Advances in chitosan-based wound dressings: Modifications, fabrications, applications and prospects

Chitosan-based matrix as a carrier for bacteriophages

Wound healing is a dynamic and complex process where infection prevention is essential. Chitosan, thanks to its bactericidal activity against gram-positive and gram-negative bacteria, as well as anti-inflammatory and hemostatic properties, is an excellent candidate to design dressings for difficult-to-heal wound treatment. The great advantage of this biopolymer is its capacity to be chemically modified, which allows for the production of various functional forms, depending on the needs and subsequent use. Moreover, chitosan can be an excellent polymer matrix for bacteriophage (phage) packing as a novel alternative/supportive antibacterial therapy approach. This study is focused on the preparation and characteristics of chitosan-based material in the form of a film with the addition of Pseudomonas lytic phages (KTN4, KT28, and LUZ19), which would exhibit antibacterial activity as a potential dressing that accelerates the wound healing. We investigated the method of producing a polymer based on microcrystalline chitosan (MKCh) to serve as the matrix for phage deposition. We described some important parameters such as average molar mass, swelling capacity, surface morphology, phage release profile, and antibacterial activity tested in the Pseudomonas aeruginosa bacterial model. The chitosan polysaccharide turned out to interact with phage particles immobilizing them within a material matrix. Nevertheless, with the high hydrophilicity and swelling features of the prepared material, the external solution of bacterial culture was absorbed and phages went in direct contact with bacteria causing their lysis in the polymer matrix. KEY POINTS: • A novel chitosan-based matrix with the addition of active phages was prepared • Phage interactions with the chitosan matrix were determined as electrostatic • Phages in the matrix work through direct contact with the bacterial cells.

Enhancing the porosity of chitosan sponges with CBD by adding antimicrobial violacein

Given the growing interest in non-toxic materials with good anti-inflammatory and antimicrobial mechanical properties, this work focuses on preparing chitosan sponges with violacein and cannabis oil crosslinked with dialdehyde chitosan. The sponge was tested for its physicochemical and biological properties, presenting a high swelling rate, good thermal stability, and satisfactory mechanical properties. The obtained sponge's water vapor transmission rate was 2101 g/m2/day and is within the recommended values for ideal wound dressings. Notably, adding violacein favorably affected the material's porosity, which is essential for dressing materials. In addition, studies have shown that the designed material interacts with human serum albumin and exhibits good antioxidant and anti-inflammatory properties. The antibacterial properties of the prepared biomaterial were assessed using the Microtox test against A. fisherii (Gram-negative bacterium) and S. aureus (Gram-positive bacterium). The investigated material provides potential therapeutic benefits due to the synergistic action of chitosan, violacein, and cannabis oil so that it could be used as a dressing material. The natural origin of the substances could provide an attractive and sustainable alternative to traditional commercially available dressings.

Physical, antibacterial, blood coagulation, and healing promotion evaluations of chitosan derivative-based composite films

Chitosan is a potentially suitable material for wound dressing, but is undesirably water-insoluble. Although chitosan can be modified to produce water-soluble derivatives, the best chitosan derivative for wound dressings remains unclear. The present study introduced three water-soluble chitosan derivatives, namely, carboxymethyl chitosan, quaternized chitosan (QCS), and carboxymethyl quaternized chitosan, and explored the physical properties, biochemical properties, and wound care effectiveness of films of these derivatives. The QCS-based film exhibited higher absorption ability, mechanical properties, water-vapor permeability, electroconductivity, and antioxidant capacity than the other films. Most importantly, the cationic quaternary ammonium groups facilitated the antibacterial activity (>95 %) and blood coagulant capacity of the QCS-based film. As this film also promoted wound healing, it presented as an ideal candidate for wound dressings.

Development and characterization of three-dimensional antibacterial nanocomposite sponges of chitosan, silver nanoparticles and halloysite nanotubes

In this work, we developed novel nanocomposite three-dimensional (3D) scaffolds composed of chitosan (CTS), halloysite nanotubes (HNTs) and silver nanoparticles (AgNPs) with enhanced antimicrobial activity and fibroblast cell compatibility for their potential use in wound dressing applications. A stock CTS-HNT solution was obtained by mixing water-dispersed HNTs with CTS aqueous-acid solution, and then, AgNPs, in different concentrations, were synthesized in the CTS-HNT solution via a CTS-mediated in situ reduction method. Finally, freeze-gelation was used to obtain CTS-HNT-AgNP 3D porous scaffolds (sponges). Morphology analysis showed that synthesized AgNPs were spherical with an average diameter of 11 nm. HNTs' presence did not affect the AgNPs morphology or size but improved the mechanical properties of the scaffolds, where CTS-HNT sponges exhibited a 5 times larger compression stress than bare-CTS sponges. AgNPs in the scaffolds further increased their mechanical strength in correlation to the AgNP concentration, and conferred them improved antibacterial activity against Gram-negative and Gram-positive bacteria, inhibiting the planktonic proliferation and adhesion of bacteria in a AgNP concentration depending on manner. In vitro cell viability and immunofluorescence assays exhibited that human fibroblast (HF) culture was supported by the sponges, where HF retained their phenotype upon culture on the sponges. Present CTS-HNT-AgNP sponges showed promising mechanical, antibacterial and cytocompatibility properties to be used as potential scaffolds for wound dressing applications.

