Pomegranate-Like CuO2@SiO2 Nanospheres as H2O2 Self-Supplying and Robust Oxygen Generators for Enhanced Antibacterial Activity

Micro-environment-triggered chemodynamic treatment for boosting bacteria elimination at low-temperature by synergistic effect of photothermal treatment and nanozyme catalysis

An injectable hydrogel dressing, Zr/Fc-MOF@CuO2@FH, was constructed by combing acid-triggered chemodynamic treatment (CDT) with low-temperature photothermal treatment (LT-PTT) to effectively eliminate bacteria without harming the surrounding normal tissues. The Zr/Fc-MOF acts as both photothermal reagent and nanozyme to generate reactive oxygen species (ROS). The CuO2 nanolayer can be decomposed by the acidic microenvironment of the bacterial infection to release Cu2+ and H2O2, which not only induces Fenton-like reaction but also enhances the catalytic capability of the Zr/Fc-MOF. The generated heat augments ROS production, resulting in highly efficient bacterial elimination at low temperature. Precisely, injectable hydrogel dressing can match irregular wound sites, which shortens the distance of heat dissipation and ROS diffusion to bacteria, thus improving sterilization efficacy and decreasing non-specific systemic toxicity. Both in vitro and in vivo experiments validated the predominant sterilization efficiency of drug-resistant methicillin-resistant Staphylococcus aureus (MRSA) and kanamycin-resistant Escherichia coli (KREC), presenting great potential for application in clinical therapy.

Remodeling Microenvironment for Implant-Associated Osteomyelitis by Dual Metal Peroxide

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

Engineering H2O2 Self-Supplying Platform for Xdynamic Therapies via Ru-Cu Peroxide Nanocarrier: Tumor Microenvironment-Mediated Synergistic Therapy

Of the most common, hypoxia, overexpressed glutathione (GSH), and insufficient H2O2 concentration in the tumor microenvironment (TME) are the main barriers to the advancment of reactive oxygen species (ROS) mediated Xdynamic therapies (X = photo, chemodynamic, chemo). Maximizing Fenton catalytic efficiency is crucial in chemodynamic therapy (CDT), yet endogenous H2O2 levels are not sufficient to attain better anticancer efficacy. Specifically, there is a need to amplify Fenton reactivity within tumors, leveraging the unique attributes of the TME. Herein, for the first time, we design RuxCu1-xO2-Ce6/CPT (RCpCCPT) anticancer nanoagent for TME-mediated synergistic therapy based on heterogeneous Ru-Cu peroxide nanodots (RuxCu1-xO2 NDs) and chlorine e6 (Ce6), loaded with ROS-responsive thioketal (TK) linked-camptothecin (CPT). The Ru-Cu peroxide NDs (RCp NDs, x = 0.50) possess the highest oxygen vacancy (OV) density, which grants them the potential to form massive Lewis's acid sites for peroxide adsorption, while the dispersibility and targetability of the NDs were improved via surface modification using hyaluronic acid (HA). In TME, RCpCCPT degrades, releasing H2O2, Ru2+/3+, and Cu+/2+ ions, which cooperatively facilitate hydroxyl radical (•OH) formation and deactivate antioxidant GSH enzymes through a cocatalytic loop, resulting in excellent tumor therapeutic efficacy. Furthermore, when combined with laser treatment, RCpCCPT produces singlet oxygen (1O2) for PDT, which induces cell apoptosis at tumor sites. Following ROS generation, the TK linkage is disrupted, releasing up to 92% of the CPT within 48 h. In vitro investigations showed that laser-treated RCpCCPT caused 81.5% cell death from PDT/CDT and chemotherapy (CT). RCpCCPT in cancer cells produces red-blue emission in images of cells taking them in, which allows for fluorescence image-guided Xdynamic treatment. The overall results show that RCp NDs and RCpCCPT are more biocompatible and have excellent Xdynamic therapeutic effectiveness in vitro and in vivo.

