Nanoliquid Dressing with Enhancing Anti-Infection Performance under the Moderate Photothermal Effect for Wound Treatment

Enhanced diabetic foot ulcer treatment with a chitosan-based thermosensitive hydrogel loaded self-assembled multi-functional nanoparticles for antibacterial and angiogenic effects

Inhibiting bacterial growth and promoting angiogenesis are essential for enhancing wound healing in diabetic patients. Excessive oxidative stress at the wound site can also lead to an accumulation of reactive oxygen species. To address these challenges, a smart thermosensitive hydrogel loaded with therapeutic agents was developed. This formulation features self-assembled nanoparticles named CIZ, consisting of chlorogenic acid (CA), indocyanine green (ICG), and zinc ions (Zn2+). These nanoparticles are loaded into a chitosan-β-glycerophosphate hydrogel, named CIZ@G, which enables rapid gel formation under photothermal effects. The hydrogel demonstrates good biocompatibility and effectively releases drugs into diabetic foot ulcers (DFU) wound. Benefiting from the dual actions of CA and zinc ions, the hydrogel exhibits potent antioxidative and anti-inflammatory effects, enhances the expression of vascular endothelial growth factor (VEGF) and Platelet endothelial cell adhesion molecule-1 (CD31), and promotes angiogenesis. Both in vitro and in vivo experiments confirm that CIZ@G can effectively inhibit the growth of Staphylococcus aureus post-laser irradiation and accelerate wound remodeling within 14 days. This approach offers a new strategy for the treatment of diabetic foot ulcers (DFU), potentially transforming patient care in this challenging clinical area.

Novel Biomaterials for Wound Healing and Tissue Regeneration

Skin is the first defense barrier of the human body, which can resist the invasion of external dust, microorganisms and other pollutants, and ensure that the human body maintains the homeostasis of the internal environment. Once the skin is damaged, the health threat to the human body will increase. Wound repair and the human internal environment are a dynamic process. How to effectively accelerate the healing of wounds without affecting the internal environment of the human body and guarantee that the repaired tissue retains its original function as much as possible has become a research hotspot. With the advancement of technology, researchers have combined new technologies to develop and prepare various types of materials for wound healing. This article will introduce the wound repair materials developed and prepared in recent years from three types: nanofibers, composite hydrogels, and other new materials. The paper aims to provide reference for researchers in related fields to develop and prepare multifunctional materials. This may be helpful to design more ideal materials for clinical application, and then achieve better wound healing and regeneration effects.

NIR-triggered bacterial cellulose-based wound dressings for multiple synergistic therapy of infected wound

Skin wounds are repaired by a complex series of events and overlapping phases in which bacterial infection and insufficient angiogenesis at the wound site delay the healing process. Thus, functional wound dressings with enhanced antibacterial activity and angiogenic capacity have attracted attention. Herein, bacterial cellulose (BC)-based dressings were successfully fabricated by functionalization with a polydopamine (PDA) coating and copper sulfide nanoparticles (CuS NPs). Under 808 nm laser illumination, the BC/PDA/CuS composite membranes exhibited outstanding adjustable photothermal and photodynamic activities as well as controlled Cu2+ release, endowing the composite membranes with synergetic antibacterial activity. Specially, a bactericidal efficiency of 99.7 % and 88.0 % for Staphylococcus aureus and Escherichia coli was achieved after treatment with BC/PDA/CuS5 sample under NIR irradiation (0.8 W/cm2, 10 min), respectively. Moreover, the BC/PDA/CuS5 composite membrane could enhance the angiogenesis due to the released Cu2+. In vivo experiments revealed that the BC/PDA/CuS5 composite membrane dressing could accelerate the wound closure process of the full-thickness skin defects with S. aureus by synergistically reducing inflammation, enhancing collagen deposition, and promoting vascularization under NIR irradiation. Additionally, the BC/PDA/CuS5 composite membrane exhibited high biocompatibility and biosafety. This work offers a new strategy to prepare multifunctional BC-based dressing for clinical wound healing.

