Copper Peroxide-Loaded Gelatin Sponges for Wound Dressings with Antimicrobial and Accelerating Healing Properties

Controllable ion design in flexible metal organic framework film for performance regulation of electrochemical biosensing

The limitations of solvent residues, unmanageable film growth regions, and substandard performance impede the extensive utilization of metal-organic framework (MOF) films for biosensing devices. Here, we report a strategy for ion design in gas-phase synthesized flexible MOF porous film to attain universal regulation of biosensing performances. The key fabrication process involves atomic layer deposition of induced layer coupled with lithography-assisted patterning and area-selective gas-phase synthesis of MOF film within a chemical vapor deposition system. Sensing platforms are subsequently formed to achieve specific detection of H2O2, dopamine, and glucose molecules by respectively implanting Co, Fe, and Ni ions into the network structure of MOF films. Furthermore, we showcase a practical device constructed from Co ions-implanted ZIF-4 film to accomplish real-time surveillance of H2O2 concentration at mouse wound. This study specifically elucidates the electronic structure and coordination mode of ion design in MOF film, and the obtained knowledge aids in tuning the electrochemical property of MOF film for advantageous sensing devices.

Rational design of multifunctional hydrogels targeting the microenvironment of diabetic periodontitis

Periodontitis is a chronic inflammatory disease and is the primary contributor to adult tooth loss. Diabetes exacerbates periodontitis, accelerates periodontal bone resorption. Thus, effectively managing periodontitis in individuals with diabetes is a long-standing challenge. This review introduces the etiology and pathogenesis of periodontitis, and analyzes the bidirectional relationship between diabetes and periodontitis. In this review, we comprehensively summarize the four pathological microenvironments influenced by diabetic periodontitis: high glucose microenvironment, bacterial infection microenvironment, inflammatory microenvironment, and bone loss microenvironment. The hydrogel design strategies and latest research development tailored to the four microenvironments of diabetic periodontitis are mainly focused on. Finally, the challenges and potential solutions in the treatment of diabetic periodontitis are discussed. We believe this review will be helpful for researchers seeking novel avenues in the treatment of diabetic periodontitis.

A self-supplied hydrogen peroxide and nitric oxide-generating nanoplatform enhances the efficacy of chemodynamic therapy for biofilm eradication

Bacterial biofilms present a profound challenge to global public health, often resulting in persistent and recurrent infections that resist treatment. Chemodynamic therapy (CDT), leveraging the conversion of hydrogen peroxide (H2O2) to highly reactive hydroxyl radicals (•OH), has shown potential as an antibacterial approach. Nonetheless, CDT struggles to eliminate biofilms due to limited endogenous H2O2 and the protective extracellular polymeric substances (EPS) within biofilms. This study introduces a multifunctional nanoplatform designed to self-supply H2O2 and generate nitric oxide (NO) to overcome these hurdles. The nanoplatform comprises calcium peroxide (CaO2) for sustained H2O2 production, a copper-based metal-organic framework (HKUST-1) encapsulating CaO2, and l-arginine (l-Arg) as a natural NO donor. When exposed to the acidic microenvironment within biofilms, the HKUST-1 layer decomposes, releasing Cu2+ ions and l-Arg, and exposing the CaO2 core to initiate a cascade of reactions producing reactive species such as H2O2, •OH, and superoxide anions (•O2-). Subsequently, H2O2 catalyzes l-Arg to produce NO, which disperses the biofilm and reacts with •O2- to form peroxynitrite, synergistically eradicating bacteria with •OH. In vitro assays demonstrated the nanoplatform's remarkable antibiofilm efficacy against both Gram-positive Methicillin-resistant Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, significantly reducing bacterial viability and EPS content. In vivo mouse model experiments validated the nanoplatform's effectiveness in eliminating biofilms and promoting infected wound healing without adverse effects. This study represents a breakthrough in overcoming traditional CDT limitations by integrating self-supplied H2O2 with NO's biofilm-disrupting capabilities, offering a promising therapeutic strategy for biofilm-associated infection.

Exudate Unidirectional Pump to Promote Glucose Catabolism Triggering Fenton-Like Reaction for Chronic Diabetic Wounds Therapy

The massive accumulation of exudate containing high concentrations of glucose causes wound infection and triggers the release of inflammatory factors, which in turn delays the closure of diabetic wounds. In this study, a Janus membrane is constructed by combining glucose oxidase (GOx) and copper ions (Cu2+) for the treatment of diabetic wounds, which is named as Janus@GOx/Cu2+. It consists of hydrophobic, transitional, and superhydrophilic layers in a three-layer structure with gradient hydrophilicity for self-pumping properties. The Janus@GOx/Cu2+ membrane triggers a series of cascading reactions while pumping out diabetic wound exudates. First, glucose oxidase loaded onto the hydrophilic layer of the Janus@GOx/Cu2+ membrane decomposes glucose into hydrogen peroxide (H2O2) and glucuronic acid, reducing the local glucose level. The generated glucuronic acid neutralizes the local alkaline environment of chronic wounds. Simultaneously, the H2O2 interacts with the Cu2+ contained in the hydrophobic layers of the Janus@GOx/Cu2+ membrane via a Fenton-like reaction, generating hydroxyl radicals with excellent bactericidal properties. Cu2+ promotes angiogenesis and wound healing in diabetic wounds. Under the action of multiple responses, the Janus@GOx/Cu2+ membrane promotes wound healing in diabetic infections.

An all-in-one therapeutic platform for the treatment of resistant Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection is a major cause of gastric diseases. Currently, bismuth-based quadruple therapy is widely adopted for eradicating H. pylori infection. However, this first-line strategy faces several challenges such as drug resistance, intestinal dysbacteriosis, and patients' poor compliance. To overcome these problems, an all-in-one therapeutic platform (CLA-Bi-ZnO2@Lipo) that composed of liposomes loading clarithromycin (CLA), Bi, and ZnO2 hybrid nanoparticles was developed for eradicating multidrug-resistant (MDR) H. pylori. The in vitro and in vivo results showed that CLA-Bi-ZnO2@Lipo could target the infection-induced inflammatory mucosa through liposome mediated nanoparticle-tissue surface charge interaction and quickly respond to the gastric acid environment to release CLA, Bi3+, Zn2+, and H2O2. By oral administration per day, the acid triggered decomposition of CLA-Bi-ZnO2@Lipo could significantly increase intragastric pH to 6 within 30 min; The released CLA, Zn2+, and H2O2 further exerted synergistical anti-bacterial effects in which a ∼2 order higher efficacy in reducing MDR H. pylori burden was achieved in comparison with standard quadruple therapy (p < 0.05); The released Zn2+ and Bi3+ could also alleviate mucosal inflammation. Most importantly, the CLA-Bi-ZnO2@Lipo exhibited superior biosafety and nearly no side effects on intestinal flora. Overall, this study developed a highly integrated and safe anti-MDR H. pylori agent which had great potential to be used as an alternative treatment for MDR H. pylori eradication.

An adhesion-switchable hydrogel dressing for painless dressing removal without secondary damage

Hydrogels with strong adhesion to wet tissues are considered promising for wound dressings. However, the clinical application of adhesive hydrogel dressing remains a challenge due to the issues of secondary damage during dressing changes. Herein, we fabricated an adhesion-switchable hydrogel formed with poly(acrylamide)-co-poly(N-isopropyl acrylamide), quaternary ammonium chitosan and tannic acid. This hydrogel forms instant and robust adhesion to the skin at body temperature. However, as the temperature rises above the lower critical solution temperature (LCST), the hydrogel loses its adhesion towards the wound area due to the temperature-dependent volume phase transition of the copolymer, occurring around 45 °C. Consequently, the designed hydrogel can be easily detached from adhered tissues upon demand, providing a facile and effective method for painless dressing changes without secondary damage. This hydrogel holds great promise for long-term application in wound dressings.