O-carboxymethyl chitosan in biomedicine: A review

O-carboxymethyl chitosan (O-CMC) is a chitosan derivative produced through the substitution of hydroxyl (-OH) functional groups in glucosamine units with carboxymethyl (-CH2COOH) substituents, effectively addressing the inherent solubility issues of chitosan in aqueous solutions. O-CMC has garnered significant interest due to its enhanced solubility, elevated viscosity, minimal toxicity, and advantageous biocompatibility properties. Furthermore, O-CMC demonstrates antibacterial, antifungal, and antioxidant characteristics, rendering it a promising candidate for various biomedical uses such as wound healing, tissue engineering, anti-tumor therapies, biosensors, and bioimaging. Additionally, O-CMC is well-suited for the fabrication of nanoparticles, hydrogels, films, microcapsules, and tablets, offering opportunities for effective drug delivery systems. This review outlines the distinctive features of O-CMC, offers analyses of advancements and future potential based on current research, examines significant obstacles for clinical implementation, and foresees its ongoing significant impacts in the realm of biomedicine.

A multifunctional chitosan based porous membrane for pH-responsive antibacterial activity and promotion of infected wound healing

Unsatisfactory mechanical and antibacterial properties restricted the solo use of chitosan (CS) as a wound dressing. In this work, a novel CS/hydroxyapatite/ZIF-8 (CS/HAp/ZIF-8, CHZ-10) porous membrane was facilely constructed by in situ loading of ZIF-8 on CS/HAp. The advantages of the three compositions were rationally integrated, and the multifunctionality and practicality of this CS-based dressing were improved. HAp not only improved the mechanical strength and stability of CS, but also promoted cell proliferation and accelerated hemostasis with its released Ca2+. Meanwhile, ZIF-8 enhanced the antibacterial activity of CS by releasing antibacterial Zn2+ in a pH-responsive and sustainable manner, avoiding the bio-accumulation toxicity of heavy metals. Compared with CS/HAp and conventionally used gauze, CHZ-10 exhibited superior coagulation and hemolytic ability, as well as outstanding antibacterial activity against E. coli and S. aureus. Besides, both in vivo observation and histological evaluation demonstrated that CHZ-10 could not only effectively inhibit bacterial infection and reduce inflammation of the wound, but also promote its re-epithelialization, granulation, tissue formation and collagen fibre growth, leading to effectively enhanced wound-healing. This work provides a new method for the easy construction of multifunctional antibacterial dressings based on CS, showing promise for application in clinical wound care.

Chitosan-Based Hydrogels as Antibacterial/Antioxidant/Anti-Inflammation Multifunctional Dressings for Chronic Wound Healing

Due to repeated microbial infection, persistent inflammation, excessive oxidative stress, and cell dysfunction, chronic wounds are difficult to heal, posing a serious threat to public health. Therefore, developing multifunctional wound dressings that can regulate the complex microenvironment of chronic wounds and enhance cellular function holds great significance. Recently, chitosan has emerged as a promising biopolymer for wound healing due to its excellent biocompatibility, biodegradability, and versatile bioactivity. The aim of this review is to provide a comprehensive understanding of the mechanisms of delayed chronic wound healing and discuss the healing-promoting properties of chitosan and its derivatives, such as good biocompatibility, antibacterial activity, hemostatic capacity, and the ability to promote tissue regeneration. On this basis, the potential applications of chitosan-based hydrogels are summarized in chronic wound healing, including providing a suitable microenvironment, eliminating bacterial infections, promoting hemostasis, inhibiting chronic inflammation, alleviating oxidative stress, and promoting tissue regeneration. In addition, the concerns and perspectives for the clinical application of chitosan-based hydrogels are also discussed.

