Near-Infrared Regulated Nanozymatic/Photothermal/Photodynamic Triple-Therapy for Combating Multidrug-Resistant Bacterial Infections via Oxygen-Vacancy Molybdenum Trioxide Nanodots

Rough Ag2S@H-CeO2 photonic nanocomposites for effective eradication of drug-resistant bacteria and improved healing of infected cutaneous wounds

With the continuous increasing threat of drug-resistant bacteria induced cutaneous wound infections, there is a growing demand for novel effective antibiotics-alternative antibacterial strategies for clinical anti-infective therapy. Here, we report the fabrication and antibacterial efficacy of Ag2S@H-CeO2 photonic nanocomposites with rough surface through in-situ growth of Ag2S nanoparticles on CeO2 hollow spheres. With excellent photothermal property and peroxidase-like activity, as well as increased bacterial adhesion, the photonic nanocomposites demonstrated a broad-spectrum synergistic antibacterial effect against Gram-positive, Gram-positive bacteria and fungi as well biofilm in vitro. Significantly, the nanocomposites can effectively eradicate drug-resistant bacteria such as Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (ESBL E. coli). Notably, in vivo assessments validated its synergistic therapeutic potential in the treatment of MRSA-infected cutaneous wounds, all while maintaining excellent biosafety and biocompatibility. Our study offers a competitive and promising strategy for the development of a multifunctional synergistic antibacterial platform poised to effectively treat drug-resistant bacteria-infected cutaneous wounds.

Advancements in wound management: integrating nanotechnology and smart materials for enhanced therapeutic interventions

Wound management spans various techniques and materials tailored to address acute and chronic non-healing wounds, with the primary objective of achieving successful wound closure. Chronic wounds pose additional challenges, often necessitating dressings to prepare the wound bed for subsequent surgical procedures like skin grafting. Ideal dressing materials should not only expedite wound healing but also mitigate protein, electrolyte, and fluid loss while minimizing pain and infection risk. Nanotechnology has emerged as a transformative tool in wound care, revolutionizing the landscape of biomedical dressings. Its application offers remarkable efficacy in accelerating wound healing and combating bacterial infections, representing a significant advancement in wound care practices. Integration of nanotechnology into dressings has resulted in enhanced properties, including improved mechanical strength and controlled drug release, facilitating tailored therapeutic interventions. This review article comprehensively explores recent breakthroughs in wound healing therapies, with a focus on innovative medical dressings such as nano-enzymes. Additionally, the utilization of smart materials, like hydrogels and electroactive polymers, in wound dressings offers dynamic functionalities to promote tissue regeneration. Emerging concepts such as bio-fabrication, microfluidic systems, bio-responsive scaffolds, and personalized therapeutics show promise in expediting wound healing and minimizing scarring. Through an in-depth exploration of these advancements, this review aims to catalyze a paradigm shift in wound care strategies, promoting a patient-centric approach to therapeutic interventions.

Cu-MoOx-based nanozyme with enhanced peroxidase like activity for quinolone antibiotics detection

The abuse of antibiotics has seriously threatened human health and living environment. Nevertheless, the detection of quinolones is currently mainly performed by high-cost and cumbersome means, such as High-Performance Liquid Chromatography (HPLC). Herein, we reported a novel method based on copper-doped MoOx nanoparticles (Cu-MoOx NPs) with peroxidase-like enhancement activity for the easy preparation, sensitive and rapid visualization of quinolone detection. Cu-MoOx NPs can make the chromogenic substrate 3,3',5,5'-Tetramethylbenzidine (TMB) change from colorless to blue. Moreover, the addition of quantitative quinolone antibiotics can significantly accelerate the TMB oxidation reaction. Based on this phenomenon, a colorimetric method for detecting quinolone antibiotics was established with a good linear relationship ranging from 1 × 10-6 M to 1.3 × 10-4 M, and the detection limit was 0.310 μM for ciprofloxacin (CIP) and 0.520 μM for levofloxacin (LVFX). Furthermore, the mechanism was also explored, and the results showed that the peroxidase-like activity of Cu-MoOx NPs was probably derived from the generated OH, 1O2, oxygen vacancies and partially reduced Cu+, and on the other hand was derived from quinolone antibiotics and nanozymes electrostatic interaction between them.

Graphene Quantum Dots Nanoantibiotic-Sensitized TiO2- x Heterojunctions for Sonodynamic-Nanocatalytic Therapy of Multidrug-Resistant Bacterial Infections

The exploration of sonodynamic therapy (SDT) as a possible replacement for antibiotics by creating reactive oxygen species (ROS) is suggested as a non-drug-resistant theranostic method. However, the low-efficiency ROS generation and complex tumor microenvironment which can deplete ROS and promote tumor growth will cause the compromised antibacterial efficacy of SDT. Herein, through an oxygen vacancy engineering strategy, TiO2- x microspheres with an abundance of Ti3+ are synthesized using a straightforward reductant co-assembly approach. The narrow bandgaps and Ti3+/Ti4+-mediated multiple-enzyme catalytic activities of the obtained TiO2- x microspheres make them suitable for use as sonosensitizers and nanozymes. When graphene quantum dot (GQD) nanoantibiotics are deposited on TiO2- x microspheres, the resulting GQD/TiO2- x shows an increased production of ROS, which can be ascribed to the accelerated separation of electron-hole pairs, as well as the peroxidase-like catalytic activity mediated by Ti3+, and the depletion of glutathione mediated by Ti4+. Moreover, the catalytic activities of TiO2- x microspheres are amplified by the heterojunctions-accelerated carrier transfer. In addition, GQDs can inhibit Topo I, displaying strong antibacterial activity and further enhancing the antibacterial activity. Collectively, the combination of GQD/TiO2- x-mediated SDT/NCT with nanoantibiotics can result in a synergistic effect, allowing for multimodal antibacterial treatment that effectively promotes wound healing.

Prussian blue-decorated indocyanine green-loaded mesoporous silica nanohybrid for synergistic photothermal-photodynamic-chemodynamic therapy against methicillin-resistant Staphylococcus aureus

Nanomaterial-based synergistic antibacterial agents are considered as promising tools to combat infections caused by antibiotic-resistant bacteria. Herein, multifunctional mesoporous silica nanoparticle (MSN)-based nanocomposites were fabricated for synergistic photothermal/photodynamic/chemodynamic therapy against methicillin-resistant Staphylococcus aureus (MRSA). MSN loaded with indocyanine green (ICG) as a core, while Prussian blue (PB) nanostructure was decorated on MSN surface via in situ growth method to form a core-shell nanohybrid (MSN-ICG@PB). Upon a near infrared (NIR) laser excitation, MSN-ICG@PB (200 μg mL-1) exhibited highly efficient singlet oxygen (1O2) generation and hyperthermia effect (48.7℃). In the presence of exogenous H2O2, PB with peroxidase-like activity promoted the generation of toxic hydroxyl radicals (•OH) to achieve chemodynamic therapy (CDT). PTT can greatly increase the permeability of bacterial lipid membrane, facilitating the generated 1O2 and •OH to kill bacteria more efficiently. Under NIR irradiation and exogenous H2O2, MSN-ICG@PB (200 μg mL-1) with good biocompatibility exhibited a synergistic antibacterial effect against MRSA with high bacterial killing efficiency (>98 %). Moreover, due to the synergistic bactericidal mechanism, MSN-ICG@PB with satisfactory biosafety makes it a promising antimicrobial agent to fight against MRSA.

Engineering Ag-Decorated Graphene Oxide Nano-Photothermal Platforms with Enhanced Antibacterial Properties for Promoting Infectious Wound Healing

Introduction

Graphene oxide (GO) nanoparticles have emerged as a compelling photothermal agent (PHTA) in the realm of photothermal antibacterial therapy, owing to their cost-effectiveness, facile synthesis, and remarkable photostability. Nevertheless, the therapeutic efficacy of GO nanoparticles is commonly hindered by their inherent drawback of low photothermal conversion efficiency (PCE).