Digital imaging-in-flow (FlowCAM) and probabilistic machine learning to assess the sonolytic disinfection of cyanobacteria in sewage wastewater

Assessing the cyanobacteria disinfection in sewage and its compliance with international-standards requires determining the concentration and viability, which can be achieve using Imaging Flow Cytometry device called FlowCAM. The objective is to thoroughly investigate the sonolytic morphological changes and disinfection-performance towards toxic cyanobacteria existing in sewage using the FlowCAM. After optimizing the process conditions, over 80% decline in cyanobacterial cell counts was observed, accompanied by an additional 10-15% of cells exhibiting injuries, as confirmed through morphological investigation. Moreover, for the first time, the experimentally collected data was utilized to build deep-learning probabilistic-neural-networks (PNN) and natural-gradient-boosting (NGBoost) models for predicting disinfection efficiency and ABD area as target outputs. The findings suggest that the NGBoost model exhibited superior prediction performance for both targets, with high test coefficient of determination (R2 > 0.87) and lower test errors (RMSE < 7.10, MAE < 4.14). The confidence interval examination in NGBoost prediction performance showed a minute variation from the experimentally calculated values, suggesting a high accuracy in model prediction. Finally, SHAP analysis suggests the sonolytic time alone contributes around 50% to the cyanobacteria disinfection. Overall, the findings demonstrate the effectiveness of the FlowCAM device and the potential of machine-learning modeling in predicting disinfection outcomes.

Enzyme-triggered on-demand release of a H2O2-self-supplying CuO2@Fe3O4 nanoagent for enhanced chemodyamic antimicrobial therapy and wound healing

Nanoagents for chemodynamic therapy (CDT) hold a promising future in the field of antimicrobials, especially copper peroxide (CuO2) (CP) nanomaterials which have garnered significant attention due to their ability to self-supply H2O2. Nevertheless, the poor stability of CuO2 remains a critical challenge which restricts its practical application in the antibacterial field. In this study, an advanced nano-antimicrobial system HA-CP@Fe3O4 with enzyme-responsive properties is developed by coating hyaluronic acid (HA) on CuO2-loaded iron tetraoxide nanoparticles. The coating of HA not only stabilizes the CuO2 nanomaterials but also provides responsiveness towards the enzyme hyaluronidase, which is typically secreted by some bacteria. The outer layer of HA in HA-CP@Fe3O4 undergoes decomposition in the presence of hyaluronidase-secreting bacteria, resulting in the release of CuO2@Fe3O4. The released CuO2@Fe3O4 then self-supplies H2O2 and generates reactive oxygen species (ROS) within the infected microenvironment through Fenton and Russell effects, to ultimately achieve effective and precise antimicrobial activity. Simultaneously, the magnetic property provided by Fe3O4 allows the substance to be directed towards the infection site. Both in vitro and in vivo tests demonstrated that HA-CP@Fe3O4 exhibited excellent antimicrobial capabilities at low concentration (30 μg mL-1), exceptional biocompatibility and the ability to accelerate wound healing. The findings of this work offer a new and promising approach for targeted and precise CDT.

Transition Metal High-Entropy Nanozyme: Multi-Site Orbital Coupling Modulated High-Efficiency Peroxidase Mimics

Strong substrate affinity and high catalytic efficiency are persistently pursued to generate high-performance nanozymes. Herein, with unique surface atomic configurations and distinct d-orbital coupling features of different metal components, a class of highly efficient MnFeCoNiCu transition metal high-entropy nanozymes (HEzymes) is prepared for the first time. Density functional theory calculations demonstrate that improved d-orbital coupling between different metals increases the electron density near the Fermi energy level (EF ) and shifts the position of the overall d-band center with respect to EF , thereby boosting the efficiency of site-to-site electron transfer while also enhancing the adsorption of oxygen intermediates during catalysis. As such, the proposed HEzymes exhibit superior substrate affinities and catalytic efficiencies comparable to that of natural horseradish peroxidase (HRP). Finally, HEzymes with superb peroxidase (POD)-like activity are used in biosensing and antibacterial applications. These results suggest that HEzymes have great potential as new-generation nanozymes.

