposomes. With respect to anti-MRSA activity and biocompatibility, formulation CATL-CHG (cationic liposomes in CHG) is considered to be the most promising formulation for the treatment of MRSA-related skin infections.

Peptide-Mimicking Poly(2-oxazoline)s Possessing Potent Antifungal Activity and BBB Penetrating Property to Treat Invasive Infections and Meningitis

Invasive fungal infections, including meningitis, cause a high mortality rate due to few available antifungal drugs and frequently associated side effects and quick emergence of drug-resistant fungi. The restrictive permeability of the blood-brain barrier (BBB) further limits the efficacy of antifungal agents substantially in treating meningitis. Hereby, we design and synthesize guanidinium-functionalized poly(2-oxazoline)s by mimicking cell-penetrating peptides. The optimal polymer, PGMeOx10 bearing a methylene spacer arm, displays potent activities against the drug-resistant fungi and biofilm, negligible toxicity, and insusceptibility to antimicrobial resistance. Moreover, PGMeOx10 can break BBB retractions to exert promising antifungal functions in the brain. PGMeOx10 demonstrates potent in vivo antifungal therapeutic efficacy in mouse models including skin infection, systemic infections, and meningitis. PGMeOx10 effectively rescues infected mice and reduces fungal burden and inflammation in the brain. These results and the excellent biosafety of poly(2-oxazoline)s indicate the effectiveness and potential of our strategy to design promising antifungal agents in treating systemic infections and meningitis.

Carbon Dots' Potential in Wound Healing: Inducing M2 Macrophage Polarization and Demonstrating Antibacterial Properties for Accelerated Recovery

Bacterial infections and persistent inflammation can impede the intrinsic healing process of wounds. To combat this issue, researchers have delved into the potential use of carbon dots (CDs) in the regulation of inflammation and counteract infections. These CDs were synthesized using a microwave-assisted hydrothermal process and have demonstrated outstanding antibacterial and antibiofilm properties against Gram-positive and Gram-negative bacteria. Additionally, CDs displayed biocompatibility at therapeutic concentrations and the ability to specifically target mitochondria. CD treatment effectively nullified lipopolysaccharide-triggered reactive oxygen species production by macrophages, while simultaneously promoting macrophage polarization toward an anti-inflammatory phenotype (M2), leading to a reduction in inflammation and an acceleration in wound healing. In vitro scratch assays also revealed that CDs facilitated the tissue-repairing process by stimulating epithelial cell migration during reepithelialization. In vivo studies using CDs topically applied to lipopolysaccharide (LPS)-stimulated wounds in C57/BL6 mice demonstrated significant improvements in wound healing due to enhanced fibroblast proliferation, angiogenesis, and collagen deposition. Crucially, histological investigations showed no indications of systemic toxicity in vital organs. Collectively, the application of CDs has shown immense potential in speeding up the wound-healing process by regulating inflammation, preventing bacterial infections, and promoting tissue repair. These results suggest that further clinical translation of CDs should be considered.

Sustainable functionalized chitosan based nano-composites for wound dressings applications: A review

Functionalized chitosan nanocomposites have been studied for wound dressing applications due to their excellent antibacterial and anti-fungal properties. Polysaccharides show excellent antibacterial and drug-release properties and can be utilized for wound healing. In this article, we comprise distinct approaches for chitosan functionalization, such as photosensitizers, dendrimers, graft copolymerization, quaternization, acylation, carboxyalkylation, phosphorylation, sulfation, and thiolation. The current review article has also discussed brief insights on chitosan nanoparticle processing for biomedical applications, including wound dressings. The chitosan nanoparticle preparation technologies have been discussed, focusing on wound dressings owing to their targeted and controlled drug release behavior. The future directions of chitosan research include; a) finding an effective solution for chronic wounds, which are unable to heal completely; b) providing effective wound healing solutions for diabetic wounds and venous leg ulcers; c) to better understanding the wound healing mechanism with such materials which can help provide the optimum solution for wound dressing; d) to provide an improved treatment option for wound healing.

Polysaccharide based transdermal patches for chronic wound healing: Recent advances and clinical perspective

Polysaccharides form a major class of natural polymers with diverse applications in biomedical science and tissue engineering. One of the key thrust areas for polysaccharide materials is skin tissue engineering and regeneration, whose market is estimated to reach around 31 billion USD globally by 2030, with a compounded annual growth rate of 10.46 %. Out of this, chronic wound healing and management is a major concern, especially for underdeveloped and developing nations, mainly due to poor access to medical interventions for such societies. Polysaccharide materials have shown promising results and clinical potential in recent decades with regard to chronic wound healing. Their low cost, ease of fabrication, biodegradability, and ability to form hydrogels make them ideal candidates for managing and healing such difficult-to-heal wounds. The present review presents a summary of the recently explored polysaccharide-based transdermal patches for managing and healing chronic wounds. Their efficacy and potency of healing both as active and passive wound dressings are evaluated in several in-vitro and in-vivo models. Finally, their clinical performances and future challenges are summarized to draw a road map towards their role in advanced wound care.

Positively Charged Semiconductor Conjugated Polymer Nanomaterials with Photothermal Activity for Antibacterial and Antibiofilm Activities In Vitro and In Vivo

Biofilm infections are associated with most human bacterial infections and are prone to bacterial multidrug resistance. There is an urgent need to develop an alternative approach to antibacterial and antibiofilm agents. Herein, two positively charged semiconductor conjugated polymer nanoparticles (SPPD and SPND) were prepared for additive antibacterial and antibiofilm activities with the aid of positive charge and photothermal therapy (PTT). The positive charge of SPPD and SPND was helpful in adhering to the surface of bacteria. With an 808 nm laser irradiation, the photothermal activity of SPPD and SPND could be effectively transferred to bacteria and biofilms. Under the additive effect of positive charge and PTT, the inhibition rate of Staphylococcus aureus (S. aureus) treated with SPPD and SPND (40 μg/mL) could reach more than 99.2%, and the antibacterial activities of SPPD and SPND against S. aureus biofilms were 93.5 and 95.8%. SPPD presented better biocompatibility than SPND and exhibited good antibiofilm properties in biofilm-infected mice. Overall, this additive treatment strategy of positive charge and PTT provided an optional approach to combat biofilms.

Chitosan-based hydrogel wound dressing: From mechanism to applications, a review

As promising biomaterials, hydrogels are widely used in the medical engineering field, especially in wound repairing. Compared with traditional wound dressings, such as gauze and bandage, hydrogel could absorb and retain more water without dissolving or losing its three-dimensional structure, thus avoiding secondary injury and promoting wound healing. Chitosan and its derivatives have become hot research topics for hydrogel wound dressing production due to their unique molecular structure and diverse biological activities. In this review, the mechanism of wound healing was introduced systematically. The mechanism of action of chitosan in the first three stages of wound repair (hemostasis, antimicrobial properties and progranulation), the effect of chitosan deacetylation and the molecular weight on its performance are analyzed. Additionally, the recent progress in intelligent and drug-loaded chitosan-based hydrogels and the features and advantages of chitosan were discussed. Finally, the challenges and prospects for the future development of chitosan-based hydrogels were discussed.