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

Effect of sodium alginate block type on the physicochemical properties and curcumin release behavior of quaternized chitosan-oxidized sodium alginate Schiff base hydrogels

Controlling bioactive ingredients release by modulating the 3D network structure of cross-linked hydrogels is important for functional food development. Hereby, oxidized sodium alginate (OSA) with varying aldehyde contents was formed by periodate oxidation of sodium alginate (SA) with different β-d-mannuronic acid (M) and α-l-guluronic acid (G) ratios (M/G = 1:2, 1:1, and 2:1) and its structure was characterized. Moreover, hydrogels were prepared via Schiff base and electrostatic interactions between quaternized chitosan (QCS) and OSA. The properties of hydrogels such as microstructure, thermal stability, swelling and controlled release were investigated. The results showed that OSA with M/G = 1:2 had the highest content of aldehyde groups, and the hydrogel formed by it and QCS had higher thermal stability and a denser network structure with the lowest equilibrium swelling rate, which could better control the release of curcumin. Additionally, it had good self-healing and can recover rapidly after the rupture of its network structure.

Multifunctional polypeptide-based hydrogel bio-adhesives with pro-healing activities and their working principles

Wound healing is a complex physiological process involving hemostasis, inflammation, proliferation, and tissue remodeling. Therefore, there is an urgent need for suitable wound dressings for effective and systematical wound management. Polypeptide-based hydrogel bio-adhesives offer unique advantages and are ideal candidates. However, comprehensive reviews on polypeptide-based hydrogel bio-adhesives for wound healing are still lacking. In this review, the physiological mechanisms and evaluation parameters of wound healing were first described in detail. Then, the working principles of hydrogel bio-adhesives were summarized. Recent advances made in multifunctional polypeptide-based hydrogel bio-adhesives involving gelatin, silk fibroin, fibrin, keratin, poly-γ-glutamic acid, ɛ-poly-lysine, serum albumin, and elastin with pro-healing activities in wound healing and tissue repair were reviewed. Finally, the current status, challenges, developments, and future trends of polypeptide-based hydrogel bio-adhesives were discussed, hoping that further developments would be stimulated to meet the growing needs of their clinical applications.

AgNPs loaded adenine-modified chitosan composite POSS-PEG hybrid hydrogel with enhanced antibacterial and cell proliferation properties for promotion of infected wound healing

Wound healing is a dynamic and complex process, it's urgent to develop new wound dressings with excellent performance to promote wound healing at the different stages. Here, a novel composite hydrogel dressing composed by silver nanoparticles (AgNPs) impregnated adenine-modified chitosan (CS-A) and octafunctionalized polyhedral oligomeric silsesquioxane (POSS) of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) solution was presented to solve the problem of wound infection. Modification of chitosan with adenine, not only can improve the water solubility of chitosan, but also introduce bioactive substances to promote cell proliferation. CS-A and POSS-PEG-CHO were cross-linked by Schiff-base reaction to form the injectable self-healing hydrogel. On this basis, AgNPs were added into the hydrogel, which endows the hydrogel with better antibacterial activity. Moreover, this kind of hydrogel exhibits excellent cell proliferation properties. Studies demonstrated that the hydrogel can significantly accelerate the closure of infected wounds. The histological analysis and immunofluorescence staining demonstrated that the wounds treated with the composite hydrogel exhibited fewer inflammatory cells, more collagen deposition and angiogenesis, faster regeneration of epithelial tissue. Above all, adenine-modified chitosan composite hydrogel with AgNPs loaded was considered as a dressing material with great application potential for promoting the healing of infected wounds.

Sulfated glyco-based hydrogels as self-healing, adhesive, and anti-inflammatory dressings for wound healing

Hydrogels have emerged as a new type of wound dressing materials that involved in different stages of the healing processes. However, most of the existing wound dressings mainly offer a protective and moisturizing layer to prevent cross-infection, while the anti-inflammatory and anti-oxidative properties are frequently induced by extra addition of other bioactive molecules. Here, a novel type of sulfated glyco-functionalized hydrogels for wound dressing was prepared through the hybrid supramolecular co-assembly of carbohydrate segments (FG, FGS and FG3S), fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF), and diphenylalanine-dopamine (FFD). Implanting sulfated carbohydrates can mimic the structure of glycosaminoglycans (GAGs), promoting cell proliferation and migration, along with anti-inflammatory effects. In situ polymerization of FFD introduced a secondary covalent network to the hydrogel, meanwhile, providing anti-oxidation and adhesion properties to wound surfaces. Furthermore, the dynamic supramolecular interactions within the hydrogels also confer self-healing capabilities to the wound dressing materials. In vivo experiments further demonstrated significantly accelerated healing rates with the multifunctional hydrogel FG3S-FFD, indicating high application potential.