Nanomedicine for the Detection and Treatment of Ocular Bacterial Infections

Ocular bacterial infection is a prevalent cause of blindness worldwide, with substantial consequences for normal human life. Traditional treatments for ocular bacterial infections areless effective, necessitating the development of novel techniques to enable accurate diagnosis, precise drug delivery, and effective treatment alternatives. With the rapid advancement of nanoscience and biomedicine, increasing emphasis has been placed on multifunctional nanosystems to overcome the challenges posed by ocular bacterial infections. Given the advantages of nanotechnology in the biomedical industry, it can be utilized to diagnose ocular bacterial infections, administer medications, and treat them. In this review, the recent advancements in nanosystems for the detection and treatment of ocular bacterial infections are discussed; this includes the latest application scenarios of nanomaterials for ocular bacterial infections, in addition to the impact of their essential characteristics on bioavailability, tissue permeability, and inflammatory microenvironment. Through an in-depth investigation into the effect of sophisticated ocular barriers, antibacterial drug formulations, and ocular metabolism on drug delivery systems, this review highlights the challenges faced by ophthalmic medicine and encourages basic research and future clinical transformation based on ophthalmic antibacterial nanomedicine.

Powering mesoporous silica nanoparticles into bioactive nanoplatforms for antibacterial therapies: strategies and challenges

Bacterial infection has been a major threat to worldwide human health, in particular with the ever-increasing level of antimicrobial resistance. Given the complex microenvironment of bacterial infections, conventional use of antibiotics typically renders a low efficacy in infection control, thus calling for novel strategies for effective antibacterial therapies. As an excellent candidate for antibiotics delivery, mesoporous silica nanoparticles (MSNs) demonstrate unique physicochemical advantages in antibacterial therapies. Beyond the delivery capability, extensive efforts have been devoted in engineering MSNs to be bioactive to further synergize the therapeutic effect in infection control. In this review, we critically reviewed the essential properties of MSNs that benefit their antibacterial application, followed by a themed summary of strategies in manipulating MSNs into bioactive nanoplatforms for enhanced antibacterial therapies. The chemically functionalized platform, photo-synergized platform, physical antibacterial platform and targeting-directed platform are introduced in details, where the clinical translation challenges of these MSNs-based antibacterial nanoplatforms are briefly discussed afterwards. This review provides critical information of the emerging trend in turning bioinert MSNs into bioactive antibacterial agents, paving the way to inspire and translate novel MSNs-based nanotherapies in combating bacterial infection diseases.

Redox and Near-Infrared Light-Responsive Nanoplatform for Enhanced Pesticide Delivery and Pest Control in Rice: Construction, Efficacy, and Potential Mechanisms

The brown planthopper, Nilaparvata lugens (Stål), is a major rice pest in various Asian countries, causing significant negative impacts on rice yield and quality. In this study, we developed a novel nanoplatform (NIT@MON@CuS) for pesticide delivery that responds to redox and near-infrared light stimuli. The nanoplatform consisted of CuS nanoparticles with mesoporous organic silica (MON), loaded with nitenpyram (NIT). With an average size of 190 nm and a loading efficiency of 22%, NIT@MON@CuS exhibited remarkable thermal response in the near-infrared region, demonstrating excellent photothermal conversion ability and stability. In vitro release kinetics demonstrated the rapid release of nitenpyram under near-infrared light and glutathione conditions, facilitating a satisfactory temperature increase and accelerated drug release. The NIT@MON@CuS-treated group exhibited a higher mortality of N. lugens, increasing from 62 to 88% compared to the group treated with nitenpyram technical after 96 h. Bioassay revealed that NIT@MON@CuS significantly enhanced nitenpyram toxicity by more than 1.4-fold against both laboratory insecticide-resistant and field strains of N. lugens. Furthermore, RT-qPCR results demonstrated that MON@CuS had the capability to reduce P450 gene expression, thereby improving the sensitivity of N. lugens to insecticides. These findings suggest that MON@CuS holds great potential as an intelligent pest control platform, offering a sustainable and efficient approach to protect crops against pests.