Methods

Herein, we engineer the Ag/GO-GelMA platform by growing the Ag on the surface of GO and encapsulating the Ag/GO nanoparticles into the GelMA hydrogels.

Results

The resulting Ag/GO-GelMA platform demonstrates a significantly enhanced PCE (47.6%), surpassing that of pure GO (11.8%) by more than fourfold. As expected, the Ag/GO-GelMA platform, which was designed to integrate the benefits of Ag/GO nanoparticles (high PCE) and hydrogel (slowly releasing Ag+ to exert an inherent antibacterial effect), has been shown to exhibit exceptional antibacterial efficacy. Furthermore, transcriptome analyses demonstrated that the Ag/GO-GelMA platform could significantly down-regulate pathways linked to inflammation (the MAPK and PI3K-Akt pathways) and had the ability to promote cell migration.

Discussion

Taken together, this study presents the design of a potent photothermal antibacterial platform (Ag/GO-GelMA) aimed at enhancing the healing of infectious wounds. The platform utilizes a handy method to enhance the PCE of GO, thereby making notable progress in the utilization of GO nano-PHTAs.

Melanin as a Photothermal Agent in Antimicrobial Systems

Bacterial infection is one of the most problematic issues for human health and the resistance of bacteria to traditional antibiotics is a matter of huge concern. Therefore, research is focusing on the development of new strategies to efficiently kill these microorganisms. Recently, melanin is starting to be investigated for this purpose. Indeed, this very versatile material presents outstanding photothermal properties, already studied for photothermal therapy, which can be very useful for the light-induced eradication of bacteria. In this review, we present antibacterial melanin applications based on the photothermal effect, focusing both on the single action of melanin and on its combination with other antibacterial systems. Melanin, also thanks to its biocompatibility and ease of functionalization, has been demonstrated to be easily applicable as an antimicrobial agent, especially for the treatment of local infections.

Synergistic enhancement of fluorescein-K3[Fe(CN)6] CL by MoO3-x NPs for sensitive and noninvasive detection of uric acid in saliva

MoO3-x NPs was rapidly synthesized at room temperature by an easy stirring method. It was interesting to find that MoO3-x NPs induce OH- to generate active free radicals (ROS), which is a highly promising property in chemiluminescence (CL). Benefiting from the abundant oxygen vacancy, MoO3-x NPs adsorbs H2O2 and turn it into ·OH. The oxidase activity of fluorescein under visible light had already been reported, which catalyzes dissolved oxygen to become O2-· and continue to convert to H2O2. By creating the synergy effect with fluorescein, MoO3-x NPs strengthen the CL intensity of K3[Fe(CN)6]-fluorescein system significantly. Utilizing the quench effect of uric acid for the CL intensity, we developed a rapid, simple, and highly sensitive CL platform for uric acid detection. The linear range was 5-80 µM and the detection limit (LOD) for uric acid was 3.11 µM (S/N = 3). This work expanded the application of MoO3-x NPs in the CL field and developed a simple and highly sensitive CL sensing system to detect UA in human saliva.

Nanozyme-Incorporated Microneedles for the Treatment of Chronic Wounds

Acute wounds are converted to chronic wounds due to advanced age and diabetic complications. Nanozymes catalyze ROS production to kill bacteria without causing drug resistance, while microneedles (MNs) can break through the skin barrier to deliver drugs effectively. Nanozymes can be intergrateded into MNs delivery systems to improve painless drug delivery. It can also reduce the effective dose of drug sterilization while increasing delivery efficiency and effectively killing wounded bacteria while preventing drug resistance. This paper describes various types of metal nanozymes from previous studies and compares their mutual enhancement with nanozymes. The pooled results show that the MNs, through material innovation, are able to both penetrate the scab and deliver nanozymes and exert additional anti-inflammatory and bactericidal effects. The catalytic effect of some of the nanozymes can also accelerate the lysis of the MNs or create a cascade reaction against inflammation and infection. However, the issue of increased toxicity associated with skin penetration and clinical translation remains a challenge. This study reviews the latest published results and corresponding challenges associated with the use of MNs combined with nanozymes for the treatment of wounds, providing further information for future research.

Copper selenide nanosheets with photothermal therapy-related properties and multienzyme activity for highly effective eradication of drug resistance

Bacterial infections are among the most significant causes of death in humans. Chronic misuse or uncontrolled use of antibiotics promotes the emergence of multidrug-resistant superbugs that threaten public health through the food chain and cause environmental pollution. Based on the above considerations, copper selenide nanosheets (CuSe NSs) with photothermal therapy (PTT)- and photodynamic therapy (PDT)-related properties have been fabricated. These CuSe NSs possess enhanced PDT-related properties and can convert O2 into highly toxic reactive oxygen species (ROS), which can cause significant oxidative stress and damage to bacteria. In addition, CuSe NSs can efficiently consume glutathione (GSH) at bacterial infection sites, thus further enhancing their sterilization efficacy. In vitro antibacterial experiments with near-infrared (NIR) irradiation have shown that CuSe NSs have excellent photothermal bactericidal properties. These experiments also showed that CuSe NSs exerted excellent bactericidal effects on wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) and significantly promoted the healing of infected wounds. Because of their superior biological safety, CuSe NSs are novel copper-based antimicrobial agents that are expected to enter clinical trials, serving as a modern approach to the major problem of treating bacterially infected wounds.

Injectable and Near-Infrared Light-Controllable Fibrin Hydrogels with Antimicrobial and Immunomodulating Properties for Infected Wound Healing

The management of infected wounds poses a significant challenge due to the growing issue of antibiotic resistance, underscoring the urgent necessity to innovate and implement alternative therapeutic strategies. These strategies should be capable of eliminating bacterial infections in infected wounds while circumventing the induction of multi-drug resistance. In the current study, we developed an easily prepared and injectable fibrin gel (FG) loaded with nanoparticles (NPs) that exhibit antibacterial and immunomodulatory properties to facilitate the healing of infected wounds. Initially, a novel type of NP was generated through the electrostatic interaction between the photothermal agent, mPEG-modified polydopamine (MPDA), and the nitric oxide (NO) donor, S-nitrosocysteamine (SNO). This interaction resulted in the formation of NPs referred to as SNO-loaded MPDA (SMPDA). Subsequently, the SMPDA was encapsulated into the FG using a double-barreled syringe, thereby producing the SMPDA-loaded FG (SMPDA/G). Experimental results revealed that SMPDA/G could effectively eliminate bacterial infections and alter the immune microenvironment. This efficacy is attributed to the synergistic combination of NO therapy and photothermal therapy, along with the role of SMPDA in facilitating M2 macrophage polarization within the gel. Accordingly, these findings suggest that the SMPDA/G holds substantial promise for clinical application in infected wound healing.

Boron Cluster Renders Organic Radicals Water-Stable for Photothermal Anti-Infections

Water-stable organic radicals are promising photothermal conversion candidates for photothermal therapy (PTT). However, organic radicals are usually unstable in biological environments, which greatly hinders their wide application. Here, we have developed a chaotropic effect-based and photoinduced water-stable supramolecular radical (MB12-2) for efficient antibacterial PTT. The supramolecular radical precursor MB12-1 was constructed by the chaotropic effect between closo-dodecaborate cluster (B12H122-) and N,N'-dimethylated dipyridinium thiazolo [5,4-d] thiazole (MPT2+). Subsequently, with triethanolamine (TEOA) serving as an electron donor, MB12-1 could transform to its radical form MB12-2 through photoinduced electron transfer (PET) under 435-nm laser irradiation. The N2 adsorption-desorption analysis confirmed that MB12-2 was tightly packed through the introduction of B12H122-, which effectively enhanced its stability via a spatial site-blocked effect. Moreover, the half-life of MB12-2 in water was calculated through ultraviolet-visible light (UV-vis) absorption spectra results for periods as long as 20 days. In addition, in the skin infection model, MB12-2, as a wound dressing, showed remarkable photothermal antibacterial activity (>97%) under 660-nm laser irradiation and promoted wound healing. This study presents a simple method for designing long-term water-stable supramolecular radicals, offering a novel avenue for noncontact treatments for bacterial infections.

