A dynamically cross-linked catechol-grafted chitosan/gelatin hydrogel dressing synergised with photothermal therapy and baicalin reduces wound infection and accelerates wound healing

State-of-the-art in natural hydrogel-based wound dressings: Design, functionalization, and fabrication approaches

Natural hydrogel-based wound dressings, synthesized from biopolymers such as chitosan, sodium alginate, and cellulose, are gaining recognition in wound care due to their ability to promote healing through biocompatibility, moisture retention, and biodegradability. These materials foster an ideal healing environment by supporting cell proliferation and tissue regeneration while providing a protective barrier against infection. For chronic or infected wounds, enhancing the therapeutic performance of these hydrogels is essential. This review critically evaluates advanced functionalization strategies, including chemical modifications to optimize hydrogel properties, the incorporation of bioactive agents like growth factors and antimicrobial compounds, and the development of stimuli-responsive hydrogels that adjust to environmental cues such as pH, temperature, and enzymatic activity. Furthermore, fabrication techniques-such as solution casting, freeze-drying, electrospinning, and 3D printing-are discussed for their potential to generate tailored dressings with specific mechanical properties and bioactive capabilities. By highlighting key innovations and challenges, this review provides a comprehensive roadmap for the design, functionalization, and fabrication of natural hydrogel-based wound dressings, identifying critical areas for future research and development.

Multi-functional chitosan fiber-based dressings prepared by screen printing of baicalein and activated charcoal

In this study, chitosan needle-punched nonwovens (CS) was screen-printed with functional inks containing baicalein (Bai) and activated charcoal (AC) to prepare multifunctional dressings (AC + Bai@CS). The polyelectrolyte interaction between chitosan (matrix) and sodium carboxymethylcellulose (binder) facilitated the firm attachment of Bai and AC to the CS. Moreover, the screen-printed ink did not impact the surface hydrophilicity and the excellent air permeability (1837.5 ± 34.03 mm/s) of AC + Bai@CS. The printing of baicalein on the chitosan matrix resulted in a synergistic effect, leading to the AC + Bai@CS exhibiting enhanced antibacterial, antioxidant, and anti-inflammatory properties while maintaining cytocompatible characteristics. Furthermore, the deodorization rates of AC + Bai@CS against ammonia and acetic acid were 84.2 ± 1.6 % and 75.4 ± 1.1 %, respectively, indicating its potential deodorization effect on chronic wounds. This study presents a novel approach to developing multifunctional wound dressings via facile screen printing.

An antimicrobial and adhesive conductive chitosan quaternary ammonium salt hydrogel dressing for combined electrical stimulation and photothermal treatment to promote wound healing

The aim of this study is to investigate the effect of the adhesive, conductive hydrogel on wound healing when used as a therapeutic dressing. Herein, a dressing of PVA/QCS/TP@Fe3+ (PQTF) was designed and prepared integrating polyvinyl alcohol (PVA), chitosan quaternary ammonium salt (QCS), tea polyphenol (TP), and ferric ions (Fe3+) by a simple one-pot and freeze-thaw method. In view of the comprehensive properties of PQTF600 hydrogel, including adhesion, electrical conductivity, and swelling performance, PQTF600 was selected for subsequent in vitro and in vivo healing promotion studies. PQTF600 had good adhesion and conductive ability, which was suitable for human motion monitoring and wound treatment. Notably, the PQTF600 showed and controllable human safety temperature thresholds (~44.8 °C) under near-infrared light (NIR). Meanwhile, PQTF600 achieved nearly 100 % antibacterial activity against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Pseudomonas putida (P. putida), methicillin-resistant Staphylococcus aureus (MRSA). In addition, the PQTF600 hydrogel dressing was demonstrated to achieve 99.59 ± 4.11 % would healing rate in a mouse trauma model under the dual stimulation of NIR (808 nm) and electricity (1.5 V direct current). The versatile PQTF600 hydrogel is a promising dressing for enhancing wound closure integrating with electrical stimulation (ES) and photothermal therapy.