Fenton-like Reaction Inspired "·OH Catalyzed" Osteogenic Process for the Treatment of Osteoporosis

Inspired by the Fenton-like reaction, this work combines copper peroxide (CP) nanoparticles with black phosphorus (BP) nanosheets to form a hydroxyl radical (·OH)-centered "catalytic" osteogenic system. CP-produced ·OH interacts with BP to rapidly produce a large amount of phosphate ions, thus accelerating self-mineralization and promoting bone formation. In turn, BP not only exerts anti-inflammatory effects, thereby providing a favorable microenvironment for bone formation, but also offsets the potential toxicity of CP induced by reactive oxygen species (ROS). Together with copper ions (Cu2+), phosphate ions are also released as a byproduct of this process, which can contribute to the comprehensive promotion of osteogenesis.

Citrus flavonoids-loaded chitosan derivatives-route nanofilm as drug delivery systems for cutaneous wound healing

This study focuses on creating new forms of biomimetic nanofiber composites by combining copolymerizing and electrospinning approaches in the field of nanomedicine. The process involved utilizing the melt polymerization of proline (Pr) and hydroxyl proline (Hyp) to synthesize polymers based on Pr (PPE) and Hyp (PHPE). These polymers were then used in a grafting copolymerization process with chitosan (CS) to produce PHPC (1560 ± 81.08 KDa). A novel electrospun nanofiber scaffold was then produced using PHPC and/or CS, hyaluronic acid, polyvinyl alcohol, and naringenin (NR) as a loading drug. Finally, Mouse Dermal Fibroblast (MDF) cells were introduced to the wound dressing and assessed their therapeutic potential for wound healing in rats. The scaffolds were characterized by FTIR, NMR, DSC, and SEM analysis, which confirmed the amino acid grafting, loading drug, and porous and nanofibrous structures (>225 nm). The results showed that the PHPC-based scaffolds were more effective for swelling/absorption of wound secretions, had more elasticity/elongation, faster drug release, more MDF-cytocompatibility, and antibacterial activity against multidrug-resistant S. aureus compared to CS-based scaffolds. The in vivo studies showed that NR in combination with MDF can accelerate cell migration/proliferation, and remodeling phases of wound healing in both PHPC/CS-based scaffolds. Moreover, PHPC-based scaffolds promote collagen content, and better wound contraction, epithelialization, and neovascularization than CS-based, showing potential as wound-dressing.

A pH-Responsive Polycaprolactone-Copper Peroxide Composite Coating Fabricated via Suspension Flame Spraying for Antimicrobial Applications

In this study, a pH-responsive polycaprolactone (PCL)-copper peroxide (CuO2) composite antibacterial coating was developed by suspension flame spraying. The successful synthesis of CuO2 nanoparticles and fabrication of the PCL-CuO2 composite coatings were confirmed by microstructural and chemical analysis. The composite coatings were structurally homogeneous, with the chemical properties of PCL well maintained. The acidic environment was found to effectively accelerate the dissociation of CuO2, allowing the simultaneous release of Cu2+ and H2O2. Antimicrobial tests clearly revealed the enhanced antibacterial properties of the PCL-CuO2 composite coating against both Escherichia coli and Staphylococcus aureus under acidic conditions, with a bactericidal effect of over 99.99%. This study presents a promising approach for constructing pH-responsive antimicrobial coatings for biomedical applications.

Remodeling Microenvironment for Implant-Associated Osteomyelitis by Dual Metal Peroxide

Implant-associated osteomyelitis (IAOM) is characterized by bone infection and destruction; current therapy of antibiotic treatment and surgical debridement often results in drug resistance and bone defect. It is challenging to develop an antibiotic-free bactericidal and osteogenic-enhanced strategy for IAOM. Herein, an IAOM-tailored antibacterial and osteoinductive composite of copper (Cu)-strontium (Sr) peroxide nanoparticles (CSp NPs), encapsulated in polyethylene glycol diacrylate (PEGDA) (CSp@PEGDA), is designed. The dual functional CSp NPs display hydrogen peroxide (H2O2) self-supplying and Fenton catalytic Cu2+ ions' release, generating plenty of hydroxyl radical (•OH) in a pH-responsive manner for bacterial killing, while the released Sr2+ promotes the in vitro osteogenicity regarding cell proliferation, alkaline phosphatase activity, extracellular matrix calcification, and osteo-associated genes expression. The integration of Cu2+ and Sr2+ in CSp NPs together with the coated PEGDA hydrogel ensures the stable and sustainable ion release during short- and long-term periods. Benefitted from the injectablity and photo-crosslink ability, CSp@PEGDA is able to thoroughly fill the infectious site and gelate in situ for bacterial elimination and bone regeneration, which is verified through in vivo evaluation using a clinical-simulating IAOM mouse model. These favorable abilities of CSp@PEGDA precisely meet the multiple therapeutic needs and pave a promising way for implant-associated osteomyelitis treatment.

Multifunctional Self-Healing Carbon Dot-Gelatin Bioadhesive: Improved Tissue Adhesion with Simultaneous Drug Delivery, Optical Tracking, and Photoactivated Sterilization

Bioadhesives with all-inclusive properties for simultaneous strong and robust adhesion, cohesion, tracking, drug delivery, self-sterilization, and nontoxicity are still farfetched. Herein, a carbon dot (CD) is made to infuse each of the above-desired aspects with gelatin, an inexpensive edible protein. The CD derived through controlled hydrothermal pyrolysis of dopamine and terephthaldehyde retained -NH2, -OH, -COOH, and, most importantly, -CHO functionality on the CD surface for efficient skin adhesion and cross-linking. Facile fabrication of CD-gelatin bioadhesive through covalent conjugation of -CHO of the CD with -NH2 of gelatin through Schiff base formation was accomplished. This imparts remarkable self-healing attributes as well as excellent adhesion and cohesion evident from physicomechanical analysis in a porcine skin model. Improved porosity of the bioadhesive allows loading hemin as a model drug whose disembarkment is tracked with intrinsic CD photoluminescence. In a significant achievement, antibiotic-free self-sterilization of bioadhesive is demonstrated through visible light (white LED, 23 W)-irradiated photosensitization of the CD to produce reactive oxygen species for annihilation of both Gram-positive and Gram-negative bacteria with exceptional efficacy (99.9%). Thus, a comprehensive CD-gelatin bioadhesive for superficial and localized wound management is reported as a promising step for the transformation of the bioadhesive domain through controlled nanotization for futuristic clinical translations.