MoOxNWs with mechanical damage - oriented synergistic photothermal / photodynamic therapy for highly effective treating wound infections

Reactive oxygen species (ROS)-based therapy has emerged as a promising antibacterial strategy. However, it faces the limitations of uncontrollable space-time release and excessive lipid peroxidation, which may lead to a series of metabolic disorders and decreased immune function. In this study, mechanical damage by molybdenum oxide nanowires (MoOxNWs) is introduced as a synergistic factor to enhance the photothermal and photodynamic effects for controllable and efficient antibacterial therapy. Through their sharp ends, the nanowires can effectively pierce and damage the bacterial cells, thus facilitating the entry of externally generated ROS into the cells. The ROS are generated via photodynamic effect of the nanowires under a mere 5 min of near-infrared light irradiation. This approach enhances the photothermal (by 27.3 %) and photodynamic properties of ROS generation. MoOxNWs (100 μg·mL-1) achieve sterilisation rates of 97.67 % for extended-spectrum β-lactamase-producing E. coli and 96.34 % for methicillin-resistant Staphylococcus aureus, which are comparable or even exceeding the efficacy of most MoOx-based antibacterial agents. Moreover, they exhibit good biocompatibility and low in vivo toxicity.

An NIR-II-enhanced nanozyme to promote wound healing in methicillin-resistant Staphylococcus aureus infections

Deep tissue bacterial infections, especially methicillin-resistant Staphylococcus aureus (MRSA) infections, pose challenges to clinical therapy due to their low debridement efficiency and relapsing. Molybdenum disulfide (MoS2) is used in the antibacterial field as a classic photothermal agent (NIR-I) with good biocompatibility. However, due to its limited NIR-I tissue penetration ability and single treatment mode, MoS2 has poor therapeutic effects on deep tissue infection. Herein, we prepared a defect-type hybrid 2H-MoS2 nanozyme (MoWS2) using hydrothermal method fabricate the MoWS2 composite, which is a new antibacterial strategy involving photothermal and enzyme catalysis, and further enhances the activity of the nanozyme through overheating. The regulation of 2H-MoS2 defects through tungsten ion doping endows MoWS2 with better near-infrared two-region absorption (NIR-II) and enzyme catalytic performance. Antibacterial activity experiments in vitro have shown that MoWS2 can achieve efficient bactericidal activity and biofilm clearance through hyperthermia and reactive oxygen species (ROS). Deep MRSA infection experiments have shown that MoWS2 rapidly removes bacteria from subcutaneous infected tissues through photothermal therapy (PTT) and chemodynamic therapy (CDT), accelerates the dissipation of abscesses, and promotes the healing of infected wounds. Additionally, the versatile treatment mode of MoWS2 was further confirmed through tissue sectioning and immunofluorescence staining analysis. Overall, these results provide a feasible approach for achieving efficient treatment of deep tissue infections through tungsten ion doping to regulate defective 2H-MoS2. STATEMENT OF SIGNIFICANCE: The photothermal effect of MoS2 nanosheets in the NIR-I (650-900 nm) window in anti-MRSA therapy is considered to be highly reliable and efficient in PTA. However, most of the developed PPT therapies or antimicrobial systems based on PTT therapies developed with 1T-MoS2 have in vivo sterilization temperatures of more than 55°C, which have the risk of damaging the normal tissues of the skin. In this study, we prepared W@MoS2 with a good photothermal effect (36.9%) in the NIR-II window and good peroxidase-like activity. The combined effect of PTT and CDT has a stronger bactericidal effect while avoiding high-temperature damage, which makes the W@MoS2 material more advantageous in terms of antimicrobial effect.

A Comparative Analysis of the Antibacterial Spectrum of Ultrasmall Manganese Ferrite Nanozymes with Varied Surface Modifications

Bacterial infectious diseases pose a significant global challenge. However, conventional antibacterial agents exhibit limited therapeutic effectiveness due to the emergence of drug resistance, necessitating the exploration of novel antibacterial strategies. Nanozymes have emerged as a highly promising alternative to antibiotics, owing to their particular catalytic activities against pathogens. Herein, we synthesized ultrasmall-sized MnFe2O4 nanozymes with different charges (MnFe2O4-COOH, MnFe2O4-PEG, MnFe2O4-NH2) and assessed their antibacterial capabilities. It was found that MnFe2O4 nanozymes exhibited both antibacterial and antibiofilm properties attributed to their excellent peroxidase-like activities and small sizes, enabling them to penetrate biofilms and interact with bacteria. Moreover, MnFe2O4 nanozymes effectively expedite wound healing within 12 days and facilitate tissue repair and regeneration while concurrently reducing inflammation. MnFe2O4-COOH displayed favorable antibacterial activity against Gram-positive bacteria, with 80% bacterial removal efficiency against MRSA by interacting with phosphatidylglycerol (PG) and cardiolipin (CL) of the membrane. By interacting with negatively charged bacteria surfaces, MnFe2O4-NH2 demonstrated the most significant and broad-spectrum antibacterial activity, with 95 and 85% removal efficiency against methicillin-resistant Staphylococcus aureus (MRSA) and P. aeruginosa, respectively. MnFe2O4-PEG dissipated membrane potential and reduced ATP levels in MRSA and P. aeruginosa, showing relatively broad-spectrum antibacterial activity. To conclude, MnFe2O4 nanozymes offer a promising therapeutic approach for treating wound infections.

Biocompatible N-carbazoleacetic acid decorated CuxO nanoparticles as self-cascading platforms for synergistic single near-infrared triggered phototherapy treating microbial infections

In this work, positively charged N-carbazoleacetic acid decorated CuxO nanoparticles (CuxO-CAA NPs) as novel biocompatible nanozymes have been successfully prepared through a one-step hydrothermal method. CuxO-CAA can serve as a self-cascading platform through effective GSH-OXD-like and POD-like activities, and the former can induce continuous generation of H2O2 through the catalytic oxidation of overexpressed GSH in the bacterial infection microenvironment, which in turn acts as a substrate for the latter to yield ˙OH via Fenton-like reaction, without introducing exogenous H2O2. Upon NIR irradiation, CuxO-CAA NPs possess a high photothermal conversion effect, which can further improve the enzymatic activity for increasing the production rate of H2O2 and ˙OH. Besides, the photodynamic performance of CuxO-CAA NPs can produce 1O2. The generated ROS and hyperthermia have synergetic effects on bacterial mortality. More importantly, CuxO-CAA NPs are more stable and biosafe than Cu2O, and can generate electrostatic adsorption with negatively charged bacterial cell membranes and accelerate bacterial death. Antibacterial results demonstrate that CuxO-CAA NPs are lethal against methicillin-resistant Staphylococcus aureus (MRSA) and ampicillin-resistant Escherichia coli (AREC) through destroying the bacterial membrane and disrupting the bacterial biofilm formation. MRSA-infected animal wound models show that CuxO-CAA NPs can efficiently promote wound healing without causing toxicity to the organism.

Mussel-inspired "all-in-one" sodium alginate/carboxymethyl chitosan hydrogel patch promotes healing of infected wound

Hydrogels have been widely used as wound dressings to accelerate wound healing. However, due to the impaired skin barrier at the wound site, external bacteria can easily invade the wound and cause infection. In this study, we designed a dopamine-modified sodium alginate/carboxymethyl chitosan/polyvinylpyrrolidone (CPD) hydrogel, which was able to promote wound healing while preventing wound infection. Due to the high content of catechol groups, the CPD hydrogel exhibited good tissue adhesion ability and a significant scavenging ability for DPPH• and PTIO• radicals. Under near-infrared laser irradiation, the temperature of CPD hydrogel increased significantly, which significantly killed the Staphylococcus aureus and Escherichia coli. The cell migration test confirmed that CPD hydrogel could promote the cell migration ratio. In the in vivo wound healing test for infected full-thickness skin defect, CPD hydrogel significantly inhibited bacterial proliferation and enhanced wound healing rate. Therefore, the multifunctional hydrogel is expected to be applied to wound healing.