Effects of montmorillonite on the loading and release of Piper betle L. extract applied for wound dressing based on chitosan/polyvinyl alcohol

In this study, we investigate the influence of montmorillonite (MMT) on the loading and release of Piper betle L. extract (PLE)-a medicinal herb containing active secondary metabolites with antibacterial, antioxidant, and anti-inflammatory effects. MMT (1 %, 3 %, 5 %) was blended into the chitosan/polyvinyl alcohol (CS/PVA) biocomposite film by the solution evaporation method, and then PLE was loaded onto this biocomposite using the immersion method. The tensile strength and the ability to absorb exudates of the CS/PVA film improved with the increase in MMT content. The MMT 3 % film was considered to have the best properties: good mechanical properties with a tensile strength of 27.44 ± 0.27 MPa and elongation at break of 14.57 ± 0.30 %, potential for wound dressing due to its ability to absorb wound exudate (swelling degree 61.70 ± 0.30 %) and a suitable water vapor transmission rate (1999 ± 47 g/m2·d). The presence of MMT (1 %, 3 %, 5 %) in the CS/PVA film led to an increase in the PLE loading efficiency of the films compared to the film without MMT, up to 1.65, 1.73, and 1.87 times, respectively. The MMT 3 % and 5 % films also exhibited a sustained PLE release effect for up to 24 h. MMT increased PLE bioavailability through bioactivity tests: antibacterial activity against both E. coli and S. aureus, antioxidant activity, effective healing of 2nd-degree burn wounds, and biocompatibility with the L929 fibroblasts cell line. The combination of physicochemical properties and biological activities proved that the MMT/PLE drug delivery system based on the CS/PVA biocomposite is promising for wound dressing.

Preparation of pH-sensitive porous polylactic acid-based medical dressing with self-pumping function

Excessive exudation from the wound site and the difficulty of determining the state of wound healing can make medical management more difficult and, in extreme cases, lead to wound deterioration. In this study, we fabricated a pH-sensitive colorimetric chronic wound dressing with self-pumping function using electrostatic spinning technology. It consisted of three layers: a polylactic acid-curcumin (PCPLLA) hydrophobic layer, a hydrolyzed polyacrylonitrile (HPAN) transfer layer, and a polyacrylonitrile-purple kale anthocyanin (PAN-PCA) hydrophilic layer. The results showed that the preparation of porous PLLA fiber membrane loaded with 0.2 % Cur was achieved by adjusting the spinning-related parameters, which could ensure that the composite dressing had sufficient anti-inflammatory, antibacterial and antioxidant properties. The HPAN membrane treated with alkali for 30 min had significantly enhanced liquid wetting ability, and the unidirectional transport of liquid could be achieved by simple combination with the 20 um PCPLLA fiber membrane. In addition, the 4 % loaded PCA showed more obvious color difference than the colorimetric membrane. In vivo and ex vivo experiments have demonstrated the potential of multifunctional dressings for the treatment of chronic wounds.

Enhanced physiochemical, antibacterial, and hemostatic performance of collagen-quaternized chitosan-graphene oxide sponges for promoting infectious wound healing

Bacteria-infected wound healing has attracted widespread attention in biomedical engineering. Wound dressing is a potential strategy for repairing infectious wounds. However, the development of wound dressing with appropriate physiochemical, antibacterial, and hemostatic properties, remains challenging. Hence, there is a motivation to develop new synthetic dressings to improve bacteria-infected wound healing. Here, we fabricate a biocompatible sponge through the covalent crosslinking of collagen (Col), quaternized chitosan (QCS), and graphene oxide (GO). The resulting Col-QCS-GO sponge shows an elastic modulus of 1.93-fold higher than Col sponge due to enhanced crosslinking degree by GO incorporation. Moreover, the fabricated Col-QCS-GO sponge shows favorable porosity (84.30 ± 3.12 %), water absorption / retention (2658.0 ± 113.4 % / 1114.0 ± 65.7 %), and hemostasis capacities (blood loss <50.0 mg). Furthermore, the antibacterial property of the Col-QCS-GO sponge under near-infrared (NIR) irradiation is significantly enhanced (the inhibition rates are 99.9 % for S. aureus and 99.9 % for E. coli) due to the inherent antibacterial properties of QCS and the photothermal antibacterial capabilities of GO. Finally, the Col-QCS-GO+NIR sponge exhibits the lowest percentage of wound area (9.05 ± 1.42 %) at day 14 compared to the control group (31.61 ± 1.76 %). This study provides new insights for developing innovative sponges for bacteria-infected wound healing.