Chitosan-based hydrogels: From preparation to applications, a review

Chitosan, derived from the deacetylation of chitin, is an abundant natural biopolymer on earth. Chitosan and its derivatives have become promising biological materials because of their unique molecular structure and excellent biological activities. The reactive functional groups of chitosan such as the amino and hydroxyl groups play a crucial role in facilitating the synthesis of three-dimensional hydrogel. Chitosan-based hydrogels have been widely used in medical, pharmaceutical, and environmental fields for years. Nowadays, chitosan-based hydrogels have been found in a wide range of applications in the food industry such as food sensors, dye adsorbents and nutrient carriers. In this review, recently developed methods for the preparation of chitosan-based hydrogels were given, and the biological activities of chitosan-based hydrogels were systematically introduced. Additionally, the recent progress in food sensors, packaging, dye adsorbents, and nutrient carriers was discussed. Finally, the challenges and prospects for the future development of chitosan-based hydrogels were discussed.

Recent Advances of Chitosan-Based Hydrogels for Skin-Wound Dressings

The management of wound healing represents a significant clinical challenge due to the complicated processes involved. Chitosan has remarkable properties that effectively prevent certain microorganisms from entering the body and positively influence both red blood cell aggregation and platelet adhesion and aggregation in the bloodstream, resulting in a favorable hemostatic outcome. In recent years, chitosan-based hydrogels have been widely used as wound dressings due to their biodegradability, biocompatibility, safety, non-toxicity, bioadhesiveness, and soft texture resembling the extracellular matrix. This article first summarizes an overview of the main chemical modifications of chitosan for wound dressings and then reviews the desired properties of chitosan-based hydrogel dressings. The applications of chitosan-based hydrogels in wound healing, including burn wounds, surgical wounds, infected wounds, and diabetic wounds are then discussed. Finally, future prospects for chitosan-based hydrogels as wound dressings are discussed. It is anticipated that this review will form a basis for the development of a range of chitosan-based hydrogel dressings for clinical treatment.

Chitosan-based multifunctional hydrogel with bio-adhesion and antioxidant properties for efficient wound hemostasis

Benefiting from the biocompatibility, adhesiveness, and natural extracellular matrix-mimicking ability, hydrogels have received increasing research in recent years. In this study, a hydrogel system composed of dopamine, quaternized ammoniated chitosan (QCS), and polyvinylpyrrolidone was reported to exhibit fast hemostatic properties in Sprague-Dawley rat tail amputation and liver bleeding models. The results showed that this hydrogel had good hemostatic properties. The designed hydrogel showed high swelling ratios in H2O, PBS, and 0.9 % NaCl solution, indicating its capability to absorb tissue residual exudate and form a stable hydrogel. Compared with the control group, the blood loss in Sprague-Dawley rat tail amputation and liver bleeding were reduced by nearly 78 % and 76 %, respectively. Interestingly, dopamine endowed the hydrogel with antioxidant properties, thus holding a great application promise in inflammatory wounds. Furthermore, the designed hydrogel demonstrated good and reversible adhesion properties (12.23 ± 0.22 kPa-24.31 ± 0.55 kPa), ensuring its firm attachment to bleeding wounds of pig skin in wet environments. This research points out a novel path for designing chitosan-based hydrogels for biomedical applications.

Injectable thermosensitive hydrogel loading erythropoietin and FK506 alleviates gingival inflammation and promotes periodontal tissue regeneration

Background: Periodontitis is a chronic multifactorial inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth-supporting apparatus. Therefore, there is significant potential in the discovery of drugs that inhibit periodontal inflammatory responses and promote periodontal regeneration. Methods: In this study, we generated a periodontitis rat model to detect the effects of chitosan/β-sodium glycerophosphate (β-GP)/glycolic acid (GA) hydrogel carried Erythropoietin and FK506 (EPO-FK506-CS/β-GP/GA). A total of forty-eight male Wistar rats were used to establish the periodontitis model. Drug injection was administered every 3 days for a total of five times over a 2-week period. After a period of 2 weeks following implantation, the rats underwent anesthesia, and a section of their maxillae encompassing the maxillary first and second molars, along with the alveolar bone, was obtained. micro-CT scanning, histopathology, immunohistochemistry and reverse transcription-quantitative PCR (RT-qPCR) assays were performed. Meanwhile, ELISA assay was performed to detect the levels of inflammatory mediators (TNF-α, IL-6 and IL-1β). Results: The synthesis and characterization of EPO-FK506-CS/β-GP/GA revealed that the hydrogel has stability and sustained release of drugs. The application of FK506+EPO was found to significantly enhance new bone formation in the defect area, as evidenced by the results of HE staining. Additionally, the use of FK506+EPO in the treated groups led to a notable increase in the density of alveolar bone, as observed through micro-CT analysis, when compared to the Model group. EPO-FK506-CS/β-GP/GA hydrogel exhibited notable efficacy in modulating inflammatory mediators (TNF-α, IL-6 and IL-1β). Furthermore, the osteoinductive properties of the EPO-FK506-CS/β-GP/GA hydrogel were extensive, as evidenced by a significant upregulation in the expression of key markers (Collagen I, Runx2, OPN, and OCN) associated with osteoblastic differentiation. Conclusion: Taken together, EPO-FK506-CS/β-GP/GA hydrogel alleviates gingival inflammation and promotes periodontal tissue regeneration in the periodontitis.