Nanozyme with tailored selectivity and highly catalytic activity for efficient sensing of endotoxin and sourcing gram-negative bacteria

Endotoxin detection is important for determining bacterial contamination and infection in fields of food, pharmaceutical and clinical disease diagnosis. The horseshoe crab deformed cell lysate analysis is regarded as the gold-standard method, but the endangered and high-cost horseshoe crab animals required in sensing process further raise animal ethical issues and hinder their applications. The colorimetric methods based on nanozymes are simple and economical, but the low selectivity and sensitivity are still the bottleneck for their further application. Herein, we successfully developed a phenylboronic acid functionalized iron-based nanozyme with higher selectivity and highly catalytic activity for endotoxin sensing. The as-prepared colorimetric sensor using the obtained nanozyme as sensing probes shows a good linear relationship for endotoxin sensing in the range of 1-20 μg mL-1, with a LOD = 0.42 μg mL-1, along with good selectivity and reproducibility. The sensor can also be well applied to detecting endotoxin in practical samples such as beer and serum. Moreover, the parameters including time and temperature which could affect the endotoxin release from E. coli were also studied and optimized, based on the relationship between endotoxin and Gram-negative bacteria, the as-prepared sensor achieves the qualitative and quantification of E. coli.

Atomically dispersed nanozyme-based synergistic mild photothermal/nanocatalytic therapy for eradicating multidrug-resistant bacteria and accelerating infected wound healing

Constructing a synergistic multiple-modal antibacterial platform for multi-drug-resistant (MDR) bacterial eradication and effective treatment of infected wounds remains an important and challenging goal. Herein, we developed a multifunctional Cu/Mn dual single-atom nanozyme (Cu/Mn-DSAzymes)-based synergistic mild photothermal/nanocatalytic-therapy for a MDR bacterium-infected wound. Cu/Mn-DSAzymes with collaborative effects exhibit remarkable dual CAT-like and OXD-like enzyme activities and could efficiently catalyze cascade enzymatic reactions with a low level of H2O2 as an initial reactant to produce reparative O2 and lethal ˙O2-. Moreover, a black N-doped carbon nanosheet supports of Cu/Mn-DSAzymes show superior NIR-II-triggered photothermal performance, endowing them with photothermal-enhanced dual enzyme catalysis. In addition, such enhanced dual enzyme catalysis likely improves the susceptibility and lethality of photothermal effects on MDR bacteria. In vitro and in vivo studies demonstrate that Cu/Mn-DSAzyme-mediated synergistic nanocatalytic and photothermal effects possess dramatic antibacterial outcomes against MDR bacteria and evidently reduced inflammation at wound sites. Moreover, the combined photothermal effect and O2 release mediated by Cu/Mn-DSAzymes promotes macrophage polarization to reparative M2 phenotype, collagen deposition, and angiogenesis, considerably accelerating wound healing. Therefore, Cu/Mn-DSAzyme-based synergetic dual-modal antibacterial therapy is a promising strategy for MDR bacterium-infected wound treatment, owing to their excellent antibacterial ability and significant tissue remodeling effects.

Advanced nanozymes possess peroxidase-like catalytic activities in biomedical and antibacterial fields: review and progress

Infectious diseases caused by bacterial invasions have imposed a significant global health and economic burden. More worryingly, multidrug-resistant (MDR) pathogenic bacteria born under the abuse of antibiotics have further escalated the status quo. Nowadays, at the crossroads of multiple disciplines such as chemistry, nanoscience and biomedicine, nanozymes, as enzyme-mimicking nanomaterials, not only possess excellent bactericidal ability but also reduce the possibility of inducing resistance. Thus, nanozymes are promising to serve as an alternative to traditional antibiotics. Nanozymes that mimic peroxidase (POD) activity are also known as POD nanozymes. In recent years, POD nanozymes have become one of the most frequently reported and effective nanozymes due to their broad-spectrum bactericidal properties and unique sterilization mechanism. In this review, we introduce the mechanism as well as the classification of POD nanozymes. More importantly, to further improve the antibacterial efficacy of POD nanozymes, we elaborate on three aspects: (1) improving the physicochemical properties; (2) regulating the catalytic microenvironment; and (3) designing multimodel POD nanozymes. In addition, we review the nanosafety of POD nanozymes for discussing their potential toxicity. Finally, the remaining challenges of POD nanozymes and possible future directions are discussed. This work provides a systematic summary of POD nanozymes and hopefully contributes to the early clinical translation.

Thermal-Driven Curcumin Release Film with Dual-Mode Synergistic Antibacterial Behavior for Efficient Tangerine Preservation

Antimicrobial packing showed great potential in extending the shelf life of food. However, developing a new biocomposite film with an intelligent and efficient antimicrobial performance is still desirable. Herein, a Fe-MoOx encapsulated with curcumin (Cur) filled chitosan-based composite film (CCF films) was prepared by solvent casting method. The total color differences of the CCF films were less than 30%, and satisfactory surface color, transparency, hydrophobicity, and thermal stability were also obtained. Besides, the UV-light/water/oxygen barrier capability and mechanical properties were enhanced with the incorporation of Cur@Fe-MoOx. Moreover, CCF films showed photothermal performance and thermal-controlled curcumin release ability, which endowed the CCF0.15 film with excellent antibacterial capability toward E. coli (≥99.95%) and S. aureus (≥99.96%) due to the synergistic antibacterial effect. Fe-MoOx exhibited high cell viability and less than 5% hemolysis even under the concentration of 500 μg mL-1. Based on those unique characteristics, the CCF0.15 film was chosen for tangerine preservation. The CCF0.15 film could prolong the shelf life of tangerine by at least 9 days compared with the unpacking group, and the tangerines could maintain the freshness characteristics over a 24 day storage period. Such thermal-mediated antibacterial film proposed by our work showed promising potential in food packaging.

Hollow Mesoporous Molybdenum Single-Atom Nanozyme-Based Reactor for Enhanced Cascade Catalytic Antibacterial Therapy

Purpose

The remarkable peroxidase-like activity of single-atom nanozymes (SAzymes) allows them to catalyze the conversion of H2O2 to •OH, rendering them highly promising for antibacterial applications. However, their practical in vivo application is hindered by the near-neutral pH and insufficient H2O2 levels present in physiological systems. This study was aimed at developing a SAzyme-based nanoreactor and investigating its in vivo antibacterial activity.

Methods

We developed a hollow mesoporous molybdenum single-atom nanozyme (HMMo-SAzyme) using a controlled chemical etching approach and pyrolysis strategy. The HMMo-SAzyme not only exhibited excellent catalytic activity but also served as an effective nanocarrier. By loading glucose oxidase (GOx) with HMMo-SAzyme and encapsulating it with hyaluronic acid (HA), a nanoreactor (HMMo/GOx@HA) was constructed as glucose-triggered cascade catalyst for combating bacterial infection in vivo.

Results

Hyaluronidase (HAase) at the site of infection degraded HA, allowing GOx to convert glucose into gluconic acid and H2O2. An acid environment significantly enhanced the catalytic activity of HMMo-SAzyme to promote the further catalytic conversion of H2O2 to •OH for bacterial elimination. In vitro and in vivo experiments demonstrated that the nanoreactor had excellent antibacterial activity and negligible biological toxicity.

Conclusion

This study represents a significant advancement in developing a cascade catalytic system with high efficiency based on hollow mesoporous SAzyme, promising the advancement of biological applications of SAzyme.