Hollow Copper Sulfide Photothermal Nanodelivery Platform Boosts Angiogenesis of Diabetic Wound by Scavenging Reactive Oxygen Species

Sharply rising oxidative stress and ineffectual angiogenesis have imposed restrictions on diabetic wound healing. Here, a photothermal-responsive nanodelivery platform (HHC) was prepared by peroxidase (CAT)-loaded hollow copper sulfide dispersed in photocurable methacrylamide hyaluronan. The HHC could scavenge reactive oxygen species (ROS) and promote angiogenesis by photothermally driven CAT and Cu2+ release. Under near-infrared light irradiation, the HHC presented safe photothermal performance (<43 °C), efficient bacteriostatic ability against E. coli and S. aureus. It could rapidly release CAT into the external environment for decomposing H2O2 and oxygen generation to alleviate oxidative stress while promoting fibroblast migration and VEGF protein expression of endothelial cells by reducing intracellular ROS levels. The nanodelivery platform presented satisfactory therapeutic effects on murine diabetic wound healing by modulating tissue inflammation, promoting collagen deposition and increasing vascularization in the neodermis. This HHC provided a viable strategy for diabetic wound dressing design.

Poly(pentahydropyrimidine)‐Based Hybrid Hydrogel with Synergistic Antibacterial and Pro‐Angiogenic Ability for the Therapy of Diabetic Foot Ulcers

Bacterial infection and impaired angiogenesis make the treatment of diabetic foot ulcers (DFU) extremely challenging. Cationic polymers are expected to treat infected wounds due to their excellent antibacterial properties, but still, it is difficult to meet the therapeutic needs of pro‐angiogenesis and anti‐infections due to their simple construction units and outmoded synthesis methods. Herein, a cationic poly(pentahydropyrimidine) (PPHP) library with strong modifiability is synthesized to construct a hybrid hydrogel with synergistic therapeutic effects for the treatment of infected DFUs. It is found that the as‐synthesized hybrid hydrogel can up‐regulate angiogenesis‐related gene (HIF‐1, VEGF, and bFGFR/bFGF) expression and targeted disruption of bacterial cell membranes, which finally promotes the healing of infected DFU (wound healing rate: 92%) within 10 days. This hydrogel, thus, holds great promise in developing new strategies to significantly enhance the treatment of DFU and other bacterial‐infected pathological diagnoses.

An injectable and thermosensitive hydrogel with nano-aided NIR-II phototherapeutic and chemical effects for periodontal antibacteria and bone regeneration

Periodontitis is a common public health problem worldwide and an inflammatory disease with irregular defect of alveolar bone caused by periodontal pathogens. Both antibacterial therapy and bone regeneration are of great importance in the treatment of periodontitis. In this study, injectable and thermosensitive hydrogels with 3D networks were used as carriers for controlled release of osteo-inductive agent (BMP-2) and Near Infrared Region-II (NIR-II) phototherapy agents (T8IC nano-particles). T8IC nano-particles were prepared by reprecipitation and acted as photosensitizer under 808 nm laser irradiation. Besides, we promoted photodynamic therapy (PDT) through adding H2O2 to facilitate the antibacterial effect instead of increasing the temperature of photothermal therapy (PTT). Hydrogel + T8IC + Laser + BMP-2 + H2O2 incorporated with mild PTT (45 °C), enhanced PDT and sustained release of BMP-2. It was present with excellent bactericidal effect, osteogenic induction and biosafety both in vitro and in vivo. Besides, immunohistochemistry staining and micro-CT analyses had confirmed that PTT and PDT could promote bone regeneration through alleviating inflammation state. Altogether, this novel approach with synergistic antibacterial effect, anti-inflammation and bone regeneration has a great potential for the treatment of periodontitis in the future.