Kaolin loaded gelatin sponges for rapid and effective hemostasis and accelerated wound healing

Severe trauma with massive active blood loss, including liver and spleen rupture, arterial bleeding and pelvic fracture, will lead disability, malformation and even death. Therefore, it is very important to develop new, fast and efficient hemostatic materials. In this study, a novel Gelatin/Kaolin (GE/KA) composite sponge was developed. Meanwhile, to further investigate the effect of kaolin content on sponge properties, we prepared four types of sponges: GE/5% KA, GE/10% KA, GE/15% KA and GE/20% KA. The results of coagulation test in vitro showed that compared to the other groups, there were more activated adhered platelets and red blood cells on the surface of GE/15% KA. The results of hemostasis test in vivo showed that compared to other experimental groups, the GE/15% KA group had significantly less hemostasis time (liver hemostasis model: 69.50 ± 2.81 s; femoral artery hemostasis model: 75.17 ± 3.06 s) and bleeding volume (liver hemostasis model: 219.02 ± 10.39 mg; femoral artery hemostasis model: 948.00 ± 50.69 mg), and was similar to the commercial hemostasis material group. Additionally, the material properties of the sponge were characterized and its biocompatibility was verified as well through cell experiments and in vivo embedding experiments. All these results indicate that the optimal content of kaolin is 15%, which provides a theoretical basis for subsequent research. All in all, the novel GE/KA composite sponge prepared in this study can be used as a multifunctional hemostatic wound dressing for the treatment of complex wounds under various trauma scenes.

Progress in copper-based materials for wound healing

Chronic wounds have become the leading cause of death, particularly among diabetic patients. Chronic wounds affect ~6.5 million patients each year, according to statistics, and wound care and management incur significant financial costs. The rising prevalence of chronic wounds, combined with the limitations of current treatments, necessitates the development of new and innovative approaches to accelerate wound healing. Copper has been extensively studied for its antibacterial and anti-inflammatory activities. Copper in its nanoparticle form could have better biological properties and many applications in health care.

Recent advances in harnessing biological macromolecules for wound management: A review

Wound dressings (WDs) are an essential component of wound management and serve as an artificial barrier to isolate the injured site from the external environment, thereby helping to prevent exogenous infections and supporting healing. However, maintaining a moist wound environment, providing protection from infection, good biocompatibility, and allowing for gas exchange, remain a challenge in device design. Functional wound dressings (FWDs) prepared from hybrid biological macromolecule-based materials can enhance efficacy of these systems for skin wound management. This review aims to provide an overview of the state-of-the-art FWDs within the field of wound management, with a specific focus on hybrid biomaterials, techniques, and applications developed over the past five years. In addition, we highlight the incorporation of biological macromolecules in WDs, the emergence of smart WDs, and discuss the existing challenges and future prospects for the development of advanced WDs.

A novel approach to wound healing: Green synthetic nano-zinc oxide embedded with sodium alginate and polyvinyl alcohol hydrogels for dressings

Wound healing constitutes a formidable challenge within the healthcare system, attributable to infection risks and protracted recovery periods. The pressing need for innovative wound healing methods has spurred the urgency to develop novel approaches. This study sought to advance wound healing by introducing a novel approach employing a composite sponge dressing. The composite sponge dressing, derived from LFL-ZnO (synthesized through the green methodology utilizing Lactobacillus plantarum ZDY2013 fermentation liquid), polyvinyl alcohol (PVA), and sodium alginate (SA) via a freeze-thaw cycle and freeze-drying molding process, demonstrated notable properties. The findings elucidate the commendable swelling, moisturizing, and mechanical attributes of the SA/LFL-ZnO/PVA composite sponge dressing, characterized by a porous structure. Remarkably, the dressing incorporating LFL-ZnO exhibited substantial inhibition against both methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (S. aureus). Hemolysis and cytotoxicity tests corroborated the excellent biocompatibility of the sponge dressing. In vivo evaluation of the therapeutic efficacy of the 1 mg/mL LFL-ZnO composite dressing on scald wounds and S. aureus-infected wounds revealed its capacity to accelerate wound healing and exert pronounced antibacterial effects. Consequently, the composite sponge dressings synthesized in this study hold significant potential for application in wound treatment.

Recent design strategies for boosting chemodynamic therapy of bacterial infections

The emergence of drug-resistant bacteria poses a significant threat to people's lives and health as bacterial infections continue to persist. Currently, antibiotic therapy remains the primary approach for tackling bacterial infections. However, the escalating rates of drug resistance coupled with the lag in the development of novel drugs have led to diminishing effectiveness of conventional treatments. Therefore, the development of nonantibiotic-dependent therapeutic strategies has become imperative to impede the rise of bacterial resistance. The emergence of chemodynamic therapy (CDT) has opened up a new possibility due to the CDT can convert H2O2 into •OH via Fenton/Fenton-like reaction for drug-resistant bacterial treatment. However, the efficacy of CDT is limited by a variety of practical factors. To overcome this limitation, the sterilization efficiency of CDT can be enhanced by introducing the therapeutics with inherent antimicrobial capability. In addition, researchers have explored CDT-based combined therapies to augment its antimicrobial effects and mitigate its potential toxic side effects toward normal tissues. This review examines the research progress of CDT in the antimicrobial field, explores various strategies to enhance CDT efficacy and presents the synergistic effects of CDT in combination with other modalities. And last, the current challenges faced by CDT and the future research directions are discussed.

MXene-NH2/chitosan hemostatic sponges for rapid wound healing

Effective control of wound bleeding and sustained promotion of wound healing remain a major challenge for hemostatic materials. In this study, the hemostatic sponge with controllable antibacterial and adjustable continuous promotion of wound healing (CMNCu) was prepared by chitosan, aminated MXene and copper ion. Interestingly, the internal topological point-line-surface interaction endowed the CMN-Cu sponge longitudinal staggered tubular porous microstructure, combined with the lipophilic properties obtained by modified MXene, which greatly improved its flexibility, wet elasticity and blood enrichment capacity. In addition, the sponge achieved controlled release of active ingredients, which made it present highly effective antibacterial activity and long-lasting ability to promote wound healing. In vitro and in vivo experiments confirmed that CMN-Cu sponge presented high-efficient hemostatic performance. Last but not least, a series of cell experiments showed that the CMN-Cu sponge had excellent safety as a hemostatic material.

Electrospun Antimicrobial Drug Delivery Systems and Hydrogels Used for Wound Dressings

Wounds and chronic wounds can be caused by bacterial infections and lead to discomfort in patients. To solve this problem, scientists are working to create modern wound dressings with antibacterial additives, mainly because traditional materials cannot meet the general requirements for complex wounds and cannot promote wound healing. This demand is met by material engineering, through which we can create electrospun wound dressings. Electrospun wound dressings, as well as those based on hydrogels with incorporated antibacterial compounds, can meet these requirements. This manuscript reviews recent materials used as wound dressings, discussing their formation, application, and functionalization. The focus is on presenting dressings based on electrospun materials and hydrogels. In contrast, recent advancements in wound care have highlighted the potential of thermoresponsive hydrogels as dynamic and antibacterial wound dressings. These hydrogels contain adaptable polymers that offer targeted drug delivery and show promise in managing various wound types while addressing bacterial infections. In this way, the article is intended to serve as a compendium of knowledge for researchers, medical practitioners, and biomaterials engineers, providing up-to-date information on the state of the art, possibilities of innovative solutions, and potential challenges in the area of materials used in dressings.