A Nano-Autophagy Inhibitor Triggering Reciprocal Feedback Control of Cholesterol Depletion for Solid Tumor Therapy

Solid tumors are characterized by enhanced metabolism of lipid, particularly cholesterol, inspiring the exploration of metabolic therapy through cholesterol oxidase (COD)-mediated cholesterol deprivation. However, the therapeutic efficacy of COD is limited due to the hypoxic tumor microenvironment and the protective autophagy triggered by cholesterol deprivation. Herein, a combination therapy for metabolically treating solid tumors through COD in conjunction with molybdenum oxide nanodots (MONDs), which serve as both potent oxygen generators and autophagy inhibitors, is reported. MONDs convert H2 O2 (arising from COD-mediated cholesterol oxidation) into O2 , which is then recycled by COD to form reciprocal feedback for cholesterol depletion. Concurrently, MONDs can overcome autophagy-induced therapeutic resistance frequently occurring in conventional nutrient deprivation therapy by activating AKT/mTOR pathway phosphorylation. Combination therapy in the xenograft model results in an ≈5-fold increase in therapeutic efficiency as compared with COD treatment alone. This functionally cooperative metabolic coupling strategy holds great promise as a novel polytherapy approach that will benefit patients with solid tumors.

Metallic elements combine with herbal compounds upload in microneedles to promote wound healing: a review

Wound healing is a dynamic and complex restorative process, and traditional dressings reduce their therapeutic effectiveness due to the accumulation of drugs in the cuticle. As a novel drug delivery system, microneedles (MNs) can overcome the defect and deliver drugs to the deeper layers of the skin. As the core of the microneedle system, loaded drugs exert a significant influence on the therapeutic efficacy of MNs. Metallic elements and herbal compounds have been widely used in wound treatment for their ability to accelerate the healing process. Metallic elements primarily serve as antimicrobial agents and facilitate the enhancement of cell proliferation. Whereas various herbal compounds act on different targets in the inflammatory, proliferative, and remodeling phases of wound healing. The interaction between the two drugs forms nanoparticles (NPs) and metal-organic frameworks (MOFs), reducing the toxicity of the metallic elements and increasing the therapeutic effect. This article summarizes recent trends in the development of MNs made of metallic elements and herbal compounds for wound healing, describes their advantages in wound treatment, and provides a reference for the development of future MNs.

Peptide-Appended Nanosonosensitizers Targeting Tumor Glycolysis for Synergistic Sonodynamic-Immunometabolic Therapy of Spinal-Metastasized Tumors

Despite recent advancements in cancer immunotherapy, challenges have yet to be surmounted to achieve two major goals of magnifying antitumor immunity and remodeling the immunosuppressive tumor microenvironment. Here, a nanosystem (ODM-R) that integrates oxygen-deficient molybdenum oxide (ODM) nanosonosensitizers and R7 peptides with tumor metabolism regulation effects is designed and fabricated for synergistic sonodynamic-immunometabolic therapy of spinal-metastasized tumors. The ODM generates reactive oxygen species upon ultrasound irradiation to implement sonodynamic therapy (SDT), inducing cancer cell apoptosis and immunogenic cell death. The R7 attached on ODM markedly inhibits the uptake of glucose and excretion of lactic acid in cancer cells by perturbing the glycolysis process. The combination of SDT and tumor glycolysis obstruction by ODM-R guarantees satisfactory efficacy in synergizing with PD-L1 antibody to eradicate spinal-metastasized tumors, achieving concurrent sonodynamic-triggered immune activation and immunosuppressive tumor microenvironment remodeling. This work provides a proof-of-concept of nanosonosensitizers for boosting cancer immunotherapy by SDT and tumor metabolic regulation.

Tailoring the Surface and Composition of Nanozymes for Enhanced Bacterial Binding and Antibacterial Activity

With the advantages of diverse structures, tunable enzymatic activity, and high stability, nanozymes are widely used in medicine, chemistry, food, environment, and other fields. As an alternative to traditional antibiotics, nanozymes attract more and more attention from the scientific researchers in recent years. Developing nanozymes-based antibacterial materials opens up a new avenue for the bacterial disinfection and sterilization. In this review, the classification of nanozymes and their antibacterial mechanisms are discussed. The surface and composition of nanozymes are critical for the antibacterial efficacy, which can be tailored to enhance both the bacterial binding and the antibacterial activity. On the one hand, the surface modification of nanozymes enables binding and targeting of bacteria that improves the antibacterial performance of nanozymes including the biochemical recognition, the surface charge, and the surface topography. On the other hand, the composition of nanozymes can be modulated to achieve enhanced antibacterial performance including the single nanozyme-mediated synergistic and multiple nanozymes-mediated cascade catalytic antibacterial applications. In addition, the current challenges and future prospects of tailoring nanozymes for antibacterial applications are discussed. This review can provide insights into the design of future nanozymes-based materials for the antibacterial treatments.

Efficient Samarium-Grafted-C3N4-Doped α-MoO3 Used as a Dye Degrader and Antibacterial Agent: In Silico Molecular Docking Study

This study was used to evaluate the catalytic activity (CA) and bactericidal activity of α-MoO3 and Sm-g-C3N4-doped α-MoO3 composites prepared through an efficient, cost-effective coprecipitation route. Their characteristic studies verify the formation of α-MoO3 and its composites (3, 6, and 9 mL Sm-g-C3N4-doped α-MoO3), which showed high crystallinity, as confirmed by X-ray diffraction (XRD) analysis. The production of superoxide and hydroxyl radicals due to charge transfer through α-MoO3 and g-C3N4 eventually forms electrons in g-C3N4 and holes around α-MoO3. CA against Rhodamine B (RhB) in basic medium provides maximum results compared to acidic and neutral media. The bactericidal efficacy of the (9 mL) doped sample represents a greater inhibition zone of 6.10 mm against the negative bacterial strain Escherichia coli. Furthermore, in silico studies showed that the generated nanorods may inhibit DNA gyrase and dihydropteroate synthase (DHPS) enzymes.

Near-infrared active ferrocenyl porous organic polymer with photothermal enhanced enzymatic activity for combination antibacterial application

As a severe ongoing global problem, bacterial contamination exists in every aspect of human life and the search for new antibacterial agents is urgently needed. Herein, a ferrocenyl porous organic polymer (FMC-POP) broad-spectrum antibacterial agent based on synergistic photothermal and peroxidase-like activity was prepared in a facile manner via the copolymerization of ferrocene diformaldehyde and cinnamaldehyde with mannitol through the acid-responsive acetal bond. The photoactive FMC-POP, with high photothermal conversion efficiency (41.45%), could convert not only the near-infrared laser irradiation into local heat to eradicate bacteria, but also low-concentration H2O2 into radical oxygen species (˙OH) that are effective against bacteria. Compared with single-mode photothermal (PTT) and enzymatic therapies, this combination therapy could significantly improve the bactericidal effect, exhibiting a germicidal efficiency of up to 99% (vs. 80.42% for PTT and 70% for enzyme). Thus, our work paves the way for a synergistic non-invasive antimicrobial therapy, which could expand the applications of POP-based artificial enzymes in biomedicine.

Defect Engineering in Biomedical Sciences

With the promotion of nanochemistry research, large numbers of nanomaterials have been applied in vivo to produce desirable cytotoxic substances in response to endogenous or exogenous stimuli for achieving disease-specific therapy. However, the performance of nanomaterials is a critical issue that is difficult to improve and optimize under biological conditions. Defect-engineered nanoparticles have become the most researched hot materials in biomedical applications recently due to their excellent physicochemical properties, such as optical properties and redox reaction capabilities. Importantly, the properties of nanomaterials can be easily adjusted by regulating the type and concentration of defects in the nanoparticles without requiring other complex designs. Therefore, this tutorial review focuses on biomedical defect engineering and briefly discusses defect classification, introduction strategies, and characterization techniques. Several representative defective nanomaterials are especially discussed in order to reveal the relationship between defects and properties. A series of disease treatment strategies based on defective engineered nanomaterials are summarized. By summarizing the design and application of defective engineered nanomaterials, a simple but effective methodology is provided for researchers to design and improve the therapeutic effects of nanomaterial-based therapeutic platforms from a materials science perspective.