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

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

Antibacterial Chemodynamic Therapy: Materials and Strategies

The wide and frequent use of antibiotics in the treatment of bacterial infection can cause the occurrence of multidrug-resistant bacteria, which becomes a serious health threat. Therefore, it is necessary to develop antibiotic-independent treatment modalities. Chemodynamic therapy (CDT) is defined as the approach employing Fenton and/or Fenton-like reactions for generating hydroxyl radical (•OH) that can kill target cells. Recently, CDT has been successfully employed for antibacterial applications. Apart from the common Fe-mediated CDT strategy, antibacterial CDT strategies mediated by other metal elements such as copper, manganese, cobalt, molybdenum, platinum, tungsten, nickel, silver, ruthenium, and zinc have also been proposed. Furthermore, different types of materials like nanomaterials and hydrogels can be adopted for constructing CDT-involved antibacterial platforms. Besides, CDT can introduce some toxic metal elements and then achieve synergistic antibacterial effects together with reactive oxygen species. Finally, CDT can be combined with other therapies such as starvation therapy, phototherapy, and sonodynamic therapy for achieving improved antibacterial performance. This review first summarizes the advancements in antibacterial CDT and then discusses the present limitations and future research directions in this field, hoping to promote the development of more effective materials and strategies for achieving potentiated CDT.

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

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

Oxygen-Rich Graphene/ZnO2-Ag nanoframeworks with pH-Switchable Catalase/Peroxidase activity as O2 Nanobubble-Self generator for bacterial inactivation

The oxygen-rich organic/inorganic (reduced graphene oxide (rGO)/ZnO₂-Ag) nanoframeworks as suppliers of O₂ nanobubbles (NBs) with dual pH-and-temperature-sensitive behavior were developed to suppress bacterial growth. It was demonstrated that not only the rate but also the final product of oxygen-rich ZnO₂ decomposition (to an intermediate product of H₂O₂) rate was dramatically controlled by pH adjustment. Furthermore, in the presence of Ag nanoparticles, ̇OH radical generation switched to O₂ NBs evolution by shifting the pH from acidic to basic/neutral conditions, demonstrating an adjustable nanozyme function-ability between catalase and peroxidase-like activity, respectively. Antibacterial properties of the in-situ generated O₂ NBs substantially enhanced against bacterial models including methicillin-resistant Staphylococcus aureus in the presence of rGO. In fact, deflecting the electrons from their main respiratory chain to an oxygen-rich bypath through rGO significantly stimulated reactive oxygen species (ROS) generation, combating bacteria more efficiently. Moreover, NIR laser irradiation-induced temperature rise (due to the inherent photothermal properties of rGO) facilitated ZnO₂ decomposition and accelerated growth and collapse of NBs. The simultaneous microscale thermal and mechanical destructions induced stronger antibacterial behavior. These results hold great promises for designing simple organic/inorganic nanoframeworks as solid sources of NBs with tunable enzyme-like ability in response to environmental conditions suitable for forthcoming graphene-based bio-applications.

Nitrogen and fluoride co-doped graphdiyne with metal-organic framework (MOF)-derived NiCo2O4-Co3O4 nanocages as sensing layers for ultra-sensitive pesticide detection

Heteroatom doped graphdiyne (GDY) has been demonstrated to be an effective strategy for achieving outstanding electrochemical properties, including improved electrocatalytic activity, tunable electronic properties and high electronic conductivity, by producing numerous heteroatomic defects as well as active sites. Extensive efforts have been devoted to the issue of single element doping of GDY. Introducing two or more kinds of heteroatoms into GDY materials may create a synergic effect between the co-dopants, thus generating superior electrochemical performance. Nevertheless, little research on multiple elements co-doped GDY, especially in the application of constructing electrochemical biosensor. Herein, nitrogen and fluoride co-doped GDY (N-F-GDY) has been synthesized and employed to combine with NiCo₂O₄-Co₃O₄ hollow multishelled nanocages to establish an ultrasensitive electrochemical biosensor for the assay of pesticide residue. The as-prepared electrochemical biosensor possesses a wide linear range of 0.448 pM-44.8 nM for monocrotophos detection and a low detection limit of 0.0166 fM (S/N = 3).

