Chitosan based hydrogels and their applications for drug delivery in wound dressings: A review

Recent advances in smart hydrogels derived from polysaccharides and their applications for wound dressing and healing

Owing to their inherent biocompatibility and biodegradability, hydrogels derived from polysaccharides have emerged as promising candidates for wound management. However, the complex nature of wound healing often requires the development of smart hydrogels---intelligent materials capable of responding dynamically to specific physical or chemical stimuli. Over the past decade, an increasing number of stimuli-responsive polysaccharide-based hydrogels have been developed to treat various types of wounds. While a range of hydrogel types and their versatile functions for wound management have been discussed in the literature, there is still a need for a review of the crosslinking strategies used to create smart hydrogels from polysaccharides. This review provides a comprehensive overview of how stimuli-responsive hydrogels can be designed and made using five key polysaccharides: chitosan, hyaluronic acid, alginate, dextran, and cellulose. Various methods, such as chemical crosslinking, dynamic crosslinking, and physical crosslinking, which are used to form networks within these hydrogels, ultimately determine their ability to respond to stimuli, have been explored. This article further looks at different polysaccharide-based hydrogel wound dressings that can respond to factors such as reactive oxygen species, temperature, pH, glucose, light, and ultrasound in the wound environment and discusses how these responses can enhance wound healing. Finally, this review provides insights into how stimuli-responsive polysaccharide-based hydrogels can be developed further as advanced wound dressings in the future.

From waste to wonder: Biomass-derived nanocellulose and lignin-based nanomaterials in biomedical applications

Cellulose and lignin, as the most abundant biomass resources in nature, have been widely utilized in conventional industry. While their high-value potential remained underexplored for decades, recent advancements in nanotechnology and processing techniques have revealed their unique physicochemical properties, biocompatibility, and optical characteristics at the nanoscale, sparking significant interest in biomedical applications. Nanocellulose (NC), characterized by its high surface area, superior mechanical strength, and excellent biocompatibility, holds great promise in drug delivery, wound dressing, and tissue engineering. Similarly, lignin nanoparticles (LNPs) and lignin-based carbon quantum dots (L-CQDs), known for their multi-functionality, low toxicity, and outstanding fluorescence properties, emerge as sustainable alternatives for bio-imaging and bioanalytical detection. This review provides an overview of the hierarchical structure of biomass resources, details the preparation methods of cellulose- and lignin-based nanomaterials, and highlights their advancements in biomedical applications. Furthermore, it addresses the challenges and limitations associated with the clinical applications of these nanomaterials, offering insights and guidance for future research and development.

Chitosan, derivatives, and its nanoparticles: Preparation, physicochemical properties, biological activities, and biomedical applications - A comprehensive review

Chitosan, derived from the deacetylation of chitin, is the second most widely used natural polymer, valued for its nontoxic, biocompatible, and biodegradable properties. These attributes have driven extensive research into diverse applications of chitosan and various derivatives. The key characteristics of chitosan muco-adhesion, permeability enhancement, drug release modulation, and antimicrobial activity are primarily due to its amino and hydroxyl groups. However, the limited solubility of raw chitosan in water and most organic solvents has posed challenges for broader application. Numerous chemically modified derivatives have been developed to address these inadequacies with improved physical and chemical properties. Among these derivatives, chitosan nanoparticles have emerged as versatile drug carriers with precise release kinetics and the capacity for targeted delivery, greatly enhancing drug efficacy and safety profiles for therapeutic applications. Due to these unique physicochemical properties, chitosan and chitosan nanoparticles are promising for improved drug delivery, vaccine administration, transplantation, gene therapy, and diagnostics. This review examines the physicochemical properties and bioactivities of chitosan and chitosan nanoparticles, emphasizing their broad-ranging biomedical applications.

Injectable thermosensitive antibiotic-laden chitosan hydrogel for regenerative endodontics

Injectable biomaterials, such as thermosensitive chitosan (CH)-based hydrogels, present a highly translational potential in dentistry due to their minimally invasive application, adaptability to irregular defects/shapes, and ability to carry therapeutic drugs. This work explores the incorporation of azithromycin (AZI) into thermosensitive CH hydrogels for use as an intracanal medication in regenerative endodontic procedures (REPs). The morphological and chemical characteristics of the hydrogel were assessed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The thermosensitivity, gelation kinetics, compressive strength, cytocompatibility, and antibacterial efficacy were evaluated according to well-established protocols. An in vivo model of periapical disease and evoked bleeding in rats' immature permanent teeth was performed to determine disinfection, tissue repair, and root formation. AZI was successfully incorporated into interconnected porous CH hydrogels, which retained their thermosensitivity. The mechanical and rheological findings indicated that adding AZI did not adversely affect the hydrogels' strength and injectability. Incorporating 3 % and 5 % AZI into the hydrogels led to minimal cytotoxic effects compared to higher concentrations while enhancing the antibacterial response against endodontic bacteria. AZI-laden hydrogel significantly decreased E. faecalis biofilm compared to the controls. Regarding tissue response, the 3 % AZI-laden hydrogel improved mineralized tissue formation and vascularization compared to untreated teeth and those treated with double antibiotic paste. Our findings demonstrate that adding 3 % AZI into CH hydrogels ablates infection and supports neotissue formation in vivo when applied to a clinically relevant model of regenerative endodontics.

Functional polysaccharide-based hydrogel in bone regeneration: From fundamentals to advanced applications

Bone regeneration is limited and generally requires external intervention to promote effective repair. Autografts, allografts, and xenografts as traditional methods for addressing bone defects have been widely utilized, their clinical applicability is limited due to their respective disadvantages. Fortunately, functional polysaccharide hydrogels have gained significant attention in bone regeneration due to their exceptional drug-loading capacity, biocompatibility, and ease of chemical modification. They also provide an optimal microenvironment for bone repair and regeneration. This review provides an overview of various functional polysaccharide hydrogels derived from biocompatible materials, focusing on their applications in intelligent delivery systems, bone tissue regeneration, and cartilage defect repair. Particularly, the incorporation of bioactive molecules into the design of functional polysaccharide hydrogels has been shown to significantly enhance bone regeneration. Additionally, this review emphasizes the preparation methods for functional polysaccharide hydrogels and associated the bone healing mechanisms. Finally, the limitations and future prospects of functional polysaccharide hydrogels are thoroughly evaluated.

An Injectable Chitosan Hydrochloride-Sodium Alginate Hydrogel Adjuvant Capable of Eliciting Potent Humoral and Cellular Immunity

Adjuvants can enhance the immune effects of vaccines. Currently, the most commonly used and validated are aluminum and oil-emulsion adjuvants. However, these adjuvants are not without flaws; for instance, aluminum adjuvants can cause adverse reactions and irritation at the injection site. Consequently, the development of new, safe, and effective adjuvants remains a prominent topic in vaccine research. In this study, we synthesized a composite hydrogel by combining sodium alginate (SA) and the chitosan derivative chitosan hydrochloride (CHCL) to explore the feasibility of this polymer composite hydrogel as a novel immunoadjuvant. Our results indicate that this hydrogel material possesses good biocompatibility and antibacterial properties, is easily injectable, and locally initiates vaccine responses by stimulating the phagocytosis of protein antigens by dendritic cells (DCs). Additionally, they offer sustained exposure to vaccine antigens. After administration, a transient inflammatory niche is created to prolong immune system activation. Importantly, our study demonstrated that the CHCL-SA hydrogel loaded with antigens effectively stimulated the body to produce a humoral immune response and enhance the maturation of the CD8+ T lymphocyte subset. In murine tumor challenge experiments, the CHCL-SA supplemented antigen group significantly inhibited tumor cell growth and improved mouse survival rates. In summary, we developed an injectable CHCL-SA hydrogel adjuvant with great potential for enhancing the efficacy of vaccines.