β-Carotene laden antibacterial and antioxidant gelatin/polyglyceryl stearate nano-hydrogel system for burn wound healing application

Worldwide, burn wounds are severe health issues prone to bacterial infections and challenging to treat with traditional wound dressings. Therefore, a highly desirable biological macromolecules-based wound dressing with good antioxidant, antibacterial, biocompatible, and a large surface area is required. Herein, aim to develop a biological macromolecules-based physically cross-linked gelatin/polyglyceryl stearate/graphene oxide (GPGO) hydrogel to treat burn wounds. Four sets of hydrogels were prepared by varying GO concentrations. FT-IR, FE-SEM, viscosity analysis, mechanical and thermal stability confirmed the successful preparation of hydrogels with desired properties. Further, β-carotene (0.5 mg/mL) was encapsulated in hydrogels to enhance the antioxidant activity, and a cumulative release as well as kinetics at pH 6.4 and 7.4 was performed. With an increase in GO concentration, hydrogels showed sustained release of β-carotene. Among all, GPGO-3 β hydrogel showed the highest antioxidant potency (57.75 %), hemocompatible (<5 %), cytocompatible (viable with NIH 3T3 cells), cell migration, proliferation, and in vitro wound healing. Also, GPGO-3 β hydrogel showed efficient antibacterial activity (%inhibition of 85.5 % and 80.2 % and zone of 11 mm and 9.8 mm against S. aureus and E. coli). These results demonstrated the ability of GPGO-3 β hydrogel as a promising candidate for burn wound healing applications.

Guiding the Path to Healing: CuO2 -Laden Nanocomposite Membrane for Diabetic Wound Treatment

Diabetic chronic wounds pose significant clinical challenges due to their characteristic features of impaired extracellular matrix (ECM) function, diminished angiogenesis, chronic inflammation, and increased susceptibility to infection. To tackle these challenges and provide a comprehensive therapeutic approach for diabetic wounds, the first coaxial electrospun nanocomposite membrane is developed that incorporates multifunctional copper peroxide nanoparticles (n-CuO2 ). The membrane's nanofiber possesses a unique "core/sheath" structure consisting of n-CuO2 +PVP (Polyvinylpyrrolidone)/PCL (Polycaprolactone) composite sheath and a PCL core. When exposed to the wound's moist environment, PVP within the sheath gradually disintegrates, releasing the embedded n-CuO2 . Under a weakly acidic microenvironment (typically diabetic and infected wounds), n-CuO2 decomposes to release H2 O2 and Cu2+ ions and subsequently produce ·OH through chemodynamic reactions. This enables the anti-bacterial activity mediated by reactive oxygen species (ROS), suppressing the inflammation while enhancing angiogenesis. At the same time, the dissolution of PVP unveils unique nano-grooved surface patterns on the nanofibers, providing desirable cell-guiding function required for accelerated skin regeneration. Through meticulous material selection and design, this study pioneers the development of functional nanocomposites for multi-modal wound therapy, which holds great promise in guiding the path to healing for diabetic wounds.

Composites based on alginate containing formylphosphazene-crosslinked chitosan and its Cu(II) complex as an antibiotic-free antibacterial hydrogel dressing with enhanced cytocompatibility

Hydrogels based on chitosan or alginate biopolymers are believed to be desirable for covering skin lesions. In this research, we explored the potential of a new composite hydrogels series of sodium alginate (Alg) filled with cross-linked chitosan to use as hydrogel wound dressings. Cross-linked chitosan (CSPN) was synthesized by Schiff-base reaction with aldehydated cyclophosphazene, and its Cu(II) complex was manufactured and identified. Then, their powder suspension and Alg were transformed into hydrogel via ion-crosslinking with Ca2+. The hydrogel constituents were investigated by using FTIR, XRD, rheological techniques, and thermal analysis including TGA (DTG) and DSC. Moreover, structure optimization calculations were performed with the Material Studio 2017 program based on DFT-D per Dmol3 module. Examination of Alg's interactions with CSPN and CSPN-Cu using this module demonstrated that Alg molecules can be well adsorbed to the particle's surface. By changing the dosage of CSPN and CSPN-Cu, the number and size of pores, swelling rate, degradation behavior, protein absorption rate, cytotoxicity and blood compatibility were changed significantly. Subsequently, we employed erythromycin as a model drug to assess the entrapment efficiency, loading capacity, and drug release rate. FITC staining was selected to verify the hydrogels' intracellular uptake. Assuring the cytocompatibility of Alg-based hydrogels was approved by assessing the survival rate of fibroblast cells using MTT assay. However, the presence of Cu(II) in the developed hydrogels caused a significant antibacterial effect, which was comparable to the antibiotic-containing hydrogels. Our findings predict these porous, biodegradable, and mechanically stable hydrogels potentially have a promising future in the wound healing as antibiotic-free antibacterial dressings.

A nanozyme-reinforced injectable photodynamic hydrogel for combating biofilm infection

Bacterial biofilm-associated infectious diseases remain serious menaces to human health. Recently, photodynamic therapy (PDT) has become a prospective strategy for combating biofilm infection. However, anaerobic conditions in a biofilm greatly inhibit its therapeutic efficacy. Here, a nanozyme-reinforced injectable hydrogel is prepared using Ca2+-crosslinked sodium alginate incorporated with photosensitizer-loaded MnO2 nanosheets and CaO2 nanoparticles for O2 self-sufficient PDT to eradicate biofilm infection. In our design, CaO2 reacts with water to produce locally concentrated H2O2, which could be catalyzed by MnO2 nanosheets (catalase-mimic nanozymes) to generate O2 and greatly relieve the hypoxic conditions in the biofilm, thus significantly strengthening PDT efficacy. In vitro assays confirmed that the hybrid hydrogel not only exhibits high-performance bactericidal activity in combating both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli but also shows great efficacy in eliminating biofilm infection. Moreover, benefiting from its good syringeability, the hybrid hydrogel is prone to fit irregular wounds and exhibits high efficiency in promoting wound healing in a biofilm-infected mice model. Besides, no obvious toxicity is detected in the hybrid hydrogel. Overall, we envision that our designed hydrogel could provide a prospective solution for combating biofilm-associated infections.

Copper-based dressing: Efficacy in a wound infection of ex vivo human skin

This study aimed to evaluate the wound healing and antibacterial effects of two experimental copper dressings compared to a commercial silver dressing. Burn wounds were created in the ex vivo human skin biopsies, then were infected by Staphylococcus aureus. Tissues were treated with copper dressings, silver dressing, or a dressing without any antibacterial component. An infected wound tissue without treatment was considered as the control group. Three days after treatments, tissues were analyzed by bacterial count and histology staining, while their media was used to assess the expression of cytokines and chemokines. Histology staining confirmed the presence of second-degree burn wounds and colonization of bacteria in the surface and superficial layer of tissues. The results demonstrated a higher antibacterial effect, improved epithelium formation, and decreased wound area in one of the copper dressings compared to other dressings. Markers associated with infection control increased in both the copper and silver-treated groups. The cytokine profiling analysis revealed increased expression of markers related to angiogenesis and anti-inflammatory responses and decreased pro-inflammatory cytokine responses in the infected wound treated with one of the copper dressings. Our results confirmed the efficacy of the experimental copper dressing in reducing bacteria and promoting wound healing.

A multifunctional PAN/PVP nanofiber sponge wound dressing loaded with ZIF-8-derived carbon nanoparticles with adjustable wetness for rapid wound disinfection and exudate management

Rapid and safe disinfection and exudate management are two major challenges in infected wound care. Therefore, in this work, we developed a novel wound dressing via encapsulating ZIF-8-derived carbon nanoparticles in a hydrophilic nanofiber sponge to address severe wound infection and heavy exudate problems. The dressing can effectively kill bacteria through chemo-photothermal synergistic therapy. Meanwhile, the hydrophilic nanofiber sponge can quickly absorb wound exudate around the wound and accelerate the evaporation rate of liquid through the photothermal effect and its own structure; therefore, it is possible to remove excess liquid and regulate its wetness. In this way, it prevents the problem of wound overhydration often caused by hydrophilic dressings. In our experiment, the dressing showed good antibacterial performance and biocompatibility in vitro and could effectively control wound infection, absorb wound exudate and promote skin wound healing in vivo. Its good therapeutic effect is not only due to effective infection control and wound exudate management, but also because the structure of nanofibers similar to an extracellular matrix provides basic physical support and structural  signals conducive to skin tissue regeneration.

