Injectable wound dressing based on carboxymethyl chitosan triple-network hydrogel for effective wound antibacterial and hemostasis

In-situ forming carboxymethyl chitosan hydrogel containing Paeonia suffruticosa Andr. leaf extract for mixed infectious vaginitis treatment by reshaping the micro-biota

Mixed infectious vaginitis poses a serious threat to female reproductive health due to complex pathogenic factors, a long course and easy recurrence. Currently, antibiotic-based treatment methods are facing a crisis of drug resistance and secondary dysbiosis. Exploring effective drugs for the treatment of mixed vaginitis from Paeonia suffruticosa Andr., a natural traditional Chinese medicine with a long history of medicinal use, is a feasible treatment strategy. P. suffruticosa Andr. leaf extract (PLE) has significant anti-bacterial effects due to its rich content of polyphenols and flavonoids. The polyphenols in peony leaves have the potential to make carboxymethyl chitosan form in situ gel. In the current study, PLE and carboxymethyl chitosan were combined to develop another type of natural anti-bacterial anti-oxidant hydrogel for the treatment of mixed infectious vaginitis. Through a series of characterisations, CP had a three-dimensional network porous structure with good mechanical properties, high water absorption, long retention and a slow-release drug effect. The mixed infectious vaginitis mouse model induced by a mixture of pathogenic bacteria was used to investigate the therapeutic effects of CP in vivo. The appearance of the vagina, H&E colouring of the tissue and inflammatory factors (TNF-α, IL-6) confirm the good anti-vaginal effect of CP. Therefore, CP was expected to become an ideal effective strategy to improve mixed infection vaginitis due to its excellent hydrogel performance and remarkable ability to regulate flora.

Green synthesis-inspired antibacterial, antioxidant and adhesive hydrogels with ultra-fast gelation and hemostasis for promoting infected skin wound healing

Bacterial infections are a serious threat to wound healing and skin regeneration. In recent years, photothermal therapy (PTT) has become one of the most promising tools in the treatment of infectious diseases. However, wound dressings with photo-responsive properties are currently still limited by the difficulties of biosafety and thermal stability brought by the introduction of photosensitizers or photothermal agents. Therefore, how to improve the therapeutic efficiency and biosafety from material design is still a major challenge at present. In this study, the carboxymethyl chitosan (CMCS) and protocatechuic aldehyde (PA) hydrogels based on horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) enzymatic catalysis was developed. Therein, HRP and H2O2 catalyzed cross-linking while polymerizing PA, which not only endowed the hydrogels with photothermal responsiveness but also with good biosafety through this enzyme-catalyzed green approach. Meanwhile, the hydrogels possessed highly efficient bacteriostatic ability with the assistance of near infrared (NIR). Moreover, the ultra-rapid gelation, strong tissue adhesion, high swelling ability, good antioxidant property and hemostatic property of the CMCS-PA hydrogels based on HRP/H2O2 enzymatic catalysis were suitable for the treatment of skin wounds. Meanwhile, NIR-assistant CMCS-PA hydrogels based on HRP/H2O2 enzymatic catalysis reduced inflammation, decreased bacterial infection, and promoted collagen deposition and angiogenesis, which showed remarkable therapeutic effects in a skin wound infection model. All results indicate that this green approach to introduce photothermal property by HRP-catalyzed PA polymerization endows the hydrogels with efficient photothermal conversion efficiency, suggesting that they are promising to provide new options for replacing photothermal agents and photosensitizers. STATEMENT OF SIGNIFICANCE: In recent years, wound dressings with photo-responsive properties are currently still limited by the difficulties of biosafety and thermal stability brought by the introduction of agent photosensitizers or photothermal agents. In this study, the carboxymethyl chitosan and protocatechuic aldehyde hydrogels based on horseradish peroxidase and hydrogen peroxide enzymatic catalysis was developed. The photothermal properties of hydrogels were transformed from absent to present just by horseradish peroxidase-catalyzed protocatechuic aldehyde polymerization in a green approach. Meanwhile, the hydrogels possessed highly efficient bacteriostatic ability with the assistance of near infrared. The green approach of introducing photothermal properties from material design solves the biosafety challenge. Therefore, this study is expected to provide new options for alternative photothermal agents and photosensitizers.

Alginate-Chitosan Biodegradable and Biocompatible Based Hydrogel for Breast Cancer Immunotherapy and Diagnosis: A Comprehensive Review

Breast cancer is the most common type of cancer and the second leading cause of cancer-related mortality in females. There are many side effects due to chemotherapy and traditional surgery, like fatigue, loss of appetite, skin irritation, and drug resistance to cancer cells. Immunotherapy has become a hopeful approach toward cancer treatment, generating long-lasting immune responses in malignant tumor patients. Recently, hydrogel has received more attention toward cancer therapy due to its specific characteristics, such as decreased toxicity, fewer side effects, and better biocompatibility drug delivery to the particular tumor location. Researchers globally reported various investigations on hydrogel research for tumor diagnosis. The hydrogel-based multilayer platform with controlled nanostructure has received more attention for its antitumor effect. Chitosan and alginate play a leading role in the formation of the cross-link in a hydrogel. Also, they help in the stability of the hydrogel. This review discusses the properties, preparation, biocompatibility, and bioavailability of various research and clinical approaches of the multipolymer hydrogel made of alginate and chitosan for breast cancer treatment. With a focus on cases of breast cancer and the recovery rate, there is a need to find out the role of hydrogel in drug delivery for breast cancer treatment.

Accelerated full-thickness skin wound tissue regeneration by self-crosslinked chitosan hydrogel films reinforced by oxidized CNC-AgNPs stabilized Pickering emulsion for quercetin delivery

BACKGROUND

The non-toxic self-crosslinked hydrogel films designed from biocompatible materials allow for controlled drug release and have gathered remarkable attention from healthcare professionals as wound dressing materials. Thus, in the current study the chitosan (CS) film is infused with oil-in-water Pickering emulsion (PE) loaded with bioactive compound quercetin (Qu) and stabilized by dialdehyde cellulose nanocrystal-silver nanoparticles (DCNC-AgNPs). The DCNC-AgNPs play a dual role in stabilizing PE and are involved in the self-crosslinking with CS films. Also, this film could combine the advantage of the controlled release and synergistic wound-healing effect of Qu and AgNPs.

RESULTS

The DCNC-AgNPs were synthesized using sodium periodate oxidation of CNC. The DCNC-AgNPs were used to stabilize oil-in-water PE loaded with Qu in its oil phase by high speed homogenization. Stable PEs were prepared by 20% v/v oil: water ratio with maximum encapsulation of Qu in the oil phase. The Qu-loaded PE was then added to CS solution (50% v/v) to prepare self-crosslinked films (CS-PE-Qu). After grafting CS films with PE, the surface and cross-sectional SEM images show an inter-penetrated network within the matrix between DCNC and CS due to the formation of a Schiff base bond between the reactive aldehyde groups of DCNC-AgNPs and amino groups of CS. Further, the addition of glycerol influenced the extensibility, swelling ratio, and drug release of the films. The fabricated CS-PE-Qu films were analyzed for their wound healing and tissue regeneration potential using cell scratch assay and full-thickness excisional skin wound model in mice. The as-fabricated CS-PE-Qu films showed great biocompatibility, increased HaCat cell migration, and promoted collagen synthesis in HDFa cells. In addition, the CS-PE-Qu films exhibited non-hemolysis and improved wound closure rate in mice compared to CS, CS-Qu, and CS-blank PE. The H&E staining of the wounded skin tissue indicated the wounded tissue regeneration in CS-PE-Qu films treated mice.

CONCLUSION

Results obtained here confirm the wound healing benefits of CS-PE-Qu films and project them as promising biocompatible material and well suited for full-thickness wound healing in clinical applications.