Advanced drug delivery systems for the management of local conditions

Localized disorders, even though originally confined to a specific body part, can progress into potentially life-threatening systemic disorders if treated inappropriately. Local treatment is often highly challenging due to poor penetration of therapeutic agents from their vehicles into the affected body site. Systemic treatment on the other hand often comes with unspecific side effects. The skin is the largest organ of the body, and conditions such as wounds and bacterial or fungal infections disrupt its natural barrier properties, important for the homeostasis of the human body. Advanced drug delivery systems for treating these conditions could greatly improve the treatment outcome and patient compliance. Other parts of the body that are of interest regarding localized treatment are, for example, the eyes along with mucosal tissues which are present in the vagina and lungs. Rather than focusing on specific diseases or parts of the body, this review provides an overview of the different drug delivery platforms that have been employed for enhanced local treatment. The following systems will be discussed: nanoparticle-based systems, such as nanocrystals, polymeric, lipidic, and inorganic nanoparticles, and nanogels; cyclodextrin inclusion complexes; and several devices like microarray patches, wound dressings, and films.

Chitosan-based dental barrier membrane for periodontal guided tissue regeneration and guided bone regeneration: A review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are two common dental regenerative procedures used to repair periodontal defects caused by periodontitis. In both procedures, a barrier membrane is placed at the interface between the soft tissue and the periodontal defect, serving to impede the infiltration of soft tissue while creating a secluded space for periodontal regeneration. Recently, barrier membranes based on chitosan (CS) have emerged as a promising avenue for these applications. However, despite numerous studies on the development of CS-based membranes, comprehensive review articles specifically addressing their progress in GTR/GBR applications remain scarce. Herein, we review recent research and advancements in the use of CS-based membranes for periodontal GTR and GBR. The review begins by highlighting the advantageous properties of CS that make it a suitable biomaterial for GTR/GBR applications. Next, the development of composite CS-based membranes, reinforced with various compositions like bioactive fillers and therapeutic agents, is discussed in detail based on recent literature, with a focus on their enhanced efficacy in promoting periodontal regeneration. Finally, the review explores the emergence of functionally graded CS-based membranes, emphasizing their potential to address specific challenges encountered in GTR/GBR procedures.

Hyaluronic acid-based hydrogels as codelivery systems: The effect of intermolecular interactions investigated by HR-MAS and solid-state NMR Spectroscopy

Hydrogels based on hyaluronic acid and agarose-carbomer, due to their peculiar 3D architecture and biocompatibility, are promising candidates for pharmaceutical strategies based on the codelivery of drugs targeting different diseases. The successful development of these applications requires a precise understanding of drug-drug interactions and their effects on transport and release mechanisms. In this study, such an investigation is carried out on hydrogels loaded with ethosuximide and sodium salicylate at different concentrations. Intermolecular interactions and transport properties are characterized by means of High Resolution Magic Angle Spinning and solid-state Magic Angle Spinning NMR Spectroscopy. At variance with our previous findings on single-drug formulations, the two drugs exhibit closely similar diffusion patterns when co-loaded in the HA-based hydrogels, plausibly due to drug-drug intermolecular interactions. At the highest drug concentrations, where superdiffusion comes into play, we find a fraction of molecules with time-varying diffusion coefficients. A trapping-release mechanism is proposed to explain this observation, which also accounts for the role of drug-hydrogel interactions in drug diffusion motion. The effects of drug-drug interactions on release profiles are finally assessed by means of in vitro release experiments.

Thermosensitive, injectable, antibacterial glabridin liposome/chitosan dual network hydrogel for diabetic wound healing

Thermosensitive hydrogels show great potential in healing diabetic wounds, but they are still challenged by the long healing time, risk of infectivity, and accumulation of melanin. Herein, a dual network hydrogel is designed, which consists of chlorogenic acid (CA) modified chitosan (CS) (CA@CS), poly(N-isopropylacrylamide) (PNIPAm), and glabridin liposomes (GL). The gelation transition temperature of the hydrogel is 32-34 °C, which thus endows it with superior injectability at ambient temperature. Moreover, GL/PNIPAm/CA@CS also exhibits excellent biocompatibility, and can promote the growth of epidermal cells, and the healing of diabetic wounds. GL/PNIPAm/CA@CS can also control the immune reactions by enhancing the release of CD206, and decreasing the formation of CD86 and ROS, which further promotes the production of CD31 and VEGF, and reduces the expression of pro-inflammatory factors, thus aiding in the healing of diabetic wounds. Furthermore, GL/PNIPAm/CA@CS can also suppress the growth bacterial, which can thus decrease the wound microbiota levels and facilitate the recovery of diabetic wounds. More importantly, it can reduce melanin production by 80 % due to the action of glabridin. Consequently, GL/PNIPAm/CA@CS shows significant promise in enhancing the wound healing in future and decreasing the accumulation of melanin.

Multiple-Layer Chitosan-Based Patches Medicated With LTX-109 Antimicrobial Peptide for Modulated Local Therapy in the Management of Chronic Wounds

In response to the critical issue of chronic wound management, this research explores the development of a multiple-layer biomaterial loaded with LTX-109 a novel broad-spectrum topical antimicrobial peptide currently investigated for the treatment of bacterial skin infections. The novel patch is conceived to load and preserve the function of LTX-109, release it on site in a progressive manner, and therefore make available a device for simultaneous wounds disinfection and tissues healing. Chitosan, tannic acid and glycerol along with the solvent casting process are selected for the development of a multilayer structure in which each single layer is designed by choosing a specific composition and stability to tune its behavior and function. On the top, a protective layer to protect the wound from external contaminations, in the middle a medicated layer loaded with LTX-109 and at the bottom a multifunctional layer to modulate the release of LTX-109. Extensive characterizations show that the patch meets the essential requirements for creating an effective wound healing environment, such as absorption of exudate, maintenance of good oxygen and moisture permeability, biodegradability, biocompatibility, and sustained release of LTX-109 with fully retained antibacterial activity as demonstrated by MIC values obtained against reference bacteria.

Efficacy of 3D-printed chitosan‑cerium oxide dressings coated with vancomycin-loaded alginate for chronic wounds management

Multifunctional wound dressings with antibacterial and antioxidant properties hold significant promise for treating chronic wounds; however, achieving a balance of these characteristics while maintaining biocompatibility is challenging. To enhance this balance, this study focuses on the design and development of 3D-printed chitosan-matrix composite scaffolds, which are incorporated with varying amounts of cerium oxide nanoparticles (0, 1, 3, 5, and 7 wt%) and subsequently coated with a vancomycin-loaded alginate layer. The structure, antibiotic drug delivery kinetics, biodegradation, swelling, biocompatibility, antibacterial, antioxidant, and cell migration behaviors of the fabricated dressings were evaluated in-vitro. The findings reveal that all of the formulations demonstrated a robust antibacterial effect against S. aureus bacterial strains in disk diffusion tests. Furthermore, the dressings containing cerium oxide nanoparticles exhibited proper antioxidant capabilities, with over 78.1 % reactive oxygen species (ROS) scavenging efficiency achieved with 7 % cerium oxide nanoparticles. The sample containing 5 % cerium oxide nanoparticles was identified as the optimal formulation, characterized by the most favorable cell biocompatibility, an ROS scavenging ability of over 73.4 %, and the potential to close the wound bed within 24 h. This study highlights that these dressings are promising for managing chronic wounds by preventing infection and oxidative stress in a correct therapeutic sequence.