Sprayed PAA-CaO2 nanoparticles combined with calcium ions and reactive oxygen species for antibacterial and wound healing

The most common socioeconomic healthcare issues in clinical are burns, surgical incisions and other skin injuries. Skin lesion healing can be achieved with nanomedicines and other drug application techniques. This study developed a nano-spray based on cross-linked amorphous calcium peroxide (CaO2) nanoparticles of polyacrylic acid (PAA) for treating skin wounds (PAA-CaO2 nanoparticles). CaO2 serves as a 'drug' precursor, steadily and continuously releasing calcium ions (Ca2+) and hydrogen peroxide (H2O2) under mildly acidic conditions, while PAA-CaO2 nanoparticles exhibited good spray behavior in aqueous form. Tests demonstrated that PAA-CaO2 nanoparticles exhibited low cytotoxicity and allowed L929 cells proliferation and migration in vitro. The effectiveness of PAA-CaO2 nanoparticles in promoting wound healing and inhibiting bacterial growth in vivo was assessed in SD rats using full-thickness skin defect and Staphylococcus aureus (S.aureus)-infected wound models based thereon. The results revealed that PAA-CaO2 nanoparticles demonstrated significant advantages in both aspects. Notably, the infected rats' skin defects healed in 12 days. The benefits are linked to the functional role of Ca2+ coalesces with H2O2 as known antibacterial and healing-promoted agents. Therefore, we developed nanoscale PAA-CaO2 sprays to prevent bacterial development and heal skin lesions.

Radially Electrospun Fibrous Membrane Incorporated with Copper Peroxide Nanodots Capable of Self-Catalyzed Chemodynamic Therapy for Angiogenesis and Healing Acceleration of Diabetic Wounds

Vascular dysfunction severely hinders the healing process of diabetic wounds. Therefore, a radially structured fibrous membrane was fabricated through electrospinning by using a polycaprolactone (PCL) and polyvinylpyrrolidone (PVP) mixed solution containing copper peroxide nanoparticles (CPs) as the chemodynamic therapy (CDT) agents, aiming to simultaneously accelerate tissue regeneration and angiogenesis. The fabricated membrane allowed for the in situ H₂O₂ generation activated by the acidic diabetic microenvironment and the subsequent Fenton-type reactions to realize 99.4% elimination against Staphylococcus aureus. Besides, the released Cu²⁺ ions significantly enhanced the expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in human umbilical vein endothelial cells (HUVECs), and they showed enhanced in vitro angiogenesis. Interestingly, the CP-embedded membrane also guided cell spreading and orientated migration of L929 fibroblasts along the fiber distribution through the radially aligned topology. The in vivo implantation indicated that the raidally structured membrane modified by CPs not only dramatically accelerated wound healing of diabetic Sprague-Dawley (SD) rats in 14 days but also promoted angiogenesis in wound sites. The combination of the in situ CDT with the radially structured morphology of the functional membrane is highly promising in applications to promote diabetic wound healing through anti-infection and revascularization.

Mussel-Inspired Multifunctional Hydrogels with Adhesive, Self-Healing, Antioxidative, and Antibacterial Activity for Wound Healing

Antibacterial hydrogel wound dressings with adhesive and antioxidant activity are desirable for treating skin injuries in clinical care. Hereby, a series of multifunctional hydrogel wound dressings with high adhesive, self-healing, antioxidant, and antibacterial activity were designed and fabricated using dopamine (DA) and quercetin (QT). The multifunctional hydrogels were constructed by the interpenetrated quaternized chitosan chain segments and polyacrylamide network. The catechol groups on DA, QT, and the quaternary ammonium groups in the hydrogel system endow hydrogels with high strength, excellent adhesion, and self-healing ability. The results confirmed the admirable hemocompatibility and remarkable antibacterial activity of the multifunction hydrogels against Staphylococcus aureus and Escherichia coli. Consequently, multifunction hydrogels with satisfactory adhesive and antibacterial activity are appropriate alternative materials in the fields of tissue adhesive and wound dressing applications.

Why traditional herbal medicine promotes wound healing: Research from immune response, wound microbiome to controlled delivery

Impaired wound healing in chronic wounds has been a significant challenge for clinicians and researchers for decades. Traditional herbal medicine (THM) has a long history of promoting wound healing, making them culturally accepted and trusted by a great number of people in the world. However, for a long time, the understanding of herbal medicine has been limited and incomplete, particularly in the allopathic medicine-dominated research system. The therapeutic effects of individual components isolated from THM are found less pronounced compared to synthetic chemical medicine, and the clinical efficacy is always inferior to herbs. In the present article, we review and discuss underlying mechanisms of the skin microbiome involved in the wound healing process; THM in regulating immune responses and commensal microbiome. We additionally propose few pioneer ideas and studies in the development of therapeutic strategies for controlled delivery of herbal medicine. This review aims to promote wound care with a focus on wound microbiome, immune response, and topical drug delivery systems. Finally, future development trends, challenges, and research directions are discussed.

Alginate based photothermal cryogels boost ferrous-supply for enhanced antibacterial chemodynamic therapy and accelerated wound healing

Uncontrolled hemorrhage is a main cause of pre-hospital death. Given the importance of hemostatic wound dressings in pre-hospital emergency treatment, novel composite materials are required for fast hemostasis, synergistic bacterial ablation with negligible resistance and wound healing acceleration. Herein, multifunctional SCTF cryogels were fabricated by the simultaneous cross-linking of sodium alginate (SA) and tannic acid (TA) with Fe³⁺ ions. As a result, the prepared SCTF cryogels consisted of Fe³⁺/TA-based metal phenolic networks (MPNs) and Fe³⁺/SA-based 3D skeleton for collagen (CA). MPNs endowed the cryogels with photothermal effect, photothermal-enhanced Fenton activity and pH/photothermal dual-responsive release property of TA and Fe²⁺, which were beneficial for the antibacterial capacity. Due to the intrinsic high porosity, in vitro and in vivo assays demonstrated that SCTF cryogels possessed good hemostatic capacity. Moreover, the synergistic photothermal therapy (PTT), chemodynamic therapy (CDT) and pH/photothermal responsive chemo-therapy dramatically enhanced the bactericidal efficacy of SCTF cryogels both in vitro and in vivo. Eventually, their outstanding healing-accelerating effects were confirmed via animal experiments, which were attributed to the presence of CA and TA. Therefore, the developed composite materials could offer new strategy on exploiting multifunctional wound dressing for clinical applications in the future.

pH-Responsive wound dressings: advances and prospects

Wound healing is a complex and dynamic process, in which the pH value plays an important role in reflecting the wound status. Wound dressings are materials that are able to accelerate the healing process. Among the multifunctional advanced wound dressings developed in recent years, pH-responsive wound dressings, especially hydrogels, show great potential owing to their unique properties of adjusting their functions according to the wound conditions, thereby allowing the wound to heal in a regulated manner. However, a comprehensive review of pH-responsive wound dressings is lacking. This review summarizes the design strategies and advanced functions of pH-responsive hydrogel wound dressings, including their excellent antibacterial properties and significant pro-healing abilities. Other advanced pH-responsive materials, such as nanofibers, composite films, nanoparticle clusters, and microneedles, are also classified and discussed. Next, the pH-monitoring functions of pH-responsive wound dressings and the related pH indicators are summarized in detail. Finally, the achievements, challenges, and future development trends of pH-responsive wound dressings are discussed.