Antibacterial adhesive based on oxidized tannic acid-chitosan for rapid hemostasis

Currently, bacterial infections and bleeding interfere with wound healing, and multifunctional hydrogels with appropriate blood homeostasis, skin adhesion, and antibacterial activity are desirable. In this study, chitosan-based hydrogels were synthesized using oxidized tannic acid (OTA) and Fe3+ as cross-linkers (CS-OTA-Fe) by forming covalent, non-covalent, and metal coordination bonds between Fe3+ and OTA. Our results demonstrated that CS-OTA-Fe hydrogels showed antibacterial properties against Gram-positive bacteria (Staphylococcus aureus)and Gram-negative bacteria (Escherichia coli), low hemolysis rate (< 2 %), rapid blood clotting ability, in vitro (< 2 min), and in vivo (90 s) in mouse liver bleeding. Additionally, increasing the chitosan concentration from 3 wt% to 4.5 wt% enhanced cross-linking in the network, leading to a significant improvement in the strength (from 106 ± 8 kPa to 168 ± 12 kPa) and compressive modulus (from 50 ± 9 kPa to 102 ± 14 kPa) of hydrogels. Moreover, CS-OTA-Fe hydrogels revealed significant adhesive strength (87 ± 8 kPa) to the cow's skin tissue and cytocompatibility against L929 fibroblasts. Overall, multifunctional CS-OTA-Fe hydrogels with tunable mechanical properties, excellent tissue adhesive, self-healing ability, good cytocompatibility, and fast hemostasis and antibacterial properties could be promising candidates for biomedical applications.

Chitosan-based injectable hydrogel with multifunction for wound healing: A critical review

Different types of clinical wounds are difficult to treat while infected by bacteria. Wound repair involves multiple cellular and molecular interactions, which is a complicated process. However, wound repair often suffers from abnormal cellular functions or pathways that result in unavoidable side effects, so there is an urgent need for a material that can heal wounds quickly and with few side effects. Based on these needs, hydrogels with injectable properties have been confirmed to be able to undergo self-healing, which provides favorable conditions for wound healing. Notably, as a biopolymer with excellent easy-to-modify properties from a wide range of natural sources, chitosan can be used to prepare injectable hydrogel with multifunction for wound healing because of its outstanding flowability and injectability. Especially, chitosan-based hydrogels with marked biocompatibility, non-toxicity, and bio-adhesion properties are ideal for facilitating wound healing. In this review, the characteristics and healing mechanisms of different wounds are briefly summarized. In addition, the preparation and characterization of injectable chitosan hydrogels in recent years are classified. Additionally, the bioactive properties of this type of hydrogel in vitro and in vivo are demonstrated, and future trend in wound healing is prospected.

Synthesis of novel chitosan/sodium hyaluronate/iridium hydrogel nanocomposite for wound healing application

A novel chitosan/sodium hyaluronate/iridium (CHI/SH/Ir) hydrogel nanocomposite with a unique microstructure containing vertically aligned pores is fabricated via an electrophoresis technique. The formation of orderly vertical pores in CHI/SH/Ir hydrogel nanocomposite is due to the confinement of hydrogen bubbles produced from the water electrolysis during electrophoresis that limits their lateral movement and coalescence. In a wet state, the diameter for the vertical pores is 600-700 μm. With a thickness of 500 μm, the CHI/SH/Ir hydrogel nanocomposite exhibits a porosity of 76.7 % and a water uptake of 350 %. Its tensile strength is almost doubled to 8.7 MPa, as compared to that of counterpart without the addition of iridium. In CHI/SH/Ir hydrogel nanocomposite, the iridium nanoparticles are homogeneously distributed with an average size of 3 nm. The CHI/SH/Ir electrophoresis suspension exhibits a negligible cytotoxicity. In cell migration test using the human keratinocytes HaCaT cells, the CHI/SH/Ir hydrogel nanocomposite reveals a relative migration of 122.15 ± 9.02 % (p < 0.001) as compared to the blank sample. The presence of vertically aligned pores with the use of SH and iridium nanoparticles indicates a promising opportunity in wound healing application.

Synthesis, Characterization, and Evaluation of Silver Nanoparticle-Loaded Carboxymethyl Chitosan with Sulfobetaine Methacrylate Hydrogel Nanocomposites for Biomedical Applications

In this study, nanocomposites of AgNPs encapsulated in carboxymethyl chitosan (CMCS) with sulfobetaine methacrylate (SB) hydrogel (AgNPs/CMCS-SB) were synthesized. The UV-Vis spectra indicated the presence of AgNPs, with a broad peak at around 424 nm, while the AgNPs-loaded CMCS-SB nanocomposite exhibited absorption peaks at 445 nm. The size and dispersion of AgNPs varied with the concentration of the AgNO3 solution, affecting swelling rates: 148.37 ± 15.63%, 172.26 ± 18.14%, and 159.17 ± 16.59% for 1.0 mM, 3.0 mM, and 5.0 mM AgNPs/CMCS-SB, respectively. Additionally, water absorption capacity increased with AgNPs content, peaking at 11.04 ± 0.54% for the 3.0 mM AgNPs/CMCS-SB nanocomposite. Silver release from the nanocomposite was influenced by AgNO3 concentration, showing rapid initial release followed by a slower rate over time for the 3.0 mM AgNPs/CMCS-SB. XRD patterns affirmed the presence of AgNPs, showcasing characteristic peaks indicative of a face-centered cubic (fcc) structure. The FTIR spectra highlighted interactions between AgNPs and CMCS-SB, with noticeable shifts in characteristic bands. In addition, SEM and TEM images validated spherical AgNPs within the CMCS-SB hydrogel network, averaging approximately 70 and 30 nm in diameter, respectively. The nanocomposite exhibited significant antibacterial activity against S. aureus and E. coli, with inhibition rates of 98.9 ± 0.21% and 99.2 ± 0.14%, respectively, for the 3.0 mM AgNPs/CMCS-SB nanocomposite. Moreover, cytotoxicity assays showcased the efficacy of AgNPs/CMCS-SB against human colorectal cancer cells (HCT-116 cells), with the strongest cytotoxicity (61.7 ± 4.3%) at 100 μg/mL. These results suggest the synthesized AgNPs/CMCS-SB nanocomposites possess promising attributes for various biomedical applications, including antimicrobial and anticancer activities, positioning them as compelling candidates for further advancement in biomedicine.

pH-Responsive Calcium Ions and Crocetin Releasing Hydrogel for Accelerating Skin Wound Healing

The ideal and highly anticipated dressing for skin wounds should provide a moist environment, possess antibacterial properties, and ensure sustained drug release. In the present work, a hyaluronic acid-based hydrogel was formed by cross-linking crocetin and CaCO3@polyelectrolyte materials (CaCO3@PEM) microspheres with HA hydrogels via hydrogen bond and amido bonding (CaCO3@PEM@Cro@HA hydrogel, CPC@HA hydrogel). Moreover, the CPC@HA hydrogel had the capability of sustained, controlled release of calcium ions and crocetin via pH-sensitive and accelerated skin wound healing. The experiment results showed that the CPC@HA hydrogel exhibited porous network structures, stable physical properties, and had antibacterial properties and biocompatibility in vitro. In addition, the CPC@HA hydrogel covering on the skin wound could reduce inflammation and promote wound healing. The high expression of angiogenic cytokines (CD31) and epidermal terminal differentiation markers (Loricrin) of wound healing tissue suggested the CPC@HA hydrogel also had the function of promoting the remodeling of regenerated skin. Overall, CPC@HA hydrogel has promising potential for clinical applications in accelerating skin wound repair.