Development of a pH-Responsive Antimicrobial and Potent Antioxidant Hydrogel for Accelerated Wound Healing: A Game Changer in Drug Delivery

Stimuli-responsive hydrogels have the capability to alter their state in response to changes in physiological signals within their application environment, providing distinct benefits in drug delivery applications. Here, the acidic pH typically found in acutely infected wounds can be effectively managed by incorporating a pH-responsive Ag+ loaded system within the hydrogel, thereby ensuring efficient drug use and preventing potential toxicity from the sudden release of silver ions. The antimicrobial composite hydrogel HAMA/GelMA-CA/Ag+ provides some tissue adhesion and accelerates wound healing. GelMA-CA is synthesized by modifying gelatin methacryloyl (GelMA) with caffeic acid (CA), while hyaluronic acid methacryloyl (HAMA) is introduced to prepare a double network hydrogel. Silver nitrate is then introduced to make it pH-responsive through the formation of coordination between the polyphenolic structure of caffeic acid and the silver ions. The composite hydrogel exhibited excellent antioxidant properties and strong antimicrobial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Furthermore, the composite hydrogel accelerated the promotion of wound healing in a rat model of S. aureus-infected wounds. In conclusion, the HAMA/GelMA-CA/Ag+ hydrogel is a promising bioactive material that can be used as a wound dressing to promote the healing of acutely infected wounds.

Mechanically improved chitosan/graphene oxide nanocomposite hydrogel for sustained release of levofloxacin

This study introduces a novel chitosan/graphene oxide (CS/GO) nanocomposite hydrogel designed for the sustained release of levofloxacin. The hydrogel was synthesized using electrostatic interactions and chemical cross-linking, resulting in significant mechanical reinforcement (G' = 0.94 MPa, G" = 0.088 MPa) and homogeneous distribution of GO. It exhibited excellent swelling properties (1380 % at 0.05 wt% GO, 1070 % at 0.2 wt% GO at pH 2). Levofloxacin release was faster (∼95 % in 5 h) at 0.05 wt% GO and more sustained (∼97 % over 24 h) at 0.2 wt% GO. This hydrogel demonstrates potential as a robust platform for controlled drug delivery.

Development of low-molecular-weight polysaccharide-based wound dressings for full-thickness cutaneous wound healing via coacervate formation

The development of polysaccharide-based wound dressings that are easy to prepare, adhere to tissue, adapt to diverse shapes and exhibit tunable mechanical properties holds significant clinical interest. This study introduced a simple spontaneous liquid-liquid phase separation technique employing low-molecular-weight and high polyion concentration of chitosan (CS) and hyaluronic acid (HA) to fabricate CS/HA coacervates. Upon increasing the molecular weight of chitosan from 7 kDa to 250 kDa, a transition in the CS/HA coacervates from liquid-like state to an elastic liquid and eventually to a solid-like state was observed. The resulting CS/HA coacervates demonstrated robust water resistance and adhesion to skin tissue. Notably, the molecular weight of chitosan significantly influenced the mechanical properties and hydration levels of the CS/HA coacervates. Moreover, in vivo studies using a full-thickness cutaneous defect model revealed that the CS/HA coacervates, prepared using 100 kDa chitosan, markedly accelerate wound healing. The coacervates' ease of preparation, wet adhesion, heterogeneous structure, suitability for irregularly shaped wounds, and exceptional wound healing promotion of the coacervates qualify them as an optimal wound dressing.

Injectable Chitosan Hydrogel Particles as Nasal Packing Materials After Endoscopic Sinus Surgery for Treatment of Chronic Sinusitis

After endoscopic sinus surgery (ESS), nasal packing is often used to stop bleeding and promote wound healing. Because maintaining a moist environment is important to enhance wound healing, hydrogel-based wound dressings are effective to promote wound healing. Chitosan is used in the medical field because of its high hemostatic and wound healing properties. We developed a pH-neutral and non-toxic chitosan hydrogel, which was difficult to achieve using conventional methods. In this study, we show in animal experiments that the chitosan hydrogel (hydrogel particles) had higher wound healing properties than a commercially available solid wound dressing (dry state) composed of the same polymer. Additionally, we applied the injectable chitosan hydrogel particles as nasal packing materials to patients with bilateral chronic sinusitis undergoing ESS in a pilot clinical study. Concerning symptom scores, though the results narrowly missed statistical differences (p < 0.05), the average scores of our chitosan hydrogel were superior to those of a commercially available wound dressing (especially p = 0.09 for nasal bleeding). These findings suggest that the injectable chitosan hydrogel could be a viable option as a packing material following ESS.

Evaluation of smart bi-functional dressing based on polysaccharide hydrogels and Brassica oleracea extract for wound healing and continuous monitoring

Skin wounds can drive global impacts, socially and economically, in parallel with their elevated incidence rate. Therefore, utilizing the dual-activity of Brassica Oleracea (Red Cabbage) extract, of being pH-sensitive and biologically active in designing novel, therapeutic, and pH-sensitive wound dressings with an easily stripped-off feature, is critical. Wound dressings were designed using two separate hydrogels based on chitosan (CS) and hydroxyethylcellulose (HEC), each loaded with RCE. The pH sensitivity of prepared bandages exhibited a noticeable visual change in color during wound treatment. Wound closure has reached 99.69 % for CS/RCE dressings. Results showed that RCE had raised the hydroxyproline and collagen content in the healed skin. Histopathological investigation proves that skin returned to its regular thickness within 10 days of treatment. RCE showed marked improvement in the healing quality by acting as an antioxidant, anti-inflammatory, and antimicrobial agent. Therefore, dual-function dressings are potential candidates to sense and cure skin wounds.

Chitosan-gelatin composite hydrogel antibacterial film for food packaging

Antibacterial hydrogel film can serve as food packaging materials to prevent bacteria growth and spread, thereby extending shelf life and improve food safety. In this study, an efficient antibacterial hydrogel film (CLG) was prepared with chitosan, lysine, and gelatin. The light transmission of the CLG hydrogel film was over 80 % in the visible region, facilitating the observation of chicken breast storage conditions. Additionally, the swelling ratios of the hydrogel films decreased with increasing gelatin concentration, from 145.7 g/g (CLG1) to 92.6 g/g (CLG2) and 81.5 g/g (CLG3). This reduction was attributed to the denser network structure formed by the interaction between gelatin and the CL polymer. The Scanning Electron Microscopy (SEM) showed that the water-absorbed CLG hydrogel had a unique sponge shape. Moreover, the CLG hydrogel film exhibits high antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In a practical storage experiment, the CLG hydrogel film extended the shelf life of chicken breast by up to 4 days compared to untreated samples, while effectively reducing total volatile basic nitrogen (TVB-N) levels. This hydrogel film is expected to become a promising food packaging material.

Natural polysaccharides combined with mussel-inspired adhesion for multifunctional hydrogels in wound hemostasis and healing: A review

As naturally derived macromolecular polymers, polysaccharides have garnered significant attention in recent years as promising candidates for fabricating multifunctional hydrogels, particularly for wound healing applications, owing to their inherent biocompatibility, biodegradability, and structural diversity. However, the inherently weak skin adhesion of natural polysaccharide hydrogels has motivated the exploration of mussel-inspired catechol-based adhesion strategies to overcome this limitation. Incorporating mussel-inspired modifications into natural polysaccharides can imbue them with unique properties such as enhanced adhesion, antioxidant activity, antibacterial properties, and chelation capabilities, considerably broadening their potential for wound hemostasis and healing applications. This review comprehensively overviews recent advances in mussel-inspired polysaccharide hydrogels, focusing on the combination of natural polysaccharides, including chitosan, alginate, hyaluronic acid, cellulose, and dextran, with mussel-inspired catechol. We delve into their fabrication strategies and highlight their promising biomedical applications, with a particular emphasis on wound hemostasis and diverse wound healing processes. Mussel-inspired modification strategies for polysaccharide hydrogels are expected to remain a focal point within the fields of wound hemostasis and healing, paving the way for more impactful research endeavors.