Multifunctional Regeneration Silicon-Loaded Chitosan Hydrogels for MRSA-Infected Diabetic Wound Healing

Repeated microbial infection, excess reactive oxygen species (ROS) accumulation, cell dysfunction, and impaired angiogenesis under hyperglycemia severely inhibit diabetic wound healing. Therefore, developing multifunctional wound dressings accommodating the complex microenvironment of diabetic wounds is of great significance. Here, a multifunctional hydrogel (Regesi-CS) is prepared by loading regeneration silicon (Regesi) in the non-crosslinked chitosan (CS) solution, followed by freeze-drying and hydration. As expected, the blank non-crosslinked CS hydrogel (1%) shows great antibacterial activity against Escherichia coli, Staphylococcus aureus, and methicillin-resistant S. aureus (MRSA), improves fibroblast migration, and scavenges intracellular ROS. Interestingly, after loading 1% Regesi, the Regesi-CS (1%-1%) hydrogel shows greater antibacterial activity, significantly promotes fibroblasts proliferation and migration, scavenges much more ROS, and substantially protects fibroblasts under oxidative stress, yet Regesi alone has no or even negative effects. In the MRSA-infected diabetic wound model, Regesi-CS (1%-1%) hydrogel effectively promotes wound healing by eliminating bacterial infection, enhancing granulation tissue formation, promoting collagen deposition, and improving angiogenesis. In conclusion, Regesi-CS hydrogel may be a potential wound dressing for the effective treatment and management of chronic diabetic wounds.

Triple-layered core-shell fiber dressings with enduring platelet conservation and sustained growth factor release abilities for chronic wound healing

Platelet-rich plasma (PRP) is one of the most popular biomaterials in regenerative medicine. However, the difficulties encountered in its preservation, and the requirement for on-demand preparation severely limit its application. In addition, its rapid degradation in the wound microenvironment makes the sustained release of growth factors impossible and finally reduces the therapeutic effect on chronic wounds. Here, a multifunctional dressing based on triple-layered core-shell fibers for loading and enduring preservation of PRP was developed using a one-step coaxial bioprinting technique combined with freeze-drying. The platelets were effectively dispersed and immobilized in the core layer of the fiber, leading to a sustained release of growth factors from the PRP. The rate of release can be controlled by adjusting the triple-layered core-shell structure. Simultaneously, the triple-layered core-shell structure can reduce the deactivation of PRP during freezing and storage. The experimental findings suggest that PRP exhibits sustained activity, facilitating the process of wound healing even after a storage period of 180 days. Furthermore, the protective mechanism of PRP by the triple-layered core-shell fiber was investigated, and the conditions for freeze-drying and storage were optimized, further enhancing the long-term storability of PRP. As a result, the multifunctional core-shell fiber dressings developed in this study offer a novel approach for sustained growth factor release and the enduring preservation of active PRP.

Gelatin/carboxymethyl chitosan/aloe juice hydrogels with skin-like endurance and quick recovery: Preparation, characterization, and properties

Gelatin-based hydrogels have gained considerable attention due to their resemblance to the extracellular matrix and hydrophilic three-dimensional network structure. Apart from providing an air-permeable and moist environment, these hydrogels optimize the inflammatory microenvironment of the wounds. These properties make gelatin-based hydrogels highly competitive in the field of wound dressings. In this study, a series of composite hydrogels were prepared using gelatin (Gel) and carboxymethyl chitosan (CMCh) as primary materials, glutaraldehyde as a crosslinker, and aloe vera juice as an anti-inflammatory component. The properties of the hydrogel, including its rheological properties, microscopic structures, mechanical properties, swelling ratios, thermal stability, antibacterial properties, and biocompatibility, were investigated. The results demonstrate that the gelatin-based hydrogels exhibit good elasticity and rapid self-healing ability. The hydrogels exhibited slight shear behavior, which is advantageous for skin care applications. Furthermore, the inclusion of aloe vera juice into the hydrogel resulted in a dense structure, improved mechanical properties and enhanced swelling ratio. The Gel/CMCh/Aloe hydrogels tolerate a compressive strength similar to that of human skin. Moreover, the hydrogels displayed excellent cytocompatibility with HFF-1 cells, and exhibited antibacterial activity against E. coli and S. aureus. Lomefloxacin was used as a model drug to study the releasing behavior of the Gel/CMCh/aloe hydrogels. The results showed that the drug was released rapidly at the initial stage, and could continue to be released for 12 h, the maximum releasing rate exceeded 20 %. These findings suggest that the gelatin-based hydrogels hold great promise as effective wound dressings.

Anti-adhesive and antibacterial chitosan/PEO nanofiber dressings with high breathability for promoting wound healing

Wound dressings are crucial for wound healing. Ideal wound dressings should possess many functions such as wettability, antibacterial activity and anti-adherent property to promote wound healing. In the present study solution blown spinning (SBS) technology was applied to prepare chitosan/polyethylene oxide (CS/PEO) nanofiber dressings in high efficiency. The obtained nanofiber dressings were treated with anhydrous ethanol to improve the fiber structure and enhance the functionality of the fiber dressings. The results show that the treated nanofibers had higher crystallinities and higher CS contents. The CS/PEO nanofiber dressings fabricated by using no additives and crosslinking had excellent wettability, water stability and antibacterial activity against Escherichia coli and Staphylococcus aureus reached to over 99.99 %. In addition, the CS/PEO nanofiber dressings exhibited high breathability, antioxidant activity and anti-adhesion function. The in vivo animal experiment confirmed that the nanofiber dressings enhanced cell proliferation and significantly accelerated the wound healing within 10 days. The developed CS/PEO nanofiber dressings have great potential in the clinical field of wound healing.