All-in-one bioactive properties of photothermal nanofibers for accelerating diabetic wound healing

Diabetic wound healing has attracted widespread attention in biomedical engineering. However, the harsh hypoxic microenvironment (HME) comprising high glucose levels, local bleeding, and bacterial infection often leads to the formation of hyperplastic scars, increasing the clinical demand for wound dressings. Here, we report a comprehensive strategy using near-infrared NIR-assisted oxygen delivery combined with the bioactive nature of biopolymers for remodeling the HME. Black phosphorus (BP) nanosheets and hemoglobin (Hb) were self-assembled layerwise onto electrospun poly-l-lactide (PLLA) nanofibers using charged quaternized chitosan (QCS) and hyaluronic acid. BP converts NIR radiation into heat and stimulates Hb to release oxygen in situ. QCS is a hemostatic and broad-spectrum antibacterial material. Moderate BP-derived photothermal therapy can increase the sensitivity of bacteria to QCS. A series of composite wound dressings (coded as PQBH-n) with different numbers of layers were fabricated, and the in vivo diabetic wound healing potentials were tested. The molecular mechanism can be partly attributed to the cytokine-cytokine receptor interaction. Notably, this comprehensive strategy based on NIR-assisted oxygen delivery combined with the bioactive properties of biopolymers is not only applicable for fabricating multifunctional wound dressings but also has a great potential in expanding biomedical engineering fields.

H2O2 Self-Supplying and GSH-Depleting Nanocatalyst for Copper Metabolism-Based Synergistic Chemodynamic Therapy and Chemotherapy

Chemodynamic therapy (CDT) that involves the use of Fenton catalysts to convert endogenous hydrogen peroxide (H₂O₂) to hydroxyl radicals (·OH) constitutes a promising strategy for cancer therapy; however, insufficient endogenous H₂O₂ and glutathione (GSH) overexpression render its efficiency unsatisfactory. Herein, we present an intelligent nanocatalyst that comprises copper peroxide nanodots and DOX-loaded mesoporous silica nanoparticles (MSNs) (DOX@MSN@CuO₂) and can self-supply exogenous H₂O₂ and respond to specific tumor microenvironments (TME). Following endocytosis into tumor cells, DOX@MSN@CuO₂ initially decomposes into Cu²⁺ and exogenous H₂O₂ in the weakly acidic TME. Subsequently, Cu²⁺ reacts with high GSH concentrations, thereby inducing GSH depletion and reducing Cu²⁺ to Cu⁺ Next, the generated Cu⁺ undergoes Fenton-like reactions with exogenous H₂O₂ to accelerate toxic ·OH production, which exhibits a rapid reaction rate and is responsible for tumor cell apoptosis, thereby enhancing CDT. Furthermore, the successful delivery of DOX from the MSNs achieves chemotherapy and CDT integration. Thus, this excellent strategy can resolve the problem of insufficient CDT efficacy due to limited H₂O₂ and GSH overexpression. Integrating H₂O₂ self-supply and GSH deletion enhances CDT, and DOX-induced chemotherapy endows DOX@MSN@CuO₂ with effective tumor growth-inhibiting properties alongside minimal side effects in vivo.

Ultrasound activatable microneedles for bilaterally augmented sono-chemodynamic and sonothermal antibacterial therapy