Photodynamic Therapy, Probiotics, Acetic Acid, and Essential Oil in the Treatment of Chronic Wounds Infected with Pseudomonas aeruginosa

As a prevalent medical problem that burdens millions of patients across the world, chronic wounds pose a challenge to the healthcare system. These wounds, often existing as a comorbidity, are vulnerable to infections. Consequently, infections hinder the healing process and complicate clinical management and treatment. While antibiotic drugs remain a popular treatment for infected chronic wounds, the recent rise of antibiotic-resistant strains has hastened the need for alternative treatments. Future impacts of chronic wounds are likely to increase with aging populations and growing obesity rates. With the need for more effective novel treatments, promising research into various wound therapies has seen an increased demand. This review summarizes photodynamic therapy, probiotics, acetic acid, and essential oil studies as developing antibiotic-free treatments for chronic wounds infected with Pseudomonas aeruginosa. Clinicians may find this review informative by gaining a better understanding of the state of current research into various antibiotic-free treatments. Furthermore. this review provides clinical significance, as clinicians may seek to implement photodynamic therapy, probiotics, acetic acid, or essential oils into their own practice.

Biofilm Homeostasis Interference Therapy via 1 O2 -Sensitized Hyperthermia and Immune Microenvironment Re-Rousing for Biofilm-Associated Infections Elimination

The recurrence of biofilm-associated infections (BAIs) remains high after implant-associated surgery. Biofilms on the implant surface reportedly shelter bacteria from antibiotics and evade innate immune defenses. Moreover, little is currently known about eliminating residual bacteria that can induce biofilm reinfection. Herein, novel "interference-regulation strategy" based on bovine serum albumin-iridium oxide nanoparticles (BIONPs) as biofilm homeostasis interrupter and immunomodulator via singlet oxygen (¹ O₂ )-sensitized mild hyperthermia for combating BAIs is reported. The catalase-like BIONPs convert abundant H₂ O₂ inside the biofilm-microenvironment (BME) to sufficient oxygen gas (O₂ ), which can efficiently enhance the generation of ¹ O₂ under near-infrared irradiation. The ¹ O₂ -induced biofilm homeostasis disturbance (e.g., sigB, groEL, agr-A, icaD, eDNA) can disrupt the sophisticated defense system of biofilm, further enhancing the sensitivity of biofilms to mild hyperthermia. Moreover, the mild hyperthermia-induced bacterial membrane disintegration results in protein leakage and ¹ O₂ penetration to kill bacteria inside the biofilm. Subsequently, BIONPs-induced immunosuppressive microenvironment re-rousing successfully re-polarizes macrophages to pro-inflammatory M1 phenotype in vivo to devour residual biofilm and prevent biofilm reconstruction. Collectively, this ¹ O₂ -sensitized mild hyperthermia can yield great refractory BAIs treatment via biofilm homeostasis interference, mild-hyperthermia, and immunotherapy, providing a novel and effective anti-biofilm strategy.

Nanomaterials for the treatment of bacterial infection by photothermal/photodynamic synergism

In the past few decades, great progress has been made in the field of nanomaterials against bacterial infection. However, with the widespread emergence of drug-resistant bacteria, people try their best to explore and develop new antibacterial strategies to fight bacteria without obtaining or increasing drug resistance. Recently, multi-mode synergistic therapy has been considered as an effective scheme for the treatment of bacterial infections, especially the combination of photothermal therapy (PTT) and photodynamic therapy (PDT) with controllable, non-invasive, small side effects and broad-spectrum antibacterial characteristics. It can not only improve the efficiency of antibiotics, but also do not promote antibiotic resistance. Therefore, multifunctional nanomaterials which combine the advantages of PTT and PDT are more and more used in the treatment of bacterial infections. However, there is still a lack of a comprehensive review of the synergistic effect of PTT and PDT in anti-infection. This review first focuses on the synthesis of synergistic photothermal/photodynamic nanomaterials and discusses the ways and challenges of photothermal/photodynamic synergism, as well as the future research direction of photothermal/photodynamic synergistic antibacterial nanomaterials.

AIEgen-Based Nanomaterials for Bacterial Imaging and Antimicrobial Applications: Recent Advances and Perspectives

Microbial infections have always been a thorny problem. Multi-drug resistant (MDR) bacterial infections rendered the antibiotics commonly used in clinical treatment helpless. Nanomaterials based on aggregation-induced emission luminogens (AIEgens) recently made great progress in the fight against microbial infections. As a family of photosensitive antimicrobial materials, AIEgens enable the fluorescent tracing of microorganisms and the production of reactive oxygen (ROS) and/or heat upon light irradiation for photodynamic and photothermal treatments targeting microorganisms. The novel nanomaterials constructed by combining polymers, antibiotics, metal complexes, peptides, and other materials retain the excellent antimicrobial properties of AIEgens while giving other materials excellent properties, further enhancing the antimicrobial effect of the material. This paper reviews the research progress of AIEgen-based nanomaterials in the field of antimicrobial activity, focusing on the materials' preparation and their related antimicrobial strategies. Finally, it concludes with an outlook on some of the problems and challenges still facing the field.

Activity Regulating Strategies of Nanozymes for Biomedical Applications

On accounts of the advantages of inherent high stability, ease of preparation and superior catalytic activities, nanozymes have attracted tremendous potential in diverse biomedical applications as alternatives to natural enzymes. Optimizing the activity of nanozymes is significant for widening and boosting the applications into practical level. As the research of the catalytic activity regulation strategies of nanozymes is boosting, it is essential to timely review, summarize, and analyze the advances in structure-activity relationships for further inspiring ingenious research into this prosperous area. Herein, the activity regulation methods of nanozymes in the recent 5 years are systematically summarized, including size and morphology, doping, vacancy, surface modification, and hybridization, followed by a discussion of the latest biomedical applications consisting of biosensing, antibacterial, and tumor therapy. Finally, the challenges and opportunities in this rapidly developing field is presented for inspiring more and more research into this infant yet promising area.

NIR regulated upconversion nanoparticles@metal-organic framework composite hydrogel dressing with catalase-like performance and enhanced antibacterial efficacy for accelerating wound healing

Developing a hydrogel dressing with excellent antibacterial efficacy for accelerating wound healing is high desirable in clinical applications. In this work, NIR regulated metal-organic framework composite hydrogel dressing was constructed for enhanced antibacterial efficacy and accelerated wound healing via the compounding between hydrogel and UCNPs@ZrMOF-Pt nanoparticles. The visible light emitted from upconvertion nanoparticles (UCNPs) activated porphyrin based metal-organic framework (MOF) in composite hydrogel to generate ¹O₂ for photodynamic antibacterial therapy under NIR laser irradiation. Moreover, the UCNPs@ZrMOF-Pt in composite hydrogel with catalase-like performance could effectively convert the high concentration H₂O₂ in wound to abundant O₂, which relieved the hypoxic in infected wound. Thus, the photodynamic antibacterial efficacy was remarkably enhanced, leading to accelerate the wound healing. This work presented a novel strategy for high efficient antibacterial therapy and accelerated wound healing.

Oxygen vacancy mediated α-MoO3 bactericidal nanocatalyst in the dark: Surface structure dependent superoxide generation and antibacterial mechanisms

Understanding bacteria inactivation mechanisms of nanomaterials on the surface molecular level is of prime importance for the development of antibacterial materials and their application in restraining the transmission of pathogenic microorganisms. This study prepared an oxygen vacancy-mediated bactericidal nanocatalyst α-MoO₃ which exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus in the dark. By manipulating the surface structure of α-MoO₃, the facile tuning of superoxide radical (•O₂^-) generation can be achieved, which was confirmed by electron paramagnetic resonance. •O₂^- disrupted bacterial membrane through attacking lipopolysaccharide (LPS) and phosphatidylethanolamine (PE). Intracellular reactive oxygen species (ROS) experiments confirm that oxidative stress induced by •O₂^- also played a vital role in bacterial inactivation, which might account for DNA damage verified by comet assays. The α-MoO₃ with rich oxygen vacancies also exhibited good antibacterial efficiency (＞99.00 %) toward airborne microbes under dark conditions, indicating its potential to impede the transmission of pathogenic microbes.