Assessment of hemostatic ability of biomaterial based on chitosan andEclipta prostrataL. extract

The biomaterials based on chitosan andEclipta prostrataL. extract have been prepared by microemulsion method and solution method (with and without sodium tripolyphosphate (STPP) as a cross-linking agent). The main component inEclipta prostrataL. extract is flavonoid groups. The structure of the chitosan/extract biomaterials was studied by infrared spectroscopy. The chitosan/extract biomaterial using STPP cross-linker appeared an absorption band at 1152 cm-1attributed to the vibrations of C-O-P bonds, which proved that chitosan has crosslinked with STPP. The morphology of the biomaterials was investigated by the dynamic light scattering technique and field emission scanning electron microscopy. The obtained results showed that the particle size of the chitosan/extract biomaterials prepared by microemulsion method and solution method with STPP ranged from 68.06 nm to 1484 nm, with an average particle size of 304.9-1019 nm. The microemulsion method produced biomaterials with much smaller average particle size than the solution method using cross-linkers. The hemostatic ability of the biomaterials was better than that of the control sample based on the time of blood clotting formation and glomerular aggregation ability. The sample with the ratio ofE. prostrataL. extract: chitosan of 1:30 had the lowest hemostasis time (6 min 46 s) and its glomerular aggregation rate after 5 min was 13.05%. This indicated that the biomaterials based on chitosan andE. prostrataL. extract are promising for application in biomedicine as hemostatic materials.

Polyvinyl alcohol/carboxymethyl chitosan-based hydrogels loaded with taxifolin liposomes promote diabetic wound healing by inhibiting inflammation and regulating autophagy

With the improvement of modern living standards, the challenge of diabetic wound healing has significantly impacted the public health system. In this study, our objective was to enhance the bioactivity of taxifolin (TAX) by encapsulating it in liposomes using a thin film dispersion method. Additionally, polyvinyl alcohol/carboxymethyl chitosan-based hydrogels were prepared through repeated freeze-thawing. In vitro and in vivo experiments were conducted to investigate the properties of the hydrogel and its effectiveness in promoting wound healing in diabetic mice. The results of the experiments revealed that the encapsulation efficiency of taxifolin liposomes (TL) was 89.80 ± 4.10 %, with a drug loading capacity of 17.58 ± 2.04 %. Scanning electron microscopy analysis demonstrated that the prepared hydrogels possessed a porous structure, facilitating gas exchange and the absorption of wound exudates. Furthermore, the wound repair experiments in diabetic mice showed that the TL-loaded hydrogels (TL-Gels) could expedite wound healing by suppressing the inflammatory response and promoting the expression of autophagy-related proteins. Overall, this study highlights that TL-Gels effectively reduce wound healing time by modulating the inflammatory response and autophagy-related protein expression, thus offering promising prospects for the treatment of hard-to-heal wounds induced by diabetes.

Remodelers of the vascular microenvironment: The effect of biopolymeric hydrogels on vascular diseases

Vascular disease is the leading health problem worldwide. Vascular microenvironment encompasses diverse cell types, including those within the vascular wall, blood cells, stromal cells, and immune cells. Initiation of the inflammatory state of the vascular microenvironment and changes in its mechanics can profoundly affect vascular homeostasis. Biomedical materials play a crucial role in modern medicine, hydrogels, characterized by their high-water content, have been increasingly utilized as a three-dimensional interaction network. In recent times, the remarkable progress in utilizing hydrogels and understanding vascular microenvironment have enabled the treatment of vascular diseases. In this review, we give an emphasis on the utilization of hydrogels and their advantages in the various vascular diseases including atherosclerosis, aneurysm, vascular ulcers of the lower limbs and myocardial infarction. Further, we highlight the importance and advantages of hydrogels as artificial microenvironments.

Ganoderma lucidum polysaccharide hydrogel accelerates diabetic wound healing by regulating macrophage polarization

Impaired macrophage polarization or the high levels of reactive oxygen species (ROS) produced by high glucose conditions and bacterial infection are the primary factors that make healing diabetic wounds difficult. Here, we prepared an OGLP-CMC/SA hydrogel with a double network structure that was synthesized with oxidized Ganoderma lucidum polysaccharide (OGLP), sodium alginate (SA) and carboxymethyl chitosan (CMC) as the matrix. The results showed that the OGLP-CMC/SA hydrogel had good mechanical properties, tissue adhesion, oxidation resistance and biocompatibility. Moreover, the hydrogel could effectively improve the proliferation and migration of fibroblasts, also can enhance antibacterial properties. We found that the OGLP-CMC/SA hydrogel can promote the polarization of M1 macrophages towards the M2 and decrease intracellular ROS levels, effectively reduce the inflammatory response, and promote epidermal growth, the development of skin appendages and collagen deposition in wounds, which hasten diabetic wound healing. Therefore, using this versatile biologically active new hydrogel network constructed with OGLP provides a promising therapeutic strategy for chronic diabetic wound repair.

Cowberry extract loaded chitosan hydrogel with photothermal and antioxidant properties promotes infected wound healing

Bacterial infection and oxidative stress impede clinical wound healing. Herein, the plant-derived cowberry extract (CE) was first explored as a natural photothermal agent and antioxidant to deal with bacterial infection and oxidative stress. After loading in the carboxymethyl chitosan (CMCs)/oxidized dextran (Odex) hydrogel, the photothermal effect of CE was highly enhanced by CMCs. The controlled temperature induced by CE-containing hydrogel under NIR laser irradiation could rapidly (10 min) and effectively kill Staphylococcus aureus (S. aureus, 99.3 %) and Escherichia coli (E. coli, 94.6 %). Besides, this hydrogel exhibited a fast gelation and hemostasis abilities, high stability, adhesion and ROS scavenging capabilities, as well as good injectability and biocompatibility. Above superior properties make this hydrogel to accelerate the wound healing in S. aureus-infected mice, and it is expected to be a potential clinical wound dressing.

Functional hemostatic hydrogels: design based on procoagulant principles

Uncontrolled hemorrhage results in various complications and is currently the leading cause of death in the general population. Traditional hemostatic methods have drawbacks that may lead to ineffective hemostasis and even the risk of secondary injury. Therefore, there is an urgent need for more effective hemostatic techniques. Polymeric hemostatic materials, particularly hydrogels, are ideal due to their biocompatibility, flexibility, absorption, and versatility. Functional hemostatic hydrogels can enhance hemostasis by creating physical circumstances conducive to hemostasis or by directly interfering with the physiological processes of hemostasis. The procoagulant principles include increasing the concentration of localized hemostatic substances or establishing a physical barrier at the physical level and intervention in blood cells or the coagulation cascade at the physiological level. Moreover, synergistic hemostasis can combine these functions. However, some hydrogels are ineffective in promoting hemostasis or have a limited application scope. These defects have impeded the advancement of hemostatic hydrogels. To provide inspiration and resources for new designs, this review provides an overview of the procoagulant principles of hemostatic hydrogels. We also discuss the challenges in developing effective hemostatic hydrogels and provide viewpoints.

Poly (γ) glutamic acid: a unique microbial biopolymer with diverse commercial applicability

Microbial biopolymers have emerged as promising solutions for environmental pollution-related human health issues. Poly-γ-glutamic acid (γ-PGA), a natural anionic polymeric compound, is composed of highly viscous homo-polyamide of D and L-glutamic acid units. The extracellular water solubility of PGA biopolymer facilitates its complete biodegradation and makes it safe for humans. The unique properties have enabled its applications in healthcare, pharmaceuticals, water treatment, foods, and other domains. It is applied as a thickener, taste-masking agent, stabilizer, texture modifier, moisturizer, bitterness-reducing agent, probiotics cryoprotectant, and protein crystallization agent in food industries. γ-PGA is employed as a biological adhesive, drug carrier, and non-viral vector for safe gene delivery in tissue engineering, pharmaceuticals, and medicine. It is also used as a moisturizer to improve the quality of hair care and skincare cosmetic products. In agriculture, it serves as an ideal stabilizer, environment-friendly fertilizer synergist, plant-growth promoter, metal biosorbent in soil washing, and animal feed additive to reduce body fat and enhance egg-shell strength.

Multifunctional hydrogel bioscaffolds based on polysaccharide to promote wound healing: A review

Various types of skin wounds pose challenges in terms of healing and susceptibility to infection, which can have a significant impact on physical and mental well-being, and in severe cases, may result in amputation. Conventional wound dressings often fail to provide optimal support for these wounds, thereby impeding the healing process. As a result, there has been considerable interest in the development of multifunctional polymer matrix hydrogel scaffolds for wound healing. This review offers a comprehensive review of the characteristics of polysaccharide-based hydrogel scaffolds, as well as their applications in different types of wounds. Additionally, it evaluates the advantages and disadvantages associated with various types of multifunctional polymer and polysaccharide-based hydrogel scaffolds. The objective is to provide a theoretical foundation for the utilization of multifunctional hydrogel scaffolds in promoting wound healing.

