A photocrosslinked methacrylated carboxymethyl chitosan/oxidized locust bean gum double network hydrogel for cartilage repair

An adhesive, antibacterial hydrogel wound dressing fabricated by dopamine-grafted oxidized sodium alginate and methacrylated carboxymethyl chitosan incorporated with Cu(II) complex

Effective wound dressings play an important role in preventing infections and promoting wound healing. Most polysaccharide-based hydrogel dressings have the drawbacks of weak tissue adhesion and poor antibacterial properties. Herein, a multifunctional dopamine-grafted oxidized sodium alginate-methacrylated carboxymethyl chitosan/gallic acid‑copper(II) complex (OD-CM/GA-CuIIUV) hydrogel was fabricated through Schiff base bonds and photo-crosslinked polymerization between dopamine-grafted oxidized sodium alginate (OSA-DA) and methacrylated carboxymethyl chitosan (CMC-MA), with the integration of gallic acid‑copper(II) complexes (GA-CuII). The double cross-linked network and mussel-inspired adhesion mechanism endowed the hydrogel with attractive physicochemical properties, including excellent self-healing properties, pH-responsive biodegradability, robust toughness, and a maximum adhesion strength of 15.06 kPa. Moreover, the composite hydrogel exhibited an antibacterial ratio of > 99 % against Escherichia coli and Staphylococcus aureus, as well as good antioxidant activity. The MTT assay showed that the cell viability of the composite hydrogel reached > 85 %. The in vivo full-thickness skin defect healing assays in rats demonstrated that the composite hydrogel remarkably accelerated wound repair by attenuating the inflammatory response and promoting epithelial tissue remodeling. Therefore, this novel multifunctional hydrogel has potential applications in biomedical wound dressing.

The preparation of 3D-printed self-healing hydrogels composed of carboxymethyl chitosan and oxidized dextran via stereolithography for biomedical applications

This study presents a new approach for fabricating 3D-printed self-healing hydrogels via light-assisted 3D printing, utilizing Schiff-base and covalent bonding formations resulting from the reaction between amine and aldehyde functional groups alongside the photopolymerization of methacrylate groups. Two distinct polymers, carboxymethyl chitosan (CMCs) and dextran, were first modified to yield methacrylate-modified carboxymethyl chitosan (CMCs-MA) and oxidized dextran (OD). The structural modifications of these polymers were confirmed using spectroscopic techniques, including 1H NMR and FTIR analyses. Variations in polymer concentration and degree of oxidation resulted in significant differences in the physical properties of resulting hydrogels (e.g., mechanical performance, swelling ratio, and microstructure) and biological responses. The compressive moduli revealed in the range of 14.31 ± 1.38 to 26.20 ± 3.31 kPa. Chondrocytes cultured with various hydrogel formulations exhibited distinct cell morphology and adhesion differences, driven by the interaction between the mechanical and biochemical properties of the hydrogel. We have developed a strategy for fabricating 3D-printed self-healing hydrogels with tunable stiffness, enabling the regulation of chondrocyte morphology and demonstrating significant potential for biomedical applications.

Rapid preparation of injectable dual-network hydrogels for biomedical applications using UV-triggered sulfhydryl click reactions

The use of hydrogels to mimic natural cartilage implantation can effectively solve the current problems of insufficient cartilage donors and low rate of injury healing. In particular, injectable hydrogels are less invasive in clinical applications and better able to fill uneven injury surfaces. Here, we prepared NorCS and CS-SH by modifying chitosan with 5-norbornene-2-carboxylic acid and N-Acetyl-L-cysteine, respectively. Dual-network hydrogels were prepared by using UV-triggered thiol-ene click reaction between NorCS and CS-SH and the metal coordination between SA and Ca2+. The prepared hydrogels can be cross-linked quickly and exhibit excellent degradability, self-healing and injectable properties. At the same time, the hydrogel also showed good cytocompatibility and could significantly restore the motor function of mice. This study provides an effective strategy for preparing injectable hydrogels capable of rapid cross-linking.

Antioxidant hydrogels for the treatment of osteoarthritis: mechanisms and recent advances

Articular cartilage has limited self-healing ability, resulting in injuries often evolving into osteoarthritis (OA), which poses a significant challenge in the medical field. Although some treatments exist to reduce pain and damage, there is a lack of effective means to promote cartilage regeneration. Reactive Oxygen Species (ROS) have been found to increase significantly in the OA micro-environment. They play a key role in biological systems by participating in cell signaling and maintaining cellular homeostasis. Abnormal ROS expression, caused by internal and external stimuli and tissue damage, leads to elevated levels of oxidative stress, inflammatory responses, cell damage, and impaired tissue repair. To prevent excessive ROS accumulation at injury sites, biological materials can be engineered to respond to the damaged microenvironment, release active components in an orderly manner, regulate ROS levels, reduce oxidative stress, and promote tissue regeneration. Hydrogels have garnered significant attention due to their excellent biocompatibility, tunable physicochemical properties, and drug delivery capabilities. Numerous antioxidant hydrogels have been developed and proven effective in alleviating oxidative stress. This paper discusses a comprehensive treatment strategy that combines antioxidant hydrogels with existing treatments for OA and explores the potential applications of antioxidant hydrogels in cartilage tissue engineering.