Extracellular matrix-based biomaterials in burn wound repair: A promising therapeutic strategy

Burns are common traumatic injuries affecting many people worldwide. Development of specialized burn units, advances in acute care modalities, and burn prevention programs have successfully reduced the mortality rate of severe burns. Autologous skin grafting has been considered as the gold standard for wound coverage after the removal of burned skin. For full-thickness burns of a larger scale, however, the autograft donor site may be quickly exhausted, so that alternative skin coverage is necessary. Although rapid progress has been made in the development of skin substitutes for burn wounds during the last decade, no skin substitute has fulfilled the criteria as a perfect replacement for the damaged skin. Extracellular matrix (ECM) derived components have emerged as a source for the engineering of biomaterials capable of inducing desirable cell-specific responses and one of the most promising biomaterials for burn wound healing. Among these, acellular dermal matrix, small intestinal submucosa, and amniotic membrane have been applied to treat burn wounds with acceptable outcomes. This review has explored the use of biomaterials derived from naturally occurring ECM and their derivatives for approaches aiming to promote burn wound healing, and summarized the ECM-based wound dressings products applicable in burn wound and postburn scar contracture to date.

Novel chitosan-based hydrogels as promising wound dressing materials with advanced properties

Herein, four different grafted chitosans were synthesized by covalent attachment of glycine, L-arginine, L-glutamic acid, or L-cysteine to the chitosan chains. All products were subsequently permethylated to obtain their corresponding quaternary ammonium salts to enhance the inherent antimicrobial properties of native chitosan. In all cases, transparent hydrogels with the following remarkable characteristics were obtained: i) high-water absorption capacity (32-44 g H2O per g of polymer), ii) viscoelastic behavior at low deformations, iii) flexibility when subjected to deformations and iv) stability over long time scales. All the permethylated derivatives successfully inhibited 100 % of the growth of S. aureus. They also exhibited higher antimicrobial activity against E. coli than native chitosan. The structure of the chemically crosslinked products was more stable under external perturbations than that of the physically crosslinked ones. Between the chemically crosslinked products, the permethylated glutamic acid-grafted chitosan exhibited a noteworthy higher water absorption capacity with respect to that modified with cysteine, which makes it the most promising material for various industrial applications, including biomedical and food industries. Regarding biomedical applications, this derivative met the required physicochemical criteria for wound dressings, which encourages the pursuit of biological studies necessary to ensure the safety of its use for this application.

Advancements of Biomacromolecular Hydrogel Applications in Food Nutrition and Health

Hydrogels exhibit remarkable degradability, biocompatibility and functionality, which position them as highly promising materials for applications within the food and pharmaceutical industries. Although many relevant studies on hydrogels have been reported in the chemical industry, materials, and other fields, there have been few reviews on their potential applications in food nutrition and human health. This study aims to address this gap by reviewing the functional properties of hydrogels and assessing their value in terms of food nutrition and human health. The use of hydrogels in preserving bioactive ingredients, food packaging and food distribution is delved into specifically in this review. Hydrogels can serve as cutting-edge materials for food packaging and delivery, ensuring the preservation of nutritional activity within food products, facilitating targeted delivery of bioactive compounds and regulating the digestion and absorption processes in the human body, thereby promoting human health. Moreover, hydrogels find applications in in vitro cell and tissue culture, human tissue repair, as well as chronic disease prevention and treatment. These broad applications have attracted great attention in the fields of human food nutrition and health. Ultimately, this paper serves as a valuable reference for further utilization and exploration of hydrogels in these respective fields.

Synthesis of copper hexaferrite magnetic nanoparticles based on carboxymethyl cellulose modified with polyacrylic acid (CMC/PAA/CuFe12O19) for loading and release of Levothyroxine

Hypothyroidism is a disease that is treated using levothyroxine sodium orally, and its oral use causes some problems in its absorption. A potential alternative to improve its administration is the use of drug delivery systems. This research aimed to prepare CMC/PAA/CuFe12O19 magnetic nano polymer and investigate its performance in the loading and release of Levothyroxine. The CuFe12O19 nanoparticles were synthesized by the co-precipitation method and then CMC/PAA/CuFe12O19 nanopolymer was fabricated to enhance properties. The structure, morphology, magnetic properties, and surface area of CMC/PAA/CuFe12O19 were characterized using different techniques such as XRD, FESEM, VSM, and BET. Levothyroxine was used as a model drug and loading and releasing of Levothyroxine onto CMC/PAA/CuFe12O19 nanopolymer were investigated at pH = 1.2 and pH 7.4. The release of DOX from the CMC/PAA/CuFe12O19 showed a pH-sensitive behavior and released 75 % of Levothyroxine during 3 days at pH = 7.4. The release kinetic analysis, encompassing of Zero order, the First order, the Higuchi, and the Korsmeyer-Peppas models, revealed significant fitting with the First order model at both pH 1.2 (R2 = 0.996) and pH 7.4 (R2 = 0.991) media. Therefore, CMC/PAA/CuFe12O19 nanopolymer could be used as a potential carrier for Levothyroxine delivery.

Hydrogels comprising oxidized carboxymethyl cellulose and water-soluble chitosan at varied oxidation levels: Synthesis, characterization, and adsorptive toward methylene blue

Chitosan, as a biomaterial, has increasingly garnered attention. However, its limited solubility in water-only dissolving in certain dilute acidic solutions-substantially restricts its broader application. In this investigation, chitosan underwent a solubilization modification to acquire water solubility, facilitating its dissolution in neutral aqueous mediums. Subsequently, this water-soluble chitosan (WSC) was interlinked with oxidized carboxymethyl cellulose (OCMC), characterized by varied oxidation extents, to synthesize hydrogels. Structural characterization verified the formation of imine bonds resulting from crosslinking interactions between the amino groups of water-soluble chitosan and the aldehyde groups of oxidized carboxymethyl cellulose. Employing performance characterization analysis, it was discerned that an increase in the oxidation level of the oxidized carboxymethyl cellulose corresponded to a denser hydrogel network architecture and the hardness increased from 3.01 N to 6.16 N. Moreover, the capacity of these hydrogels to adsorb methylene blue was meticulously examined. Notably, the hydrogel denoted as WSC/66%OCMC manifested an adsorption capability of 28.08 mg/g for methylene blue. Analytical findings from adsorption kinetics and isotherm studies indicate that the adsorption mechanism of the WSC/66%OCMC hydrogel follows the pseudo-second-order kinetic model and corresponds to the Freundlich isotherm model.

Nanostructured layered double hydroxide (NLDH) - Zn/Al-based materials: strategy to improve performance for zirconium sorption from acidic sulfate solution

Zirconium is a highly stable radionuclide commonly used in various nuclear operations. However, removing zirconium from wastewater streams is crucial to protect the environment and human health. To achieve this, a zinc and aluminum nanostructured layered double hydroxide (Zn/Al-NLDH) was prepared and investigated for effective removal of zirconium from aqueous solutions. This study examined the prepared Zn/Al-NLDH's structural and textural properties and the impact of various factors on its adsorption performance. The Langmuir isotherm and Pseudo-second order kinetic models were found to be the best fit for the adsorption process of Zr(vi). This suggests that the adsorption process is uniform, involves the formation of a monolayer, and is chemisorption in nature. The maximum uptake capacity was 117.6 mg g-1, and the process was endothermic, spontaneous, and feasible. About 96% of Zr(vi) was successfully desorbed from the loaded sorbent using 1.0 M hydrochloric acid, and the Zn/Al-NLDH sorbent remained stable for six consecutive sorption/desorption cycles. These findings emphasize the high potential of Zn/Al-NLDH to act as a remarkable sorbent for efficiently tackling water contaminants.

