Light-Programmable Nanocomposite Hydrogel for State-Switchable Wound Healing Promotion and Bacterial Infection Elimination

Detecting N-Phenyl-2-Naphthylamine, L-Arabinose, D-Mannose, L-Phenylalanine, L-Methionine, and D-Trehalose via Photocurrent Measurement

The concentration of small molecules reflects the normality of physiological processes in the human body, making the development of simple and efficient detection equipment essential. In this work, inspired by a facile strategy in point-of-care detection, two devices were fabricated to detect small molecules via photocurrent measurement. A linear response of the photocurrent against the concentration of the small molecules was found. In the first device, metal ions were introduced into gel substrates made by xanthan gum to enhance photocurrent response. N-phenyl-2-naphthylamine was measured when iron or manganese ions were used. L-Phenylalanine was measured when the gel was modified by samarium, iron, cerium, or ytterbium ions. L-(+)-Arabinose was detected via the gels modified by iron or holmium ions. D-(+)-Mannose was detected when the gel was modified by ytterbium, manganese, chromium, or sodium ions. L-Methionine was detected in the gels modified by samarium, zinc, or chromium ions. The second device was based on a paper sheet. A sugar-like molecule was first synthesized, which was then used to modify the paper. The detection was possible since the photocurrent showed a linear trend against the concentration of D-Trehalose. A linear fit was conducted to derive the sensitivity, whose value was found to be 5542.4. This work offers a novel, simple, and environmentally sustainable platform that is potentially useful in remote areas lacking medical devices.

Facile Surface Modification with Croconaine-Functionalized Polymer on Polypropylene for Antifouling and NIR-Light-Mediated Photothermal Sterilization

Biomedical-device-associated infection (BAI) is undoubtedly a major concern and a serious challenge in modern medicine. Therefore, the development of biomedical materials that are capable of resisting or killing bacteria is of great importance. In this work, a croconaine-functionalized polymer with antifouling and near-infrared (NIR) photothermal bactericidal properties was prepared and facilely modified on polypropylene (PP) to combat medical device infections. Croconaine dye is elaborately modified as a "living" initiator, termed CR-4EBiB, for preparing amphiphilic block polymers by atom transfer radical polymerization (ATRP). In the formed polymer coating, the hydrophobic block can strongly adhere to the surface of the PP substrate, whereas the hydrophilic block is located on the outer layer by solvent-induced resistance to bacterial adhesion. Under the irradiation of an NIR laser (808 nm), the croconaine dye in the coating achieved maximum conversion of light to heat to effectively kill E. coli, S. aureus, and methicillin-resistant Staphylococcus aureus (MRSA). This work provides a facile and promising strategy for the development of implantable antibacterial biomedical materials.

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.

Traditional Herb (Moxa) Modified Zinc Oxide Nanosheets for Quick, Efficient and High Tissue Penetration Therapy of Fungal Infection

Fungal infection possesses the characteristics of high invasion depth and easy formation of a biofilm under the skin, which greatly hinders the treatment process. Here, traditional Chinese medicine moxa is carbonized and modified with zinc oxide (ZnO) nanosheets to synthesize carbonized moxa@ZnO (CMZ) with the dual response properties of yellow light (YL) and ultrasound (US) for synergistic antifungal therapy. CMZ with narrow bandgap can respond to long-wavelength YL that is highly safe and helpful for skin repair. Simultaneously, CMZ with a piezoelectric effect can further enhance the photocatalytic efficiency under the stimulation of US with high tissue penetration. Gene mechanism investigation indicates that when exposed to US and YL irradiation, CMZ-based therapy can adjust the expression of genes associated with fungal virulence, metabolic activity, mycelial growth and biofilm development, thus efficaciously eradicating planktonic Candida albicans (C. albicans) and mature biofilm. Importantly, despite the 1.00 cm thick tissue barrier, CMZ can rapidly eliminate 99.9% of C. albicans within 4 min, showing a satisfactory deep fungicidal efficacy. The in vivo therapeutic effect of this strategy is demonstrated in both open wound and deep cutaneous infection tests, speaking of dramatically better efficacy than the traditional fungicide ketoconazole (KTZ).

Nature-Derived Polysaccharide-Based Composite Hydrogels for Promoting Wound Healing

Numerous innovative advancements in dressing technology for wound healing have emerged. Among the various types of wound dressings available, hydrogel dressings, structured with a three-dimensional network and composed of predominantly hydrophilic components, are widely used for wound care due to their remarkable capacity to absorb abundant wound exudate, maintain a moisture environment, provide soothing and cooling effects, and mimic the extracellular matrix. Composite hydrogel dressings, one of the evolved dressings, address the limitations of traditional hydrogel dressings by incorporating additional components, including particles, fibers, fabrics, or foams, within the hydrogels, effectively promoting wound treatment and healing. The added elements enhance the features or add specific functionalities of the dressings, such as sensitivity to external factors, adhesiveness, mechanical strength, control over the release of therapeutic agents, antioxidant and antimicrobial properties, and tissue regeneration behavior. They can be categorized as natural or synthetic based on the origin of the main components of the hydrogel network. This review focuses on recent research on developing natural polysaccharide-based composite hydrogel wound dressings. It explores their preparation and composition, the reinforcement materials integrated into hydrogels, and therapeutic agents. Furthermore, it discusses their features and the specific types of wounds where applied.

