Biodegradable Nickel Disulfide Nanozymes with GSH-Depleting Function for High-Efficiency Photothermal-Catalytic Antibacterial Therapy

Multifunctional CuTax nanozyme-based chitosan edible coatings for fruit preservation

The preservation of fresh fruits is critically challenged by oxidative degradation and microbial contamination, which lead to quality deterioration and reduced shelf life. In this study, we took advantage of the multiple benefits of Taxfolin (Tax) and copper to develop CuTax nanozymes, and which were showed to have excellent free radical scavenging ability, as evidenced by 90.3 % ± 0.2 % DPPH and 85.61 % ± 0.08 % ABTS free radical scavenging rates. Additionally, the CuTax exhibited peroxidase-like (POD-like) activity and effective glutathione (GSH) depletion. Moreover, the CuTax were found to effectively suppress the colony formation of E. coli and S. aureus, reduce bacterial viability, and disrupt bacterial structures. Ultimately, a CuTax/CS composite coating/films for food preservation was successfully developed using chitosan (CS) as a carrier and the protective efficacy against food spoilage was evaluated using bananas and apples as representative fruits. These findings suggest that CuTax/CS composite coatings offer a multifunctional approach to active food packaging that effectively extend the shelf life and preserve the quality of fresh fruits.

pH-responsive molybdenum disulphide composite nanomaterials for skin wound healing using "ROS leveraging" synergistic immunomodulation

With the increasing prevalence of drug-resistant bacterial infections, wound bacterial infections have evolved into an escalating medical problem that poses a threat to the individual health as well as global public health. Traditional drug therapy not only suffers from a single treatment method, low drug utilisation and limited therapeutic effect, but long-term antibiotic abuse has significantly increased bacterial resistance. It is imperative to develop an antibiotic-free biomaterial with antibacterial and anti-inflammatory properties. The current use of photothermal therapy (PTT) and photodynamic therapy (PDT) relies on the generation of massive reactive oxygen species (ROS), which inevitably aggravates the inflammatory response. Herein, we developed AuAg bimetallic nanoparticles based on PDA modification and prepared a novel MoS2-based composite nanomaterials (AuAg@PDA-MoS2 NPs) with multiple mechanisms of antibacterial and anti-inflammatory potentials through the adhesion of PDA. In the early phase, PDT and PTT generated a large amount of ROS for rapid sterilisation. While in the later stage, MoS2 mimicked the peroxidase activity to leverage the ROS, balancing the generation of ROS in the infected environment to achieve the long-term anti-inflammatory. In vitro experiments showed that the killing efficiency of AuAg@PDA-MoS2 NPs was nearly 99 % under the irradiation of 808 nm near-infrared light for 10 min, which demonstrated excellent antibacterial activity. In vivo experiments showed that 808 nm NIR-assisted AuAg@PDA-MoS2 NPs to effectively inhibit infection, alleviated the inflammation, and accelerated the wound healing process. Therefore, AuAg@PDA-MoS2 NPs as a novel biomaterial could achieve programmed antimicrobial and anti-inflammatory effects, which has a promising potential for future application in the treatment of infected wounds.

Current advances in nanozyme-based nanodynamic therapies for cancer

Nanozymes are nano-catalysis materials with enzyme-like activities, which can repair the defects of natural enzyme such as harsh catalytic conditions, and harness their strengths to treat tumor. The emerging nanodynamic therapies improved drug selectivity and decreased drug tolerance, while causing efficient cell apoptosis through the generated reactive oxygen species (ROS). Nanodynamic therapies based on nanozymes can improve the complicated tumor microenvironment (TME) to reduce the defect rate of nanodynamic therapies, and provide more options for tumor treatment. This review summarized the characteristics and applications of nanozymes with different activities and the factors influencing the activity of nanozymes. We also focused on the application of nanozymes in nanodynamic therapies, including photodynamic therapy (PDT), chemodynamic therapy (CDT), and sonodynamic therapy (SDT). Moreover, we discussed the strategies for optimizing nanodynamic therapies based on nanozymes for tumor treatment in detail, and provided a systematic review of tactics for synergies with other tumor therapies. Ultimately, we analyzed the shortcomings of nanodynamic therapies based on nanozymes and the relevant research prospect, which would provide sufficient evidence and lay a foundation for further research. STATEMENT OF SIGNIFICANCE: 1. The novelty and significance of the work with respect to the existing literatures. (1) Recent advances in nanozyme-based nanodynamic therapies are comprehensively and systematically reviewed, and strategies to address the limitations and challenges of current therapies based on nanozymes are discussed firstly. (2) The mechanism of nanozymes in nanodynamic therapies is described for the first time. The synergistic therapies, prospects, and challenges of nanozyme-based nanodynamic therapies are innovatively discussed. 2. The scientific impact and interest to our readership. This review focuses on the recent progress of nanozyme-based nanodynamic therapies. This review indicates the way forward for the combined treatment of nanozymes and nanodynamic therapies, and lays a foundation for facilitating theoretical development in clinic.

Antimicrobial materials based on photothermal action and their application in wound treatment

Considering the increasing abundance of antibiotic-resistant bacteria, novel antimicrobial approaches need to be investigated. Photothermal therapy (PTT), an innovative noninvasive therapeutic technique, has demonstrated significant potential in addressing drug-resistant bacteria and bacterial biofilms. However, when used in isolation, PTT requires higher-temperature conditions to effectively eradicate bacteria, thereby potentially harming healthy tissues and inducing new inflammation. This study aims to present a comprehensive review of nanomaterials with intrinsic antimicrobial properties, antimicrobial materials relying on photothermal action, and nanomaterials using drug delivery antimicrobial action, along with their applications in antimicrobials. Additionally, the synergistic mechanisms of these antimicrobial approaches are elucidated. The review provides a reference for developing multifunctional photothermal nanoplatforms for treating bacterially infected wounds.

An acidity-triggered aggregation nanoplatform based on degradable mesoporous organosilica nanoparticles for precise drug delivery and phototherapy of focal bacterial infection

It is crucial to precisely strike the bacterially infected area and avoid damaging healthy tissue in bacterial infection treatment. Herein, we report an acidity-triggered aggregation antibacterial nanoplatform based on biodegradable mesoporous organic silica nanoparticles (MON NPs). The surface of MON NPs modified with polydopamine (PDA) encapsulated ciprofloxacin (CIP) and methylene blue (MB) and was then further grafted with glycol chitosan to obtain MB/CIP@MON-PDA-GCS NPs (MCMPG NPs). In the bacterial infection environment with acidic characteristics, glycol chitosan (GCS) becomes positively charged. Consequently, the positively charged acidity-triggered GCS enables MCMPG NPs to accumulate on the negatively charged bacterial surfaces in the infected area and not in healthy tissue. The targeted method allows for the precise release of CIP and MB, ensuring the spatial accuracy of photodynamic therapy (PDT) and photothermal therapy (PTT) for effective bacteria-specific treatment.