Trends in sustainable chitosan-based hydrogel technology for circular biomedical engineering: A review

Eco-friendly materials have emerged in biomedical engineering, driving major advances in chitosan-based hydrogels. These hydrogels offer a promising green alternative to conventional polymers due to their non-toxicity, biodegradability, biocompatibility, environmental friendliness, affordability, and easy accessibility. Known for their remarkable properties such as drug encapsulation, delivery capabilities, biosensing, functional scaffolding, and antimicrobial behavior, chitosan hydrogels are at the forefront of biomedical research. This paper explores the fabrication and modification methods of chitosan hydrogels for diverse applications, highlighting their role in advancing climate-neutral healthcare technologies. It reviews significant scientific advancements and trends chitosan hydrogels focusing on cancer diagnosis, drug delivery, and wound care. Additionally, it addresses current challenges and green synthesis practices that support a circular economy, enhancing biomedical sustainability. By providing an in-depth analysis of the latest evidence on climate-neutral management, this review aims to facilitate informed decision-making and foster the development of sustainable strategies leveraging chitosan hydrogel technology. The insights from this comprehensive examination are pivotal for steering future research and applications in sustainable biomedical solutions.

Evaluation of composition effects on the tissue-adhesive, mechanical and physical properties of physically crosslinked hydrogels based on chitosan and pullulan for wound healing applications

Tissue adhesion of hydrogels plays an important role in wound healing, which can improve the efficiency of wound treatment, stop bleeding, facilitate tissue growth and wound closure. However, most non-covalent crosslinked hydrogels have weak tissue adhesion and rheological properties. Furthermore, it remains a challenge to synthesize a fully physically crosslinked hydrogel with good rheological properties without compromising its tissue adhesion strength. In this paper, a physically crosslinked hydrogel was developed from a mixture of chitosan and pullulan in different polymer volume ratios using aqueous NaOH. Fourier transform infrared spectroscopy, scanning electron microscopy, thermal analysis, rheological and lap shear tests were used to evaluate the influence of polymer volume ratios on the rheological, and tissue adhesive properties of the hydrogels. It was found that the hydrogels possessed high tissue adhesive strength ranging from 18.0 ± 0.90 to 49.0 ± 2.45 kPa and good storage moduli up to 5.157 ± 1.062 kPa. Gentamicin was incorporated into this polymer matrix and the release profile was investigated. The ratio of chitosan and pullulan to obtain hydrogels with optimum viscoelastic and tissue adhesive properties was identified to be CS/PUL 2:1. These results indicated that the synthesized hydrogels can be potential materials for biomedical applications such as medical adhesives and wound dressings.

Elastic Nanofibrous Dressings with Mesenchymal Stem Cell-Recruiting and Protecting Characteristics for Promoting Diabetic Wound Healing

Diabetic wounds that do not heal for a long time challenge global healthcare. Mesenchymal stem cell (MSC) therapy has positive significance in promoting diabetic wound healing. However, traditional MSC therapy involves exogenous MSCs, which brings many limitations and unsatisfactory treatment. Moreover, the maintenance of MSC viability and function is difficult because of the high level of reactive oxygen species (ROS) in diabetic wounds. Therefore, we developed a nanofibrous dressing to recruit and protect endogenous MSCs while avoiding the inherent disadvantages of exogenous MSCs. Ceria nanoparticles capable of ROS scavenging are integrated into the nanofibrous dressings, together with Apt19S, a DNA aptamer with affinity and selectivity for MSCs. In addition, the homogenization and freeze-drying technology give the nanofibrous dressings good elasticity, which protects the wound from external pressure. Further experiments in diabetic mice show that the dressing has excellent endogenous MSC recruitment and anti-inflammatory properties, thereby synergistically promoting diabetic wound healing. This study is expected to explore an efficient method of stem cell therapy, providing a new way to construct high-performance wound dressings.

Kinetics of Calcite Nucleation onto Sulfated Chitosan Derivatives and Implications for Water-Polysaccharide Interactions during Crystallization of Sparingly Soluble Salts

Anionic macromolecules are found at sites of CaCO3 biomineralization in diverse organisms, but their roles in crystallization are not well-understood. We prepared a series of sulfated chitosan derivatives with varied positions and degrees of sulfation, DS(SO3 -), and measured calcite nucleation rate onto these materials. Fitting the classical nucleation theory model to the kinetic data reveals the interfacial free energy of the calcite-polysaccharide-solution system, γnet, is lowest for nonsulfated controls and increases with DS(SO3 -). The kinetic prefactor also increases with DS(SO3 -). Simulations of Ca2+-H2O-chitosan systems show greater water structuring around sulfate groups compared to uncharged substituents, independent of sulfate location. Ca2+-SO3 - interactions are solvent-separated by distances that are inversely correlated with DS(SO3 -) of the polysaccharide. The simulations also predict SO3 - and NH3 + groups affect the solvation waters and HCO3 - ions associated with Ca2+. Integrating the experimental and computational evidence suggests sulfate groups influence nucleation by increasing the difficulty of displacing near-surface water, thereby increasing γnet. By correlating γnet and net charge per monosaccharide for diverse polysaccharides, we suggest the solvent-separated interactions of functional groups with Ca2+ influence thermodynamic and kinetic components to crystallization by similar solvent-dominated processes. The findings reiterate the importance of establishing water structure and properties at macromolecule-solution interfaces.

Development of alginate/chitosan hydrogel loaded with obestatin and evaluation of collagen type I, III, VEGF and TGF-β1 gene expression for skin repair in a rat model (in vitro and in vitro study)

BACKGROUND

Skin injuries have long been recognized as a prevalent type of physical injury. As a result, numerous research studies have been performed to discover an effective mechanism for wound healing. Therefore, tissue engineering of skin has developed as a potential solution for traditional methods of treating skin injuries.

METHODS AND MATERIALS

Alginate/Chitosan hydrogel was mixed with 1, 10, 100, and 150 µM Obestatin, and evaluated the morphology, cumulative release, hemocompatibility and cytocompatibility, water absorption, cell viability, weight loss, and antibacterial characteristics of three-dimensional (3D) alginate (Alg) and chitosan (Cs) hydrogels during the process of wound curing. Various concentrations of Obestatin (Obes) were utilized for this purpose. Finally, the hydrogels that were made were tested on a full-thickness dermal wound in a Wistar rat model. The curative effects were determined by analyzing RNA expression and examining tissue stained with Masson's trichrome (MT) and hematoxylin-eosin (H&E).

RESULTS

The biodegradability of this hydrogel was verified using weight loss testing, which demonstrated a reduction of around 90% after a period of 3 days. Furthermore, the MTT assay demonstrated that hydrogels have a beneficial effect on cell proliferation without inducing any harmful effects. Furthermore, the hydrogels produced demonstrated higher wound closure in vivo compared to the wounds treated with gauze (negative control group). Among the hydrogel groups, the chitosan/alginate/obestatin 100 µM group exhibited the apical percentage of wound closure, gene expression, and secondary epithelialization, but in 150 µM concentrations, we saw a lower rate of cell growth and proliferation and increase in hemolysis. In addition, RT-PCR analysis demonstrated that a concentration of 100 µM obestatin resulted in an upregulation in the expression of mRNA for vascular endothelial growth factor (VEGF), collagen type I & type III, and transforming growth factor-beta (TGF-β).

CONCLUSION

The present study suggests that 3D Alg/Cs hydrogels with a concentration of 100 µM obestatin have the potential for clinical application in the treatment of skin injuries.