Recent Progress of Photothermal Therapy Based on Conjugated Nanomaterials in Combating Microbial Infections

Photothermal therapy has the advantages of non-invasiveness, low toxicity, simple operation, a broad spectrum of antibacterial ability, and non-proneness to developing drug resistance, which provide it with irreplaceable superiority in fighting against microbial infection. The effect of photothermal therapy is closely related to the choice of photothermal agent. Conjugated nanomaterials are potential candidates for photothermal agents because of their easy modification, excellent photothermal conversion efficiency, good photostability, and biodegradability. In this paper, the application of photothermal agents based on conjugated nanomaterials in photothermal antimicrobial treatment is reviewed, including conjugated small molecules, conjugated oligomers, conjugated polymers, and pseudo-conjugated polymers. At the same time, the application of conjugated nanomaterials in the combination of photothermal therapy (PTT) and photodynamic therapy (PDT) is briefly introduced. Finally, the research status, limitations, and prospects of photothermal therapy using conjugated nanomaterials as photothermal agents are discussed.

In Situ Fabrication of Silver Peroxide Hybrid Ultrathin Co-Based Metal-Organic Frameworks for Enhanced Chemodynamic Antibacterial Therapy

Bacterial-induced infectious diseases have always caused an unavoidable problem and lead to an increasing threat to human health. Hence, there is an urgent need for effective antibacterial strategies to treat infectious diseases. Current methods are often ineffective and require large amounts of hydrogen peroxide (H₂O₂), with harmful effects on normal healthy tissue. Chemodynamic therapy (CDT) provides an ideal infection microenvironment (IME)-activated paradigm to tackle bacterial-related diseases. To take full advantage of the specificity of IME and enhanced CDT for wounds with bacterial infection, we have designed an intelligent antibacterial system that exploits nanocatalytic ZIF-67@Ag₂O₂ nanosheets. In this system, silver peroxide nanoparticles (Ag₂O₂ NPs) were grown on ultrathin zeolitic imidazolate framework-67 (ZIF-67) nanosheets by in situ oxidation, and then, ZIF-67@Ag₂O₂ nanosheets with the ability to self-generate H₂O₂ were triggered by the mildly acidic environment of IME. Lamellar ZIF-67 nanosheets were shown to rapidly degrade and release Co²⁺, allowing the conversion of less reactive H₂O₂ into the highly toxic reactive oxygen species hydroxyl radicals (^•OH) for enhanced CDT antibacterial properties. In vivo results revealed that the ZIF-67@Ag₂O₂ nanosheet system exhibits excellent antibacterial performance against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The proposed hybrid strategy demonstrates a promising therapeutic strategy to enable antibacterial agents with IME-responsive nanocatalytic activity to circumvent antibiotic resistance against bacterial infections.

Injectable Intrinsic Photothermal Hydrogel Bioadhesive with On-Demand Removability for Wound Closure and MRSA-Infected Wound Healing

Photothermal hydrogel adhesives have yielded promising results for wound closure and infected wound treatment in recent years. However, photothermal hydrogel bioadhesives with on-demand removability without additional nanomaterials-based photothermal agents have rarely been reported in the literature. In this work, an injectable intrinsic photothermal hydrogel bioadhesive with an on-demand removal trait is developed through dynamic cross-linking of gelatin (Gel), tannic acid (TA) quinone, and borax for closing skin incisions and accelerating methicillin-resistant Staphylococcus aureus (MRSA) infected wound healing. The TA quinone containing polyphenol and quinone groups with multifunctional adhesiveness and intrinsic photothermal performance confer the hydrogel adhesive with near-infrared (NIR) responsive antibacterial activity. The cross-linking of pH-sensitive boronic ester (polyphenol-B) and Schiff base bonds endow the hydrogel with great self-healing capacity and on-demand removability. Moreover, the hydrogel possesses good biocompatibility, injectability, and hemostasis. The in vivo experiment in a rat cutaneous incision model and full-thickness MRSA-infected wound model indicate that the smart hydrogel can close wounds efficiently and treat infected ones, demonstrating its superiority in noninvasive treatment of cutaneous incisions and enhancing infected full-thickness wound healing.

Engineering functional natural polymer-based nanocomposite hydrogels for wound healing

Skin injury occurs due to acute trauma, chronic trauma, infection, and surgical intervention, which can result in severe dysfunction and even death in humans. Therefore, clinical intervention is critical for the treatment of skin wounds. One idealized method is to use wound dressings to protect skin wounds and promote wound healing. Among these wound dressings, nanocomposite natural polymer hydrogels (NNPHs) are multifunctional wound dressings for wound healing. The combination of nanomaterials and natural polymer hydrogels avoids the shortcomings of a single component. Moreover, nanomaterials could provide improved antibacterial, anti-inflammatory, antioxidant, stimuli-responsive, electrically conductive and mechanical properties of hydrogels to accelerate wound healing. This review focuses on recent advancements in NNPHs for skin wound healing and repair. Initially, the functions and requirements of NNPHs as wound dressings were introduced. Second, the design, preparation and capacities of representative NNPHs are classified based on their nanomaterial. Third, skin wound repair applications of NNPHs have been summarized based on the types of wounds. Finally, the potential issues of NNPHs are discussed, and future research is proposed to prepare idealized multifunctional NNPHs for skin tissue regeneration.