Chemodynamic therapy (CDT) employs Fenton catalysts to kill bacteria by converting hydrogen peroxide (H₂O₂) into toxic hydroxyl radical (•OH). Among them, Fenton-type metal peroxide nanoparticles fascinate nanomaterials with intriguing physiochemical properties, but research on this antibacterial agent is still in its infancy. Herein, a distinct CuO₂/TiO₂ heterostructure constituted of ultrasmall copper peroxide (CuO₂) nanoclusters and sonosensitized ultrathin oxygen vacancy-rich porous titanium oxide (OV-TiO₂) nanosheets was developed and was incorporated into microneedles for bilaterally augmented sono-chemodynamic and sonothermal antibacterial therapy. Engineering CuO₂ nanoclusters on the surface of TiO₂ nanosheets not only endows the Fenton catalytic activity for sono-chemodynamic therapy (SCDT), but also improves the sonodynamic and sonothermal performance of TiO₂ by narrowing the bandgap of TiO₂ and suppressing the recombination of electron-hole pairs. The high efficacy of this CuO₂/TiO₂ integrated microneedle (CTMN) patch was systematically demonstrated both in vitro and in vivo with the eliminating rate >99.9999% against multidrug resistant (MDR) pathogens in 5 min as well as accelerated wound tissue healing. This work highlights a promisingly new and efficient strategy for the development of sonosensitive and chemoreactive nanomedicine for non-antibiotic therapies. STATEMENT OF SIGNIFICANCE: Feton-type metal peroxides, a novel nanomaterial with self-supplied oxygen and hydrogen peroxide, can achieve effective antimicrobial activity in vitro. However, there is a lack of effective nanomaterial delivery systems and suitable means for in vivo activation/enhancement of antimicrobial activity during bacterial infected skin wound treatment. In this study, we designed and prepared efficient ultrasound activable microneedles that effectively addressed the deficiencies mentioned above and established a new paradigm for efficient utilization of metal peroxide nanomaterials and ultrasound based strategies. Noticeably, copper peroxide nanoclusters/oxygen vacancy-rich porous titanium oxide nanosheets (CuO₂/TiO₂) integrated microneedle (CTMN) patch combines advantages of both sono-chemodynamic and sonothermal antibacterial therapy, achieving one of the most instant and effective antibacterial efficacy (>99.9999% in 5 min) in vivo reported till now.

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

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

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.

Multifunctional mesoporous silica-cerium oxide nanozymes facilitate miR129 delivery for high-quality healing of radiation-induced skin injury

Radiation-induced skin injury (RISI) is an important challenge for clinical treatments. The main causes of RISI include hypoxia in the wound microenvironment, reactive oxygen species (ROS) activation, and downregulation of DNA repair proteins. Here, a multiple radioresistance strategy was designed for microRNA therapy and attenuating hypoxia. A novel mesoporous silica (MS) firmly anchored and dispersed cerium (IV) oxide (CeO₂) nanoparticles to form MS-CeO₂ nanocomposites, which exhibit superior activity in inhibiting radiation-induced ROS and HIF-1α activation and ultimately promote RISI wound healing. The miR129 serum concentrations in patients can promote radioresistance by directly targeting RAD17 and regulating the Chk2 pathway. Subsequently, MS-CeO₂ nanocomposites with miR129 were conjugated with iRGD-grafted polyoxyethylene glycol (short for nano-miR129), which increased the stability and antibacterial character, efficiently delivered miR129 to wound blood capillaries, and exhibited low toxicity. Notably, nano-miR129 promoted radioresistance and enhanced anti-ROS therapeutic efficacy in a subcutaneous RISI mouse model. Overall, this MS-CeO₂ nanozyme and miR129-based multiresistance radiotherapy protection strategy provided a promising therapeutic approach for RISI.

Cu-Ce oxide Co-loaded silicon nanocapsules for hydrogen peroxide self-supplied Fenton-like catalysis and synergistically antibacterial therapy