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.

Boron in wound healing: a comprehensive investigation of its diverse mechanisms

Chronic wounds present a significant clinical challenge due to their prolonged healing time and susceptibility to infection. Boron, a trace element with diverse biological functions, has emerged as a promising therapeutic agent in wound healing. This review article comprehensively investigates the mechanisms underlying the beneficial effects of boron compounds in wound healing. Boron exerts its healing properties through multiple pathways, including anti-inflammatory, antimicrobial, antioxidant, and pro-proliferative effects. Inflammation is a crucial component of the wound-healing process, and boron has been shown to modulate inflammatory responses by inhibiting pro-inflammatory cytokines and promoting the resolution of inflammation. Furthermore, boron exhibits antimicrobial activity against a wide range of pathogens commonly associated with chronic wounds, thereby reducing the risk of infection and promoting wound closure. The antioxidant properties of boron help protect cells from oxidative stress, a common feature of chronic wounds that can impair healing. Additionally, boron stimulates cell proliferation and migration, as well as essential tissue regeneration and wound closure processes. Overall, this review highlights the potential of boron as a novel therapeutic approach for treating chronic wounds, offering insights into its diverse mechanisms of action and clinical implications.

NH2-MIL-88B@TP-TA@CuS for photothermal catalytic synergistic antibacterial activity

Reactive oxygen species (ROS) provide a promising way to fight bacterial infection and meet the persistent challenge of antibiotic resistance. Nanoenzyme mimics natural enzyme and becomes an effective regulator of ROS level. In this study, NH2-MIL-88B with high specific surface area was selected as the core, and the covalent organic skeleton material TP-TA COF was wrapped by "sequential growth" technology. Subsequently, through the second hydrothermal treatment, the inorganic material CuS with excellent photothermal performance was integrated into the outer layer, and the NH2-MIL-88B@TP-TA@CuSX composite nanoenzyme was synthesized. Different from the traditional nano-enzyme, NH2-MIL-88B@TP-TA@CuSX nano-enzyme still has good catalytic effect under neutral conditions (pH=7). In addition, NH2-MIL-88B@TP-TA@CuSX has good near infrared (NIR) absorption rate and high photothermal conversion efficiency (PTCE is 48.7 %), which can be used for photothermal treatment (PTT) of bacteria. Mild photothermal effect can further enhance the enzyme-like catalytic activity of NH2-MIL-88B@TP-TA@CuSX, so that H2O2 can be more efficiently catalyzed to produce a large number of ROS. The experimental results in vitro show that NH2-MIL-88B@TP-TA@CuSX can effectively kill Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in the presence of laser irradiation and H2O2.

Construction of CXCR4 Receptor-Targeted CuFeSe2 Nano Theranostic Platform and Its Application in MR/CT Dual Model Imaging and Photothermal Therapy

Introduction

Targeting, imaging, and treating tumors represent major clinical challenges. Developing effective theranostic agents to address these issues is an urgent need.

Methods

We introduce an "all-in-one" tumor-targeted theranostic platform using CuFeSe2-based composite nanoparticles (CuFeSe2@PA) for magnetic resonance (MR) and computed tomography (CT) dual model imaging-guided hyperthermia tumor ablation. Plerixafor (AMD3100) is bonded to the surface of CuFeSe2 as a targeting unit. Due to the robust interaction between AMD3100 and the overexpressed Chemokine CXC type receptor 4 (CXCR4) on the membrane of 4T1 cancer cells, CuFeSe2@PA specifically recognizes 4T1 cancer cells, enriching the tumor region.

Results

CuFeSe2@PA serves as a contrast agent for T2-weighted MR imaging (relaxivity value of 1.61 mM-1 s-1) and CT imaging. Moreover, it effectively suppresses tumor growth through photothermal therapy (PTT) owing to its high photothermal conversion capability and stability, with minimized side effects demonstrated both in vitro and in vivo.

Discussion

CuFeSe2@PA nanoparticles show potential as dual-mode imaging contrast agents for MR and CT and provide an effective means of tumor treatment through photothermal therapy. The surface modification with Plerixafor enhances the targeting ability of the nanoparticles, performing more significant efficacy and biocompatibility in the 4T1 cancer cell model. The study demonstrates that CuFeSe2@PA is a promising multifunctional theranostic platform with clinical application potential.

Catalytic Nanoparticles in Biomedical Applications: Exploiting Advanced Nanozymes for Therapeutics and Diagnostics

Catalytic nanoparticles (CNPs) as heterogeneous catalyst reveals superior activity due to their physio-chemical features, such as high surface-to-volume ratio and unique optical, electric, and magnetic properties. The CNPs, based on their physio-chemical nature, can either increase the reactive oxygen species (ROS) level for tumor and antibacterial therapy or eliminate the ROS for cytoprotection, anti-inflammation, and anti-aging. In addition, the catalytic activity of nanozymes can specifically trigger a specific reaction accompanied by the optical feature change, presenting the feasibility of biosensor and bioimaging applications. Undoubtedly, CNPs play a pivotal role in pushing the evolution of technologies in medical and clinical fields, and advanced strategies and nanomaterials rely on the input of chemical experts to develop. Herein, a systematic and comprehensive review of the challenges and recent development of CNPs for biomedical applications is presented from the viewpoint of advanced nanomaterial with unique catalytic activity and additional functions. Furthermore, the biosafety issue of applying biodegradable and non-biodegradable nanozymes and future perspectives are critically discussed to guide a promising direction in developing span-new nanozymes and more intelligent strategies for overcoming the current clinical limitations.

Effect of precipitant on pro-oxidative and antibacterial properties of CeO2 nanoparticles - an experimental study

In this study, the synthesis of pro-oxidative cerium-oxide nanozymes (CeO2 NZs) is reliably performed via the co-precipitation method using ceric ammonium nitrate as a precursor and ammonium carbonate as a precipitating agent. Different samples of CeO2 NZs were prepared by varying the amount of the precipitant. The synthesized NZs were characterized by ultraviolet-visible (UV-vis) spectroscopy, particle size analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM) and then checked for their pro-oxidative (peroxidase and oxidase) activity. Furthermore, we studied the NZ kinetics and antibacterial properties of synthesized samples.