Long duration sodium hyaluronate hydrogel with dual functions of both growth prompting and acid-triggered antibacterial activity for bacteria-infected wound healing

Conventional wound dressings are monolithically designed to cover the injured areas as well as absorb the exudates at injured site. Furthermore, antibacterial drugs and growth prompting factors are additionally appended to realize sensible and omnibearing wound management, exhibiting long and tedious treatment process in practice. Consequently, the creation of multifunctional wound dressings that combines wound repair enhancement with antibacterial properties turns out to be significant for simplifying wound managements. In our investigation, electronegative human epidermal growth factor (hEGF) was combined with the positively charged Zn-Al layered double hydroxides (Zn-Al LDHs) via electrostatic interaction while the obtained hEGF/LDH was integrated with sodium hyaluronate hydrogel (SH) hydrogel, forming a composite hydrogel with synergistic benefits for wound management. The innovative hEGF/LDH@SH hydrogel equipped with fine biocompatibility was designed to optimize wound healing in which hEGF stimulates epithelial cell growth while LDH released antibacterial factor Zn2+ against Methicillin-resistant staphylococcus aureus (MRSA) and Escherichia coli (E.coli) under acidic wound environment. Additionally, the SH hydrogel constructed a three-dimensional structure that not only safeguarded the wound area but also maintained a moist environment conducive to recovery. The synthesized hEGF/LDH was confirmed via fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermo-gravimetry (TG) measurements. The release of Zn2+ from Zn-Al LDH under acid circumstance was detected via inductively coupled plasma (ICP) and the in vitro bactericidal experiments endowed the antibacterial property of hEGF/LDH@SH hydrogel. In vitro drug release experiments illustrated the controlled-release of hEGF from hEGF/LDH which promoted the long-term affect of hEGF at wound site. In vitro cell experiments verified that the hEGF/LDH@SH hydrogel motivated the promotion on cell proliferation and migration without cytotoxicity. An in vivo study of the repairing of MRSA-infected wound in mice indicated that hEGF/LDH@SH hydrogel serves as a simple and novel, innoxious and efficient wound healing approach. This brand new hydrogel possesses properties of promoting the regeneration of skin tissue, achieving antimicrobial therapy without any accessional antibacterial drugs as well as realizing controlled release of hEGF.

Surface modification of polysulfone reverse osmosis membrane with chitosan-modified zinc oxide for water desalination

Decreasing groundwater levels, increasing world population, and pollution of water resources by industries lead to the use of new technologies for augmenting the fresh water supply such as its desalination. Chitosan-modified zinc oxide (C-ZnO) nanoparticles were synthesized and used for surface modification of polysulfone (PSf) in water desalination. PSf /C-ZnO membrane was fabricated through the phase inversion method and characterized by Fourier transfer infrared (FTIR), X-Ray diffraction (XRD), field emission scanning electron microscope (FESEM), atomic force microscope (AFM), energy dispersive X-ray (EDX), Braunauer-Emmett-Teller (BET), and contact angle. The nanoparticle effect on the membrane properties was investigated by measuring the pure water flux and solute rejection under two constant pressures, at 6 and 10 bar, and the salts concentration of MgSO4, MgCl2, NaCl, and CaCl2 at 1 gL-1. The results showed that nanoparticles increased the hydrophilicity of the pristine PSf membrane while slightly decreasing the water permeability. Moreover, the salt rejection increased with the nanoparticle addition up to 0.2 wt.% while it decreased with 0.5 wt.% nanoparticle due to changing the membrane finger-like pores sublayer structure.

Effect of Drying Methods on the Thermal and Mechanical Behavior of Bacterial Cellulose Aerogel

Bacterial cellulose (BC) presents significant promise as a biomaterial, boasting unique qualities such as exceptional cellulose purity, robust mechanical strength, heightened crystalline structure, and biodegradability. Several studies have highlighted specific effects, such as the impact of dehydration/rehydration on BC tensile strength, the influence of polymer treatment methods on mechanical properties, the correlation between microorganism type, drying method, and Young's modulus value, and the relationship between culture medium composition, pH, and crystallinity. Drying methods are crucial to the structure, performance, and application of BC films. Research findings indicate that the method used for drying can influence the mechanical properties of BC films, including parameters such as tensile strength, Young's modulus, and water absorption capacity, as well as the micromorphology, crystallinity, and thermal characteristics of the material. Their versatility makes them potential biomaterials applicable in various fields, including thermal and acoustic insulation, owing to their distinct thermal and mechanical attributes. This review delves into the thermal and mechanical behavior of bacterial cellulose aerogels, which are profoundly impacted by their drying mechanism.

Composite hydrogels with antioxidant and robust adhesive properties for the prevention of radiation-induced dermatitis

Radiotherapy is a pivotal means of cancer treatment, but it often leads to radiation dermatitis, a skin injury caused by radiation-induced excess reactive oxygen species (ROS). Scavenging free radicals in the course of radiation therapy will be an effective means to prevent radiation dermatitis. This study demonstrates a novel double network hydrogel doped with MoS2 nanosheets for the prevention of radiation-induced dermatitis. The resultant SPM hydrogel constructed from polyacrylamide (PAM) and sodium alginate (SA) nanofiber presented favorable mechanical and adhesion properties. It could conform well to the human body's irregular contours without secondary dressing fixation, making it suitable for skin protection applications. The in vitro and in vivo experiments showed that the antioxidant properties conferred by MoS2 nanosheets enable SPM to effectively mitigate excessive ROS and reduce oxidative stress, thereby preventing radiation dermatitis caused by oxidative damage. Biosafety assessments indicated good biocompatibility of the composite hydrogel, suggesting SPM's practicality and potential as an external dressing for skin radiation protection.

Polymer-Based Wound Dressings Loaded with Essential Oil for the Treatment of Wounds: A Review

Wound healing can result in complex problems, and discovering an effective method to improve the healing process is essential. Polymeric biomaterials have structures similar to those identified in the extracellular matrix of the tissue to be regenerated and also avoid chronic inflammation, and immunological reactions. To obtain smart and effective dressings, bioactive agents, such as essential oils, are also used to promote a wide range of biological properties, which can accelerate the healing process. Therefore, we intend to explore advances in the potential for applying hybrid materials in wound healing. For this, fifty scientific articles dated from 2010 to 2023 were investigated using the Web of Science, Scopus, Science Direct, and PubMed databases. The principles of the healing process, use of polymers, type and properties of essential oils and processing techniques, and characteristics of dressings were identified. Thus, the plants Syzygium romanticum or Eugenia caryophyllata, Origanum vulgare, and Cinnamomum zeylanicum present prospects for application in clinical trials due to their proven effects on wound healing and reducing the incidence of inflammatory cells in the site of injury. The antimicrobial effect of essential oils is mainly due to polyphenols and terpenes such as eugenol, cinnamaldehyde, carvacrol, and thymol.

Hybrid Hydrogels for Immunoregulation and Proangiogenesis through Mild Heat Stimulation to Accelerate Whole-Process Diabetic Wound Healing

Intense and persistent oxidative stress, excessive inflammation, and impaired angiogenesis severely hinder diabetic wound healing. Bioactive hydrogel dressings with immunoregulatory and proangiogenic properties have great promise in treating diabetic wounds. However, the therapeutic effects of dressings always depend on drugs with side effects, expensive cytokines, and cell therapies. Herein, a novel dynamic borate-bonds crosslinked hybrid multifunctional hydrogel dressings with photothermal properties are developed to regulate the microenvironment of diabetic wound sites and accelerate the whole process of its healing without additional medication. The hydrogel is composed of phenylboronic acid-modified chitosan and hyaluronic acid (HA) crosslinked by tannic acid (TA) through borate bonds and Prussian blue nanoparticles (PBNPs) with photothermal response characteristics are embedded in the polymer networks. The results indicate hydrogels show inherent broad-spectrum antioxidative activities through the integrated interaction of borate bonds, TA, and PBNPs. Meanwhile, combined with the regulation of macrophage phenotype by HA, the inflammatory microenvironment of diabetic wounds is transformed. Moreover, the angiogenesis is then enhanced by the mild photothermal effect of PBNPs, followed by promoted epithelialization and collagen deposition. In summary, this hybrid hydrogel system accelerates all stages of wound repair through antioxidative stress, immunomodulation, and proangiogenesis, showing great potential applications in diabetic wound management.

