Electroactive Hydrogels with Photothermal/Photodynamic Effects for Effective Wound Healing Assisted by Polydopamine-Modified Graphene Oxide

Near-infrared light-responsive copper-cerium bimetallic oxide nanozyme with antibacterial and antioxidant abilities for periodontitis therapy

Periodontitis, a chronic inflammatory disease of the supporting tissue around teeth, is triggered by periodontal pathogens. Clinical treatments face the problem of bacterial resistance and most therapies focus on a single function, lacking the multifunctional treatment of antibacterial, antioxidant, anti-inflammatory, and osteogenic properties. In our study, we developed a copper-cerium bimetallic oxide (CuCeOx) nanozyme with near-infrared (NIR) light responsiveness for the periodontitis therapy. Under the excitation of 808 nm NIR light, CuCeOx displayed excellent photodynamic and photothermal activities, efficiently generating reactive oxygen species (ROS) and heat. After the treatment of the CuCeOx/NIR system, the inhibition rate of Porphyromonas gingivalis (P. gingivalis), the main periodontitis pathogen, reached 98.69 ± 0.23 % in vitro. Without the NIR light irradiation, CuCeOx, acting as a nanozyme, exhibited enzyme-like activity in scavenging ROS, effectively alleviating the cellular oxidative stress. Furthermore, CuCeOx significantly mitigated the cellular inflammatory response induced by lipopolysaccharide (LPS) and promoted osteogenesis under the oxidative stress condition. Notably, the CuCeOx exhibited excellent blood compatibility (hemolysis < 5 %). The efficacy of the CuCeOx/NIR system in vivo was also investigated. H&E staining results demonstrated a significant reduction in periodontal tissue inflammation following treatment. Micro-CT analysis revealed that CuCeOx effectively inhibited the alveolar bone loss. Additionally, we found CuCeOx regulated the Nrf2/HO-1 signaling pathway both in vitro and in vivo. In conclusion, the multifunctional nanomaterial CuCeOx provides a promising strategy for the treatment of periodontitis.

Synergistic photothermal and photodynamic therapy to promote bacteria-infected wound healing using ZnO@PDA/Ag-integrated waterborne polyurethane films

Light-induced antibacterial effects aim to overcome the limitations of antibiotic-resistant bacteria and provide an effective solution for wound healing applications. This research focuses on developing a multifunctional wound dressing based on waterborne polyurethane (WPU) adorned with a hybrid photo nano-sensitizer (ZnO@PDA/Ag) that demonstrates near-infrared (NIR)-triggered synergistic photothermal and photodynamic effects. Through a facile synthesis process, zinc oxide (ZnO) nanoparticles were coated with polydopamine (PDA) to enhance biocompatibility, photothermic effect, and charge transfer efficiency due to a surface sensitization and passivation strategy. The synthesis was followed by the in situ reduction and decoration of plasmon silver nanoparticles (Ag NPs) to augment photodynamic activity. The structure, chemical composition, and morphology of the ZnO@PDA/Ag nano-sensitizer were examined and the results confirmed the successful synthesis. Furthermore, based on photo-thermal and fluorescence signal measurements under near-infrared (NIR) irradiation, the ZnO@PDA/Ag nanoparticles in aqueous dispersions exhibit effective light-to-heat conversion, as well as a strong ability for NIR-induced singlet oxygen generation. The WPU films incorporating the ZnO@PDA/Ag nano-sensitizer exhibit complete phototherapy inhibition of both Gram-negative E. coli and Gram-positive S. aureus bacteria. In addition, the films exhibited an appropriate biocompatibility in contact with L929 fibroblast cells. Moreover, in vivo studies in a rat wound model demonstrated accelerated wound healing and tissue regeneration with the application of ZnO@PDA/Ag in WPU nanocomposite film, particularly under NIR light irradiation. Histological analysis confirmed the formation of mature epithelial layers and minimal inflammatory response, indicating the potential of this film for clinical wound management.