Modulating the local coordination environment of cobalt single-atomic nanozymes for enhanced catalytic therapy against bacteria

Single-atomic nanozymes (SANZs) characterized by atomically dispersed single metal atoms have recently contributed to breakthroughs in biomedicine due to their satisfactory catalytic activity and superior selectivity compared to their nanoscale counterparts. The catalytic performance of SANZs can be improved by modulating their coordination structure. Therefore, adjusting the coordination number of the metal atoms in the active center is a potential method for enhancing the catalytic therapy effect. In this study, we synthesized various atomically dispersed Co nanozymes with different nitrogen coordination numbers for peroxidase (POD)-mimicking single-atomic catalytic antibacterial therapy. Among the single-atomic Co nanozymes with nitrogen coordination numbers of 3 (SACNZs-N₃-C) and 4 (SACNZs-N₄-C), single-atomic Co nanozymes with a coordination number of 2 (SACNZs-N₂-C) had the highest POD-like catalytic activity. Kinetic assays and Density functional theory (DFT) calculations indicated that reducing the coordination number can lower the reaction energy barrier of single-atomic Co nanozymes (SACNZs-N_x-C), thereby increasing their catalytic performance. In vitro and in vivo antibacterial assays demonstrated that SACNZs-N₂-C had the best antibacterial effect. This study provides proof of concept for enhancing single-atomic catalytic therapy by regulating the coordination number for various biomedical applications, such as tumor therapy and wound disinfection. STATEMENT OF SIGNIFICANCE: The use of nanozymes that contain single-atomic catalytic sites has been shown to effectively promote the healing of bacteria-infected wounds by exhibiting peroxidase-like activity. The homogeneous coordination environment of the catalytic site has been associated with high antimicrobial activity, which provides insight into designing new active structures and understanding their mechanisms of action. In this study, we designed a series of cobalt single-atomic nanozymes (PSACNZs-N_x-C) with different coordination environments by shearing the Co-N bond and modifying polyvinylpyrrolidone (PVP). The synthesized PSACNZs-N_x-C demonstrated enhanced antibacterial activity against both Gram-positive and Gram-negative bacterial strains, and showed good biocompatibility in both in vivo and in vitro experiments.

Hybrid gelatin-sulfated alginate scaffolds as dermal substitutes can dramatically accelerate healing of full-thickness diabetic wounds

Diabetic foot ulcers (DFUs) are defined as chronic and non-healing wounds that cause skin disorders. Here, we introduce a novel biodegradable gelatin/sulfated alginate hybrid scaffold as a dermal substitute to accelerate the healing of full-thickness diabetic ulcers in a diabetic mouse model. The hybrid scaffold possessing different weight ratios of sulfated alginate, from 10 % up to 50 %, were prepared through chemical crosslinking by carbodiimide chemistry and further freeze-drying. Based on the in vitro cytotoxicity experiments, the hybrid scaffolds not only showed no cytotoxicity, but the cell growth also dramatically increased by increasing the sulfated alginate content. Finally, the pathology of hybrid scaffolds as the dermal substitutes for healing of full-thickness diabetic wounds showed the more appropriate formation of epidermal layer, more homogeneous distribution of collagenous tissue and lower penetration of immune cells for the hybrid scaffolds-treated wounds.

Citric acid modified ultrasmall copper peroxide nanozyme for in situ remediation of environmental sulfonylurea herbicide contamination

Herbicide residues in the environment threaten high-quality agriculture and human health. Consequently, in situ remediation of herbicide contamination is vital. We synthesized a novel self-catalyzed nanozyme, ultrasmall (2-3 nm) copper peroxide nanodots modified by citric acid (CP@CA) for this purpose, which can break down into H₂O₂ and Cu²⁺ in water or soil. Ubiquitous glutathione reduces Cu²⁺ into Cu⁺, which promotes the decomposition of H₂O₂ into •OH through a Fenton-like reaction under mild acid conditions created by the presence of citric acid. The generated •OH efficiently degrade nicosulfuron in water and soil, and the maximum degradation efficiency could be achieved at 97.58% in water at 56 min. The possible degradation mechanisms of nicosulfuron were proposed through the 25 intermediates detected. The overall ecotoxicity of the nicosulfuron system was significantly reduced after CP@CA treatment. Furthermore, CP@CA had little impact on active components of soil bacterial community. Moreover, CP@CA nanozyme could effectively remove seven other sulfonylurea herbicides from the water. In this paper, a high-efficiency method for herbicide degradation was proposed, which provides a new reference for the in situ remediation of herbicide pollution.

In Vitro and In Vivo Characterization Methods for Evaluation of Modern Wound Dressings

Chronic wound management represents a major challenge in the healthcare sector owing to its delayed wound-healing process progression and huge financial burden. In this regard, wound dressings provide an appropriate platform for facilitating wound healing for several decades. However, adherent traditional wound dressings do not provide effective wound healing for highly exudating chronic wounds and need the development of newer and innovative wound dressings to facilitate accelerated wound healing. In addition, these dressings need frequent changing, resulting in more pain and discomfort. In order to overcome these issues, a wide range of affordable and innovative modern wound dressings have been developed and explored recently to accelerate and improve the wound healing process. However, a comprehensive understanding of various in vitro and in vivo characterization methods being utilized for the evaluation of different modern wound dressings is lacking. In this context, an overview of modern dressings and their complete in vitro and in vivo characterization methods for wound healing assessment is provided in this review. Herein, various emerging modern wound dressings with advantages and challenges have also been reviewed. Furthermore, different in vitro wound healing assays and in vivo wound models being utilized for the evaluation of wound healing progression and wound healing rate using wound dressings are discussed in detail. Finally, a summary of modern wound dressings with challenges and the future outlook is highlighted.

Magnetocontrollable droplet mobility on liquid crystal-infused porous surfaces

Magnetocontrollable droplet mobility on surfaces of both solids and simple fluids have been widely used in a wide range of applications. However, little is understood about the effect of the magnetic field on the wettability and mobility of droplets on structured fluids. Here, we report the manipulation of the dynamic behaviors of water droplets on a film of thermotropic liquid crystals (LCs). We find that the static wetting behavior and static friction of water droplets on a 4'-octyl-4-biphenylcarbonitrile (8CB) film strongly depend on the LC mesophases, and that a magnetic field caused no measurable change to these properties. However, we find that the droplet dynamics can be affected by a magnetic field as it slides on a nematic 8CB film, but not on isotropic 8CB, and is dependent on both the direction and strength of the magnetic field. By measuring the dynamic friction of a droplet sliding on a nematic 8CB film, we find that a magnetic field alters the internal orientational ordering of the 8CB which in turn affects its viscosity. We support this interpretation with a scaling argument using the LC magnetic coherence length that includes (i) the elastic energy from the long-range orientational ordering of 8CB and (ii) the free energy from the interaction between 8CB and a magnetic field. Overall, these results advance our understanding of droplet mobility on LC films and enable new designs for responsive surfaces that can manipulate the mobility of water droplets.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (further details of the stability of LCIPS against water-induced dewetting, the interfacial tension and contact angle measurement using a goniometer, the estimation of the thickness of LC wrapping layer at air-water interface on droplets, SEM measurements, the average sliding velocity of a water droplet on 5CB, E7, silicone oil, and mineral oil films with and without a magnetic field, representative force diagram (F _d versus time) of a 3-µL water droplet moving at a speed of 0.1 mm/s on a nematic 8CB film, F _dynamic acting on 3 µL water droplets moving at speeds of 0.1-1 mm/s on an isotropic 8CB film, the calculated magnetic coherence length as a function of the magnitude of the magnetic field applied to the nematic LCIPS, and the apparent advancing and receding contact angles of a moving water droplet on nematic LCIPS as a function of time, and polarized light micrographs (top view) of a nematic 8CB film between two DMOAP-functionalized glass slides before and after applying a horizontal magnetic field) is available in the online version of this article at 10.1007/s12274-022-5318-y.