Chitosan nonwoven fabric composited calcium alginate and adenosine diphosphate as a hemostatic bandage for acute bleeding wounds

Acute bleeding following accidental injury is a leading cause of mortality. However, conventional hemostatic bandages impede wound healing by inducing excessive blood loss, dehydration, and adherence to granulation tissue. Strategies such as incorporating active hemostatic agents and implementing chemical modifications can augment the properties of these bandages. Nevertheless, the presence of remote thrombosis and initiators may pose risks to human health. Here, a hemostatic bandage was developed by physically combined chitosan nonwoven fabric, calcium alginate sponge, and adenosine diphosphate. The presented hemostatic bandage not only exhibits active and passive mechanisms for promoting clotting but also demonstrates excellent mechanical properties, breathability, ease of removal without causing damage to the wound bed or surrounding tissues, as well as maintaining an optimal moist environment conducive to wound healing. In vitro evaluation results indicated that the hemostatic bandage possesses favorable cytocompatibility with low levels of hemolysis. Furthermore, it effectively aggregates various blood cells while activating platelets synergistically to promote both extrinsic and intrinsic coagulation pathways. In an in vivo rat model study involving liver laceration and femoral artery injury scenarios, our developed hemostatic bandage demonstrated rapid clot formation capabilities along with reduced blood loss compared to commercially available fabrics.

Dual properties of pharmacological activities and preparation excipient: Bletilla striata polysaccharides

Bletilla striata has been used for thousands of years and shows the functions of stopping bleeding, reducing swelling, and promoting healing in traditional applications. For Bletilla striata, Bletilla striata polysaccharides (BSP) is the main active ingredient, exhibiting biological functions of anti-inflammatory, anti-oxidant, anti-fibrotic, immune modulation, anti-glycation, and so on. In addition, BSP has exhibited the characteristics of excipient such as bio-adhesion, bio-degradability, and bio-safety and has been prepared into a series of preparations such as nanoparticles, microspheres, microneedles, hydrogels, etc. BSP, as both a drug and an excipient, has already aroused more and more attention. In this review, publications in recent years related to the extraction and identification, biological activities, and excipient application of BSP are reviewed. Specifically, we focused on the advances in the application of BSP as a formulation excipient. We hold opinion that BSP not only needed more researches in the mechanisms, but also the development into hydrogels, nano-formulations, tissue engineering, and so on. And we believe that this paper provides a beneficial reference for further BSP innovation and in-depth research and promotes the use of these natural products in pharmaceutical applications.

Surface modification of polyvinyl chloride with sodium alginate/carboxymethyl chitosan and heparin for realizing the anticoagulation

Thrombosis of extracorporeal circuits causes significant morbidity and mortality worldwide. In this study, plasma treatment technology and chemical grafting method were used to construct heparinized surfaces on the PVC substrate, which could not only reduce thrombosis but also decrease the side effects of the direct injection of anticoagulants. The PVC substrate was modified by plasma treatment technology firstly to obtain the active surface with the hydroxyl groups used for grafting. Then, heparin was grafted onto the modified PVC surface using different grafting strategies to prepare different heparinized surfaces. The experimental results indicated that the sodium alginate (SA) and carboxymethyl chitosan (CCS) used as interlayers could significantly increase the graft density of heparin to improve the anticoagulant effects and hemocompatibility of heparinized surfaces. In addition, the modification of heparin can further improve the anticoagulant effects. The CCS/low-molecular-weight heparin (LWMH) surface has the best anticoagulant properties, which can prolong the activated partial thromboplastin time (APTT) values of human plasma for about 35 s, reduce the hemolysis rates to <0.3 %, and perform well in the in-vitro blood circulation test. The heparinized surfaces prepared in this work have great application potential in anticoagulant treatment for medical devices.

A Chitosan-Based Biomaterial Combined with Mesenchymal Stem Cell-Conditioned Medium for Wound Healing and Skin Regeneration

The aim of this study was to provide a beneficial treatment effect of novel chitosan bio-polymeric material enriched with mesenchymal stem cell products derived from the canine adipose tissue (AT-MSC) on the artificial skin defect in a rabbit model. For the objectivity of the regeneration evaluation, we used histological analysis and a scoring system created by us, taking into account all the attributes of regeneration, such as inflammatory reaction, necrosis, granulation, formation of individual skin layers and hair follicles. We observed an acceleration and improvement in the healing of an artificially created skin defect after eight and ten weeks in comparison with negative control (spontaneous healing without biomaterial). Moreover, we were able to described hair follicles and epidermis layer in histological skin samples treated with a chitosan-based biomaterial on the eighth week after grafting.