Biofilm microenvironment-activated multimodal therapy nanoplatform for effective anti-bacterial treatment and wound healing

Antimicrobial drug development faces challenges from bacterial resistance, biofilms, and excessive inflammation. Here, we design an intelligent nanoplatform utilizing mesoporous silica nanoparticles doped with copper ions for loading copper sulfide (DM/Cu2+-CuS). The mesoporous silica doped with tetrasulfide bonds responds to the biofilm microenvironment (BME), releasing Cu2+ions, CuS along with hydrogen sulfide (H2S) gas. The release of hydrogen sulfide within 72 h reached 793.5 µM, significantly higher than that observed with conventional small molecule donors. H2S induces macrophages polarization towards the M2 phenotype, reducing inflammation and synergistically accelerating endothelial cell proliferation and migration with Cu2+ions. In addition, H2S disrupts extracellular DNA within biofilms, synergistically photothermal enhanced peroxidase-like activity of CuS to effectively eradicate biofilms. Remarkably, DM-mediated consumption of endogenous glutathione enhances the anti-biofilm activity of H2S and improves oxygen species (ROS) destruction efficiency. The combination of photothermal therapy (PTT), chemodynamic therapy (CDT), and gas treatment achieves sterilization rates of 99.3 % and 99.6 % against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively, in vitro under 808 nm laser irradiation. Additionally, in vivo experiments demonstrate a significant biosafety and antibacterial potential. In summary, the H2S donor developed in this study exhibits enhanced biocompatibility and controlled release properties. By integrating BME-responsive gas therapy with antibacterial ions, PTT and CDT, a synergistic multimodal strategy is proposed to offer new therapeutic approaches for wound healing. STATEMENT OF SIGNIFICANCE: The advanced DMOS/Cu2+-CuS (DMCC) multimodal therapeutic nanoplatform has been developed for the treatment of drug-resistant bacterial wound infections and has exhibited enhanced therapeutic efficacy through the synergistic effects of photothermal therapy, chemodynamic therapy, Cu2+ions, and H2S. The DMCC exhibited exceptional biocompatibility and could release CuS, Cu2+, and H2S in response to elevated concentrations of glutathione within the biofilm microenvironment. H2S effectively disrupted the biofilm structure. Meanwhile, peroxidase activity of CuS combined with GSH-mediated reduction of Cu2+ to Cu+ generated abundant hydroxyl radicals under acidic conditions, leading to efficient eradication of pathogenic bacteria. Furthermore, both H2S and Cu2+ could modulate M2 macrophages polarization and regulate immune microenvironment dynamics. These strategies collectively provided a novel approach for developing antibacterial nanomedical platforms.

Engineering Platelet Membrane-Coated Bimetallic MOFs as Biodegradable Nanozymes for Efficient Antibacterial Therapy

Nanocatalytic-based wound therapeutics present a promising strategy for generating reactive oxygen species (ROS) to antipathogen to promote wound healing. However, the full clinical potential of these nanocatalysts is limited by their low reactivity, limited targeting ability, and poor biodegradability in the wound microenvironment. Herein, a bio-organic nanozyme is developed by encapsulating a FeZn-based bimetallic organic framework (MOF) (MIL-88B-Fe/Zn) in platelet membranes (PM@MIL-88B-Fe/Zn) for antimicrobial activity during wound healing. The introduction of Zn in MIL-88B-Fe/Zn modulates the electronic structure of Fe thus accelerating the catalytic kinetics of its peroxidase-like activity to catalytically generate powerful ROS. The platelet membrane coating of MOF innovatively enhanced the interaction between nanoparticles and the biological environment, further developing bacterial-targeted therapy with excellent antibacterial activity against both gram-positive and gram-negative bacteria. Furthermore, this nanozyme markedly suppressed the levels of inflammatory cytokines and promoted angiogenesis in vivo to effectively treat skin surface wounds and accelerate wound healing. PM@MIL-88B-Fe/Zn exhibited superior biodegradability, favourable metabolism and non-toxic accumulation, eliminating concerns regarding side effects from long-term exposure. The high catalytic reactivity, excellent targeting features, and biodegradability of these nanoenzymes developed in this study provide useful insights into the design and synthesis of nanocatalysts/nanozymes for practical biomedical applications.

Iron-Single-Atom Nanozyme with NIR Enhanced Catalytic Activities for Facilitating MRSA-Infected Wound Therapy

Patients with methicillin-resistant Staphylococcus aureus (MRSA) infections may have higher death rates than those with non-drug-resistant infections. Nanozymes offer a promising approach to eliminating bacteria by producing reactive oxygen species. However, most of the conventional nanozyme technologies encounter significant challenges with respect to size, composition, and a naturally low number of active sites. The present study synthesizes a iron-single-atom structure (Fe-SAC) via nitrogen doped-carbon, a Fe-N5 catalyst (Fe-SAC) with a high metal loading (4.3 wt.%). This catalyst permits the development of nanozymes consisting of single-atom structures with active sites resembling enzymes, embedded within nanomaterials. Fe-SAC displays peroxidase-like activities upon exposure to H2O2. This structure facilitates the production of hydroxyl radicals, well-known for their strong bactericidal effects. Furthermore, the photothermal properties augment the bactericidal efficacy of Fe-SAC. The findings reveal that Fe-SAC disrupts the bacterial cell membranes and the biofilms, contributing to their antibacterial effects. The bactericidal properties of Fe-SAC are harnessed, which eradicates the MRSA infections in wounds and improves wound healing. Taken together, these findings suggest that single Fe atom nanozymes offer a novel perspective on the catalytic mechanism and design, holding immense potential as next-generation nanozymes.

Cysteine and homocysteine can be exploited by GPX4 in ferroptosis inhibition independent of GSH synthesis

Ferroptosis is inhibited by glutathione peroxidase 4 (GPX4), an antioxidant enzyme that uses reduced glutathione (GSH) as a cofactor to detoxify lipid hydroperoxides. As a selenoprotein, the core function of GPX4 is the thiol-dependent redox reaction. In addition to GSH, other small molecules such as cysteine and homocysteine also contain thiols; yet, whether GPX4 can exploit cysteine and homocysteine to directly detoxify lipid hydroperoxides and inhibit ferroptosis has not been addressed. In this study, we found that cysteine and homocysteine inhibit ferroptosis in a GPX4-dependent manner. However, cysteine inhibits ferroptosis independent of GSH synthesis, and homocysteine inhibits ferroptosis through non-cysteine and non-GSH pathway. Furthermore, we used molecular docking and GPX4 activity analysis to study the binding patterns and affinity between GPX4 and GSH, cysteine, and homocysteine. We found that besides GSH, cysteine and homocysteine are also able to serve as substrates for GPX4 though the affinities of GPX4 with cysteine and homocysteine are lower than that with GSH. Importantly, GPX family and the GSH synthetase pathway might be asynchronously evolved. When GSH synthetase is absent, for example in Flexibacter, the fGPX exhibits higher affinity with cysteine and homocysteine than GSH. Taken together, the present study provided the understanding of the role of thiol-dependent redox systems in protecting cells from ferroptosis and propose that GSH might be a substitute for cysteine or homocysteine to be used as a cofactor for GPX4 during the evolution of aerobic metabolism.