Recent Advances in Functional Hydrogel for Repair of Abdominal Wall Defects: A Review

The abdominal wall plays a crucial role in safeguarding the internal organs of the body, serving as an essential protective barrier. Defects in the abdominal wall are common due to surgery, infection, or trauma. Complex defects have limited self-healing capacity and require external intervention. Traditional treatments have drawbacks, and biomaterials have not fully achieved the desired outcomes. Hydrogel has emerged as a promising strategy that is extensively studied and applied in promoting tissue regeneration by filling or repairing damaged tissue due to its unique properties. This review summarizes the five prominent properties and advances in using hydrogels to enhance the healing and repair of abdominal wall defects: (a) good biocompatibility with host tissues that reduces adverse reactions and immune responses while supporting cell adhesion migration proliferation; (b) tunable mechanical properties matching those of the abdominal wall that adapt to normal movement deformations while reducing tissue stress, thereby influencing regulating cell behavior tissue regeneration; (c) drug carriers continuously delivering drugs and bioactive molecules to sites optimizing healing processes enhancing tissue regeneration; (d) promotion of cell interactions by simulating hydrated extracellular matrix environments, providing physical support, space, and cues for cell migration, adhesion, and proliferation; (e) easy manipulation and application in surgical procedures, allowing precise placement and close adhesion to the defective abdominal wall, providing mechanical support. Additionally, the advances of hydrogels for repairing defects in the abdominal wall are also mentioned. Finally, an overview is provided on the current obstacles and constraints faced by hydrogels, along with potential prospects in the repair of abdominal wall defects.

Measurement of the degree of deacetylation in chitosan films by FTIR, 1H NMR and UV spectrophotometry

The chitosan films were prepared from shrimp, squid, and crab to corroborate that regardless of the source of the chitosan, it was possible to measure the degree of deacetylation. In this work, the degree of deacetylation of chitosan was evaluated via UV, FTIR and 1H NMR spectrophotometry methodologies. Values in a range of 74 to 99% degree of deacetylation (DD) were obtained and varied depending on the method used and the source of chitosan. The spectrophotometric method is one of the most commonly used for this determination; however, it has the limitation that D-glucosamine and N-acetylglucosamine share similar wavelengths. All three methods were simple and provided rapid analysis; however, NMR, in particular, was expensive due to its equipment specifications. For this reason, its important to select the simplest method than can be routinely used.•The simplest used technique to determine the degree of deacetylation is infrared spectroscopy.•The degree of acetylation of chitosan is related to its physicochemical properties; its determination is an important parameter due to its association with chitosan applications in different industrial areas.•The 1H NMR method is very precise and requires expensive equipment and trained personal. Thus, it cannot be used routinely to determine the degree of deacetylation.

Progress in the Preparation and Application of Inulin-Based Hydrogels

Inulin, a natural polysaccharide, has emerged as a promising precursor for the preparation of hydrogels due to its biocompatibility, biodegradability, and structural versatility. This review provides a comprehensive overview of the recent progress in the preparation, characterization, and diverse applications of inulin-based hydrogels. Different synthesis strategies, including physical methods (thermal induction and non-thermal induction), chemical methods (free-radical polymerization and chemical crosslinking), and enzymatic approaches, are discussed in detail. The unique properties of inulin-based hydrogels, such as stimuli-responsiveness, antibacterial activity, and their potential as fat replacers, are highlighted. Special emphasis is given to their promising applications in drug delivery systems, especially for colon-targeted delivery, due to the selective degradation of inulin via colonic microflora. The ability to incorporate both hydrophilic and hydrophobic drugs further expands their therapeutic potential. In addition, the applications of inulin-based hydrogels in responsive materials, the food industry, wound dressings, and tissue engineering are discussed. While significant progress has been achieved, challenges and prospects in optimizing synthesis, improving mechanical properties, and exploring new functionalities are discussed. Overall, this review highlights the remarkable properties of inulin-based hydrogels as a promising class of biomaterials with immense potential in the biomedical, pharmaceutical, and materials science fields.

An Injectable, Self-Healing, Adhesive Multifunctional Hydrogel Promotes Bacteria-Infected Wound Healing

Bacterial infections have a serious impact on public health. It is urgent to develop antibacterial hydrogels with good biocompatibility to reduce the use of antibiotics. In this study, poly(lipoic acid-co-sodium lipoate)-phytic acid (P(LA-SL)-PA) hydrogels are prepared by a simple mixture of the natural small molecules lipoic acid (LA) and phytic acid (PA) in a mild and green reaction environment. The crosslinking network is constructed through the connection of covalent disulfide bonds as well as the hydrogen bonds, which endow the injectable and self-healing properties. The P(LA-SL)-PA hydrogels exhibit an adjustable compression modulus and adhesion. The in vitro agar plates assay indicates that the antibacterial rate of hydrogels against Escherichia coli and Staphylococcus aureus is close to 95%. In the rat-infected wound model, the P(LA-SL)-PA hydrogels adhere closely to the tissue and promote epithelialization and collagen deposition with a significant effect on wound healing. These results prove that the P(LA-SL)-PA hydrogels could act as effective wound dressings for promoting the healing of infected wounds.

Unveiling the potential of biomaterials and their synergistic fusion in tissue engineering

Inspired by nature, tissue engineering aims to employ intricate mechanisms for advanced clinical interventions, unlocking inherent biological potential and propelling medical breakthroughs. Therefore, medical, and pharmaceutical fields are growing interest in tissue and organ replacement, repair, and regeneration by this technology. Three primary mechanisms are currently used in tissue engineering: transplantation of cells (I), injection of growth factors (II) and cellular seeding in scaffolds (III). However, to develop scaffolds presenting highest potential, reinforcement with polymeric materials is growing interest. For instance, natural and synthetic polymers can be used. Regardless, chitosan and keratin are two biopolymers presenting great biocompatibility, biodegradability and non-antigenic properties for tissue engineering purposes offering restoration and revitalization. Therefore, combination of chitosan and keratin has been studied and results exhibit highly porous scaffolds providing optimal environment for tissue cultivation. This review aims to give an historical as well as current overview of tissue engineering, presenting mechanisms used and polymers involved in the field.

Current research status and development prospects of embolic microspheres containing biological macromolecules and others

Transcatheter arterial embolization (TACE) has been used in the treatment of malignant tumors, sudden hemorrhage, uterine fibroids, and other diseases, and with advances in imaging techniques and devices, materials science, and drug release technology, more and more embolic agents that are drug-carrying, self-imaging, or have multiple functions are being developed. Microspheres provide safer and more effective therapeutic results as embolic agents, with their unique spherical appearance and good embolic properties. Embolic microspheres are the key to arterial embolization, blocking blood flow and nutrient supply to the tumor target. This review summarizes some of the currently published embolic microspheres, classifies embolic microspheres according to matrix, and summarizes the characteristics of the microsphere materials, the current status of research, directions, and the value of existing and potential applications. It provides a direction to promote the development of embolic microspheres towards multifunctionalization, and provides a reference to promote the research and application of embolic microspheres in the treatment of tumors.

Synthesis of poly(ionic liquid-OH) mediated deacetylated chitin and its hydrogels: A study on their applications in controlled release of paracetamol and urea

Due to the biodegradable and biocompatible nature of chitin and chitosan, they are extensively used in the synthesis of hydrogels for various applications. In this work, deacetylation of chitin is carried out with alkaline poly(dimethyldiallylammonium-hydroxide) that gave a higher amount of water-soluble chitin (with 84 % of the degree of deacetylation = chitosan0.84) compared to deacetylation using NaOH. The water-soluble chitosan0.84 is used as intercalating chains for the preparation of acrylic acid and vinylimidazole-based hydrogels. The quaternization of imidazole groups is done with 1,ω-dibromoalkanes, which sets off the crosslinking in the above polymer network. A set of three chitosan0.84 intercalated hydrogels, namely Cs-C4-hydrogel, Cs-C5-hydrogel, and Cs-C10-hydrogel are prepared bearing butyl, pentyl, and decyl chains as respective crosslinkers. The swell ratios of these intercalated hydrogels are compared with those of non-intercalated hydrogels (C4-hydrogel, C5-hydrogel, and C10-hydrogel). Chitosan0.84 intercalated Cs-C10-hydrogel has excellent swelling properties (2330 % swelling ratio) among six synthesized hydrogels. SEM analysis reveals that decyl crosslinker-bearing hydrogels are highly porous. The multi-functionality of Cs-C10-hydrogel and C10-hydrogel is explored towards -the controlled release of paracetamol/urea, and methyleneblue dye absorption. These studies disclose that chitosan0.84 intercalated hydrogels are showing superior-swelling behavior, high paracetamol/urea loading capacities and better dye entrapment than their non-intercalated counterparts.