Primary Amine Functionalized Carbon Dots for Dead and Alive Bacterial Imaging

Small molecular dyes are commonly used for bacterial imaging, but they still meet a bottleneck of biological toxicity and fluorescence photobleaching. Carbon dots have shown high potential for bio-imaging due to their low cost and negligible toxicity and anti-photobleaching. However, there is still large space to enhance the quantum yield of the carbon quantum dots and to clarify their mechanisms of bacterial imaging. Using carbon dots for dyeing alive bacteria is difficult because of the thick density and complicated structure of bacterial cell walls. In this work, both dead or alive bacterial cell imaging can be achieved using the primary amine functionalized carbon dots based on their small size, excellent quantum yield and primary amine functional groups. Four types of carbon quantum dots were prepared and estimated for the bacterial imaging. It was found that the spermine as one of precursors can obviously enhance the quantum yield of carbon dots, which showed a high quantum yield of 66.46% and high fluorescence bleaching-resistance (70% can be maintained upon 3-h-irradiation). Furthermore, a mild modifying method was employed to bound ethylenediamine on the surface of the spermine-carbon dots, which is favorable for staining not only the dead bacterial cells but also the alive ones. Investigations of physical structure and chemical groups indicated the existence of primary amine groups on the surface of spermine-carbon quantum dots (which own a much higher quantum yield) which can stain alive bacterial cells visibly. The imaging mechanism was studied in detail, which provides a preliminary reference for exploring efficient and environment-friendly carbon dots for bacterial imaging.

Unimolecular micelles from star-shaped block polymers by photocontrolled BIT-RDRP for PTT/PDT synergistic therapy

Unimolecular micelles (UIMs) exhibit promising potential in the precise diagnosis and accurate treatment of tumor tissues, a pressing problem in the field of medical treatment, because of their perfect stability in the complex and variable microenvironment. In this study, porphyrin-based four-armed star-shaped block polymers with narrow molar mass dispersity (Đ = 1.34) were facilely prepared by photocontrolled bromine-iodine transformation reversible-deactivation radical polymerization (BIT-RDRP). A photothermal conversion dye, ketocyanine, was covalently linked onto the PEG and then introduced into the polymers through a "grafting onto" strategy to obtain polymeric nanomaterial, THPP-4PMMA-b-4P(PEGMA-co-APMA)@NIR-800, with dual PTT/PDT function. The resulting polymers could form monodispersed UIMs in the water below critical aggregation concentration, meanwhile maintaining the capacities of singlet oxygen release and photothermal conversion. Importantly, the UIMs displayed excellent biocompatibility while exerting superior PTT and/or PDT therapeutic effects under the irradiation of specific wavelengths of light, according to in vitro cellular experiments, which is expected to become a new hot spot for cancer therapy and anti-tumor research. Overall, stable and powerful UIMs with dual PTT/PDT function is provided, which are expected to be competitive candidates in cancer therapy.

GSH-depleting and H2O2-self-supplying hybrid nanozymes for intensive catalytic antibacterial therapy by photothermal-augmented co-catalysis

Nanozyme-based chemodynamic therapy (CDT) has shown tremendous potential in the treatment of bacterial infections. However, the CDT antibacterial efficacy is severely limited by the catalytic activity of nanozymes or the infection microenvironments such as insufficient hydrogen peroxide (H₂O₂) and overexpressed glutathione (GSH). Herein, a versatile hybrid nanozyme (MoS₂/CuO₂) is rationally constructed by simply decorating ultrasmall CuO₂ nanodots onto lamellar MoS₂ platelets of hydrangea-like MoS₂ nanocarrier via a covalent Cu-S bond. The MoS₂/CuO₂ nanozyme exhibits the peroxidase-mimic activity for catalytically converting H₂O₂ produced by acid-triggered decomposition of the decorated CuO₂ into hydroxyl radical (•OH). Meanwhile, the MoS₂/CuO₂ can consume GSH overexpressed in the infection sites via redox reaction mediated by polyvalent transition metal ions (Cu²⁺ and Mo⁶⁺) for enhanced CDT. More importantly, MoS₂ support can promote the conversion of Cu²⁺ to Cu⁺ by a co-catalytic reaction based on the Mo⁴⁺/Mo⁶⁺ redox couples, and provide photonic hyperthermia (PTT) to augment the peroxidase-mimic activity. The developed MoS₂/CuO₂ nanozymes possesses a desirable catalytic property, as well as a remarkably improved antibacterial efficiency both in vitro and in vivo. Taken together, this study proposes a synergetic multiple enhancement strategy to successfully construct the versatile hybrid nanozymes for intensive in vivo PTT/CDT dual-mode anti-infective therapy. STATEMENT OF SIGNIFICANCE: Chemodynamic therapy (CDT) has shown great potentialities in the treatment of bacterial infections, while its therapeutic efficiency is severely limited by the infection microenvironments such as insufficient hydrogen peroxide (H₂O₂) and overexpressed glutathione (GSH). Here, we rationally construct a hybrid nanozyme (MoS₂/CuO₂) with peroxidase-like activity that can enhance CDT by regulating local microenvironments, that is, simultaneously self-supplying H₂O₂ and consuming GSH. Importantly, MoS₂ support can promote the conversion of Cu²⁺ to Cu⁺ by the Mo⁴⁺/Mo⁶⁺ redox couples, and provide photonic hyperthermia (PTT) to augment the peroxidase-mimic activity. The developed MoS₂/CuO₂ shows desirable PTT/CDT dual-mode antibacterial efficacy both in vitro and in vivo. This study proposes a versatile hybrid nanozyme with multiple enhancement effects for intensive in vivo anti-infective therapy.

Microenvironment-Adaptive Nanozyme for Accelerating Drug-Resistant Bacteria-Infected Wound Healing

Reactive oxygen species (ROS) are favorable for antibacterial infection but their overproduction results in serious inflammatory response and aggravates the hypoxic state of the wound tissue, which is detrimental to healing stages of proliferation and remodeling. Here, an atomic-dispersion Fe-doped oxygen-deficient molybdenum oxide MoO_{3- X} (ADFM) bifunctional nanozyme, featuring implanted peroxidase-like and enhanced catalase-like activity, is developed for decomposing H₂ O₂ into strongly oxidizing hydroxyl radicals (•OH) for prevention of bacterial infection and into plentiful O₂ for healing stages. Therein, the introduction of Fe into MoO_{3- X} primarily produces an asymmetric electron density difference by elongating the bond length between metal atoms, synchronously stabilizing adsorption of •OH and weakening the adsorption of O₂ . ADFM also shows unimaginably high aqueous dispersity and pH-adaptive ROS regulation in the wound microenvironment, both of which are favorable for ADFM to fully exert enzyme-like activity for timely antibacterial and efficient wound-healing action. ADFM thus achieves efficient healing of drug-resistant bacteria-infected wounds in vivo, at an ultralow dosage of 30 µg mL^-1 against 10⁶ CFU mL^-1 extended spectrum β-lactamases-producing Escherichia coli, exhibiting a wound-healing efficiency of ≈10 mm² per day, which sets a benchmark among these noble-metal-free nanozyme-based wound-healing agents.

Bioheterojunction-Engineered Polyetheretherketone Implants With Diabetic Infectious Micromilieu Twin-Engine Powered Disinfection for Boosted Osteogenicity

Diabetic infectious micromilieu (DIM) leads to a critical failure rate of osseointegration by virtue of two main peculiarities: high levels of topical glucose and inevitable infection. To tackle the daunting issue, a bioheterojunction-engineered orthopedic polyetheretherketone (PEEK) implant consisting of copper sulfide/graphene oxide (CuS/GO) bioheterojunctions (bioHJs) and glucose oxidase (GOx) is conceived and developed for DIM enhanced disinfection and boosted osseointegration. Under hyperglycemic micromilieu, GOx can convert surrounding glucose into hydrogen peroxide (H₂ O₂ ). Then, upon infectious micromilieu, the bioHJs enable the catalyzation of H₂ O₂ to highly germicidal hydroxyl radical (·OH). As a result, the engineered implants massacre pathogenic bacteria through DIM twin-engine powered photo-chemodynamic therapy in vitro and in vivo. In addition, the engineered implants considerably facilitate cell viability and osteogenic activity of osteoblasts under a hyperglycemic microenvironment via synergistic induction of copper ions (Cu²⁺ ) and GO. In vivo studies using bone defect models of diabetic rats at 4 and 8 weeks further authenticate that bioHJ-engineering PEEK implants substantially elevate their osseointegration through biofilm elimination and vascularization, as well as macrophage reprogramming. Altogether, the present study puts forward a tactic that arms orthopedic implants with DIM twin-engine powered antibacterial and formidable osteogenic capacities for diabetic stalled osseointegration.