Photothermal/lysozyme-catalyzed hydrolysis dual-modality therapy via halloysite nanotube-based platform for effective bacterial eradication

Bacterial biofilm seriously impedes the healing of infected wound, remaining a major challenge in wound repair. Antibiotic-free antibacterial strategies based on nanotechnology are emerging as promising tools to combat bacterial infections. Here, halloysite nanotube (HNT), as a natural clay mineral, was employed to fabricate a multifunctional platform (designated as HNTs@CuS@PDA-Lys) through a layer-by-layer strategy for treating bacterial infections by utilizing synergistic lysozyme (Lys)-photothermal therapy (PTT). Specifically, amino-modified HNTs were first decorated with copper sulfide (CuS), followed by coated with a polydopamine (PDA) layer, then functionalized with antimicrobial enzyme Lys onto the surface of PDA via cation-π interactions. The as-prepared HNTs@CuS@PDA-Lys at a low dose (200 μg/mL) exhibited excellent synergistic Lys-photothermal bactericidal activity against Escherichia coli (E. coli) (100.0 ± 0.2 %) and Staphyloccocus aureus (S. aureus) (99.9 ± 0.1 %), eliminated 75.9 ± 2.0 % of S. aureus biofilm under near-infrared (NIR) irradiation (808 nm, 1.5 W/cm²). In vivo experiments using a S. aureus-infected rat model showed HNTs@CuS@PDA-Lys could rapidly kill bacteria and accelerate wound healing process. Overall, this multifunctional nanoplatform combines the advantages of PTT and Lys, providing a cost-efficient, environmental friendly strategy for bacterial and biofilm eradication, demonstrating the potential applications in the field of biomedicine.

Surface-charge-switch triggered self assembly of vancomycin modified carbon nanodots for enhanced photothermal eradication of vancomycin-resistant Enterococci biofilms

A new type of vancomycin (Van)-modified carbon nanodots (CNDs@Van) with pH-responsive surface charge switchable activity was successfully developed by covalently cross-linking Van on the surface of carbon nanodots (CNDs). Polymeric Van was formed on the surface of CNDs by covalent modification, which enhanced the targeted binding of CNDs@Van to vancomycin-resistant enterococci (VRE) biofilms and effectively reduced the carboxyl groups on the surface of CNDs to achieve pH-responsive surface charge switching. Most importantly, CNDs@Van was free at pH 7.4, but assembled at pH 5.5 owing to surface charge switching from negative to zero, resulting in remarkably enhanced near-infrared (NIR) absorption and photothermal properties. CNDs@Van exhibited good biocompatibility, low cytotoxicity, and weak hemolytic effects under physiological conditions (pH 7.4). Regarding targeted binding to VRE bacteria, CNDs@Van self-assembled in a weakly acidic environment (pH 5.5) generated by VRE biofilms, giving enhanced photokilling effects in in vitro and in vivo assays. Therefore, potentially, CNDs@Van can be used as a novel antimicrobial agent against VRE bacterial infections and their biofilms.

Mesenchymal Stem Cell Derived Extracellular Vesicles: Promising Nanomedicine for Cutaneous Wound Treatment