Antibacterial strategies based on reactive oxygen species (ROS) have opened up a new avenue for overcoming the great challenges of antibiotics topic including lack of broad-spectrum antibiotics and the emergence of super-resistant bacteria. Herein, we leveraged a strategy of constructing synergistic catalytic active sites to develop a simple yet efficient Fenton-like active nanocomposite, and investigated its catalysis mechanism and antibacterial performance thoroughly. This strategy provides a new direction for boosting the catalytic activity of nanocomposite catalysts for wide application. Specifically, by uniformly loading copper oxide and ceria onto the surface of silica nanocapsules (SiO₂ NCs), we fabricated a bimetallic oxide nanocomposite Cu_0.75Ce_0.62O₂@SiO₂ NC, which performed superior Fenton-like capability in a wide pH range without additional exogenetic hydrogen peroxide (H₂O₂). Such excellent catalytic activity was originated from the charge interaction between the two metal oxide components, where formation of Cu⁺ and oxygen vacancies (OVs) was mutually reinforcing, resulting in a synergistic effect to produce H₂O₂ and catalyze the generation of •OH under the slight acid condition (pH = 6.0). In view of the outstanding Fenton-like activity, the Cu_0.75Ce_0.62O₂@SiO₂ NC was employed in antimicrobial testing, which demonstrated exceptional high in vitro antimicrobial efficacy against both the S. aureus and E. coli in a neutral environment (pH = 7.4). The excellent performance of the bimetallic nanocomposite Cu_0.75Ce_0.62O₂@SiO₂ NC, including its facile and mild preparation, high water-solubility and stability, superior catalytic and antimicrobial performances, manifests a promising broad-spectrum antibiotic that can be anticipated to deal with the contamination of the environment by bacteria.

Injectable self-healing hydrogel fabricated from antibacterial carbon dots and ɛ-polylysine for promoting bacteria-infected wound healing

Developing highly efficient pharmaceuticals to eradicate pathogens and facilitate wound healing is of great concern. Despite some cationic carbon dots (CDs) have been used for sterilization, hardly any anionic CDs with antimicrobial activity have appeared. In the present work, we engineered a string of anionic CDs (especially CD31) as valid broad-spectrum bactericides to kill bacteria. Furthermore, CD31 conjugated with ɛ-polylysine (Plys) to construct injectable, and self-healing hydrogel (CD-Plys) that possess the advantages of remarkable broad spectrum antibacterial activity, excellent wound healing ability and satisfied biocompatibility. CD-Plys could dramatically accelerate wound healing with epithelization and enhanced angiogenesis. Taken together, this work provides a two-pronged strategy to explore CDs-based antimicrobial agents for disease therapy and tissue engineering.

Copper peroxide coated upconversion nanoparticle modified with glucose oxidase for H2O2 self-supplying starvation-enhanced chemodynamic therapy in vitro

Chemodynamic therapy (CDT) can convert endogenous hydrogen peroxide (H₂O₂) to highly reactive hydroxyl radical (˙OH) through Fenton or Fenton-like reaction to kill tumor cells, which is a promising anticancer strategy. However, the limited H₂O₂ and overexpressed glutathione (GSH) in tumor cells make CDT ineffective. Here, an efficient nanocomposite, UCN@CuO₂-GOx (UCCuG), was synthesized, realizing both starvation therapy and H₂O₂ self-supplying CDT in vitro. In this case, the glucose oxidase (GOx) of the nanocomposite could consume glucose for starvation therapy after the UCCuG nanocomposite entered tumor cells. In addition, the acidic environment of the lysosome triggered the release of Cu²⁺ and H₂O₂ by the decomposition of UCCu; then, Cu²⁺ was reduced to Cu⁺ by GSH in tumor cells; and finally, Cu⁺ catalyzed the released H₂O₂ to generate ˙OH for CDT. The in vitro experiments demonstrated starvation-enhanced CDT with remarkable results. Meanwhile, under 980 nm laser irradiation, the upconversion luminescence signal of UCN in the UCCuG nanocomposite was reduced due to the CuO₂-GOx coating, while it gradually recovered after the UCCuG nanocomposite reacted with glucose and GSH under the tumor microenvironment (TME). Such a luminescent intensity recovery process is expected to monitor the TME-activated therapeutic effect in real time. This strategy may solve the problem of insufficient CDT efficacy caused by limited endogenous H₂O₂ and overexpressed GSH in tumor cells. This multifunctional nanocomposite demonstrates the promising application of starvation-enhanced CDT in tumor treatment.