Management of non-compressible hemorrhage and re-bleeding by a liquid hemostatic polysaccharide floccuronic acid

Effective management of excessive bleeding requires liquid hemostatic agents, especially in scenarios involving uncompressible and postoperative hemorrhage. This study introduces the microbial exopolysaccharide floccuronic acid (FA) as a liquid hemostatic agent, characterized by a high weight average molecular weight of 2.38 × 108 Da. The investigation focuses on the flocculation effect, hemostatic efficiency in both in vitro and in vivo settings, elucidating its hemostatic mechanism, and assessing its safety profile. Results reveal that FA solution significantly accelerates the coagulation process, leading to the formation of compact clots while specifically interfering with fibrin. Notably, FA demonstrates excellent hemostatic effects in animal liver models and a rat arterial rebleeding model. The biocompatible and biodegradable characteristics further underscore FA's potential as a valuable liquid hemostatic material, particularly suited for non-compressible and re-bleeding scenarios.

Tissue adhesives based on chitosan for skin wound healing: Where do we stand in this era? A review

Chitosan has been commonly used as an adhesive dressing material due to its excellent biocompatibility, degradability, and renewability. Tissue adhesives are outstanding among wound dressings because they can close the wound, absorb excess tissue exudate from the wound site, provide a moist environment, and act as a carrier for loading various bioactive molecules. They have been widely used in both preclinical and clinical treatment of skin wounds. This review summarizes recent research progresses in the application of chitosan and its derivatives for tissue adhesives. We also introduce their biomedical effects on wound adhesion, contamination isolation, antibacterial, immune regulation, and wound healing, and the strategies to achieve these functions when used as wound dressings. Finally, challenges and future perspectives of chitosan-based tissue adhesives are discussed for wound healing.

Functional electrospun nanofibers: fabrication, properties, and applications in wound-healing process

Electrostatic spinning as a technique for producing nanoscale fibers has recently attracted increasing attention due to its simplicity, versatility, and loadability. Nanofibers prepared by electrostatic spinning have been widely studied, especially in biomedical applications, because of their high specific surface area, high porosity, easy size control, and easy surface functionalization. Wound healing is a highly complex and dynamic process that is a crucial step in the body's healing process to recover from tissue injury or other forms of damage. Single-component nanofibers are more or less limited in terms of structural properties and do not fully satisfy various needs of the materials. This review aims to provide an in-depth analysis of the literature on the use of electrostatically spun nanofibers to promote wound healing, to overview the infinite possibilities for researchers to tap into their biomedical applications through functional composite modification of nanofibers for advanced and multifunctional materials, and to propose directions and perspectives for future research.

Antimicrobial peptide-modified AIE visual composite wound dressing for promoting rapid healing of infected wounds

Wound infection is a major problem faced during wound healing. Therefore, it is necessary to develop wound dressings with excellent antimicrobial properties. Here, a smart response system of PVA-TPE/HA-AMP/SF/ALG wound dressing was prepared by a combination of chemical cross-linking and freeze-drying methods. We grafted AMP onto HA to endow the wound dressing with bacterial resistance and slow release of AMP. At the same time, the system detects bacterial activity in real time for precise antimicrobial activity (through the use of PVA-TPE) and modulates inflammation to reduce bacterial infection (through the use of AMP). In addition, the PVA-TPE/HA-AMP/SF/ALG wound dressing has a good three-dimensional mesh structure, which promotes cell proliferation, enhances collagen deposition and angiogenesis, and thus effectively promotes rapid healing of infected wounds. Moreover, it can induce the expression of inflammatory factors such as VEGF, TNF-α, IFN-γ, IL-4 and TGF-β1 in infected wounds through the Wnt/CAMK/p-PKC signaling pathway, inhibit inflammatory responses, promote wound healing and reduce scar formation. Therefore, the PVA-TPE/HA-AMP/SF/ALG wound dressing smart response system shows great promise in infected wound healing.

Electrospun Antimicrobial Drug Delivery Systems and Hydrogels Used for Wound Dressings

Wounds and chronic wounds can be caused by bacterial infections and lead to discomfort in patients. To solve this problem, scientists are working to create modern wound dressings with antibacterial additives, mainly because traditional materials cannot meet the general requirements for complex wounds and cannot promote wound healing. This demand is met by material engineering, through which we can create electrospun wound dressings. Electrospun wound dressings, as well as those based on hydrogels with incorporated antibacterial compounds, can meet these requirements. This manuscript reviews recent materials used as wound dressings, discussing their formation, application, and functionalization. The focus is on presenting dressings based on electrospun materials and hydrogels. In contrast, recent advancements in wound care have highlighted the potential of thermoresponsive hydrogels as dynamic and antibacterial wound dressings. These hydrogels contain adaptable polymers that offer targeted drug delivery and show promise in managing various wound types while addressing bacterial infections. In this way, the article is intended to serve as a compendium of knowledge for researchers, medical practitioners, and biomaterials engineers, providing up-to-date information on the state of the art, possibilities of innovative solutions, and potential challenges in the area of materials used in dressings.

Progress in injectable hydrogels for the treatment of incompressible bleeding: an update

Uncontrollable haemorrhage from deep, noncompressible wounds remains a persistent and intractable challenge, accounting for a very high proportion of deaths in both war and disaster situations. Recently, injectable hydrogels have been increasingly studied as potential haemostatic materials, highlighting their enormous potential for the management of noncompressible haemorrhages. In this review, we summarize haemostatic mechanisms, commonly used clinical haemostatic methods, and the research progress on injectable haemostatic hydrogels. We emphasize the current status of injectable hydrogels as haemostatic materials, including their physical and chemical properties, design strategy, haemostatic mechanisms, and application in various types of wounds. We discuss the advantages and disadvantages of injectable hydrogels as haemostatic materials, as well as the opportunities and challenges involved. Finally, we propose cutting-edge research avenues to address these challenges and opportunities, including the combination of injectable hydrogels with advanced materials and innovative strategies to increase their biocompatibility and tune their degradation profile. Surface modifications for promoting cell adhesion and proliferation, as well as the delivery of growth factors or other biologics for optimal wound healing, are also suggested. We believe that this paper will inform researchers about the current status of the use of injectable haemostatic hydrogels for noncompressible haemorrhage and spark new ideas for those striving to propel this field forward.

A pH-responsive, injectable and self-healing chitosan-coumarin hydrogel based on Schiff base and hydrogen bonds

Smart hydrogels have shown great potential applications in disease treatment due to their controlled and local drug-release ability. Herein, a smart hydrogel with pH-responsive, injectable, and self-healing properties for controlled release of taxifolin (TFL) was prepared by freezing-thawing and photo-crosslinking methods. The crosslinking network of hydrogels (CS-CA hydrogels) was constructed by the hydrogen bonds, Schiff base bonds, and cyclobutane rings using chitosan (CS) and coumarin (CA) as raw materials. The CS-CA hydrogel demonstrated a compressive strength of 1.04 MPa, a self-healing efficiency of 99.9 %, and could maintain structural and functional integrity after injection. In addition, the drug release rate and shape of the CS-CA hydrogels were tunable due to its pH sensitivity. The TFL cumulative release reached 60 % within 12 h at pH = 4, and after equilibration, the cumulative release of TFL at pH = 4 (80 %) was significantly higher than at pH = 9.2 (50 %). The CCK8 experiment showed that the resulting hydrogel had no cytotoxicity. Meanwhile, subcutaneous implantation experiments in mice showed that the CS-CA hydrogels had favorable biodegradability and compatibility.