Protein/polysaccharide-based hydrogels loaded probiotic-mediated therapeutic systems: A review

The natural characteristics of protein/polysaccharide-based hydrogels, as a potential drug delivery platform, have attracted extensive attention. Probiotics have attracted renewed interest in drug research because of their beneficial effects on host health. The idea of using probiotics loaded on protein/polysaccharide-based hydrogels as potential drugs to treat different diseases has been put forward and shows great prospects. Based on this, in this review, we highlight the design strategy of hydrogels loaded probiotic-mediated therapy systems and review the potential diseases that have been proved to be treatable in the laboratory, including promoting wound healing and improving intestinal health and vaginal health, and discuss the challenges existing in the current design.

Smart Responsive and Controlled-Release Hydrogels for Chronic Wound Treatment

Chronic wounds are a major health challenge that require new treatment strategies. Hydrogels are promising drug delivery systems for chronic wound healing because of their biocompatibility, hydration, and flexibility. However, conventional hydrogels cannot adapt to the dynamic and complex wound environment, which involves low pH, high levels of reactive oxygen species, and specific enzyme expression. Therefore, smart responsive hydrogels that can sense and respond to these stimuli are needed. Crucially, smart responsive hydrogels can modulate drug release and eliminate pathological factors by changing their properties or structures in response to internal or external stimuli, such as pH, enzymes, light, and electricity. These stimuli can also be used to trigger antibacterial responses, angiogenesis, and cell proliferation to enhance wound healing. In this review, we introduce the synthesis and principles of smart responsive hydrogels, describe their design and applications for chronic wound healing, and discuss their future development directions. We hope that this review will inspire the development of smart responsive hydrogels for chronic wound healing.

Addressing Key Questions in Organoid Models: Who, Where, How, and Why?

Organoids are three-dimensional cellular structures designed to recreate the biological characteristics of the body's native tissues and organs in vitro. There has been a recent surge in studies utilizing organoids due to their distinct advantages over traditional two-dimensional in vitro approaches. However, there is no consensus on how to define organoids. This literature review aims to clarify the concept of organoids and address the four fundamental questions pertaining to organoid models: (i) What constitutes organoids?-The cellular material. (ii) Where do organoids grow?-The extracellular scaffold. (iii) How are organoids maintained in vitro?-Via the culture media. (iv) Why are organoids suitable in vitro models?-They represent reproducible, stable, and scalable models for biological applications. Finally, this review provides an update on the organoid models employed within the female reproductive tract, underscoring their relevance in both basic biology and clinical applications.

Natural Polymer-Based Hydrogels: From Polymer to Biomedical Applications

Hydrogels prepared from natural polymer have attracted extensive attention in biomedical fields such as drug delivery, wound healing, and regenerative medicine due to their good biocompatibility, degradability, and flexibility. This review outlines the commonly used natural polymer in hydrogel preparation, including cellulose, chitosan, collagen/gelatin, alginate, hyaluronic acid, starch, guar gum, agarose, and dextran. The polymeric structure and process/synthesis of natural polymers are illustrated, and natural polymer-based hydrogels including the hydrogel formation and properties are elaborated. Subsequently, the biomedical applications of hydrogels based on natural polymer in drug delivery, tissue regeneration, wound healing, and other biomedical fields are summarized. Finally, the future perspectives of natural polymers and hydrogels based on them are discussed. For natural polymers, novel technologies such as enzymatic and biological methods have been developed to improve their structural properties, and the development of new natural-based polymers or natural polymer derivatives with high performance is still very important and challenging. For natural polymer-based hydrogels, novel hydrogel materials, like double-network hydrogel, multifunctional composite hydrogels, and hydrogel microrobots have been designed to meet the advanced requirements in biomedical applications, and new strategies such as dual-cross-linking, microfluidic chip, micropatterning, and 3D/4D bioprinting have been explored to fabricate advanced hydrogel materials with designed properties for biomedical applications. Overall, natural polymeric hydrogels have attracted increasing interest in biomedical applications, and the development of novel natural polymer-based materials and new strategies/methods for hydrogel fabrication are highly desirable and still challenging.