Sterilized Polyhexanide-Releasing Chitosan Membranes with Potential for Use in Antimicrobial Wound Dressings

Wound infection is a common complication of chronic wounds. It can impair healing, which may not occur without external help. Antimicrobial dressings (AMDs) are a type of external help to infected chronic wounds. In this study, highly porous membranes made of only chitosan and containing the antiseptic polyhexanide (poly(hexamethylene biguanide); PHMB) were prepared by cryogelation, aiming to be used in AMDs. These membranes exhibited a water swelling capacity of 748%, a water drop penetration time of 11 s in a dry membrane and a water vapor transmission rate of 34,400 g H2O/m2/24 h when in contact with water. The best drug loading method involved simultaneous loading by soaking in a PHMB solution and sterilization by autoclaving, resulting in sterilized, drug-loaded membranes. When these membranes and a commercial PHMB-releasing AMD were assayed under the same conditions, albeit far from the in vivo conditions, their drug release kinetics were comparable, releasing PHMB for ca. 6 and 4 h, respectively. These membranes exhibited high antibacterial activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are bacterial species commonly found in infected wounds and blood clotting activity. The obtained results suggest that these membranes may have potential for use in the development of AMDs.

Polyvinyl-alcohol, chitosan and graphene-oxide composed conductive hydrogel for electrically controlled fluorescein sodium transdermal release

Accurate and controlled release of drug molecules is crucial for transdermal drug delivery. Electricity, as an adjustable parameter, offers the potential for precise and controllable drug delivery. However, challenges exist in selecting the appropriate drug carrier, electrical parameters, and release model to achieve controlled electronic drug release. To overcome these challenges, this study designed a functional hydrogel using polyvinyl alcohol, chitosan, and graphene oxide as components that can conduct electricity, and constructed a drug transdermal release model using fluorescein sodium salt with proper electrical parameters. The results demonstrated that the hydrogel system exhibited low cytotoxicity, good conductivity, and desirable drug delivery characteristics. The study also integrated the effects of drug release and tissue repair promotion under electrical stimulation. Cell growth was enhanced under low voltage direct current pulses, promoting cell migration and the release of VEGF and FGF. Furthermore, the permeability of fluorescein sodium salt in the hydrogel increased with direct current stimulation. These findings suggest that the carbohydrate polymers hydrogel could serve as a drug carrier for controlled release, and electrical stimulation offers new possibilities for functional drug delivery and transdermal therapy.

A pH-responsive ZC-QPP hydrogel for synergistic antibacterial and antioxidant treatment to enhance wound healing

The problems of bacterial resistance and high oxidation level severely limit wound healing. Therefore, we constructed a multifunctional platform of chitosan quaternary ammonium salts (QCS)/polyvinyl alcohol (PVA)/polyethylene glycol (PEG) hydrogels (QPP) loaded with ZnO@CeO2 (ZC-QPP). Firstly, the hydrogel was co-cross-linked by hydrogen and borate ester bonds, which allows easy adherence to a tissue surface for offering a protective barrier and moist environment for wounds. The chitosan quaternary ammonium salts due to their amino groups have inherent antibacterial properties to induce bacterial death. In response to the acidic conditions of the bacterial infection microenvironment, the borate ester bonds in the QPP hydrogel break and the ZC NCs dispersed in the hydrogel are released. The gradual dissociation of Zn2+ under acidic conditions can directly damage bacterial membranes. The wound site of bacterial infection always causes overexpression of reactive oxygen species (ROS) levels, often leading to inflammation and preventing rapid wound repair. CeO2 can eliminate excess ROS to reduce the inflammatory response. From in vitro and in vivo results, the high biosafety of the ZC-QPP hydrogel has demonstrated excellent antibacterial and antioxidant performance to enhance wound healing. Therefore, the ZC-QPP hydrogel opens a method to develop multifunctional synergistic therapeutic platforms combining enzyme-like nanomaterials with hydrogels for synergistic antibacterial and antioxidant treatment to promote wound healing.