Multifunctional Carbon-Based Nanocomposite Hydrogels for Wound Healing and Health Management

Compared with acute wounds, typical chronic wounds (infection, burn, and diabetic wounds) are susceptible to bacterial infection and hard to heal. As for the complexity of chronic wounds, biocompatible hydrogel dressings can be employed to regulate the microenvironment and accelerate wound healing with their controllable physical and chemical properties. Recently, various nanomaterials have been introduced into hydrogel networks to prepare functional nanocomposite hydrogels. Among them, carbon-based nanomaterials (CBNs) have attracted wide attention in the biomedical field due to their outstanding physicochemical properties. However, comprehensive reviews on the use of CBNs for multifunctional hydrogel wound dressings in the past 10 years are very scarce. This review focuses on the research progress on hydrogel dressings made with typical CBNs. Specifically, a series of CBNs (carbon dots, graphene quantum dots, fullerenes, nanodiamonds, carbon nanotubes, graphene, graphene oxide and reduced graphene oxide) employed in the preparation of hydrogels are described as well as carbon-based nanocomposite hydrogels (CBNHs) with versatility (conductivity, antibacterial, injectable and self-healing, anti-inflammatory and antioxidant properties, substance delivery, stimulus response and real-time monitoring). Moreover, applications of CBNHs in treating different chronic wounds are concretely discussed. This review may provide some new inspirations for the future development of CBNHs in wound care and tissue engineering.

Application of polydopamine as antibacterial and anti-inflammatory materials

Polydopamine (PDA), as a material mimicking the adhesive proteins of mussels in nature, has emerged as a strong candidate for developing novel antibacterial and anti-inflammatory materials due to its outstanding biomimetic adhesion, effective photothermal conversion, excellent biocompatibility and antioxidant capabilities. This review discussed in detail the intricate structure and polymerization principles of PDA, elucidated its mechanisms in combating bacterial infections and inflammation, as well as explored the innovative use of PDA-based composite materials for antibacterial and anti-inflammatory applications. By providing an in-depth analysis of PDA's capabilities and future research directions, this review addresses a crucial need for safer, more effective, and controllable antimicrobial and anti-inflammatory strategies, which aim to contribute to the development of advanced materials that can significantly impact public health.

Adhesive and Conductive Hydrogels for the Treatment of Myocardial Infarction

Myocardial infarction (MI) is a leading cause of mortality among cardiovascular diseases. Following MI, the damaged myocardium is progressively being replaced by fibrous scar tissue, which exhibits poor electrical conductivity, ultimately resulting in arrhythmias and adverse cardiac remodeling. Due to their extracellular matrix-like structure and excellent biocompatibility, hydrogels are emerging as a focal point in cardiac tissue engineering. However, traditional hydrogels lack the necessary conductivity to restore electrical signal transmission in the infarcted regions. Imparting conductivity to hydrogels while also enhancing their adhesive properties enables them to adhere closely to myocardial tissue, establish stable electrical connections, and facilitate synchronized contraction and myocardial tissue repair within the infarcted area. This paper reviews the strategies for constructing conductive and adhesive hydrogels, focusing on their application in MI repair. Furthermore, the challenges and future directions in developing adhesive and conductive hydrogels for MI repair are discussed.

MXene-Derived Multifunctional Biomaterials: New Opportunities for Wound Healing

The process of wound healing is frequently impeded by metabolic imbalances within the wound microenvironment. MXenes exhibit exceptional biocompatibility, biodegradability, photothermal conversion efficiency, conductivity, and adaptable surface functionalization, demonstrating marked potential in the development of multifunctional platforms for wound healing. Moreover, the integration of MXenes with other bioactive nanomaterials has been shown to enhance their therapeutic efficacy, paving the way for innovative approaches to wound healing. In this review, we provide a systematic exposition of the mechanisms through which MXenes facilitate wound healing and offer a comprehensive analysis of the current research landscape on MXene-based multifunctional bioactive composites in this field. By delving into the latest scientific discoveries, we identify the existing challenges and potential future trajectories for the advancement of MXenes. Our comprehensive evaluation aims to provide insightful guidance for the formulation of more effective wound healing strategies.

Progress of AI assisted synthesis of polysaccharides-based hydrogel and their applications in biomedical field

Polymeric hydrogels, characterized by their highly hydrophilic three-dimensional network structures, boast exceptional physical and chemical properties alongside high biocompatibility and biodegradability. These attributes make them indispensable in various biomedical applications such as drug delivery, tissue engineering, wound dressings and sensor technologies. With the integration of artificial intelligence (AI), hydrogels are undergoing significant transformations in design, leveraging human-machine interaction, machine learning, neural networks, and 3D/4D printing technology. This article provides a concise yet comprehensive overview of polysaccharide-based hydrogels, exploring their intrinsic properties, functionalities, preparation techniques, and classifications, alongside their progress in biomedical research. Special emphasis is placed on AI-enhanced hydrogels, underscoring their transformative potential in redefining hydrogel performance and functionality. By integrating AI technologies, these intelligent hydrogels open unprecedented opportunities in precision medicine, adaptive biomaterials, and smart healthcare systems, highlighting promising directions for future research.