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

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

One-Step Integration of Tumor Microenvironment-Responsive Calcium and Copper Peroxides Nanocomposite for Enhanced Chemodynamic/Ion-Interference Therapy

Recently, various metal peroxide nanomaterials have drawn increasing attention as an efficient hydrogen peroxide (H₂O₂) self-supplying agent for enhanced tumor therapy. However, a single kind of metal peroxide is insufficient to achieve more effective antitumor performance. Here, a hyaluronic acid modified calcium and copper peroxides nanocomposite has been synthesized by a simple one-step strategy. After effective accumulation at the tumor site due to the enhanced permeability and retention (EPR) effect and specific recognition of hyaluronate acid with CD44 protein on the surface of tumor cells, plenty of Ca²⁺, Cu²⁺, and H₂O₂ can be simultaneously released in acid and hyaluronidase overexpressed tumor microenvironment (TME), generating abundant hydroxyl radical through enhanced Fenton-type reaction between Cu²⁺ and self-supplying H₂O₂ with the assistance of glutathione depletion. Overloaded Ca²⁺ can lead to mitochondria injury and thus enhance the oxidative stress in tumor cells. Moreover, an unbalanced calcium transport channel caused by oxidative stress can further promote tumor calcification and necrosis, which is generally defined as ion-interference therapy. As a result, the synergistic effect of Fenton-like reaction by Cu²⁺ and mitochondria dysfunction by Ca²⁺ in ROS generation is performed. Therefore, a TME-responsive calcium and copper peroxides nanocomposite based on one-step integration has been successfully established and exhibits a more satisfactory antitumor efficiency than any single kind of metal peroxide.

Silver Peroxide Nanoparticles for Combined Antibacterial Sonodynamic and Photothermal Therapy

Metal peroxide nanoparticles designed to elevate the oxidative stress are considered a promising nanotherapeutics in biomedical applications, including chemotherapy, photodynamic therapy, and bacterial disinfection. However, their lack of specificity towards the therapeutic target can cause toxic side effects to healthy tissues. Here, silver peroxide nanoparticles (Ag₂ O₂ NPs) capable of controlled reactive oxygen species (ROS) release are synthesized. The release of bactericidal Ag⁺ ions and ROS is strictly regulated by external stimuli of ultrasound (US) and near-infrared (NIR) light. In vitro and in vivo investigations show that the Ag₂ O₂ NPs present enhanced antibacterial and antibiofilm capabilities with a killing efficiency >99.9999% in 10 min, significantly accelerate multi-drug resistant Staphylococcus aureus infected skin wound closure with excellent cytocompatibility and hemocompatibility. This work not only provides the first paradigm for fabricating silver peroxide nanoparticle but also introduces a highly efficient noninvasive and safe therapeutic modality for combating bacterial infectious diseases.

Biomimetic design of graphdiyne supported hemin for enhanced peroxidase-like activity

Effective electronic interactions between molecular catalysts and supports are critical for heterogeneous enzyme mimics, yet they are frequently neglected in most catalyst designs. Taking the enzyme mimics of hemin immobilized on graphdiyne (Hemin-GDY) as an example, we explicate for the first time the underlying role of GDY as a co-catalyst. Based on the robust conjugation between GDY and hemin, the delocalized π-electrons in GDY act as a ligand for Fe ions so that the orbital interactions including electron transport from GDY → Fe can induce the formation of an electron-rich Fe center and an electron-deficient π-electron conjugated system. This mechanism was validated by electron paramagnetic resonance (EPR), Raman spectroscopy, and DFT calculations. Moreover, both EPR spetra and Lineweaver-Burk plots revealed that Hemin-GDY could efficiently catalyze the decomposition of hydrogen peroxide (H₂O₂) to produce hydroxyl radical (•OH) and superoxide anion (O₂^•-) by a ping-pong type catalytic mechanism, and particularly, the catalytic activity was increased by 2.3-fold comparing to that of hemin immobilized on graphene (Hemin-GR). In addition, Hemin-GDY with the exceptional activity and stability was demonstrated for efficient catalytic degradation of organic pollutants under acidic conditions. Collectively, this work provides a theoretical basis for the design of GDY supported catalysts and renders great promises of the GDY based enzyme mimics.