Recent Advances in Sustainable Antimicrobial Food Packaging: Insights into Release Mechanisms, Design Strategies, and Applications in the Food Industry

In response to the issues of foodborne microbial contamination and carbon neutrality goals, sustainable antimicrobial food packaging (SAFP) composed of renewable or biodegradable biopolymer matrices with ecofriendly antimicrobial agents has emerged. SAFP offers longer effectiveness, wider coverage, more controllability, and better environmental performance. Analyzing SAFP information, including the release profile of each antimicrobial agent for each food, the interaction of each biomass matrix with each food, the material size, form, and preparation methods, and its service quality in real foods, is crucial. While encouraging reports exist, a comprehensive review summarizing these developments is lacking. Therefore, this review critically examines recent release-antimicrobial mechanisms, kinetics models, preparation methods, and key regulatory parameters for SAFPs based on slow- or controlled-release theory. Furthermore, it discusses fundamental physicochemical characteristics, effective concentrations, advantages, release approaches, and antimicrobial and preservative effects of various materials in food simulants or actual food. Lastly, inadequacies and future trends are explored, providing practical references to regulate the movement of active substances in different media, reduce the reliance on petrochemical-based materials, and advance food packaging and preservation technologies.

A Free-Standing Chitosan Membrane Prepared by the Vibration-Assisted Solvent Casting Method

Much attention has been paid to the surface modification of artificial skin barriers for the treatment of skin tissue damage. Chitosan is one of the natural materials that could be characterized by its biocompatibility. A number of methods for the preparation of chitosan membranes have been described in scientific articles, including solvent casting methods. This study investigates an improved technology to produce chitosan membranes. Thus, chitosan membranes were prepared using a vibration-assisted solvent casting method. First, aqueous acetic acid was used to pretreat chitosan. Then, free-standing chitosan membranes were prepared by solvent casting on nanoporous anodized aluminum oxide (AAO) membrane templates, allowing for the solvent to evaporate. Using finite element methods, a study was obtained showing the influence of chitosan solutions of different concentrations on the fluid flow into nanopores using high-frequency excitation. The height of the nanopillars and the surface area of the chitosan membrane were also evaluated. In this study, the surface area of the chitosan membrane was found to increase by 15, 10 and 6 times compared to the original flat surface area. The newly produced nanopillared chitosan membranes will be applicable in the fabrication of skin barriers due to the longer nanopillars on their surface and the larger surface area.

Photothermal and natural activity-based synergistic antibacterial effects of Ti3C2Tx MXene-loaded chitosan hydrogel against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has strong resistance to antibiotic therapy. In this regard, developing antibiotic-free antibacterial agents is of great significance to treat MRSA infections. Herein, we loaded Ti₃C₂T_x MXene nanomaterial in the non-crosslinked chitosan (CS) hydrogel. The obtained MX-CS hydrogel is expected to not only adsorb MRSA cells via CS-MRSA interactions, but also gather the MXene-induced photothermal hyperthermia, achieving the efficient and intensive anti-MRSA photothermal therapy. As a result, under NIR irradiation (808 nm, 1.6 W/cm², 5 min), MX-CS showed a greater photothermal effect than MXene alone did (30 μg/mL, 49.9 °C for MX-CS and 46.5 °C for MXene). Importantly, MRSA cells were rapidly adsorbed on MX-CS hydrogel (containing 30 μg/mL MXene) and completely inhibited (99.18 %) under NIR irradiation for 5 min. In contrast, MXene (30 μg/mL) and CS hydrogel alone only inhibited 64.52 % and 23.72 % MRSA, respectively, significantly lower than the inhibition caused by MX-CS (P < 0.001). Interestingly, when the hyperthermia was depleted by a 37 °C water bath, the bacterial inhibition rate of MX-CS significantly decreased to 24.65 %. In conclusion, MX-CS hydrogel has a remarkable synergistic anti-MRSA activity by gathering MRSA cells and MXene-induced hyperthermia, and may have great potentials in treating MRSA-infected diseases.

A bilayer mupirocin/bupivacaine-loaded wound dressing based on chitosan/poly (vinyl alcohol) nanofibrous mat: Preparation, characterization, and controlled drug release

An infected skin wound caused by external injury remains a serious challenge. Electrospun drug-loaded nanofibers with antibacterial properties based on biopolymers have been widely explored for wound healing. In this study, the double-layer CS/PVA/mupirocin (CPM) + CS/PVA/bupivacaine (CPB) mats were prepared by electrospinning method (20 % polymer weight) and then crosslinked with glutaraldehyde (GA) to optimize the water-resistant and biodegradation properties for wound dressing applications. The morphology of mats was characterized as defect-free and interconnected nanofibers by Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). Fourier Transform Infrared Spectrometry (FTIR) analysis also assessed the chemical structural properties. The porosity, surface wettability, and swelling degree of the dual-drug loaded mats were improved by about 20 %, 12°, and 200 % of the CS/PVA sample to provide a moist environment for efficient wound breathing and repairing. This highly porous mat facilitated the wound exudates absorption and air permeability excellently, reducing the chance of bacterial infections by inhibiting the growth of S. aureus bacterial colonies with a zone of 71.3 mm diameter. In vitro drug release results showed a high-burst release of 80 % and a continuous release profile for bupivacaine and mupirocin, respectively. MTT assay and in vivo tests indicated >90 % of cell viability and improvement in cell proliferation. It triply accelerated wound closure compared to the control group, reaching nearly full closure after 21 days as a potential clinical wound treatment.