Bacterial cellulose nanofiber reinforced self-healing hydrogel to construct a theranostic platform of antibacterial and enhanced wound healing

In order to promote wound healing, self-healing hydrogels with moisturizing property are employed as wound dressing. In this study, bacterial cellulose nanofibers (BCN) with high mechanical strength are used as reinforcement to improve the mechanical properties of self-healing hydrogels. A multifunctional self-healing hydrogel has been constructed by incorporating natural biomass, including Ag hybrid bacterial cellulose nanofiber (Ag-BCN), resveratrol (Res), and carbon nanodots (CNDs). The results of in vitro experiments demonstrate that the mechanical strength of the hybrid hydrogel was increased by 6 times with the addition of Ag-BCN, which also offers excellent antibacterial efficiency (S. aureus 99.99 % and E. coli 99.68 %). The hydrogel with CNDs can observe the healing process of the crack in real time and realize the controlled release of Res through photothermal effect. Moreover, the results of animal model experiments indicate that the prepared hydrogel could reduce the infection of the wound, effectively shorten the progress of wound healing (from 21d to 14 d). All the results imply that the prepared hydrogel has great promise in the application of skin wound healing.

Nanofiber-reinforced chitosan/gelatine hydrogel with photothermal, antioxidant and conductive capabilities promotes healing of infected wounds

The wound healing process was often accompanied by bacterial infection and inflammation. The combination of electrically conductive nanomaterials and wound dressings could accelerate cell proliferation through endogenous electrical signaling, effectively promoting wound healing. In this study, polypyrrole was modified with dopamine hydrochloride by an in situ polymerization to form dopamine-polypyrrole (DA-Ppy) conductive nanofibers which successfully enhanced the water dispersibility and biocompatibility of polypyrrole. The DA-Ppy nanofibers were dispersed in an aqueous solution for >48 h and still maintained good stability. In addition, the DA-Ppy nanofibers showed good photothermal properties, and the temperature could reach 59.7 °C by 1.5 W/cm2 near-infrared light irradiation (NIR) for 10 min. DA-Ppy conductive nanofibres could be well dispersed in 3,4-dihydroxyphenylpropionic acid modified chitosan-carboxymethylated β-cyclodextrin modified gelatin (CG) hydrogel due to the presence of DA, which endowed CG/DA-Ppy hydrogel with good adhesion properties, and the hydrogel adhered to the pigskin would not be dislodged by washing with running water. Under NIR, the CG/DA-Ppy hydrogel showed significant antimicrobial properties. Moreover, the CG/DA-Ppy hydrogel had excellent biocompatibility. In addition, CG/DA-Ppy hydrogel was effective in scavenging ROS, inducing macrophage polarization towards the M2 phenotype, and modulating the level of wound inflammation in vitro. Finally, it was confirmed in rat-infected wounds that the tissue regeneration effect and collagen deposition in the CG/DA-Ppy + NIR group were significantly better than the other groups in the repair of infected wounds, indicating better repair of infected wounds. The results suggested that the photothermal, antioxidant DA-Ppy conductive nanofiber had great potential for application in infected wound healing.

Tissue adhesives based on chitosan for biomedical applications

Chitosan bio-adhesives bond strongly with various biological tissues, such as skin, mucosa, and internal organs. Their adhesive ability arises from amino acid and hydroxyl groups in chitosan, facilitating interactions with tissue surfaces through chemical (ionic, covalent, and hydrogen) and physical (chain entanglement) bonding. As non-toxic, biodegradable, and biocompatible materials, chitosan bio-adhesives are a safe option for medical therapies. They are particularly suitable for drug delivery, wound healing, and tissue regeneration. In this review, we address chitosan-based bio-adhesives and the mechanisms associated with them. We also discuss different chitosan composite-based bio-adhesives and their biomedical applications in wound healing, drug delivery, hemostasis, and tissue regeneration. Finally, challenges and future perspectives for the clinical use of chitosan-based bio-adhesives are discussed.