An NIR-II-photoresponsive CoSnO3 nanozyme for mild photothermally augmented nanocatalytic cancer therapy

The main challenges of nanozyme-based tumor catalytic therapy (NCT) lie in the unsatisfactory catalytic activity accompanied by a complex tumor microenvironment (TME). A few nanozymes have been designed to possess both enzyme-like catalytic activities and photothermal properties; however, the previously reported nanozymes mainly utilize the inefficient and unsafe NIR-I laser, which has a low maximum permissible exposure limit and a limited penetration depth. Herein, we report for the first time an all-in-one strategy to realize mild NIR-II photothermally amplified NCT by synthesizing amorphous CoSnO3 nanocubes with efficient triple enzyme-like catalytic activities and photothermal conversion properties. The presence of Co2+ and Sn4+ endows CoSnO3 nanocubes with the triple enzyme-like catalytic activities, not only achieving enhanced reactive oxygen species (ROS) generation through the Co2+-mediated peroxidase-like catalytic reaction to generate ˙OH and Sn4+-mediated depletion of overexpressed GSH, but also realizing the catalytic decomposition of endogenous H2O2 for relieving tumor hypoxia. More importantly, the obtained CoSnO3 nanocubes with a high photothermal conversion efficiency of 82.1% at 1064 nm could achieve mild hyperthermia (43 °C), which further improves the triple enzyme-like catalytic activities of the CoSnO3 nanozyme. The synergetic therapeutic efficacy of the NIR-II-responsive CoSnO3 nanozyme through mild NIR-II PTT-enhanced NCT could realize all-in-one multimodal tumor therapy to completely eliminate tumors without recurrence. This study will open a new avenue to explore NIR-II-photoresponsive nanozymes for efficient tumor therapy.

Copper incorporated biomaterial-based technologies for multifunctional wound repair

The treatment of wounds is a worldwide challenge, and wound infection can affect the effectiveness of wound treatment and further increase the disease burden. Copper is an essential trace element that has been shown to have broad-spectrum antibacterial effects and to be involved in the inflammation, proliferation, and remodeling stages of wound healing. Compared to treatments such as bioactive factors and skin grafts, copper has the advantage of being low-cost and easily available, and has received a lot of attention in wound healing. Recently, biomaterials made by incorporating copper into bioactive glasses, polymeric scaffolds and hydrogels have been used to promote wound healing by the release of copper ions. In addition, copper-incorporated biomaterials with catalytic, photothermal, and photosensitive properties can also accelerate wound healing through antibacterial and wound microenvironment regulation. This review summarizes the antibacterial mechanisms of copper- incorporated biomaterials and their roles in wound healing, and discusses the current challenges. A comprehensive understanding of the role of copper in wounds will help to facilitate new preclinical and clinical studies, thus leading to the development of novel therapeutic tools.

Harnessing Transition Metal Scaffolds for Targeted Antibacterial Therapy

Antimicrobial resistance, caused by persistent adaptation and growing resistance of pathogenic bacteria to overprescribed antibiotics, poses one of the most serious and urgent threats to global public health. The limited pipeline of experimental antibiotics in development further exacerbates this looming crisis and new drugs with alternative modes of action are needed to tackle evolving pathogenic adaptation. Transition metal complexes can replenish this diminishing stockpile of drug candidates by providing compounds with unique properties that are not easily accessible using pure organic scaffolds. We spotlight four emerging strategies to harness these unique properties to develop new targeted antibacterial agents.

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.

CuS@TA-Fe Nanoparticle-Doped Multifunctional Hydrogel with Peroxide-Like Properties and Photothermal Properties for Synergistic Antimicrobial Repair of Infected Wounds

Bacterial infection is a critical factor in wound healing. Due to the abuse of antibiotics, some pathogenic bacteria have developed resistance. Thus, there is an urgent need to develop a non-antibiotic-dependent multifunctional wound dressing for the treatment of bacteria-infected wounds. In this work, a multifunctional AOCuT hydrogel embedded with CuS@TA-Fe nanoparticles (NPs) through Schiff base reaction between gelatin quaternary ammonium salt - gallic acid (O-Gel-Ga) and sodium dialdehyde alginate (ADA) along with electrostatic interactions with CuS@TA-Fe NPs is prepared. These composite hydrogels possess favorable injectability, rapid shape adaptation, electrical conductivity, photothermal antimicrobial activity, and biocompatibility. Additionally, the doped NPs not only impart fast self-healing properties and excellent adhesion performance to the hydrogels, but also provide excellent peroxide-like properties, enabling them to scavenge free radicals and exhibit anti-inflammatory and antioxidant capabilities via photothermal (PTT) and photodynamic (PDT) effects. In an S. aureus infected wound model, the composite hydrogel effectively reduces the expression level of wound inflammatory factors and accelerates collagen deposition, epithelial tissue, and vascular regeneration, thereby promoting wound healing. This safe and synergistic therapeutic system holds great promise for clinical applications in the treatment of infectious wounds.

Multifunctional AuPt Nanoparticles for Synergistic Photothermal and Radiation Therapy

Background

Photothermal therapy (PTT) has gained considerable interest as an emerging modality for cancer treatment in recent years. Radiation therapy (RT) has been widely used in the clinic as a traditional treatment method. However, RT and PTT treatments are limited by side effects and penetration depth, respectively. In addition, hypoxia within the tumor can lead to increased resistance to treatment.

Methods

We synthesized multiple sizes of AuPt by modulating the reaction conditions. The smallest size of AuPt was selected and modified with folic acid (FA) for PTT and RT synergy therapy. Various methods including transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FITR) are used to determine the structure and composition of AuPt-FA (AF). In addition, we researched the photothermal properties of AF with IR cameras and infrared lasers. Flow cytometry, colony formation assays, CCK8, and fluorescent staining for probing the treatment effect in vitro. Also, we explored the targeting of AF by TEM and In Vivo Imaging Systems (IVIS). In vivo experiments, we record changes in tumor volume and weight as well as staining of tumor sections (ROS, Ki67, and hematoxylin and eosin).

Results

The AuPt with particle size of 16 nm endows it with remarkably high photothermal conversion efficiency (46.84%) and catalase activity compared to other sizes of AuPt (30 nm and 100 nm). AF alleviates hypoxia in the tumor microenvironment, leading to the production of more reactive oxygen species (ROS) during the treatment. In addition, the therapeutic effect was significantly enhanced by combining RT and PTT, with an apoptosis rate of 81.1% in vitro and an in vivo tumor volume reduction rate of 94.0% in vivo.

Conclusion

These results demonstrate that AF potentiates the synergistic effect of PTT and RT and has the potential for clinical translation.