A skin wound represents a rupture caused by external damage or the existence of underlying pathological conditions. Sometimes, skin wound healing processes may place a heavy burden on patients, families, and society. Wound healing processes mainly consist of several continuous, dynamic, but overlapping stages, namely, the coagulation stage, inflammation stage, proliferation stage, and remodeling stage. Bacterial infection, excessive inflammation, impaired angiogenesis, and scar formation constitute the four significant factors impeding the recovery efficacy of skin wounds. This encourages scientists to develop multifunctional nanomedicines to meet challenging needs. As we know, mesenchymal stem cells (MSCs) have been widely explored for wound repair owing to their unique capability for self-renewal and multipotency. However, problems including immune concerns and legal restrictions should be properly resolved before MSC-based therapeutics are safely and widely used in clinics. Besides, maintaining the high viability/proliferation capability of MSCs during administration processes and therapy procedures is also one of the biggest technical bottlenecks. Extracellular vesicles (EVs) are cell-derived nanovesicles, that not only possess the basic characteristics and functions of their corresponding maternal cells but also contain several outstanding advantages including abundant sources, excellent biocompatibility, and convenient administration routes. Furthermore, the membrane surface and cavity are easy to flexibly modify to meet versatile application needs. Recently, MSC-derived EVs have emerged as promising therapeutics for skin wound repair. However, current reviews are too broad and rarely focused on the specific roles of EVs in the different stages of wound recovery. Therefore, it is quite necessary to demonstrate the significance of stem cell-derived EVs in promoting wound healing from several specific aspects. Here, this review primarily tries to provide critical comments on current advances in EVs derived from MSCs for wound repair, particularly elaborating on their impressive roles in effectively eliminating infections, inhibiting inflammation, promoting angiogenesis, and reducing scar formation. Last but not least, current limitations and future prospects of EVs derived from MSCs in the areas of wound repair are also objectively analyzed.

Dynamically evolving piezoelectric nanocomposites for antibacterial and repair-promoting applications in infected wound healing

Wound healing from bacterial infections is one of the major challenges in the biomedical field. The traditional single administration methods are usually accompanied with side effects or unsatisfactory efficacy. Herein, we design dynamically evolving antibacterial and repair-promoting nanocomposites (NCs) by in situ self-assembling of zeolitic imidazolate framework-8 (ZIF-8) on the surface of barium titanate (BTO), and further loading with a small amount of ciprofloxacin (CIP). The new strategy of combining pH-stimulated drug delivery and ultrasound-controlled sonodyamics has the potential to dynamically evolve in infected wound sites, offering a multifunctional therapy. In vitro study demonstrates that the enhancement generation of reactive oxygen species through the sonodynamic process due to the heterostructures and a small amount of CIP released in an acidic environment are synergistically antibacterial, and the inhibition rate was >99.9%. In addition, reduced sonodynamic effect and Zn²⁺ generated along with the gradual degradation of ZIF-8 simultanously promote cell migration and tissue regeneration. The in vivo study of full-thickness skin wounds in mouse models demonstrate a healing rate of 99.3% could be achieved under the treatment of BTO@ZIF-8/CIP NCs. This work provides a useful improvement in rational design of multi-stimulus-responsive nanomaterials for wound healing. STATEMENT OF SIGNIFICANCE: A novel piezoelectric nanocomposite was proposed to realize sonodynamic therapy and pH-stimulated drug releasing simultaneously in wound healing treatment. The dynamically evolving structure of the piezoelectric nanocomposite in acidic microenvironment has been theoretically and experimentally verified to contribute to a continuous variation of sonodymanic strength, which accompanied with the gradual releasing of drug and biocompatible Zn²⁺effectively balanced antibacterial and repair-promoting effects. Both of the in vitro and in vivo study demonstrated that the strategy could significantly accelerate wound healing, inspiring researchers to optimize the design of multi-stimulus-responsive nanomaterials for various applications in biomedical and biomaterial fields.

A core/shell nanogenerator achieving pH-responsive nitric oxide release for treatment of infected diabetic wounds

Nitric oxide is critical for eliminating infection and promoting regeneration in diabetic wounds. However, clinical uses of nitric oxide are limited by its high activity and lack of specificity in targeting infections. Herein, we develop an intelligent nitric oxide nanogenerator comprising isosorbide dinitrate (ISDN)-coated copper sulfide (CuS)/calcium carbonate (CaCO₃) core/shell nanoparticles (CuS@CaCO₃-ISDN) to target the acidic microenvironment of the infected diabetic wounds. Meaningfully, triggered by acid decomposition of CaCO₃, this nanogenerator can achieve a responsive and accelerated release of nitric oxide from ISDN through enzyme-mimicking redox processes that involve CuS nanoparticles and then inactivate biofilm bacteria through the pathways of oxidative stress and disruption of adenosine triphosphate (ATP)-related energy metabolism. Moreover, after eliminating the infection, the pH-responsive release of nitric oxide can promote the proliferation of blood vessels and tissue regeneration and accelerate diabetic wound closure. This study expands the use of nitric oxide donors in wound treatment by developing the enzyme-mimicking release strategy, and the pH-responsive core/shell nanogenerator is promising for a variety of anti-infection therapeutic applications.