A chitosan-based light-curing hydrogel dressing for accelerated healing of infected wounds

Bacterial infections, excessive reactive oxygen species (ROS) accumulation and a persistent inflammatory response severely impede the wound healing process. In this study, we developed a novel multifunctional hydrogel dressing (LCPN) based on lipoic acid modified chitosan (LAMC), polypyrrole nanoparticles (PPy NPs) and nicotinamide mononucleotide (NMN) for accelerated healing of infected wounds. The synthesized LCPN hydrogel has several properties. Modification of lipoic acid significantly enhances the water solubility of chitosan making it easier to dissolve and absorb wound secretions. Interestingly, owing to the breaking and restructuring of disulfide bonds, LCPN hydrogel can be quickly bonded under UV light without relying on photoinitiators. In addition, the incorporation of PPy NPs not only enhances the electrical conductivity of LCPN hydrogel, but also confers photothermal antimicrobial capability to LCPN hydrogel. More importantly, the sustained release of NMN in LCPN hydrogel can significantly enhance cell proliferation, migration and antioxidant capacity, which is conducive to accelerated wound healing. In vitro and in vivo experiments have shown that LCPN hydrogel has excellent biocompatibility and the ability to promote wound healing. Therefore, the prepared multifunctional hydrogel is expected to be used as a novel dressing to accelerate wound healing.

Recent advances on chitosan/hyaluronic acid-based stimuli-responsive hydrogels and composites for cancer treatment: A comprehensive review

Cancer, as leading cause of death, has a high rate of mortality worldwide. Although there is a wide variety of conventional approaches for the treatment of cancer (such as surgery and chemotherapy), they have considerable drawbacks in terms of practicality, treatment efficiency, and cost-effectiveness. Therefore, there is a fundamental requirement for the development of safe and efficient treatment modalities based on breakthrough technologies to suppress cancer. Chitosan (CS) and hyaluronic acid (HA) polysaccharides, as FDA-approved biomaterials for some biomedical applications, are potential biopolymers for the efficient treatment of cancer. CS and HA have high biocompatibility, bioavailability, biodegradability, and immunomodulatory function which guarantee their safety and non-toxicity. CS-/HA-based hydrogels (HGs)/composites stand out for their potential anticancer function, versatile preparation and modification, ease of administration, controlled/sustained drug release, and active and passive drug internalization into target cells which is crucial for efficient treatment of cancer compared with conventional treatment approaches. These HGs/composites can respond to external (magnetic, ultrasound, light, and thermal) and internal (pH, enzyme, redox, and ROS) stimuli as well which further paves the way to their manipulation, targeted drug delivery, practicality, and efficient treatment. The above-mentioned properties of CS-/HA-based HGs/composites are unique and practical in cancer treatment which can ignore the deficiencies of conventional approaches. The present manuscript comprehensively highlights the advances in the practical application of stimuli-responsive HGs/composites based on CS/HA polysaccharides.

Near-infrared light-actuated on-demand botanicals release and hyperthermia by an antibiotic-free polysaccharide-based hydrogel dressing for the synergistic treatment of wound infections

Bacterial infection is a key factor affecting wound healing. Conventional treatments might lead to the widespread emergence of drug-resistant bacteria due to the long-term and excessive use of antibiotics. It is necessary to develop an antibiotic-free method for effective treatment of bacterial wound infections. In this work, we constructed an antibiotic-free polysaccharide-based hydrogel dressing (ATB) with near-infrared light-actuated on-demand botanicals release and hyperthermia for the synergistic treatment of wound infections. The ATB hydrogel dressing was made up of agarose as a support matrix, berberine hydrochloride as the active botanicals and TA-Fe(III) nanoparticles as NIR laser-activated photothermal reagents. The ATB hydrogel dressing showed spatiotemporal botanicals release and excellent photothermal properties with NIR irradiation. With the results of in vitro and in vivo antibacterial experiments, the antibiotic-free ATB hydrogel could synergistically eliminate bacteria and accelerate wound healing. Overall, the near-infrared light-responsive ATB hydrogel could provide a promising antibiotic-free strategy for the treatment of bacterial wound infections.