Metal-organic framework-modulated Fe3O4 composite au nanoparticles for antibacterial wound healing via synergistic peroxidase-like nanozymatic catalysis

Bacterial wound infections are a serious threat due to the emergence of antibiotic resistance. Herein, we report an innovative hybrid nanozyme independent of antibiotics for antimicrobial wound healing. The hybrid nanozymes are fabricated from ultra-small Au NPs via in-situ growth on metal-organic framework (MOF)-stabilised Fe3O4 NPs (Fe3O4@MOF@Au NPs, FMA NPs). The fabricated hybrid nanozymes displayed synergistic peroxidase (POD)-like activities. It showed a remarkable level of hydroxyl radicals (·OH) in the presence of a low dose of H2O2 (0.97 mM). Further, the hybrid FMA nanozymes exhibited excellent biocompatibility and favourable antibacterial effects against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The animal experiments indicated that the hybrid nanozymes promoted wound repair with adequate biosafety. Thus, the well-designed hybrid nanozymes represent a potential strategy for healing bacterial wound infections, without any toxic side effects, suggesting possible applications in antimicrobial therapy.

Procedural Promotion of Multiple Stages in the Wound Healing Process by Graphene-Spiky Silica Heterostructured Nanoparticles

Background

Multiple stages including hemostasis, inflammation, proliferation, and remodeling were involved in the wound healing process. The increase in nanomaterials in recent years has extended the scope of tools for wound healing; however, it is still difficult to achieve the four multistage procedures simultaneously.

Materials and Methods

In this study, graphene-spiky silica heterostructured nanoparticles (GS) were synthesized for the procedural acceleration of the multistage in wound healing process. The nanobridge effect of GS was analyzed through the adhesion of two skins, the antibacterial effect was assessed in Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria, cell proliferation and migration were investigated in mouse embryonic fibroblast (NIH-3T3) cells, and the in vivo wound healing effect was examined in female BALB/c mice with a cutting wound and E. coli or S. aureus bacteria infection on the back.

Results

First, GS has a strong nanobridge effect on the rapid closure of wounds because the spiky architecture on the surface of GS facilitates the adhesion of skins, promoting the hemostasis stage. Second, graphene exhibits antimicrobial activities both in chemical and physical interactions, especially under simulated sunlight irradiation. Third, graphene plays an important role in scaffolding function, together with the spiky topographical architecture of GS, accelerating the proliferation and maturation stages.

Conclusion

By periodically promoting every stage of wound healing, GS combined with simulated sunlight irradiation could significantly accelerate wound healing. With a simple composition and compact structure but multiple functions, this strategy will be the guideline for the development of ideal wound-healing nanomaterials.

Core-Shell NiS@SrTiO3 Nanorods on Titanium for Enhanced Osseointegration via Programmed Regulation of Bacterial Infection, Angiogenesis, and Osteogenesis

Developing bone implants with dynamic self-adjustment of antibacterial, angiogenic, and osteogenic functions in line with a bone regenerative cascade is highly required in orthopedics. Herein, a unique core-shell nanorods array featuring a thin layer of NiS coated on each SrTiO3 nanorod (NiS@SrTiO3) was in situ constructed on titanium (Ti) through a two-step hydrothermal treatment. Under near-infrared (NIR) irradiation, the photoresponsive effect of NiS layer in synergy with the physical perforation of SrTiO3 nanorods initially enabled in vitro antibacterial rates of 96.5% to Escherichia coli and 93.1% to Staphylococcus aureus. With the degradation of the NiS layer, trace amounts of Ni ions were released, which accelerated angiogenesis by upregulating the expression of vascular regeneration-related factors, while the gradual exposure of SrTiO3 nanorods could simultaneously enhance the surface hydrophilicity in favor of cell adhesion and slowly release Sr ions to promote the proliferation and differentiation of MC3T3-E1 cells. The in vivo assessment verified not only the satisfactory antibacterial effect but also the superior osteogenic ability of the NiS@SrTiO3/Ti group with the aid of NIR irradiation, finally promoting the osseointegration of the Ti implant. The modification method endowing Ti implant with antibacterial, angiogenic, and osteogenic functions provides a new strategy to improve the long-term reliability of Ti-based devices.

Photothermal Conversion of Hydrogel-Based Biomaterial

Traditional energy from fossil fuels like petroleum and coal is limited and contributes to global environmental pollution and climate change. Developing sustainable and eco-friendly energy is crucial for addressing significant challenges such as climate change, energy dilemma and achieving the long-term development of human society. Biomass hydrogels, which are easily synthesized and modified, have diverse sources and can be designed for different applications. They are being extensively researched for their applications in artificial intelligence, flexible sensing, biomedicine, and food packaging. The article summarizes recent advances in the preparation and applications of biomass-based photothermal conversion hydrogels, discussing the light source, photothermal agents, matrix, and preparation methods in detail. It also explores the use of these hydrogels in seawater desalination, photothermal therapy, antibacterial agents, and light-activated materials, offering new ideas for developing sustainable, efficient, and advanced photothermal conversion biomass hydrogel materials. The article concludes with suggestions for future research, highlighting the challenges and prospects in this field and paving the way for developing of long-lasting, efficient energy materials.

Unveiling the volatile compounds and antibacterial mechanisms of action of Cupressus sempervirens L., against Bacillus subtilis and Pseudomonas aeruginosa

Cupressus sempervirens is a known traditional plant used to manage various ailments, including cancer, inflammatory and infectious diseases. In this investigation, we aimed to explore the chemical profile of Cupressus sempervirens essential oil (CSEO) as well as their antibacterial mode of action. The volatile components were characterized using gas chromatography coupled to a mass spectrometer (GC-MS). The results revealed remarkable antibacterial properties of EO derived from C. sempervirens. GC-MS analysis indicated that C. sempervirens EO characterized by δ-3-carene (47.72%), D-limonene (5.44%), β-pinene (4.36%), β-myrcene (4.02%). The oil exhibited significant inhibitory effects against a range of bacteria, including Staphylococcus aureus ATCC 29213, Bacillus subtilis ATCC 13048, Bacillus cereus (Clinical isolate), Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922. These inhibitory effects surpassed those of conventional antibiotics. Furthermore, the EO demonstrated low minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs), indicating its bactericidal nature (MBC/MIC < 4.0). Time-kill kinetics analysis showed that CSEO was particularly effective at 2 × MIC doses, rapidly reduced viable count of B. subtilis and P. aeruginosa within 8 h. This suggests that the oil acts quickly and efficiently. The cell membrane permeability test further demonstrated the impact of CSEO on the relative conductivity of B. subtilis and P. aeruginosa, both at 2 × MIC concentrations. These observations suggest that EO disrupts the bacterial membrane, thereby influencing their growth and viability. Additionally, the cell membrane integrity test indicated that the addition of CSEO to bacterial cultures resulted in the significant release of proteins from the bacterial cells. This suggests that EO affects the structural integrity of the bacterial cells. Furthermore, the anti-biofilm assay confirmed the efficacy of CSEO as a potent anti-biofilm agent. It demonstrated the oil's ability to inhibit quorum sensing, a crucial mechanism for biofilm formation, and its competitive performance compared to the tested antibiotics.