Effectiveness of Copper Nanoparticles in Wound Healing Process Using In Vivo and In Vitro Studies: A Systematic Review

Chronic wounds are defined as wounds that do not heal in an orderly and timely manner through the various stages of the healing process. Copper nanoparticles are essential in dressings for wound healing because they promote angiogenesis and skin regeneration, which hasten the healing process. This systematic investigation sought to explain how copper nanoparticles affect chronic wound healing in vivo and in vitro. We realized a systematic review of original articles studying the effectiveness of copper nanoparticles in the healing process of chronic wounds. The protocol was registered in the PROSPERO database. Several databases were searched between 2012 and January 2022 for English-language papers using MeSH terms and text related to chronic wounds, copper nanoparticles, and wound healing. Quality was evaluated using National Institute for Health and Care Excellence methodology and PRISMA guidelines. We looked at a total of 12 primary studies. Quantitative data were gathered and presented in all studies. Our results suggest that copper nanoparticles could have an excellent healing property, facilitating the liberation of growth factors that help the anti-inflammatory process of the wound and significantly improving antibacterial and antioxidant activities. In addition, copper presents a higher biocompatibility than other metallic ions, promoting regeneration and increasing skin quality.

Rational Design of Intelligent and Multifunctional Dressing to Promote Acute/Chronic Wound Healing

Currently, the clinic's treatment of acute/chronic wounds is still unsatisfactory due to the lack of functional and appropriate wound dressings. Intelligent and multifunctional dressings are considered the most advanced wound treatment modalities. It is essential to design and develop wound dressings with required functions according to the wound microenvironment in the clinical treatment. This work summarizes microenvironment characteristics of various common wounds, such as acute wound, diabetic wound, burns wound, scalded wound, mucosal wound, and ulcers wound. Furthermore, the factors of transformation from acute wounds to chronic wounds were analyzed. Then we focused on summarizing how researchers fully and thoroughly combined the complex microenvironment with modern advanced technology to ensure the usability and value of the dressing, such as photothermal-sensitive dressings, microenvironment dressing (pH-sensitive dressings, ROS-sensitive dressings, and osmotic pressure dressings), hemostatic dressing, guiding tissue regeneration dressing, microneedle dressings, and 3D/4D printing dressings. Finally, the revolutionary development of wound dressings and how to transform the existing advanced functional dressings into clinical needs as soon as possible have carried out a reasonable and meaningful outlook.

S-nitrosoglutathione functionalized polydopamine nanoparticles incorporated into chitosan/gelatin hydrogel films with NIR-controlled photothermal/NO-releasing therapy for enhanced wound healing

Nitric oxide (NO) has aroused wide interest in the treating infected wounds due to its characteristic functionalities. However, its utilization is limited due to its volatile properties, high reactivity, direct potential toxicity, and byproducts of NO donors limited its application. Herein, endogenously NO donor S-nitrosoglutathione (GSNO) was connected covalently to polydopamine nanoparticles (PDA-GSNO NPs) to minimize the loss of NO in aqueous medium. Meanwhile, near-infrared (NIR)-controlled NO release and photothermal therapy (PTT) was obtained through the photothermal conversion by PDA. Then chitosan (CS)/gelatin (GE) biocomposite hydrogel films with preferable biocompatibility, surface hydrophilicity, hydroabsorptivity, and mechanical adhesive properties were constructed. By embedding PDA-GSNO NPs into the films, a multifunctional wound dressing was fabricated. Under NIR light irradiation, the combination of PTT, NO-releasing, and CS antibacterial agents can strengthen the in vitro antimicrobial efficacy and in vivo wound healing activities. Meanwhile, the obtained wound dressing presented good biocompatibility. This work outlines an approach for combating bacterial infections and demonstrating the possibility for synergistic NO-releasing wound healing.