A Biomimetic One‐Stone‐Two‐Birds Hydrogel with Electroconductive, Photothermally Antibacterial and Bioadhesive Properties for Skin Tissue Regeneration and Mechanosensation Restoration

Severe skin wounds arising from burns, cancers, and accidents can damage the entire tissue structure, resulting in permanent somatosensory dysfunction in patients. Although emerging hydrogel dressings have shown clinical potential for accelerating wound repair, the use of an individual material to synchronously restore the tissue structure and sensory function of defective skin remains a challenge. Herein, a multifunctional hydrogel that combines electroconductive polydopamine‐capped graphene nanosheets (PrGOs) embedded in a dynamically crosslinked dual‐polysaccharide (xyloglucan and chitosan) matrix network is presented. The fabricated hydrogels have an adjustable modulus that can be matched to skin tissue at the wound site, owing to the dynamic Schiff‐based crosslinking as well as the facile photo‐triggered secondary crosslinking. Furthermore, the photothermal activity of PrGO can elevate the local temperature up to ≈50 °C, significantly restraining bacterial growth. These two factors jointly promote the regeneration of skin tissue. Tissue adhesion of hydrogels is also reported that offers a conformable and robust interface that can detect and quantify human movement and physiological signals to mimic the human skin somatosensory system. This hydrogel offers an effective one‐stone‐for‐two‐birds material that simultaneously achieves tissue regeneration and multi‐signal sensing, promoting the restoration and/or replacement of the structure and function of damaged skins.

Photothermal Fish Gelatin-Graphene Microneedle Patches for Chronic Wound Treatment

Microneedles are demonstrated as an effective strategy for chronic wound treatment. Great endeavors are devoted to developing microneedles with natural compositions and potent functions to promote therapeutic effects for wound healing. Herein, a novel graphene oxide-integrated methacrylated fish gelatin (GO-FGelMA) microneedle patch encapsulated with bacitracin and vascular endothelial growth factor (VEGF) is developed for chronic wound management. As the natural components and porous structures of FGelMA, the fabricated microneedle patches display satisfactory biocompatibility and drug-loading ability. Owing to the integration of graphene oxide, the microneedle patches can realize promoted drug release via near-infrared (NIR) irradiation. Besides, the encapsulated bacitracin and VEGF endow the microneedle patches with the ability to inhibit bacterial growth and promote angiogenesis. It is demonstrated that the GO-FGelMA microneedle patches with efficient drug release exert a positive influence on the wound healing process through reduced inflammation, enhanced wound closure, and improved tissue regeneration. Thus, it is believed that the proposed drugs-loaded GO-FGelMA microneedle patches will hold great potential in future chronic wound treatment.

Self-healing hydrogel from poly(aspartic acid) and dextran with antibacterial property for burn wound healing

Designing hydrogel dressing with intrinsic antibacterial property to promote skin injury recovery remains a significant challenge. In this research, poly(aspartic hydrazide) with grafted betaine (PAHB) was designed and reacted with oxidized dextran (OD) to fabricate biodegradable PAHB/OD hydrogel and its application as wound dressing was systematically investigated. The PAHB/OD hydrogels exhibited fast gelation, strong tissue adhesion, preferable mechanical properties and biocompatibility. The grafted betaine endowed the hydrogel with antibacterial property and antibacterial rate enhanced through photothermal performance of composited CuS nanoparticles under near infrared (NIR) radiation. The CuS composited PAHB/OD hydrogel (CuS/hydrogel) with microporous morphology was used as burn wound dressing with loaded anti-inflammatory drug diclofenac sodium (DS) in mouse model. The results showed the DS loaded CuS/hydrogel (CuS@DS/hydrogel) promoted the tissue regeneration and suppressed the inflammatory response. The histological analysis and immunohistochemical expression confirmed the CuS@DS/hydrogel promote angiogenesis of the burn wound by regulating the expression of inflammatory cytokines (IL-6 and CD68) and vascular endothelial growth factor (VEGF). Overall, the CuS@DS/hydrogel hydrogel is a promising candidate as wound dressing due to its tissue adhesive, antioxidant, antibacterial and anti-inflammatory activities.