A Novel Z-Scheme Heterostructured Bi2 S3 /Cu-TCPP Nanocomposite with Synergistically Enhanced Therapeutics against Bacterial Biofilm Infections in Periodontitis

Porphyrin-based antibacterial photodynamic therapy (aPDT) has found widespread applications in treating periodontitis. However, its clinical use is limited by poor energy absorption, resulting in limited reactive oxygen species (ROS) generation. To overcome this challenge, a novel Z-scheme heterostructured nanocomposite of Bi2 S3 /Cu-TCPP is developed. This nanocomposite exhibits highly efficient light absorption and effective electron-hole separation, thanks to the presence of heterostructures. The enhanced photocatalytic properties of the nanocomposite facilitate effective biofilm removal. Theoretical calculations confirm that the interface of the Bi2 S3 /Cu-TCPP nanocomposite readily adsorbs oxygen molecules and hydroxyl radicals, thereby improving ROS production rates. Additionally, the photothermal treatment (PTT) using Bi2 S3 nanoparticles promotes the release of Cu2+ ions, enhancing the chemodynamic therapy (CDT) effect and facilitating the eradication of dense biofilms. Furthermore, the released Cu2+ ions deplete glutathione in bacterial cells, weakening their antioxidant defense mechanisms. The synergistic effect of aPDT/PTT/CDT demonstrates potent antibacterial activity against periodontal pathogens, particularly in animal models of periodontitis, resulting in significant therapeutic effects, including inflammation alleviation and bone preservation. Therefore, this design of semiconductor-sensitized energy transfer represents an important advancement in improving aPDT efficacy and the treatment of periodontal inflammation.

Tannic acid-Fe3+ dual catalysis induced rapid polymerization of injectable poly(lysine) hydrogel for infected wound healing

Infected wounds are difficult to heal because they are vulnerable to bacterial attacks, inflammatory responses, and oxidative stress. To promote the healing of infected wounds, we developed an injectable dual-network hydrogel TFAEP (TA-Fe, APS, EPL-GMA, PVA) based on ε-poly-l-lysine-graft-glycidyl methacrylate (EPL-GMA), polyvinyl alcohol (PVA), and tannic acid-iron (TA-Fe). TA-Fe formed a stable redox pair, which acted as a dual-autocatalytic system to activate ammonium persulfate, generate free radicals, and subsequently induce EPL-GMA polymerization. Then PVA formed hydrogen bonds with TA molecules. Here, TA-Fe not only simulated peroxidase to convert H2O2 into hydroxyl radicals (OH), but also exhibited good near-infrared photothermal conversion efficiency, which all endowed the hydrogel with excellent antibacterial ability. In addition, the hydrogel could remove excessive reactive oxygen species and reactive nitrogen species, alleviating oxidative stress and reducing inflammation response due to the presence of TA molecules. Moreover, the hydrogel showed good injectability and tissue adhesion, ensuring the close adhesion of the hydrogel to the wound and achieving the maximum function. In vivo experiments demonstrated that the hydrogel promoted infected wound healing by accelerating epidermal regeneration, promoting angiogenesis and collagen deposition, and facilitating the expression of anti-inflammatory factors.

Two-dimensional TiO nanosheets with photothermal effects for wound sterilization

To combat multidrug-resistant bacteria, researchers have poured into the development and design of antimicrobial agents. Here, low-cost two-dimensional (2D) antibacterial material titanium monoxide nanosheets (TiO NSs) were prepared by an ultrasonic-assisted liquid-phase exfoliation method. When cultured with bacteria, TiO NSs showed intrinsic antimicrobial capacity, possibly due to membrane damage caused by the sharp edges of TiO NSs. Under near-infrared (NIR) laser irradiation, TiO NSs showed high photothermal conversion efficiency (PTCE) and sterilization efficiency. By combining these two antibacterial mechanisms, TiO NSs exhibited a strong killing effect on Gram-negative Escherichia coli (E. coli) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA). Especially after treatment with TiO NSs (150 μg mL-1) +near-infrared (NIR) light irradiation, both bacteria were completely killed. In vivo experiments on wound repair of bacterial infection further confirmed its antibacterial effect. In addition, TiO NSs had no obvious toxicity or side effects, so as a kind of broad-spectrum 2D antibacterial nanoagent, TiO NSs have broad application prospects in the field of pathogen infection.

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.

Cu-GA-coordination polymer nanozymes with triple enzymatic activity for wound disinfection and accelerated wound healing

During the past few years, bacterial infection and oxidative stress have become important issues for wound healing. However, the emergence of numerous drug-resistant superbugs has had a serious impact on the treatment of infected wounds. Presently, the development of new nanomaterials has become one of the most important approaches to the treatment of drug-resistant bacterial infections. Herein, coordination polymer copper-gallic acid (Cu-GA) nanorods with multi-enzyme activity is successfully prepared for efficient wound treatment of bacterial infection, which can effectively promote wound healing. Cu-GA can be efficiently prepared by a simple solution method and had good physiological stability. Interestingly, Cu-GA shows enhanced multienzyme activity (peroxidase, glutathione peroxidase, and superoxide dismutase), which can produce a large number of reactive oxygen species (ROS) under acidic conditions while scavenging ROS under neutral conditions. In acidic environment, Cu-GA possesses POD (peroxidase)-like and glutathione peroxidase (GSH-Px)-like catalytic activities that is capable of killing bacteria; but in neutral environment, Cu-GA exhibits superoxide dismutase (SOD)-like catalytic activity that can scavenge ROS and promote wound healing. In vivo studies show that Cu-GA can promote wound infection healing and have good biosafety. Cu-GA contributes to the healing of infected wounds by inhibiting bacterial growth, scavenging reactive oxygen species, and promoting angiogenesis. STATEMENT OF SIGNIFICANCE: Cu-GA-coordinated polymer nanozymes with multienzyme activity were successfully prepared for efficient wound treatment of bacterial infection, which could effectively promote wound healing. Interestingly, Cu-GA exhibited enhanced multienzyme activity (peroxidase, glutathione peroxidase, and superoxide dismutase), which could produce a large number of reactive oxygen species (ROS) under acidic conditions and scavenge ROS under neutral conditions. In vitro and in vivo studies demonstrated that Cu-GA was capable of killing bacteria, controlling inflammation, and promoting angiogenesis.

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.