Review on chitosan-based antibacterial hydrogels: Preparation, mechanisms, and applications

Chitosan (CS) is known for its remarkable properties, such as good biocompatibility, biodegradability, and renewability, in addition to its antibacterial and biological activities. However, as CS is insoluble in water, it displays limited antibacterial performance under neutral and physiological conditions. A viable solution to this problem is grafting chemically modified groups onto the CS framework, thereby increasing its solubility and enhancing its antibacterial effect. Herein, the antibacterial action mechanism of CS and its derivatives is reviewed, confirming the prevalent use of composite materials comprising CS and its derivatives as an antibacterial agent. Generally, the antimicrobial ability of CS-based biomaterials can be enhanced by incorporating supplementary polymers and antimicrobial agents. Research on CS-based composite biomaterials is ongoing and numerous types of biomaterials have been reported, including inorganic nanoparticles, antibacterial agents, and CS derivatives. The development of these composite materials has considerably expanded the application of CS-based antibacterial materials. This study reviews the latest progress in research regarding CS-based composite hydrogels for wound repair, tissue engineering, drug release, water purification, and three-dimensional printing applications. Finally, the summary and future outlook of CS-based antibacterial hydrogels are presented in anticipation of a broader range of applications of CS-based antibacterial hydrogels.

Mild hyperthermia-assisted chitosan hydrogel with photothermal antibacterial property and CAT-like activity for infected wound healing

Infected wounds pose a serious threat to public health and pose a significant challenge and financial burden worldwide. The treatment of infected wounds is now an urgent problem to be solved. Herein, mild hyperthermia-assisted hydrogels composed of carboxymethyl chitosan (CMCs), oxidized dextran (Odex), epigallocatechin gallate (EGCG) and PtNPs@PVP (CAT-like nanoenzymes) were proposed for the repair of infected wounds. The incorporation of PtNPs@PVP nanoenzymes give the hydrogels excellent photothermal property and CAT-like activity. When the temperature is maintained at 42-45 °C under 808 nm near infrared (NIR) exposure, the CMCs/Odex/EGCG/Nanoenzymes (COEN2) hydrogel demonstrated highly enhanced antibacterial ability (95.9 % in vivo), hydrogen peroxide (H2O2) scavenging ratio (85.1 % in vitro) and oxygen supply (20.7 mg/L in vitro). Furthermore, this mild-heat stimulation also promoted angiogenesis in the damaged skin area. Overall, this multifunctional hydrogel with antibacterial, antioxidant, oxygen supply, hemostasis, and angiogenesis capabilities has shown great promise in the repair of infected wounds. This study establishes the paradigm of enhanced infected wound healing by mild hyperthermia-assisted H2O2 scavenging, oxygen supplemental, and photothermal antibacterial hydrogels.

Bletilla Striata polysaccharides thermosensitive gel for photothermal treatment of bacterial infection

Skin is the most important defense shield which touched external environment directly. Effectively clearing microbes in infected wound via non-antibiotic therapy is crucial for the promotion of recovery in complex biological environments, and the wound healing is a crucial process after sterilization to avoid superinfection. Herein, a kind of Prussian blue-based photothermal responsive gel, Bletilla striata polysaccharide-mingled, isatin-functionalized Prussian blue gel (PB-ISA/BSP gel) was reported for effective treatment of bacterial infection and wound healing. The introduction of effective components of traditional Chinese medicine (TCM), isatin (ISA), enhanced the efficiency of sterilization synergistically. Furthermore, the process of wound healing was promoted by Bletilla striata polysaccharides (BSP). PB-ISA@BSP had a considerable antibacterial rate with 98.5 % under an 808 nm laser for 10 min in vitro. Besides, PB-ISA/BSP gel showed an effective antibacterial efficacy in vivo and a fast wound healing rate as well. The as-prepared functional particles can invade and destroy bacteria membrane to kill microbes. This work highlights that PB-ISA/BSP gel is a promising antibacterial agent based on synergistically enhanced photothermal effect and wound healing promotion ability and provides inspiration for future therapy based on the synergy between photothermal agent and active components in TCM.

Advances in chitosan-based hydrogels for pharmaceutical and biomedical applications: A comprehensive review

The treatment of diseases, such as cancer, is one of the most significant issues correlated with human beings health. Hydrogels (HGs) prepared from biocompatible and biodegradable materials, especially biopolymers, have been effectively employed for the sort of pharmaceutical and biomedical applications, including drug delivery systems, biosensors, and tissue engineering. Chitosan (CS), one of the most abundant bio-polysaccharide derived from chitin, is an efficient biomaterial in the prognosis, diagnosis, and treatment of diseases. CS-based HGs possess some potential advantages, like high values of bioactive encapsulation, efficient drug delivery to a target site, sustained drug release, good biocompatibility and biodegradability, high serum stability, non-immunogenicity, etc., which made them practical and useful for pharmaceutical and biomedical applications. In this review, we summarize recent achievements and advances associated with CS-based HGs for drug delivery, regenerative medicine, disease detection and therapy.

Preparation of Multi-Functional Quaternary Ammonium Chitosan/Surfactin Hydrogel and its Application in Wound Management

Hydrogel with a 3D network structure can cover the wound to stop the bleeding and support the host tissue infiltration and integration. In this study, an antibacterial hydrogel with hemostasis and the ability to promote wound healing is proposed. This hydrogel comprised surfactin, polyvinylpyrrolidone, and methacrylic anhydride (MA) grafted quaternary ammonium chitosan (CS-MA). The hydrogel formation is triggered by the ultraviolet-initiated polymerization of CS-MA, while the surfactin is complexed with the hydrogel through hydrogen bonding interaction. The results showed that this hydrogel is an adhesive hydrogel with shape adaptability, which can cover the wound surface and promote contact between the hydrogel and the wound surface. More importantly, this hydrogel can simulate the microenvironment of the primary extracellular matrix and increase collagen deposition, and inflammatory factor transformation. The designing of such a multi-functional hydrogel is expected to provide a novel approach to promoting the healing of wounds.

Effect of drainage versus no drainage after thyroid surgery on wound complications, a meta-analysis

A meta-analysis study was used to assess whether not placing a drain after thyroidectomy reduces postoperative wound complications. A critical review of the comprehensive literature up to May 2023 was conducted using four databases: PubMed, Embase, the Cochrane Library, and the web of science. Fourteen interrelated studies were reviewed after passing the inclusion and exclusion criteria established by the study and assessing the quality of the literature.95% confidence intervals (Cl) and odds ratios (OR) were calculated using fixed effects models. The data were meta-analysed using RevMan 5.3 software. The results showed that the use of drains during thyroid surgery did not have a favourable impact on patients. Intraoperative placement of drains did not reduce postoperative wound haematoma formation in patients, (OR, 0.86; 95% CI, 0.54, 1.36 p = 0.52). However, the incidence of postoperative wound infection was significantly higher in patients with drains used in intraoperative thyroid surgery, (OR, 0.22; 95% CI, 0.10, 0.45 p < 0.0001). As the sample size of the randomised controlled study used for this meta-analysis was limited, it is important to approach the findings with caution when interpreting the results.Conducting additional high-quality research with larger sample sizes is crucial in order to further confirm these results and reduce the likelihood of duplication.

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.

Injectable hydrogel for sustained delivery of progranulin derivative Atsttrin in treating diabetic fracture healing

Hydrogels with long-term storage stability, controllable sustained-release properties, and biocompatibility have been garnering attention as carriers for drug/growth factor delivery in tissue engineering applications. Chitosan (CS)/Graphene Oxide (GO)/Hydroxyethyl cellulose (HEC)/β-glycerol phosphate (β-GP) hydrogel is capable of forming a 3D gel network at physiological temperature (37 °C), rendering it an excellent candidate for use as an injectable biomaterial. This work focused on an injectable thermo-responsive CS/GO/HEC/β-GP hydrogel, which was designed to deliver Atsttrin, an engineered derivative of a known chondrogenic and anti-inflammatory growth factor-like molecule progranulin. The combination of the CS/GO/HEC/β-GP hydrogel and Atsttrin provides a unique biochemical and biomechanical environment to enhance fracture healing. CS/GO/HEC/β-GP hydrogels with increased amounts of GO exhibited rapid sol-gel transition, higher viscosity, and sustained release of Atsttrin. In addition, these hydrogels exhibited a porous interconnected structure. The combination of Atsttrin and hydrogel successfully promoted chondrogenesis and osteogenesis of bone marrow mesenchymal stem cells (bmMSCs) in vitro. Furthermore, the work also presented in vivo evidence that injection of Atsttrin-loaded CS/GO/HEC/β-GP hydrogel stimulated diabetic fracture healing by simultaneously inhibiting inflammatory and stimulating cartilage regeneration and endochondral bone formation signaling pathways. Collectively, the developed injectable thermo-responsive CS/GO/HEC/βG-P hydrogel yielded to be minimally invasive, as well as capable of prolonged and sustained delivery of Atsttrin, for therapeutic application in impaired fracture healing, particularly diabetic fracture healing.