Tannin coordinated nanozyme composite-based hybrid hydrogel eye drops for prophylactic treatment of multidrug-resistant Pseudomonas aeruginosa keratitis

Pseudomonas aeruginosa infection is a severe acute suppurative ulcer that engulfs virtually the entire tissue in a short period and leads to devastating destruction. Antibiotic therapy is a common approach for the prophylaxis and treatment of P. aeruginosa infection. However, it is often associated with serious side effects, complications, and multidrug resistance. Therefore, it has been a long-standing challenge to explore safe and effective methods for controlling P. aeruginosa infection. Herein, tannin-coordinated nanozyme composite-based hybrid hydrogels (TCNH) are developed and characterized for the prophylactic treatment of P. aeruginosa and multidrug-resistant P. aeruginosa infections using mouse keratitis as the animal model. The TCNH eye drops are constructed by photoinitiated free radical polymerization of acetylated gelatin solution containing self-synthesized tannin-coordinated Co₃O₄/Ag nanozyme composite. The as-prepared TCNH displays good dispersibility, peroxidase-like activity and in vitro/in vivo biocompatibility. The nanozyme composite in TCNH seems to penetrate the interior of bacteria and exhibited significant broad-spectrum antibacterial activity owing to its intrinsic and nanozymic catalytic properties. Furthermore, TCNH eye drops can be successfully applied to treat P. aeruginosa and multidrug-resistant P. aeruginosa keratitis. The findings of this study reveal the potential of tannin-coordinated nanozyme composite-based hybrid hydrogel eye drops for treating infectious diseases.

A synergistic chemodynamic-photodynamic-photothermal therapy platform based on biodegradable Ce-doped MoOx nanoparticles

Near-infrared light-induced catalysts are considered to be potential nanoagents for tumor therapy. Cerium (Ce) is a non-biotoxic lanthanide element and exhibits variable valence states for catalytic reactions. In this work, we report a one-step hydrothermal synthesis for Ce-doped MoO_x (CMO) nanomaterials. The obtained CMO nanomaterials show high absorption in the NIR II regime and a high photothermal conversion efficiency of 67.7% (1064 nm). Moreover, due to the doping of Ce element, the consumption of hydrogen peroxide (H₂O₂) and glutathione (GSH) is boosted which enhances the chemodynamic and photodynamic therapy simultaneously. Under NIR II laser irradiation, the designed CMO nanocatalysts induce metabolism disruption and mitochondrial damage in the tumor cells. As-prepared CMO nanomaterials also show good biocompatibility and pH-responsive degradation behavior, which can be degraded rapidly under alkaline conditions (pH = 7.4) and remain stable in acidic solution (pH = 5.6). These properties make CMO nanomaterials ideal biodegradable nanotheranostic agents for synergistic chemodynamic-photodynamic-photothermal antitumor therapy.

Nanomaterial-enabled photothermal-based solar water disinfection processes: Fundamentals, recent advances, and mechanisms

The pathogenic microorganisms in water pose a great threat to human health. Photothermal and photothermocatalytic disinfection using nanomaterials (NPs) has offered a promising and effective strategy to address the challenges in solar water disinfection (SODIS), especially in the point-of-use operations. This review aims at providing comprehensive and state-of-the-art knowledge of photothermal-based disinfection by NPs. The fundamentals and principles of photothermal-based disinfection were first introduced. Then, recent advances in developing photothermal/photothermocatalytic catalysts were systematically summarized. The light-to-heat conversion and disinfection performance of a large variety of photothermal materials were presented. Given the complicated mechanisms of photothermal-based disinfection, the attacks from reactive oxygen species and heat, the destruction of bacterial cells, and the antibacterial effects of released metal ions were highlighted. Finally, future challenges and opportunities associated with the development of cost-effective photothermal/photothermocatalytic disinfection systems were outlined. This review will provide guidance in designing future NPs and inspire more research efforts from environmental nano-communities to move towards practical water disinfection operations.

Toxin-Enabled "On-Demand" Liposomes for Enhanced Phototherapy to Treat and Protect against Methicillin-Resistant Staphylococcus aureus Infection

An effective therapeutic strategy against methicillin-resistant Staphylococcus aureus (MRSA) that does not promote further drug resistance is highly desirable. While phototherapies have demonstrated considerable promise, their application toward bacterial infections can be limited by negative off-target effects to healthy cells. Here, a smart targeted nanoformulation consisting of a liquid perfluorocarbon core stabilized by a lipid membrane coating is developed. Using vancomycin as a targeting agent, the platform is capable of specifically delivering an encapsulated photosensitizer along with oxygen to sites of MRSA infection, where high concentrations of pore-forming toxins trigger on-demand payload release. Upon subsequent near-infrared irradiation, local increases in temperature and reactive oxygen species effectively kill the bacteria. Additionally, the secreted toxins that are captured by the nanoformulation can be processed by resident immune cells to promote multiantigenic immunity that protects against secondary MRSA infections. Overall, the reported approach for the on-demand release of phototherapeutic agents into sites of infection could be applied against a wide range of high-priority pathogens.

Vacancy defect-promoted nanomaterials for efficient phototherapy and phototherapy-based multimodal Synergistic Therapy

Phototherapy and multimodal synergistic phototherapy (including synergistic photothermal and photodynamic therapy as well as combined phototherapy and other therapies) are promising to achieve accurate diagnosis and efficient treatment for tumor, providing a novel opportunity to overcome cancer. Notably, various nanomaterials have made significant contributions to phototherapy through both improving therapeutic efficiency and reducing side effects. The most key factor affecting the performance of phototherapeutic nanomaterials is their microstructure which in principle determines their physicochemical properties and the resulting phototherapeutic efficiency. Vacancy defects ubiquitously existing in phototherapeutic nanomaterials have a great influence on their microstructure, and constructing and regulating vacancy defect in phototherapeutic nanomaterials is an essential and effective strategy for modulating their microstructure and improving their phototherapeutic efficacy. Thus, this inspires growing research interest in vacancy engineering strategies and vacancy-engineered nanomaterials for phototherapy. In this review, we summarize the understanding, construction, and application of vacancy defects in phototherapeutic nanomaterials. Starting from the perspective of defect chemistry and engineering, we also review the types, structural features, and properties of vacancy defects in phototherapeutic nanomaterials. Finally, we focus on the representative vacancy defective nanomaterials recently developed through vacancy engineering for phototherapy, and discuss the significant influence and role of vacancy defects on phototherapy and multimodal synergistic phototherapy. Therefore, we sincerely hope that this review can provide a profound understanding and inspiration for the design of advanced phototherapeutic nanomaterials, and significantly promote the development of the efficient therapies against tumor.

Emerging nanozyme-based multimodal synergistic therapies in combating bacterial infections

Pathogenic infections have emerged as major threats to global public health. Multidrug resistance induced by the abuse of antibiotics makes the anti-infection therapies to be a global challenge. Thus, it is urgent to develop novel, efficient and biosafe antibiotic alternatives for future antibacterial therapy. Recently, nanozymes have emerged as promising antibiotic alternatives for combating bacterial infections. More significantly, the multimodal synergistic nanozyme-based antibacterial systems open novel disinfection pathways. In this review, we are mainly focusing on the recent research progress of nanozyme-based multimodal synergistic therapies to eliminate bacterial infections. Their antibacterial mechanism, the synergistic antibacterial systems are systematically summarized and discussed according to the combination of mechanisms and the purpose to improve their antibacterial efficiency, biosafety and specificity. Finanly, the current challenges and prospects of the multimodal synergistic antibacterial systems are proposed.