Trends in Photothermal Nanostructures for Antimicrobial Applications

The rapid development of antimicrobial resistance due to broad antibiotic utilisation in the healthcare and food industries and the non-availability of novel antibiotics represents one of the most critical public health issues worldwide. Current advances in nanotechnology allow new materials to address drug-resistant bacterial infections in specific, focused, and biologically safe ways. The unique physicochemical properties, biocompatibility, and wide range of adaptability of nanomaterials that exhibit photothermal capability can be employed to develop the next generation of photothermally induced controllable hyperthermia as antibacterial nanoplatforms. Here, we review the current state of the art in different functional classes of photothermal antibacterial nanomaterials and strategies to optimise antimicrobial efficiency. The recent achievements and trends in developing photothermally active nanostructures, including plasmonic metals, semiconductors, and carbon-based and organic photothermal polymers, and antibacterial mechanisms of action, including anti-multidrug-resistant bacteria and biofilm removal, will be discussed. Insights into the mechanisms of the photothermal effect and various factors influencing photothermal antimicrobial performance, emphasising the structure-performance relationship, are discussed. We will examine the photothermal agents' functionalisation for specific bacteria, the effects of the near-infrared light irradiation spectrum, and active photothermal materials for multimodal synergistic-based therapies to minimise side effects and maintain low costs. The most relevant applications are presented, such as antibiofilm formation, biofilm penetration or ablation, and nanomaterial-based infected wound therapy. Practical antibacterial applications employing photothermal antimicrobial agents, alone or in synergistic combination with other nanomaterials, are considered. Existing challenges and limitations in photothermal antimicrobial therapy and future perspectives are presented from the structural, functional, safety, and clinical potential points of view.

Integrated supramolecular nanovalves for photothermal augmented chemodynamic therapy through strengthened amplification of oxidative stress

The amplified oxidative stress strategy has been emerged as one promising method to enhance the chemodynamic therapy (CDT) efficacy due to the H₂O₂ up-regulation and glutathione (GSH) down-regulation behavior in tumor cells. However, how to further achieve the satisfied CDT efficacy is still a big challenge. In this paper, the supramolecular nanovalves (SNs) with oxidative amplification agents cinnamaldehyde-(phenylboronic acid pinacol ester) conjugates (CA-BE) encapsulated inside were developed to accelerate and amplify the generation of ·OH and consumption of GSH while augmenting the CDT efficacy. SNs were obtained through ferrocene/Au modified mesoporous silica nanoparticles (MSN@Au-Fc) and active targeting β-cyclodextrin modified hyaluromic acid (HA-CD). After CD44 receptor-mediated cellular internalization, the CA-BE were released to elevate H₂O₂ amount and consume GSH for the desired generation of higher cytotoxic hydroxyl radicals (·OH). Moreover, the NIR-activated MSN@Au-Fc can increase the temperature for the accelerated and amplified oxidative stress. As such, the therapeutic efficacy of our synthesized CA-BE and the accompanied hyperthermia were augmented toward synergistically inhibiting tumor growth.

Stimuli-Responsive Double Single-Atom Catalysts for Parallel Catalytic Therapy

Tumor microenvironment (TME)-induced nanocatalytic therapy is a trending strategy for tumor-targeting therapy, but the low catalytic efficiency remains to limit its therapeutic effect. The single-atom catalysts (SACs) appear as a novel type of nanozymes that possesses incredible catalytic activity. Here, we developed PEGylated manganese/iron-based SACs (Mn/Fe PSACs) by coordinating single-atom Mn/Fe to nitrogen atoms in hollow zeolitic imidazolate frameworks (ZIFs). Mn/Fe PSACs catalyze cellular hydrogen peroxide (H2O2) converting to hydroxyl radical (•OH) through a Fenton-like reaction; it also enhances the decomposition of H2O2 to O2 that continuously converts to cytotoxic superoxide ion (•O2-) via oxidase-like activity. Mn/Fe PSACs can reduce the depletion of reactive oxygen species (ROS) by consuming glutathione (GSH). Here, we demonstrated the Mn/Fe PSACs-mediated synergistic antitumor efficacy among in vitro and in vivo experiments. This study proposes new promising single-atom nanozymes with highly efficient biocatalytic sites and synergistic therapeutic effects, which will give birth to abundant inspirations in ROS-related biological applications in broad biomedical fields.

Titanium-Based Nanoarchitectures for Sonodynamic Therapy-Involved Multimodal Treatments

Sonodynamic therapy (SDT) has considerably revolutionized the healthcare sector as a viable noninvasive therapeutic procedure. It employs a combination of low-intensity ultrasound and chemical entities, known as a sonosensitizer, to produce cytotoxic reactive oxygen species (ROS) for cancer and antimicrobial therapies. With nanotechnology, several unique nanoplatforms are introduced as a sonosensitizers, including, titanium-based nanomaterials, thanks to their high biocompatibility, catalytic efficiency, and customizable physicochemical features. Additionally, developing titanium-based sonosensitizers facilitates the integration of SDT with other treatment modalities (for example, chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, and immunotherapy), hence increasing overall therapeutic results. This review summarizes the most recent developments in cancer therapy and tissue engineering using titanium nanoplatforms mediated SDT. The synthesis strategies and biosafety aspects of Titanium-based nanoplatforms for SDT are also discussed. Finally, various challenges and prospects for its further development and potential clinical translation are highlighted.

Antibacterial Nanomaterials: Mechanisms, Impacts on Antimicrobial Resistance and Design Principles

Antimicrobial resistance (AMR) is one of the biggest threats to the environment and health. AMR rapidly invalidates conventional antibiotics, and antimicrobial nanomaterials have been increasingly explored as alternatives. Interestingly, several antimicrobial nanomaterials show AMR-independent antimicrobial effects without detectable new resistance and have therefore been suggested to prevent AMR evolution. In contrast, some are found to trigger the evolution of AMR. Given these seemingly conflicting findings, a timely discussion of the two faces of antimicrobial nanomaterials is urgently needed. This review systematically compares the killing mechanisms and structure-activity relationships of antibiotics and antimicrobial nanomaterials. We then focus on nano-microbe interactions to elucidate the impacts of molecular initiating events on AMR evolution. Finally, we provide an outlook on future antimicrobial nanomaterials and propose design principles for the prevention of AMR evolution.