Advances in preparation and application of antibacterial hydrogels

Bacterial infections, especially those caused by drug-resistant bacteria, have seriously threatened human life and health. There is urgent to develop new antibacterial agents to reduce the problem of antibiotics. Biomedical materials with good antimicrobial properties have been widely used in antibacterial applications. Among them, hydrogels have become the focus of research in the field of biomedical materials due to their unique three-dimensional network structure, high hydrophilicity, and good biocompatibility. In this review, the latest research progresses about hydrogels in recent years were summarized, mainly including the preparation methods of hydrogels and their antibacterial applications. According to their different antibacterial mechanisms, several representative antibacterial hydrogels were introduced, such as antibiotics loaded hydrogels, antibiotic-free hydrogels including metal-based hydrogels, antibacterial peptide and antibacterial polymers, stimuli-responsive smart hydrogels, and light-mediated hydrogels. In addition, we also discussed the applications and challenges of antibacterial hydrogels in biomedicine, which are expected to provide new directions and ideas for the application of hydrogels in clinical antibacterial therapy.

In situ forming alginate/gelatin hybrid hydrogels containing doxorubicin loaded chitosan/AuNPs nanogels for the local therapy of breast cancer

In this study, pH-sensitive in situ gelling hydrogels based on oxidized alginate and gelatin-containing doxorubicin (DOX) loaded chitosan/gold nanoparticles (CS/AuNPs) nanogels were fabricated via Schiff-base bond formation. The obtained CS/AuNPs nanogels indicated a size distribution of about 209 nm with a zeta potential of +19.2 mV and an encapsulation efficiency of around 72.6 % for DOX. The study of the rheological properties of hydrogels showed that the value of G' is higher than G″ for all hydrogels, which confirms the elastic behavior of hydrogels in the applied frequency range. The rheological and texture analysis demonstrated the higher mechanical properties of hydrogels containing β-GP and CS/AuNPs nanogels. The release profile of DOX after 48 h indicates the 99 % and 73 % release amount at pH = 5.8 and pH = 7.4, respectively. MTT cytotoxicity study showed that the prepared hydrogels are cytocompatible on MCF-7 cells. By the Live/Dead assay, it was demonstrated that the cultured cells on DOX-free hydrogels were almost alive in the presence of CS/AuNPs nanogels. However, the hydrogel-containing drug and free DOX in the same concentration caused high death of MCF-7 cells as expected, which showed the potential of the developed hydrogels for application in the local treatment of breast cancer.

A Double Cross-Linked Injectable Hydrogel Derived from Muscular Decellularized Matrix Promotes Myoblast Proliferation and Myogenic Differentiation

Injectable hydrogels possess tremendous merits for use in muscle regeneration; however, they still lack intrinsic biological cues (such as the proliferation and differentiation of myogenic cells), thus considerably restricting their potential for therapeutic use. Herein, we developed a double cross-linked injectable hydrogel composed of methacrylamidated oxidized hyaluronic acid (MOHA) and muscular decellularized matrix (MDM). The chemical composition of the hydrogel was confirmed using 1H NMR and Fourier transform infrared spectroscopy. To achieve cross-linking, the aldehyde groups in MOHA were initially reacted with the amino groups in MDM through a Schiff-based reaction. This relatively weak cross-linking provided the MOHA/MDM hydrogel with satisfactory injectability. Furthermore, the methacrylation of MOHA facilitated a second cross-linking mechanism via UV irradiation, resulting in improved gelation ability, biomechanical properties, and swelling performance. When C2C12 myogenic cells were loaded into the hydrogel, our results showed that the addition of MDM significantly enhanced myoblast proliferation compared to the MOHA hydrogel, as demonstrated by live/dead staining and Cell Counting Kit-8 assay after seven days of in vitro cultivation. In addition, gene expression analysis using quantitative polymerase chain reaction indicated that the MOHA/MDM hydrogel promoted myogenic differentiation of C2C12 cells more effectively than the MOHA hydrogel, as evidenced by elevated expression levels of myogenin, troponin T, and MHC in the MOHA/MDM hydrogel group. Moreover, after four to eight weeks of implantation in a full-thickness abdominal wall-defect model, the MOHA/MDM hydrogel could promote the reconstruction and repair of functional skeletal muscle tissue with enhanced tetanic force and tensile strength. This study provides a new double cross-linked injectable hydrogel for use in muscular tissue engineering.

Fumaria officinalis-loaded chitosan nanoparticles dispersed in an alginate hydrogel promote diabetic wounds healing by upregulating VEGF, TGF-β, and b-FGF genes: A preclinical investigation

Diabetic wounds may become chronic if left untreated. In the current study, a potential wound dressing was developed by incorporating fumaria officinalis extract-loaded chitosan nanoparticles (FOE-CHNPs) into calcium alginate hydrogel. The produced hydrogel was evaluated regarding its microarchitecture, cytotoxicity, cell migration activity, cytoprotective potential, porosity, in vitro anti-inflammatory activity, and drug release profile. Then, the healing function of FOE-CHNPs/calcium alginate hydrogel was compared with a marketed wound care product in a rat model of diabetic wound. In vitro study showed that the hydrogel system promoted skin cells viability and migration. In vivo wound healing assay showed that the animals treated with the FOE-CHNPs/calcium alginate hydrogel had comparable wound healing potential with the GranuGEL® as the marketed wound care hydrogel. Gene expression studies showed that FOE-CHNPs/calcium alginate hydrogel upregulated the tissue expression levels of collagen type 1, collagen type 2, VEGF, b-FGF and TGF-B genes. This preclinical research, suggests potential use of FOE-loaded calcium alginate hydrogel system in treating diabetic wounds in the clinic.

Polysaccharide-Based Hydrogel from Seeds of Artemisia vulgaris: Extraction Optimization by Box-Behnken Design, pH-Responsiveness, and Sustained Drug Release

The current research work focuses on the extraction and optimization of the hydrogel (AVM) from the seeds of Artemisia vulgaris using Box-Behnken design-response surface methodology (BBD-RSM). The AVM was obtained through a hot water extraction process. The influence of different factors, including pH (U = 4 to 10), temperature (V = 25 to 110 °C), seed/water ratio, i.e., S/W ratio (W = 1/10 to 1/70 w/v), and seed/water contact time, i.e., S/W time (X = 1 to 12 h) on the yield of AVM was evaluated. The p-value for the analysis of variance (ANOVA) was found to be <0.001, indicating that the yield of AVM mainly depended on the abovementioned factors. The highest yield of AVM, i.e., 15.86%, was found at a pH of 7.12, temperature of 80.04 °C, S/W ratio of 1/33.24 w/v, and S/W time of 8.73 h according to Design-Expert Software. The study of the pH-responsive behavior of AVM in tablet form (formulation AVT3) revealed that AVM is a pH-responsive material with significantly high swelling at pH 7.4. However, less swelling was witnessed at pH 1.2. Moreover, AVM was found to be a sustained release material for esomeprazole at pH 7.4 for 12 h. The drug release from AVT3 was according to the super case-II transport mechanism and zero-order kinetics.