Fabrication of a Lignin-Copper Sulfide-Incorporated PVA Hydrogel with Near-Infrared-Activated Photothermal/Photodynamic/Peroxidase-like Performance for Combating Bacteria and Biofilms

Antibiotic-resistant bacteria and biofilms are among the most difficult challenges in infection treatment. Herein, lignin-copper sulfide (LS-CuS) nanocomposites were incorporated into a poly(vinyl alcohol) (PVA) hydrogel to fabricate a LS-CuS@PVA composite hydrogel with near-infrared-activated photothermal, photodynamic, and peroxidase-like performance. The antibacterial tests of LS-CuS@PVA exhibited the highest antibacterial rate that caused 3.8-log and 4.8-log reductions of colony forming units (CFUs) against Escherichia coli and Staphylococcus aureus in the presence of H₂O₂ under near-infrared (NIR) light irradiation for 10 min. The significantly improved bactericidal performance could be attributed to the synergistic effects of hyperthermia and reactive oxygen species (ROS). Furthermore, the LS-CuS@PVA hydrogel could eradicate the already formed biofilm and inhibit biofilm formation. Considering the highly effective antibacterial and antibiofilm activity of the LS-CuS@PVA hydrogel, this work could provide new insights for the design of poly(vinyl alcohol)-based composite hydrogels for wound healing and wound dressing.

A bionic cellulose nanofiber-based nanocage wound dressing for NIR-triggered multiple synergistic therapy of tumors and infected wounds

Tumor recurrence and drug-resistant bacterial infection are the main reasons that wounds heal with difficulty after skin tumor treatment. The near infrared- (NIR-) and pH-responsive, bionic, cellulose nanofiber-based (CNF-based) nanocage wound dressing with biocompatibility, bioviscosity, and shape adaptability is designed for dual NIR-triggered photothermal therapy of tumor and infection-induced wound healing. The wound dressing with the intertwining three dimensional (3D) nanocage network structure is skillfully constructed using NIR-responsive cellulose nanofibers and pH-responsive cellulose nanofibers as the skeleton, which endows the dressing with a high drug-loading capacity of doxorubicin (400 mg·g^-1), and indocyanine green (25 mg·g^-1). Moreover, the NIR- and pH-responsive bionic "On/Off" switches of the dressing enable a controllable and efficient drug release onto the wound area. The dual NIR-triggered wound dressing with excellent photothermal conversion performance possesses good antibacterial properties against Escherichia coli, Staphylococcus aureus, and drug-resistant Staphylococcus aureus. It could effectively eliminate bacterial biofilms and kill A375 tumor cells. Interestingly, the bionic wound dressing with shape adaptability could adapt and treat irregular postoperative skin tumor wounds and drug-resistant bacterial infection via the synergistic therapy of photothermal, photodynamic, and chemotherapy, which provides an ideal strategy for clinical intervention.

ZnL2-BPs Integrated Bone Scaffold under Sequential Photothermal Mediation: A Win-Win Strategy Delivering Antibacterial Therapy and Fostering Osteogenesis Thereafter