Multifunctional nanoreactors with nutrient consumption and ROS generation capabilities for antibacterial and skin repair

Bacterial wound infection has brought a serious threat to human health and caused huge economic losses. Attempts to develop biomaterials with excellent antibacterial effects are meaningful to promote wound healing. Herein, we report a multifunctional nanoreactor with nutrient consumption and reactive oxygen species (ROS) generation capabilities for antibacterial and skin wound repair. The nanoreactor was constructed by the encapsulation of glucose oxidase (GOx) into a Cu²⁺-doped zeolite-based imidazole framework (ZIF-8) through a one-pot synthesis method. The nanoreactor not only consumes the nutrients of bacteria by the GOx-driven oxidation reaction, but also generates highly toxic hydroxyl radicals (˙OH) to kill bacteria via a Cu⁺-mediated Fenton-like reaction. Moreover, Zn²⁺ released from the nanoreactor is also capable of exhibiting synergistic antibacterial activity. In addition to mediating Fenton-like reactions, Cu²⁺ promotes angiogenesis to accelerate wound healing. Thus, the multifunctional nanoreactor has the ability to cut off the nutrient supply and starve the bacteria, produce ROS to kill bacteria, and promote angiogenesis to accelerate wound healing, enabling it to be promising for the treatment of wound infection.

Dual-Functional Nanofibrous Patches for Accelerating Wound Healing

Bacterial infections and inflammation are two main factors for delayed wound healing. Coaxial electrospinning nanofibrous patches, by co-loading and sequential co-delivering of anti-bacterial and anti-inflammation agents, are promising wound dressing for accelerating wound healing. Herein, curcumin (Cur) was loaded into the polycaprolactone (PCL) core, and broad-spectrum antibacterial tetracycline hydrochloride (TH) was loaded into gelatin (GEL) shell to prepare PCL-Cur/GEL-TH core-shell nanofiber membranes. The fibers showed a clear co-axial structure and good water absorption capacity, hydrophilicity and mechanical properties. In vitro drug release results showed sequential release of Cur and TH, in which the coaxial mat showed good antioxidant activity by DPPH test and excellent antibacterial activity was demonstrated by a disk diffusion method. The coaxial mats showed superior biocompatibility toward human immortalized keratinocytes. This study indicates a coaxial nanofiber membrane combining anti-bacterial and anti-inflammation agents has great potential as a wound dressing for promoting wound repair.

A Self-Supplying H2O2 Modified Nanozyme-Loaded Hydrogel for Root Canal Biofilm Eradication

The success of root canal therapy depends mainly on the complete elimination of the root canal bacterial biofilm. The validity and biocompatibility of root canal disinfectant materials are imperative for the success of root canal treatment. However, the insufficiency of the currently available root canal disinfectant materials highlights that more advanced materials are still needed. In this study, a nanozyme-loaded hydrogel (Fe3O4-CaO2-Hydrogel) was modified and analyzed as a root canal disinfectant material. Fe3O4-CaO2-Hydrogel was fabricated and examined for its release profile, biocompatibility, and antibacterial activity against E. faecalis and S. sanguis biofilms in vitro. Furthermore, its efficiency in eliminating the root canal bacterial biofilm removal in SD rat teeth was also evaluated. The results in vitro showed that Fe3O4-CaO2-Hydrogel could release reactive oxygen species (ROS). Moreover, it showed good biocompatibility, disrupting bacterial cell membranes, and inhibiting exopolysaccharide production (p < 0.0001). In addition, in vivo results showed that Fe3O4-CaO2-Hydrogel strongly scavenged on root canal biofilm infection and prevented further inflammation expansion (p < 0.05). Altogether, suggesting that Fe3O4-CaO2-Hydrogel can be used as a new effective biocompatible root canal disinfectant material. Our research provides a broad prospect for clinical root canal disinfection, even extended to other refractory infections in deep sites.

Multiple Coordination-Derived Bioactive Hydrogel with Proangiogenic Hemostatic Capacity for Wound Repair

Bioactive hydrogels with multifunctional properties have shown promising potential in promoting wound repair and skin tissue regeneration. The regulation on different stages of skin wound healing (hemostasis and inflammation) is important for wound repair. Herein, a multiple coordination-derived bioactive hydrogel (SGPA) with anti-inflammatory proangiogenic hemostatic capacity for wound repair is reported. The SGPA is prepared through a facile multiple metal coordination action based on the sodium alginate, metal ions (Gd³⁺ ), and bisphosphate functionalized polycitrate. The SGPA exhibits a large porous structure, good injectability, and self-healing performance, as well as controlled biodegradation. Furthermore, the SGPA has good cytocompatibility and hemocompatibility, and can further promote the migration of endothelial cells. The SGPA hydrogel presents good hemostasis capacity in a liver hemorrhage model in vivo. The full-thickness cutaneous wound model demonstrates that the SGPA hydrogel can effectively accelerate the wound repair through down-regulating the inflammatory factors and stimulating the angiogenesis around the wound beds. This work suggests that the multiple metal-organic coordination may be a good strategy to construct the multifunctional bioactive hydrogel for wound repair.

Growth of Cu2O Nanoparticles on Two-Dimensional Zr-Ferrocene-Metal-Organic Framework Nanosheets for Photothermally Enhanced Chemodynamic Antibacterial Therapy

Two-dimensional (2D) metal-organic framework (MOF) nanosheets have been demonstrated to be promising templates for the growth of various kinds of nanomaterials on their surfaces to construct novel 2D composites, thus realizing enhanced performance in various applications. Herein, we report the growth of Cu₂O nanoparticles on 2D Zr-ferrocene (Zr-Fc)-MOF (Zr-Fc-MOF) nanosheets to prepare 2D composites for near-infrared (NIR) photothermally enhanced chemodynamic antibacterial therapy. The uniform Zr-Fc-MOF nanosheets are synthesized using the solvothermal method, followed by ultrasound sonication, and Cu₂O nanoparticles are then deposited on its surface to obtain the Cu₂O-decorated Zr-Fc-MOF (denoted as Cu₂O/Zr-Fc-MOF) 2D composite. Promisingly, the Cu₂O/Zr-Fc-MOF composite shows higher chemodynamic activity for producing ·OH via Fenton-like reaction than that of the pristine Zr-Fc-MOF nanosheets. More importantly, the chemodynamic activity of the Cu₂O/Zr-Fc-MOF composite can be further enhanced by the photothermal effect though NIR laser (808 nm) irradiation. Thus, the Cu₂O/Zr-Fc-MOF composite can be used as an efficient nanoagent for photothermally enhanced chemodynamic antibacterial therapy.