Natural biomarocmolecule-based antimicrobial hydrogel for rapid wound healing: A review

Antibacterial hydrogels are a type of hydrogel that is designed to inhibit the growth of bacteria and prevent infections. These hydrogels typically contain antibacterial agents that are either integrated into the polymer network or coated onto the surface of the hydrogel. The antibacterial agents in these hydrogels can work through a variety of mechanisms, such as disrupting bacterial cell walls or inhibiting bacterial enzyme activity. Some examples of antibacterial agents that are commonly used in hydrogels include silver nanoparticles, chitosan, and quaternary ammonium compounds. Antibacterial hydrogels have a wide range of applications, including wound dressings, catheters, and medical implants. They can help to prevent infections, reduce inflammation, and promote tissue healing. In addition, they can be designed with specific properties to suit different applications, such as high mechanical strength or controlled release of antibacterial agents over time. Hydrogel wound dressings have come a long way in recent years, and the future looks very promising for these innovative wound care products. Overall, the future of hydrogel wound dressings is very promising, and we can expect to see continued innovation and advancement in this field in the years to come.

Lignin-Cobalt Nano-Enabled Poly(pseudo)rotaxane Supramolecular Hydrogel for Treating Chronic Wounds

Chronic wounds (CWs) are a growing issue for the health care system. Their treatment requires a synergic approach to reduce both inflammation and the bacterial burden. In this work, a promising system for treating CWs was developed, comprising cobalt-lignin nanoparticles (NPs) embedded in a supramolecular (SM) hydrogel. First, NPs were obtained through cobalt reduction with phenolated lignin, and their antibacterial properties were tested against both Gram-negative and Gram-positive strains. The anti-inflammatory capacity of the NPs was proven through their ability to inhibit myeloperoxidase (MPO) and matrix metalloproteases (MMPs), which are enzymes involved in the inflammatory process and wound chronicity. Then, the NPs were loaded in an SM hydrogel based on a blend of α-cyclodextrin and custom-made poly(ether urethane)s. The nano-enabled hydrogel showed injectability, self-healing properties, and linear release of the loaded cargo. Moreover, the SM hydrogel's characteristics were optimized to absorb proteins when in contact with liquid, suggesting its capacity to uptake harmful enzymes from the wound exudate. These results render the developed multifunctional SM material an interesting candidate for the management of CWs.

Safety and Performance of Hemostatic Powders

Background

Hemorrhage, a sudden and severe leakage of blood due to the disruption of blood vessels, is one of the most common causes of death from injuries worldwide. Severe bleeding accounts for more than 35% of pre-hospital deaths and about 40% of deaths recorded within 24 hours of injury. One of the methods for achieving homeostasis is the use of hemostatic powders. This study compares the basic safety and performance of the most popular hemostatic powders.

Methods

Basic safety of commercially available products were evaluated using MTT, MEM elution assay, and endotoxin testing. The in vitro performance was evaluated using water absorption capacity, water absorption rate, and adhesion strength assays.

Results

4Seal, Starsil, and 4DryField extracts did not cause cytotoxicity in MTT and MEM elution assays. PerClot and SuperClot extracts demonstrated cytotoxic potential in MTT assay, while Arista extract was cytotoxic in both MEM elution and MTT assays. 4Seal has the lowest endotoxin contamination, followed by PerClot, 4DryField, SuperClot, Arista, and Starsil. 4Seal and Starsil showed significantly highest WAR among the tested samples, followed by 4DryField, Arista, PerClot, and SuperClot. Adhesion force is highest for 4Seal, followed by Starsil, PerClot, 4DryField Arista, and SuperClot.

Conclusion

4Seal is the most versatile in terms of safety and functional properties compared to 4DryField, Arista, PerClot, Starsil, and SuperClot.

Pullulan/Poly(vinyl alcohol) Hydrogels Loaded with Calendula officinalis Extract: Design and In Vitro Evaluation for Wound Healing Applications

The therapeutic efficiency of plant extracts has been limited by their poor pharmaceutical availability. Hydrogels have promising potential to be applied as wound dressings due to their high capacity to absorb exudates and their enhanced performance in loading and releasing plant extracts. In this work, pullulan/poly (vinyl alcohol) (P/PVA) hydrogels were first prepared using an eco-friendly method based on both a covalent and physical cross-linking approach. Then, the hydrogels were loaded with the hydroalcoholic extract of Calendula officinalis by a simple post-loading immersion method. Different loading capacities were investigated in terms of the physico-chemical properties, chemical composition, mechanical properties, and water absorption. The hydrogels exhibited high loading efficiency due to the hydrogen bonding interactions between polymer and extract. The water retention capacity as well as the mechanical properties decreased with the increase in the extract amount in hydrogel. However, higher amounts of extract in the hydrogel improved the bioadhesiveness. The release of extract from hydrogels was controlled by the Fickian diffusion mechanism. Extract-loaded hydrogels expressed high antioxidant activity, reaching 70% DPPH radical scavenging after 15 min immersion in buffer solution at pH 5.5. Additionally, loaded hydrogels showed a high antibacterial activity against Gram-positive and Gram-negative bacteria and were non-cytotoxic against HDFa cells.

Efficacy of Flowable Collagen Hemostat Evaluated in Preclinical Models of Liver Injury and Spinal Cord Exposure

Introduction

Excessive bleeding in trauma and surgical settings leads to increased operative time, reoperation rates, and overall healthcare costs. A wide range of hemostatic agents have been developed to control bleeding that can vary considerably in type of hemostatic action, ease of application, cost, risk of infection, and dependence on patient coagulation. Microfibrillar collagen-based hemostatic materials (MCH) have yielded beneficial results in a variety of applications.

Methods

A new flowable collagen product, containing a modified MCH flour, but in a more convenient flowable delivery system, was evaluated for hemostatic efficacy in preclinical models of solid organ injury and spinal cord exposure. The primary objective of this study was to compare the hemostatic potential and local tissue responses to this novel, flowable collagen-based hemostatic agent to the original flour formulation to confirm that the new method of delivery did not interfere with the hemostatic properties of the MCH flour.

Results

When observed visually, the flowable MCH flour mixed with saline (FL) provided more precise application and uniform coverage to injured tissues compared to the dry MCH flour alone (F₀). All of the treatments (FL, F₀, and gauze) exhibited comparable Lewis bleed grade at all three time points evaluated in the capsular resection liver injury model (bleed grade: 1.0-1.3; p> 0.05 in all cases). FL and F₀ exhibited comparable 100% acute hemostatic efficacy and similar long-term histomorphological properties (up to 120 days) in a capsular resection liver injury in pigs, while gauze resulted in significantly lower rates of acute hemostatic efficacy (8-42%, p<0.05 in all cases). In an ovine model of dorsal laminectomy and durotomy, FL and F₀ again exhibited comparable results without any neurological effects.

Conclusion

Flowable microfibrillar collagen was shown to yield favorable short- and long-term outcomes in two representative applications where hemostatic efficacy is critical to surgical success.

Preparation of Biocompatible Manganese Selenium-Based Nanoparticles with Antioxidant and Catalytic Functions

The specificity of the tumor microenvironment (TME) severely limits the effectiveness of tumor treatment. In this study, we prepared a composite nanoparticle of manganese dioxide and selenite by a one-step redox method, and their stability under physiological conditions was improved with a bovine serum protein modification to obtain MnO₂/Se-BSA nanoparticles (SMB NPs). In the SMB NPs, manganese dioxide and selenite endowed the SMB NPs with acid-responsive and catalytic, and antioxidant properties, respectively. The weak acid response, catalytic activity, and antioxidant properties of composite nanoparticles were verified experimentally. Moreover, in an in vitro hemolysis assay, different concentrations of nanoparticles were incubated with mouse erythrocytes, and the hemolysis ratio was less than 5%. In the cell safety assay, the cell survival ratio was as high as 95.97% after the co-culture with L929 cells at different concentrations for 24 h. In addition, the good biosafety of composite nanoparticles was verified at the animal level. Thus, this study helps to design high-performance and comprehensive therapeutic reagents that are responsive to the hypoxia, weak acidity, hydrogen peroxide overexpression nature of TME and overcome the limitations of TME.