Implant-related infections are serious complications after bone surgery and can compromise the intended functions of artificial implants, leading to surgical failure and even amputation in severe cases. Various strategies have been proposed to endow bone implants with the desirable antibacterial properties, but unfortunately, most of them inevitably suffer from some side effects detrimental to normal tissues. In this study, a multifunctional bone implant is designed to work in conjunction with sequential photothermal mediation, which can deliver antibacterial therapy (<50 °C) in the early stage and foster bone regeneration (40-42 °C) subsequently. Black phosphorus nanosheets (BPs) are coordinated with zinc sulfonate ligand (ZnL₂), and the ZnL₂-BPs are integrated into the surface of a hydroxylapatite (HA) scaffold to produce ZnL₂-BPs@HAP. In this design, BPs produce the photothermal effects and ZnL₂ increases the thermal sensitivity of peri-implant bacteria by inducing envelope stress. The biosafety of the antibacterial photothermal treatment is improved due to the mild temperature, and furthermore, gradual release of Zn²⁺ and PO₄^3- from the scaffold facilitates osteogenesis in the subsequent stage of bone healing. This strategy not only broadens the biomedical applications of photothermal treatment but also provides insights into the design of multifunctional biomaterials in other fields.

Photo-Sono Interfacial Engineering Exciting the Intrinsic Property of Herbal Nanomedicine for Rapid Broad-Spectrum Bacteria Killing

Large doses and long duration are often required for herbal medicines to kill bacteria effectively. Herein, a photoacoustic interfacial engineering strategy was utilized to endow curcumin (Cur, a kind of herbal medicine) with rapid and highly effective bacteria-killing efficacy, in which Cur was combined with CuS to form a hybrid material of CuS/Cur with tight contact through in situ nucleation and growth on the petaloid CuS surface. Due to the different work functions of CuS and Cur, the interfacial electrons were redistributed, i.e., a large number of electrons gathered on the side of CuS. In contrast, the holes gathered on the side of Cur after contact. An internal electric field was formed to drive the excited electrons to transfer from CuS to Cur, thus enhancing the separation of electron-hole pairs. Besides exerting the drug nature of Cur itself, the CuS/Cur hybrid also had photo-sono responsive ability, which endowed the hybrid with photothermal, photodynamic, and sonodynamic effects. Therefore, this Cur-based hybrid killed 99.56% of Staphylococcus aureus and 99.48% of Escherichia coli under 808 nm near-infrared light irradiation and ultrasound successively for 15 min, which was ascribed to the synergy of ROS, hyperthermia, and released Cu²⁺ together with the drug properties of Cur. This work provides a strategy to enhance the therapeutic effects of herbal medicines against pathogenic bacterial infections by exciting the intrinsic properties of herbal medicines as materials through a photo-sono interfacial engineering strategy.

Optimization of Nanostructured Copper Sulfide to Achieve Enhanced Enzyme-Mimic Activities for Improving Anti-Infection Performance

Advanced antibacterial methods are urgently needed to deal with possible infectious diseases. As promising alternatives to antibiotics, enzyme-mimic nanocatalysts face bottlenecks of low activities and indistinct catalytic mechanisms, which seriously restrict their development for anti-infection treatment. Herein, metastable copper sulfide (Cu_2-xS) nanozymes with diversiform sizes and compositions were selected to adjust the electronic structure for enhancing enzyme-mimic activities. The as-synthesized large and thin nanoplates (L/TN nanoplates), with the stoichiometric ratio of Cu_1.25S, were proven to possess the optimal peroxidase (POD)-mimic activity. Using quantum mechanics, it was theoretically revealed that the sulfur vacancies could alter the electronic structure of copper active sites and thus reduce the reaction energy barrier of H₂O₂ to·OH to promote the POD-mimic performance. Moreover, through enhanced enzyme-mimic activities, L/TN nanoplates achieved efficient depletion of glutathione and ascorbic acid for improving antibacterial performances. Further, synergizing with the NIR irradiation, the satisfactory destruction capability for bacteria and biofilm was achieved for L/TN nanoplates under an inflammatory level of hydrogen peroxide (50 μM). Altogether, this work provides a deeper understanding of geometrical and electronic properties-dependent antibacterial performance, and paves the way toward precise compositions and structures engineering of nanozymes.