A Gelatin-Based Composite Hydrogel with a "One Stone, Two Birds" Strategy for Photothermal Antibacterial and Vascularization of Infected Wounds

A functional hydrogel of dopamine-modified gelatin with photothermal properties for enhancing infected wound healing

Infected skin wound has gradually become a prevalent injury that affects overall health. Currently, biomaterials with good adhesion, efficient antibacterial properties, and angiogenesis are considered as a suitable way to effectively heal infected wound. Herein, a multifunctional hydrogel comprising gelatin, dopamine (DA), and ferric ions (Fe3+) was developed for infected wound healing. The modified gelatin-dopamine (Gel-DA) enhanced adhesive capability. Subsequently introducing ferric ions (Fe3+) to form Gel-DA-Fe3+ hydrogels by Fe3+ and catechol coordination bonds. The designed hydrogels demonstrated multifaceted functionality, encompassing photothermal antibacterial, angiogenesis, and so on. The introduction of DA enhanced the adhesion of Gel-DA-Fe3+ to the skin surface and might serve as a physical barrier to seal wound. Meanwhile, DA and Fe3+ jointly endowed good photothermal effects to composite hydrogels, which could eliminate over 95 % of bacteria. In vitro results revealed that Gel-DA-Fe3+ hydrogels had good biocompatibility and promoted HUVECs migration and tube formation. Furthermore, in vivo studies confirmed that Gel-DA-Fe3+ hydrogels markedly expedited the wound healing of rats through eradicating bacteria, accelerating the deposition of collagen, and promoting angiogenesis. What's more, Gel-DA-Fe3+ hydrogels under near-infrared laser had a more pronounced ability for wound healing. Therefore, Gel-DA-Fe3+ hydrogels had great potential for application in bacteria-infected wound healing.

Bletilla striata Polysaccharide-/Chitosan-Based Self-Healing Hydrogel with Enhanced Photothermal Effect for Rapid Healing of Diabetic Infected Wounds via the Regulation of Microenvironment

The management of diabetic ulcers poses a significant challenge worldwide, and persistent hyperglycemia makes patients susceptible to bacterial infections. Unfortunately, the overuse of antibiotics may lead to drug resistance and prolonged infections, contributing to chronic inflammation and hindering the healing process. To address these issues, a photothermal therapy technique was incorporated in the preparation of wound dressings. This innovative solution involved the formulation of a self-healing and injectable hydrogel matrix based on the Schiff base structure formed between the oxidized Bletilla striata polysaccharide (BSP) and hydroxypropyltrimethylammonium chloride chitosan. Furthermore, the introduction of CuO nanoparticles encapsulated in polydopamine imparted excellent photothermal properties to the hydrogel, which promoted the release of berberine (BER) loaded on the nanoparticles and boosted the antibacterial performance. In addition to providing a reliable physical protection to the wound, the developed hydrogel, which integrated the herbal components of BSP and BER, effectively accelerated wound closure via microenvironment regulation, including alleviated inflammatory reaction, stimulated re-epithelialization, and reduced oxidative stress based on the promising results from cell and animal experiments. These impressive outcomes highlighted their clinical potential in safeguarding the wound against bacterial intrusion and managing diabetic ulcers.

An injectable hydrogel dressing for controlled release of hydrogen sulfide pleiotropically mediates the wound microenvironment

The healing of scalded wounds faces many challenges such as chronic inflammation, oxidative stress, wound infection, and difficulties in vascular and nerve regeneration. Treating a single problem cannot effectively coordinate the complex regenerative microenvironment of scalded wounds, limiting the healing and functional recovery of the skin. Therefore, there is a need to develop a multi-effect treatment plan that can adaptively address the issues at each stage of wound healing. In this study, we propose a scheme for on-demand release of hydrogen sulfide (H2S) based on the concentration of reactive oxygen species (ROS) in the wound microenvironment. This is achieved by encapsulating peroxythiocarbamate (PTCM) in the ROS-responsive polymer poly(ethylene glycol)-poly(L-methionine) (PMet) to form nanoparticles, which are loaded into a thermosensitive injectable hydrogel, F127-poly(L-aspartic acid-N-hydroxysuccinimide) (F127-P(Asp-NHS)), to create a scald dressing. The H2S released by the hydrogel dressing on demand regulates the wound microenvironment by alleviating infection, reducing oxidative stress, and remodeling inflammation, thereby accelerating the healing of full-thickness scalded wounds. This hydrogel dressing for the adaptive release of H2S has great potential in addressing complex scalded wounds associated with infection and chronic inflammation.