Chitosan-based hydrogel dressings for diabetic wound healing via promoting M2 macrophage-polarization

A long-term inflammatory phase of diabetic wounds is the primary cause to prevent their effective healing. Bacterial infection, excess reactive oxygen species (ROS), especially failure of M2-phenotype macrophage polarization can hinder the transition of diabetic wounds from an inflammation phase to a proliferation one. Herein, a chitosan-based hydrogel dressing with the ability of regulating M2 macrophage polarization was reported. The PAAc/CFCS-Vanillin hydrogel dressing was synthesized by one step thermal polymerization of catechol-functionalized chitosan (CFCS), acrylic acid, catechol functional methacryloyl chitosan‑silver nanoparticles (CFMC-Ag NPs) and bioactive vanillin. The PAAc/CFCS-Vanillin hydrogel possessed sufficient mechanical strength and excellent adhesion properties, which helped rapidly block bleeding of wounds. Thanks to CFCS, CFMC-Ag NPs and vanillin in the hydrogel, it displayed excellent antibacterial infection in the wounds. Vanillin helped scavenge excess ROS and regulate the levels of inflammatory factors to facilitate the polarization of macrophages into the M2 phenotype. A full-thickness skin defect diabetic wound model showed that the wounds treated by the PAAc/CFCS-Vanillin hydrogel exhibited the smallest wound area, and superior granulation tissue regeneration, remarkable collagen deposition, and angiogenesis were observed in the wound tissue. Therefore, the PAAc/CFCS-Vanillin hydrogel could hold promising potential as a dressing for the treatment of diabetic chronic wounds.

Multifunctional chitosan-based hydrogel wound dressing loaded with Acanthopanax senticosus and Osmundastrum cinnamomeum: Preparation, characterization and coagulation mechanism

Considerable potential exists for the development of natural polymer hydrogels that possess notable antibacterial and anti-inflammatory properties, along with excellent biocompatibility and mechanical attributes, to expedite the healing of skin wounds. Recent endeavors have focused on formulating an optimal hydrogel dressing for wound hemostasis and repair. In this pursuit, we have crafted a composite hydrogel using carboxymethyl chitosan and alginic acid, cross-linked with EDC/NHS, and enriched with extracts from Acanthopanax senticosus and Osmundastrum cinnamomeum. This synthesized hydrogel showcases commendable features, including significant swelling capacity (135 ± 3.6%), proficient water retention (94.421 ± 0.154%), and effective water vapor permeability (5845.011 ± 467.799 g/m2/d). Moreover, our drug-loaded hydrogels (CMCS/SA/AS/OC) have demonstrated remarkable efficacy in accelerating wound healing in both in vivo and in vitro models. On the 7th day, the wound healing rate reached 94.905% ± 0.498%, and by the 14th day, the wound was nearly fully healed (98.08% ± 0.323%) with the emergence of hair coverage. Furthermore, these hydrogels exhibited remarkable hemostatic properties, the platelet activity was 89.37% ± 1.29% and the platelet adhesion rate was 66.36% ± 1.42%. In order to elucidate the coagulation mechanism of the Acanthopanax senticosus and Osmundastrum cinnamomeum extracts, a network pharmacology approach was carried out. 41 active compounds and 107 potential therapeutic targets associated with these extracts were identified, revealing a total of 132 coagulation pathways. Platelet activation and complement and coagulation cascades pathways showed the highest levels of enrichment by KEGG analysis, serving as potential mechanisms through which the active components in AS/OC may facilitate coagulation by targeting relevant factors. In summary, our study has successfully developed an innovative drug-loaded hydrogel that not only enhances wound hemostasis and healing but also provides insights into the underlying mechanisms through network pharmacology. This work establishes a robust theoretical foundation for the medical application of our hydrogel.

A Novel Strategy for Topical Administration by Combining Chitosan Hydrogel Beads with Nanostructured Lipid Carriers: Preparation, Characterization, and Evaluation

The objective of the present study was to develop and evaluate NLC-chitosan hydrogel beads for topical administration. The feasibility of the preparation technology was verified by investigating various formulation factors and the impact of chitosan hydrogel beads on the NLC. The encapsulation efficiency of NLC-chitosan hydrogel beads was above 95% in optimized process conditions. The physical characterization of the NLC-chitosan hydrogel beads showed that the NLC was distributed within the network of the chitosan hydrogel beads. Furthermore, the incorporation of NLC into the chitosan hydrogel beads was related to the electrostatic interaction between the surface of the NLC and chitosan, which influenced the lipid ordering degree of the NLC and contributed to the stability. The stability studies showed that the retention rate of quercetin in the NLC-chitosan hydrogel beads was 88.63 ± 2.57% after 10 months of storage under natural daylight. An in vitro permeation study showed that NLC-chitosan hydrogel beads exhibited superior ability in enhancing skin permeation by hydrophobic active ingredients compared to the NLC and significantly increased skin accumulation. These studies demonstrated that the use of NLC-chitosan hydrogel beads might be a promising strategy for the delivery of hydrophobic active ingredients in topical administration.

Direct ink writing of biocompatible chitosan/non-isocyanate polyurethane/cellulose nanofiber hydrogels for wound-healing applications

The demand for new biocompatible and 3D printable materials for biomedical applications is on the rise. Ideally, such materials should exhibit either biodegradability or recyclability, possess antibacterial properties, and demonstrate remarkable biocompatibility with no cytotoxic effects. In this research, we synthesized biocompatible and 3D printable hydrogels tailored for biomedical applications, such as wound healing films, by combining antibacterial double-quaternized chitosan (DQC) with cystamine-based non-isocyanate polyurethane (NIPU-Cys) - a material renowned for enhancing both the flexibility and mechanical properties of the hydrogels. To improve the rheological behavior, swelling attributes, and printability, cellulose nanofibrils were introduced into the matrix. We investigated the impact of DQC on degradability, swelling capacity, rheological behavior, printability, and cell biocompatibility. The slightly cytotoxic nature associated with quaternary chitosan was evaluated, and the optimal concentration of DQC in the hydrogel was determined to ensure biocompatibility. The resulting hydrogels were found to be suitable materials for 3D printing via a direct ink writing technique (DIW), producing porous, biocompatible hydrogels endowed with valuable attributes suitable for various wound-healing applications.

A chitosan-based antibacterial hydrogel with injectable and self-healing capabilities

The presence of bacteria directly affects wound healing. Chitosan-based hydrogel biomaterials are a solution as they offer advantages for wound-healing applications due to their strong antimicrobial properties. Here, a double-cross-linking chitosan-based hydrogel with antibacterial, self-healing, and injectable properties is reported. Thiolated chitosan was successfully prepared, and the thiolated chitosan molecules were cross-linked by Ag-S coordination to form a supramolecular hydrogel. Subsequently, the amine groups in the thiolated chitosan covalently cross-linked with genipin to further promote hydrogel formation. In vitro experimental results indicate that hydrogel can release Ag+ over an extended time, achieving an antibacterial rate of over 99% against Escherichia coli and Staphylococcus aureus. Due to the reversible and dynamic feature of Ag-S coordination, an antibacterial hydrogel exhibited injectable and self-healing capabilities. Additionally, the hydrogel showed excellent biocompatibility and biodegradability.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-023-00211-z.