Antibacterial Hydrogels for Wound Dressing Applications: Current Status, Progress, Challenges, and Trends

Bacterial infection treatment for chronic wounds has posed a major medical threat and challenge. Bacteria at the wounded sites can compete with the immune system and subsequently invade live tissues, leading to more severe tissue damage. Therefore, there is an urgent demand for wound dressings with antibacterial and anti-inflammatory properties. Considering the concept of moist healing, hydrogels with a three-dimensional (3D) network structure are widely used as wound dressings due to their excellent hydrophilicity, water retention properties, and biocompatibility. Developing antibacterial hydrogels for the treatment of infected wounds has been receiving extensive attention recently. This article categorizes antibacterial hydrogels according to their materials and antibacterial modes, and introduces the recent findings and progress regarding their status. More importantly, with the development of emerging technologies, new therapies are utilized to prepare antibacterial hydrogels such as nanoenzymes, photothermal therapy (PTT), photodynamic therapy (PDT), metal-organic frameworks (MOFs), and other external stimuli-responsive methods. Therefore, this review also examines their progress, challenges, and future trends as wound dressings. In the following studies, there will still be a focus on antibacterial hydrogels that have a high performance, multi-functions, and intelligence, especially biocompatibility, a high and long-lasting antibacterial property, responsiveness, and on-demand therapeutic ability.

A bioinspired injectable antioxidant hydrogel for prevention of postoperative adhesion

Postoperative adhesions, a prevalent complication following abdominal surgery, affect 90% of patients undergoing abdominal surgical procedures. Currently, the primary approach to prevent postoperative adhesions involves physical isolation of the surgical site and surrounding tissues using a hydrogel; however, this method represents a rudimentary strategy. Herein, considering the impact of oxidative stress and free radicals on postoperative adhesion during wound healing, an injectable antioxidant hydrogel, named PU-OHA-D, was successfully synthesized, which is formed by the crosslinking of dopamine-modified oxidized hyaluronic acid (OHA-D) and dihydrazide-terminated polyurethane (PU-ADH) through hydrazone bonding. PU-OHA-D hydrogel possesses versatile characteristics such as rapid gel formation, injectability, self-repair capability and biodegradability. Additionally, they exhibit an excellent ability to clear free radicals and superior tissue adhesion. PU-OHA-D can be injected in situ to form a hydrogel to prevent abdominal wall-cecum adhesion. Importantly, it can effectively eliminate free radicals and inhibit oxidative stress at the wound site. Thereby, it leads to collagen physiological degradation and prevents the occurrence of postoperative adhesions. The bioinspired hydrogel demonstrates its great potential in preventing postoperative adhesion and promoting wound healing.

Polydopamine Nanocarriers with Cascade-Activated Nitric Oxide Release Combined Photothermal Activity for the Therapy of Drug-Resistant Bacterial Infections

Antibiotic abuse leads to increased bacterial resistance, and the surviving planktonic bacteria aggregate and secrete extracellular polymers to form biofilms. Conventional antibacterial agents find it difficult to penetrate the biofilm, remove the bacteria wrapped in it, and produce an excellent therapeutic effect. In this study, a dual pH- and NIR-responsive nanocomposite (A-Ca@PDA) was developed to remove drug-resistant bacteria through a cascade of catalytic nitric oxide (NO) release and photothermal clearance. NO can melt in the outer package of the biofilm, facilitating the nanocomposites to have better permeability. Thermal therapy further inhibits the growth of planktonic bacteria. The locally generated high temperature and the burst release of NO together aggravate the biofilm collapse and bacterial death after NIR irradiation. The nanocomposites achieved a remarkable photothermal conversion efficiency of 47.5%, thereby exhibiting significant advancements in energy conversion. The nanocomposites exhibited remarkable efficacy in inhibiting multidrug-resistant (MDR) Escherichia coli and MDR Staphylococcus aureus, thus achieving an inhibition rate of >90%. Moreover, these nanocomposites significantly improved the wound-healing process in the MDR S. aureus-infected mice. Thus, this novel nanocomposite offers a novel strategy to combat drug-resistant bacterial infections.