Puerarin-containing rhein-crosslinked tyramine-modified hyaluronic acid hydrogel for antibacterial and anti-inflammatory wound dressings

Wound infections, posing a grave risk of severe physical consequences and even mortality, exact a substantial financial toll on society, rendering them among the most formidable challenges confronting our world today. A critical imperative is the development of hydrogel dressings endowed with immune-regulating and antibacterial properties. This study is founded upon the symbiotic physical and efficacious attributes of two small natural molecules. An injectable hydrogel is meticulously crafted by encapsulating puerarin (PUE) into tyramine-modified hyaluronic acid, subsequently introducing rhein (RHE), and catalyzing the formation of inter-phenol crosslinks with H2O2/horseradish peroxidase (HA-Tyr-R@P). Exhibiting a favorable microenvironmental impact the developed hydrogel attains an antibacterial efficacy exceeding 95 %, coupled with a wound closure rate twice that of the control group. HA-Tyr-R@P hydrogels not only inhibit bacterial growth but also mitigate inflammation, fostering wound healing, owing to their harmonized physicochemical characteristics and synergistic therapeutic effects. This work underscores the creation of a singular, versatile hydrogel platform, negating the complexities and side effects associated with pharmaceutical preparations. Furthermore, it offers new ideas for the formulation of RHE-based hydrogels for wound healing, emphasizing the pivotal role of natural small molecules in advancing biological materials.

Composite Aerogel Scaffolds Containing Flexible Silica Nanofiber and Tricalcium Phosphate Enable Skin Regeneration

Poor hemostatic ability and less vascularization at the injury site could hinder wound healing as well as adversely affect the quality of life (QOL). An ideal wound dressing should exhibit certain characteristics: (a) good hemostatic ability, (b) rapid wound healing, and (c) skin appendage formation. This necessitates the advent of innovative dressings to facilitate skin regeneration. Therapeutic ions, such as silicon ions (Si4+) and calcium ions (Ca2+), have been shown to assist in wound repair. The Si4+ released from silica (SiO2) can upregulate the expression of proteins, including the vascular endothelial growth factor (VEGF) and alpha smooth muscle actin (α-SMA), which is conducive to vascularization; Ca2+ released from tricalcium phosphate (TCP) can promote the coagulation alongside upregulating the expression of cell migration and cell differentiation related proteins, thereby facilitating the wound repair. The overarching objective of this study was to exploit short SiO2 nanofibers along with the TCP to prepare TCPx@SSF aerogels and assess their wound healing ability. Short SiO2 nanofibers were prepared by electrospinning and blended with varying proportions of TCP to afford TCPx@SSF aerogel scaffolds. The TCPx@SSF aerogels exhibited good cytocompatibility in a subcutaneous implantation model and manifested a rapid hemostatic effect (hemostatic time 75 s) in a liver trauma model in the rabbit. These aerogel scaffolds also promoted skin regeneration and exhibited rapid wound closure, epithelial tissue regeneration, and collagen deposition. Taken together, TCPx@SSF aerogels may be valuable for wound healing.

Antioxidant and antibacterial hydrogel formed by protocatechualdehyde-ferric iron complex and aminopolysaccharide for infected wound healing

To better treat bacteria-infected wounds and promote healing, new wound dressings must be developed. In this study, we obtained PA@Fe by chelating iron trivalent ions (Fe3+) with protocatechualdehyde (PA), which has a catechol structure. Subsequently, we reacted it with ethylene glycol chitosan (GC) via a Schiff base reaction and loaded vancomycin to obtain an antibacterial Gel@Van hydrogel with a photothermal response. The as-prepared Gel@Van hydrogel exhibited good injectability, self-healing, hemostasis, photothermal stability, biocompatibility, and antioxidant and antibacterial properties. Moreover, Gel@Van hydrogel achieved highly synergistic antibacterial efficacy through photothermal and antibiotic sterilization. In a mouse skin-damaged infection model, Gel@Van hydrogel had a strong ability to promote the healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds, indicating the great potential application value of Gel@Van hydrogel in the field of treating and promoting the healing of infected wounds.