Oxygen-Independent Sulfate Radical for Stimuli-Responsive Tumor Nanotherapy

Variant modalities are quested and merged into the tumor nanotherapy by leveraging the excitation from external or intratumoral incentives. However, the ubiquitous hypoxia and the insufficient content of hydrogen peroxide (H2 O2 ) in tumor microenvironments inevitably hinder the effective production of reactive oxygen species (ROS). To radically extricate from the shackles, peroxymonosulfate (PMS: HSO5- )-loaded hollow mesoporous copper sulfide (CuS) nanoparticles (NPs) are prepared as the distinct ROS donors for sulfate radical (•SO4- )-mediated and stimuli-responsive tumor nanotherapy in an oxygen-independent manner. In this therapeutic modality, the second near-infrared laser irradiation, together with the released copper ions as well as the heat produced by CuS after illumination, work together to activate PMS thus triply ensuring the copious production of •SO4- . Different from conventional ROS, the emergence of •SO4- , possessing a longer half-life and more rapid reaction, is independent of the oxygen (O2 ) and H2 O2 content within the tumor. In addition, this engineered nanosystem also exerts the function of photoacoustic imaging and skin restoration on the corresponding animal models. This study reveals the enormous potential of sulfate radical in oncotherapy and broadens pave for exploring the application of multifunctional and stimuli-responsive nanosystems in biomedicine.

A Copper Peroxide Fenton Nanoagent-Hydrogel as an In Situ pH-Responsive Wound Dressing for Effectively Trapping and Eliminating Bacteria

Bacterial infection has been a great threat to wounds due to the abuse of antibiotics and drug resistance. Elaborately constructing an efficient antibacterial strategy for accelerated healing of bacteria-infected wounds is of great importance. Herein, we develop a transferrin-conjugated copper peroxide nanoparticle-hydrogel (denoted as CP@Tf-hy) wound dressing with no toxicity to mammalian cells at a test dosage. When exposed to an initial acidic wound environment, the CP@Tf-hy simultaneously displays in situ self-supplied H₂O₂ and pH-responsive release of Fenton catalytic copper ions accompanied by highly toxic hydroxyl radical (•OH) generation against antibiotic-resistant bacteria. Meanwhile, the positively charged CP@Tf-hy can efficiently trap and restrain negatively charged bacteria to the range of •OH destruction to greatly overcome its intrinsic disadvantages of short life and diffusion distance. Importantly, the CP@Tf-hy consumes the bacterial overexpressed antioxidant glutathione while boosting Fenton catalytic copper(I) ions to generate more •OH. The synergistic effects of the enhanced Fenton reaction, responsive copper ion release, and bacterial trapping can achieve high bacterial elimination efficacy (7 log reduction). In vivo investigations demonstrate that the porous CP@Tf-hy significantly promotes hemostasis, cell proliferation, and migration of the wound, consequently accelerating bacteria-infected wound healing. The safe, low-cost, and all-in-one CP@Tf-hy holds great prospects as an antibacterial dressing for rapid resistant bacteria-infected purulent wound healing.

Near-Infrared Light-Controllable Multifunction Mesoporous Polydopamine Nanocomposites for Promoting Infected Wound Healing

The successful treatment of infected wounds requires strategies with effective antimicrobial, anti-inflammatory, and healing-promoting properties. Accordingly, the use of Cu²⁺ and tetracycline (TC), which can promote angiogenesis, re-epithelialization, and collagen deposition, also antibacterial activity, at the wound site, has shown application prospects in promoting infected wound repair. However, realizing controllable release to prolong action time and avoid potential toxicities is critical. Moreover, near-infrared light (NIR)-activated mesoporous polydopamine nanoparticles (MPDA NPs) reportedly exert anti-inflammatory effects by eliminating the reactive oxygen species generated during inflammatory responses. In this study, we assess whether Cu²⁺ and TC loaded in MPDA NPs can accelerate infected wound healing in mice. In particular, Cu²⁺ is chelated and immobilized on the surface of MPDA NPs, while a thermosensitive phase-change material (PCM; melting point: 39-40 °C), combined with antibiotics, was loaded into the MPDA NPs as a gatekeeper (PPMD@Cu/TC). Results show that PPMD@Cu/TC exhibits significant great photothermal properties with NIR irradiation, which induces the release of Cu²⁺, while inducing PCM melting and, subsequent, TC release. In combination with anti-inflammatory therapy, NIR-triggered Cu²⁺ and TC release enables the nanocomposite to eradicate bacterial wound infections and accelerate healing. Importantly, negligible damage to primary organs and satisfactory biocompatibility were observed in the murine model. Collectively, these findings highlight the therapeutic potential of this MPDA-based platform for controlling bacterial infection and accelerating wound healing.

Ionic liquids enable the preparation of a copper-loaded gel with transdermal delivery function for wound dressings

Antibacterial hydrogel dressings play an important role in wound healing and infection treatment. The majority of hydrogels are obtained through chemical cross-linking and complex synthesis or processing. Copper ions (Cu²⁺) have been involved in sterilization; however, their direct use may lead to high local concentrations and heavy metal toxic side effects. Herein, dopamine (DA) was polymerized in situ along a polyvinyl alcohol (PVA) chain and chelated copper ions (Cu²⁺) to form a mixture. Ionic liquid (IL) choline-glycolate (CGLY) was added to the mixture to form an ionic gel. CGLY promotes gel formation through intermolecular hydrogen bonds with the polymer chains and avoids the use of toxic chemical crosslinking agents. Meanwhile, CGLY can also promote the release of Cu²⁺ and generate hydrogel free radicals (˙OH) in the wound through chemodynamic therapy to kill drug-resistant bacteria. In addition, the excellent transdermal property of CGLY enables the released Cu²⁺ to stimulate cell migration and accelerate wound healing. The gel exhibits favorable biocompatibility and its use has been demonstrated in skin infection therapy of mice.

Electrospun Biodegradable Nanofibers Coated Homogenously by Cu Magnetron Sputtering Exhibit Fast Ion Release. Computational and Experimental Study

Copper-coated nanofibrous materials are desirable for catalysis, electrochemistry, sensing, and biomedical use. The preparation of copper or copper-coated nanofibers can be pretty challenging, requiring many chemical steps that we eliminated in our robust approach, where for the first time, Cu was deposited by magnetron sputtering onto temperature-sensitive polymer nanofibers. For the first time, the large-scale modeling of PCL films irradiation by molecular dynamics simulation was performed and allowed to predict the ions penetration depth and tune the deposition conditions. The Cu-coated polycaprolactone (PCL) nanofibers were thoroughly characterized and tested as antibacterial agents for various Gram-positive and Gram-negative bacteria. Fast release of Cu2+ ions (concentration up to 3.4 µg/mL) led to significant suppression of E. coli and S. aureus colonies but was insufficient against S. typhimurium and Ps. aeruginosa. The effect of Cu layer oxidation upon contact with liquid media was investigated by X-ray photoelectron spectroscopy revealing that, after two hours, 55% of Cu atoms are in form of CuO or Cu(OH)2. The Cu-coated nanofibers will be great candidates for wound dressings thanks to an interesting synergistic effect: on the one hand, the rapid release of copper ions kills bacteria, while on the other hand, it stimulates the regeneration with the activation of immune cells. Indeed, copper ions are necessary for the bacteriostatic action of cells of the immune system. The reactive CO2/C2H4 plasma polymers deposited onto PCL-Cu nanofibers can be applied to grafting of viable proteins, peptides, or drugs, and it further explores the versatility of developed nanofibers for biomedical applications use.