Enhanced physiochemical, antibacterial, and hemostatic performance of collagen-quaternized chitosan-graphene oxide sponges for promoting infectious wound healing

Bacteria-infected wound healing has attracted widespread attention in biomedical engineering. Wound dressing is a potential strategy for repairing infectious wounds. However, the development of wound dressing with appropriate physiochemical, antibacterial, and hemostatic properties, remains challenging. Hence, there is a motivation to develop new synthetic dressings to improve bacteria-infected wound healing. Here, we fabricate a biocompatible sponge through the covalent crosslinking of collagen (Col), quaternized chitosan (QCS), and graphene oxide (GO). The resulting Col-QCS-GO sponge shows an elastic modulus of 1.93-fold higher than Col sponge due to enhanced crosslinking degree by GO incorporation. Moreover, the fabricated Col-QCS-GO sponge shows favorable porosity (84.30 ± 3.12 %), water absorption / retention (2658.0 ± 113.4 % / 1114.0 ± 65.7 %), and hemostasis capacities (blood loss <50.0 mg). Furthermore, the antibacterial property of the Col-QCS-GO sponge under near-infrared (NIR) irradiation is significantly enhanced (the inhibition rates are 99.9 % for S. aureus and 99.9 % for E. coli) due to the inherent antibacterial properties of QCS and the photothermal antibacterial capabilities of GO. Finally, the Col-QCS-GO+NIR sponge exhibits the lowest percentage of wound area (9.05 ± 1.42 %) at day 14 compared to the control group (31.61 ± 1.76 %). This study provides new insights for developing innovative sponges for bacteria-infected wound healing.

Novel Photothermal Graphene-Based Hydrogels in Biomedical Applications

In the last decade, photothermal therapy (PTT) has attracted tremendous attention because it is non-invasive, shows high efficiency and antibacterial activity, and minimizes drug side effects. Previous studies demonstrated that PTT can effectively inhibit the growth of bacteria and promotes cell proliferation, accelerating wound healing and tissue regeneration. Among different NIR-responsive biomaterials, graphene-based hydrogels with photothermal properties are considered as the best candidates for biomedical applications, due to their excellent properties. This review summarizes the current advances in the development of innovative graphene-based hydrogels for PTT-based biomedical applications. Also, the information about photothermal properties and the potential applications of graphene-based hydrogels in biomedical therapies are provided. These findings provide a great potential for supporting their applications in photothermal biomedicine.

Smart Hydrogels for Tissue Regeneration

The rapid growth in the portion of the aging population has led to a consequent increase in demand for biomedical hydrogels, together with an assortment of challenges that need to be overcome in this field. Smart hydrogels can autonomously sense and respond to the physiological/pathological changes of the tissue microenvironment and continuously adapt the response according to the dynamic spatiotemporal shifts in conditions. This along with other favorable properties, make smart hydrogels excellent materials for employing toward improving the precision of treatment for age-related diseases. The key factor during the smart hydrogel design is on accurately identifying the characteristics of natural tissues and faithfully replicating the composition, structure, and biological functions of these tissues at the molecular level. Such hydrogels can accurately sense distinct physiological and external factors such as temperature and biologically active molecules, so they may in turn actively and promptly adjust their response, by regulating their own biological effects, thereby promoting damaged tissue repair. This review summarizes the design strategies employed in the creation of smart hydrogels, their response mechanisms, as well as their applications in field of tissue engineering; and concludes by briefly discussing the relevant challenges and future prospects.

Enzyme-Mineralized PVASA Hydrogels with Combined Toughness and Strength for Bone Tissue Engineering

Enzymatic mineralization is an advanced mineralization method that is often used to enhance the stiffness and strength of hydrogels, but often accompanied by brittle behavior. Moreover, the hydrogel systems with dense networks currently used for enzymatic mineralization are not ideal materials for bone repair applications. To address these issues, two usual bone repair hydrogels, poly(vinyl alcohol) (PVA) and sodium alginate (SA), were selected to form a double-network structure through repeated freeze-thawing and ionic cross-linking, followed by enzyme mineralization. The results demonstrated that both enzymatic mineralization and double-network structure improved the mechanical and biological properties and even exhibited synergistic effects. The mineralized PVASA hydrogels exhibited superior comprehensive mechanical properties, with a Young's modulus of 1.03 MPa, a storage modulus of 103 kPa, and an equilibrium swelling ratio of 132%. In particular, the PVASA hydrogel did not suffer toughness loss after mineralization, with a high toughness value of 1.86 MJ/m3. The prepared hydrogels also exhibited superior biocompatibility with a cell spreading area about 13 times that of mineralized PVA. It also effectively promoted cellular osteogenic differentiation in vitro and further promoted the formation of new bone in the femur defect region in vivo. Overall, the enzyme-mineralized PVASA hydrogel demonstrated combined strength and toughness and great potential for bone tissue engineering applications.