Antibacterial and hemostatic polyvinyl alcohol/microcrystalline cellulose reinforced sodium alginate breathable dressing containing Euphorbia humifusa extract based on microfluidic spinning technology

Antibacterial hemostatic medical dressings have become feasible solutions in response to the challenging wound-healing process. In this study, a novel fiber-type medical dressing with excellent breathable, antibacterial, and hemostatic qualities was created using sodium alginate (SA), microcrystalline cellulose (MCC), polyvinyl alcohol (PVA), and Euphorbia humifusa Willd (EHW) based on microfluidic spinning technology, and the properties of the dressing were characterized. The orthogonal test demonstrates that PVA and MCC can enhance the mechanical properties of the fiber, which is a crucial requirement for fiber assembly to form the dressing. Moreover, the presence of EHW enhances the dressing's antibacterial and hemostatic qualities. The dressings have been proven to have potent antibacterial and hemostatic properties as well as the ability to considerably speed up wound healing and skin tissue regeneration in the in-vitro and in-vivo tests. In conclusion, this innovative fiber-type medical dressing containing SA, MCC, PVA, and EHW has enormous potential for managing wounds caused by bacteria.

Reduced graphene oxide-enriched chitosan hydrogel/cellulose acetate-based nanofibers application in mild hyperthermia and skin regeneration

Asymmetric wound dressings have captured researchers' attention due to their ability to reproduce the structural and functional properties of the skin layers. Furthermore, recent studies also report the benefits of using near-infrared (NIR) radiation-activated photothermal therapies in treating infections and chronic wounds. Herein, a chitosan (CS) and reduced graphene oxide (rGO) hydrogel (CS_rGO) was combined with a polycaprolactone (PCL) and cellulose acetate (CA) electrospun membrane (PCL_CA) to create a new NIR-responsive asymmetric wound dressing. The rGO incorporation in the hydrogel increased the NIR absorption capacity and allowed a mild hyperthermy effect, a temperature increase of 12.4 °C when irradiated with a NIR laser. Moreover, the PCL_CA membrane presented a low porosity and hydrophobic nature, whereas the CS_rGO hydrogel showed the ability to provide a moist environment, prevent exudate accumulation and allow gaseous exchanges. Furthermore, the in vitro data demonstrate the capacity of the asymmetric structure to act as a barrier against bacteria penetration as well as mediating a NIR-triggered antibacterial effect. Additionally, human fibroblasts were able to adhere and proliferate in the CS_rGO hydrogel, even under NIR laser irradiation, presenting cellular viabilities superior to 90 %. Altogether, our data support the application of the NIR-responsive asymmetric wound dressings for skin regeneration.

Application of functionalized chitosan in food: A review

Environmental and sustainability issues have received increasing attention in recent years. As a natural biopolymer, chitosan has been developed as a sustainable alternative to traditional chemicals such as food preservation, food processing, food packaging, and food additives due to its abundant functional groups and excellent biological functions. This review analyzes and summarizes the unique properties of chitosan, with a particular focus on the mechanism of action for its antibacterial and antioxidant properties. This provides a lot of information for the preparation and application of chitosan-based antibacterial and antioxidant composites. In addition, chitosan is modified by physical, chemical and biological modifications to obtain a variety of functionalized chitosan-based materials. The modification not only improves the physicochemical properties of chitosan, but also enables it to have different functions and effects, showing promising applications in multifunctional fields such as food processing, food packaging, and food ingredients. In the current review, applications, challenges, and future perspectives of functionalized chitosan in food will be discussed.

Recent Reports on Polysaccharide-Based Materials for Drug Delivery

Polysaccharides constitute one of the most important families of biopolymers. Natural polysaccharide-based drug delivery systems are of constant interest to the scientific community due to their unique properties: biocompatibility, non-toxicity, biodegradability, and high availability. These promising biomaterials protect sensitive active agents and provide their controlled release in targeted sites. The application of natural polysaccharides as drug delivery systems is also intensively developed by Polish scientists. The present review focuses on case studies from the last few years authored or co-authored by research centers in Poland. A particular emphasis was placed on the diversity of the formulations in terms of the active substance carried, the drug delivery route, the composition of the material, and its preparation method.