Preparation and Characterization of Biocompatible Iron/Zirconium/Polydopamine/Carboxymethyl Chitosan Hydrogel with Fenton Catalytic Properties and Photothermal Efficacy

In recent years, multifunctional hydrogel nanoplatforms for the synergistic treatment of tumors have received a great deal of attention. Here, we prepared an iron/zirconium/polydopamine/carboxymethyl chitosan hydrogel with Fenton and photothermal effects, promising for future use in the field of synergistic therapy and prevention of tumor recurrence. The iron (Fe)-zirconium (Zr)@ polydopamine (PDA) nanoparticles were synthesized by a simple one-pot hydrothermal method using iron (III) chloride hexahydrate (FeCl₃•6H₂O), zirconium tetrachloride (ZrCl₄), and dopamine, followed by activation of the carboxyl group of carboxymethyl chitosan (CMCS) using 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC)/N(4)-hydroxycytidine (NHS). Finally, the Fe-Zr@PDA nanoparticles and the activated CMCS were mixed to form a hydrogel. On the one side, Fe ions can use hydrogen peroxide (H₂O₂) which is rich in the tumor microenvironment (TME) to produce toxic hydroxyl radicals (•OH) and kill tumor cells, and Zr can also enhance the Fenton effect; on the other side, the excellent photothermal conversion efficiency of the incorporated PDA is used to kill tumor cells under the irradiation of near-infrared light. The ability of Fe-Zr@PDA@CMCS hydrogel to produce •OH and the ability of photothermal conversion were verified in vitro, and swelling and degradation experiments confirmed the effective release and good degradation of this hydrogel in an acidic environment. The multifunctional hydrogel is biologically safe at both cellular and animal levels. Therefore, this hydrogel has a wide range of applications in the synergistic treatment of tumors and the prevention of recurrence.

An injectable hydrogel based on Bi2Se3 nanosheets and hyaluronic acid for chemo-photothermal synergistic therapy

To resolve poor accumulation caused by systemic administration, injectable and responsive hydrogels are the prospective drug delivery systems for localized tumor treatment, owning to negligible invasiveness and accurate administration. Herein, an injectable hydrogel, based on dopamine (DA) crosslinked hyaluronic acid and Bi₂Se₃ nanosheets (NSs) loading with doxorubicin (DOX) coated with polydopamine (Bi₂Se₃-DOX@PDA), was developed for synergistic chem-photothermal cancer therapy. The ultrathin functional Bi₂Se₃-DOX@PDA NSs could be responsive to the weak acidic condition and photothermal effect under NIR laser irradiation, achieving controlled release of DOX. Moreover, nanocomposite hydrogel based on hyaluronic acid matrix could be precisely administrated through intratumoral injection since its injectability and self-healing capacity, remaining at injected sites for at least 12 days. Furthermore, the excellent therapeutics effect of Bi₂Se₃-DOX@PDA nanocomposite hydrogel was demonstrated on 4 T1 xenograft tumor with outstanding injectability and negligible systemic side-effect. In short, the construction of Bi₂Se₃-DOX@PDA nanocomposite hydrogel paves a prospective path for local treatment of cancers.

Regenerated silk fibroin based on small aperture scaffolds and marginal sealing hydrogel for osteochondral defect repair

BACKGROUND

Osteochondral defects pose an enormous challenge without satisfactory repair strategy to date. In particular, the lateral integration of neo-cartilage into the surrounding native cartilage is a difficult and inadequately addressed problem determining tissue repair's success.

METHODS

Regenerated silk fibroin (RSF) based on small aperture scaffolds was prepared with n-butanol innovatively. Then, the rabbit knee chondrocytes and bone mesenchymal stem cells (BMSCs) were cultured on RSF scaffolds, and after induction of chondrogenic differentiation, cell-scaffold complexes strengthened by a 14 wt% RSF solution were prepared for in vivo experiments.

RESULTS

A porous scaffold and an RSF sealant exhibiting biocompatibility and excellent adhesive properties are developed and confirmed to promote chondrocyte migration and differentiation. Thus, osteochondral repair and superior horizontal integration are achieved in vivo with this composite.

CONCLUSIONS

Overall, the new approach of marginal sealing around the RSF scaffolds exhibits preeminent repair results, confirming the ability of this novel graft to facilitate simultaneous regeneration of cartilage-subchondral bone.

Chitosan and chito-oligosaccharide: a versatile biopolymer with endless grafting possibilities for multifarious applications

Chito-oligosaccharides (COS), derived from chitosan (CH), are attracting increasing attention as drug delivery carriers due to their biocompatibility, biodegradability, and mucoadhesive properties. Grafting, the process of chemically modifying CH/COS by adding side chains, has been used to improve their drug delivery performance by enhancing their stability, targeted delivery, and controlled release. In this review, we aim to provide an in-depth study on the recent advances in the grafting of CH/COS for multifarious applications. Moreover, the various strategies and techniques used for grafting, including chemical modification, enzymatic modification, and physical modification, are elaborated. The properties of grafted CH/COS, such as stability, solubility, and biocompatibility, were reported. Additionally, the review detailed the various applications of grafted CH/COS in drug delivery, including the delivery of small drug molecule, proteins, and RNA interference therapeutics. Furthermore, the effectiveness of grafted CH/COS in improving the pharmacokinetics and pharmacodynamics of drugs was included. Finally, the challenges and limitations associated with the use of grafted CH/COS for drug delivery and outline directions for future research are addressed. The insights provided in this review will be valuable for researchers and drug development professionals interested in the application of grafted CH/COS for multifarious applications.

Optimization of sodium alginate-galactoxyloglucan blended hydrogel beads through ionotropic gelation method

Hydrogels are 3D crosslinking networks of hydrophilic biopolymers which can able to absorb and retain large amount of water. In this present study, the Sodium alginate (SA)- Galactoxyloglucan (GXG) blended hydrogel beads were prepared and optimized through two level optimization steps. Alginates and xyloglucan are the cell wall polysaccharides biopolymers obtained from the plant sources, Sargassum sp. and Tamarindus indica L. respectively. The extracted biopolymers were confirmed and characterized by UV-Spectroscopy, FT-IR, NMR and TGA analysis. Based on the hydrophilicity, non-toxicity and biocompatibility, SA-GXG hydrogel were prepared and optimized through two-level optimization steps. The optimized hydrogel bead formulation was characterized through FT-IR, TGA and SEM analysis. From the obtained result, it is found that the polymeric formulation GXG (2 % w/v)-SA (1.5 % w/v), cross-linker (CaCl₂) concentration at 0.1 M and the cross-linking time at 15 Min showed significant swelling index. The optimized hydrogel beads are porous and show good swelling capacity and thermal stability. The optimized protocol of hydrogel beads may be useful in designing hydrogel beads for specific applications in agricultural, Biomedical and remediation sectors.

Design and characterization of adipose-derived mesenchymal stem cell loaded alginate/pullulan/hyaluronic acid hydrogel scaffold for wound healing applications

Recently, significant attention has been focused on the progression of skin equivalents to facilitate faster wound healing and thereby skin restoration. The main aim of this study was the design and characterization of a novel polysaccharide-based hydrogel scaffold by using alginate, pullulan, and hyaluronic acid polymers to provide an appropriate microenvironment to deliver Adipose-derived mesenchymal Stem Cells (ASC) in order to promote wound healing in an animal model. Characterization of synthesized hydrogel was done by using a field emission scanning electron microscope (FE-SEM), Fourier Transform-Infrared spectroscopy (FT-IR), and Differential Scanning Calorimetry (DSC). Also, contact angle analysis, the swelling and mechanical tests were performed. As a result of in vitro studies, cells can be attached, alive, and migrate through the prepared hydrogel scaffold. Finally, the therapeutic effect of the cell-seeded hydrogels was tested in the full-thickness animal wound model. Based on obtained results, the hydrogel-ASC treatment improved the healing process and accelerated wound closure.

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.