Photothermal hydrogels for infection control and tissue regeneration

In this review, we report investigating photothermal hydrogels, innovative biomedical materials designed for infection control and tissue regeneration. These hydrogels exhibit responsiveness to near-infrared (NIR) stimulation, altering their structure and properties, which is pivotal for medical applications. Photothermal hydrogels have emerged as a significant advancement in medical materials, harnessing photothermal agents (PTAs) to respond to NIR light. This responsiveness is crucial for controlling infections and promoting tissue healing. We discuss three construction methods for preparing photothermal hydrogels, emphasizing their design and synthesis, which incorporate PTAs to achieve the desired photothermal effects. The application of these hydrogels demonstrates enhanced infection control and tissue regeneration, supported by their unique photothermal properties. Although research progress in photothermal hydrogels is promising, challenges remain. We address these issues and explore future directions to enhance their therapeutic potential.

Curcumin-loaded chitosan-based hydrogels accelerating S. aureus-infected wound healing

The damaged skin for some reasons is vulnerable to invasion by bacteria and other harmful microorganisms, leading to delay of the wound healing. In order to promote the infected wound healing, curcumin was loaded with chitosan-based hydrogel was formed through phenylborate ester bonding and its properties and effects on the S. aureus-infected wound healing was tested. It was found the hydrogel showed good antioxidation on the intracellular reactive oxygen species, inhibition on the growth of S. aureus, and acceleration the infected skin healing. The ablity of hydrogel due to its regulating inflammation, promoting angiogenesis and collagen synthesis in the wound site. This research work suggested that the developed multifunctional hydrogel might be a beneficial treatment for the infected wound healing.

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.

Biomimetic Hemostatic Powder Derived from Coacervate-Immobilized Thermogelling Copolymers

Intrinsic hemostasis is an innate body response to prevent bleeding based on the sol-gel transition of blood. However, it is often inadequate for exceptional situations, such as acute injury and coagulation disorders, which typically require immediate medical intervention. Herein, we report the preparation of an efficient hemostatic powder, composed of tannic acid (TA), poly(ethylene glycol) (PEG), and poly(d,l-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(d,l-lactide-co-glycolide) triblock copolymer (TB), for biomimetic hemostasis at the bleeding sites. TA has a high affinity for biomolecules and cells and can form coacervates with PEG driven by hydrogen bonding. TB enhances the mechanical strength and provides thermoresponsiveness. The hemostatic powder can rapidly transit into a physical and biodegradable seal on wet substrates under physiological conditions, demonstrating its promise for the generation of instant artificial clots. Importantly, this process is independent of the innate blood clotting process, which could benefit those with blood clotting disorders. This biomimetic hemostatic powder is an adaptive topical sealing agent for noncompressible and irregular wounds, which is promising for biomedical applications.

Photocuring and Gelatin-Based Antibacterial Hydrogel for Skin Care

The development of moisturizing, antibacterial, and biocompatible multifunctional hydrogels is essential to protect skin and promote skin defects recovery. Gelatin has admired potential to be applied for skin care as a hydrogel in virtue of its hydrophilic biocompatible and biodegradable properties. In this study, triclosan-grafted gelatin and photo-cross-linkable methacrylated gelatin were synthesized and then combined to construct the semi-interpenetrating network and antibacterial hydrogels with the aid of a visible blue light. The antimicrobial test demonstrated that the resulting hydrogel obtained excellent inactivation capacity against E. coli, S. aureus, T. rubrum, and C. albicans with sterilizing rates of 99.998%, 99.998%, 99.19%, and 99.64%, respectively. In addition, the cytotoxicity, hemolysis, skin irritation, and rat skin wound healing experiments proved the good biocompatibility of the hydrogel. Therefore, this investigation sheds light on the development of multifunctional hydrogels in skin care.