Amorphous NiB@IrOx nanozymes trigger efficient apoptosis-ferroptosis hybrid therapy

The apoptosis-ferroptosis hybrid therapy opens up a new avenue for tumor eradication. Constructing efficient self-cascade platform is highly desired to enhance its therapeutic effect. Herein, we report on the synthesis of novel nanozyme consist of amorphous NiB alloy completely coated with an ultrathin layer of IrOx shell (A-NiB@C-IrO_x). These core-shell nanoparticles exhibited peroxidase (POD)-, catalase (CAT)- and glutathione oxidase (GSH-OXD)-like properties for inducing self-cascade catalysis. Specifically, the amorphous IrO_x shell with abundant active sites can effectively convert intratumor hydrogen peroxide (H₂O₂) to cytotoxic reactive oxygen species (ROS) and oxygen (O₂). In presence of O2, amorphous NiB core and ultrathin IrOx shell collectively catalyze the oxidation of GSH to generate H₂O₂, which is subsequently converted to ROS and O₂ by IrO_x component. Thus, these enzymatic activities endow A-NiB@C-IrO_x nanozymes with the ability of unceasing generation of ROS and O₂ and depletion of GSH. In vitro and in vivo studies demonstrate a high therapeutic efficiency of A-NiB@C-IrO_x nanozymes via apoptosis-ferroptosis combination therapy. STATEMENT OF SIGNIFICANCE: Apoptosis-ferroptosis hybrid therapy opens up new avenues for eradicating tumor cells. However, its actual therapeutic effect is still unsatisfied. Current efforts on this hybrid therapy focus on developing efficient self-cascade nanozymes to improve the efficiency of both ROS generation and GSH depletion. In this study, we constructed amorphous NiB alloy with a completed thin layer of IrO_x shell (denoted as A-NiB@C-IrO_x) for apoptosis-ferroptosis combination therapy. As expected, A-NiB@C-IrO_x can trigger efficient cascade catalytic reactions to continuously generate ROS and consume GSH, finally inducing augmented apoptosis-ferroptosis combination therapy.

Thermosensitive Hydrogel Loaded with Nickel-Copper Bimetallic Hollow Nanospheres with SOD and CAT Enzymatic-Like Activity Promotes Acute Wound Healing

Various injury defense and repair functions are performed by the skin. Free radicals secreted after injury cause oxidative stress and inflammatory responses, which make wound healing difficult. However, the current metal nanomaterials for wound repair do not have sufficient catalytic activity or complex material design and cannot properly fit wounds. Therefore, it is imperative to develop more effective therapeutic approaches. This study investigated the effect of Ni₄Cu₂ hollow nanospheres composited with F127 hydrogel on promoting wound healing by applying them to wounds. Ni₄Cu₂ hollow nanospheres exhibited a superior spatial structure, contained many catalytic sites, and could be synthesized in a simple manner. In vitro experiments showed that Ni₄Cu₂ hollow nanospheres had superoxide dismutase-like activity and promoted fibroblast migration, angiogenesis, and macrophage polarization. F127, which is a thermosensitive, nontoxic, phase-change and porous hydrogel material, has proven to be an effective choice for injectable and sprayable medical dressings. Ni₄Cu₂ hollow nanospheres were mixed with F127 hydrogel without significantly affecting its performance. In addition to adapting to the complex, irregular gaps of acute wounds, the mixture lengthened the nanozyme release time, which enhanced healing. Based on the animal experiments, the Ni₄Cu₂/F127 composite hydrogel effectively promoted wound healing, epithelial regeneration, and the formation of skin appendages such as hair follicles in mice. Furthermore, the Ni₄Cu₂/F127 composite hydrogel was nontoxic to animals and had high biological safety. The Ni₄Cu₂/F127 composite hydrogel has provided an innovative strategy to develop composite hydrogels for the treatment of acute skin wounds.

Fabrication of a Highly Efficient Wood-Based Solar Interfacial Evaporator with Self-Desalting and Sterilization Performance

Solar interfacial evaporation based on wood-derived materials has been considered a promising strategy for desalination and wastewater purification. Herein, we adopted delignified wood (DW) as the water transport substrate and lignosulfonate (LS)-modified narrow-band gap semiconductor nickel disulfide (NiS₂) as the light-absorbing agent (LS-NiS₂) to fabricate a high-efficiency evaporator (LS-NiS₂@DW). On the one hand, the high absorbance (>95%) within a broad wavelength range and excellent photothermal conversion efficiency of LS-NiS₂ endow efficient solar energy utilization. On the other hand, the hydrophilicity of DW facilitates water activation, which results in a lower evaporation enthalpy of LS-NiS₂@DW (1274.4 kJ kg^-1) than that of pure water. By combining LS-NiS₂ and DW, LS-NiS₂@DW achieved an evaporation rate as high as 2.80 kg m^-2 h^-1 under one sun irradiation (1 kW m^-2), and the evaporation efficiency reached 87.4%. Notably, LS-NiS₂@DW exhibits a high evaporation rate (2.42-2.69 kg m^-2 h^-1) in simulated seawater for 24 h with no salt crystals formed on the surface. Moreover, LS-NiS₂@DW shows high antibacterial activity with about 90% reduction in bacterial survival rate. This work could provide new perspectives for the design of a high-efficiency wood-based photothermal evaporator.

In vivo targeting capacities of different nanoparticles to prostate tissues based on a mouse model of chronic bacterial prostatitis

Chronic bacterial prostatitis usually occurs in men and seriously affects the quality of life of patients. The efficacy of chronic bacterial prostatitis treatment is limited by the difficulty for free drugs (e.g., antibiotics) to penetrate the prostate epithelium and target inflammatory tissues. The advent of nanotechnology offers the possibility to address this issue, such as the development of targeted nanoparticle delivery strategies that may overcome these important limitations. The physicochemical properties of nanoparticles, such as particle size, shape and surface modification ligands, determine their targeting effectiveness. In this study, nanoparticles with different physicochemical properties were prepared to explore and confirm their targeting capacities to inflammatory prostate tissues of chronic bacterial prostatitis, focusing on the effects of size and different modification ligands on the targeting performance. In vivo and ex vivo imaging results verified that folic acid-modified nanoparticles with a particle size of 180–190 nm via tail intravenous injection had the optimal targeting efficiency to prostate tissues. Our results provide an experimental basis and reference value for targeted therapy of prostate-related diseases with nanotechnology in the future.

Limited Role of Rhamnolipids on Cadmium Resistance for an Endogenous-Secretion Bacterium

Rhamnolipids, a type of biosurfactant, represent a potential strategy for both enhancing organismic resistance and in situ remediation of heavy metals contaminations. In-depth study of the mechanism of rhamnolipids synthesis in response to heavy metals stress, is indispensable for a wide use of biosurfactant-secreting microbes in bioremediation. In this study, we employed the wild-type and the rhlAB deficient strain (ΔrhlAB) of Pseudomonas aeruginosa, a prototypal rhamnolipids-producing soil microorganism, to investigate its responses to cadmium resistance based on its physicochemical, and physiological properties. Compared with the wild-type strain, the ΔrhlAB were more sensitive to Cd-stress at low Cd concentration (<50 mg/L), whereas there was little difference in sensitivity at higher Cd concentrations, as shown by spot titers and cell viability assays. Secreted rhamnolipids reduced intracellular Cd²⁺ accumulation to alleviate Cd²⁺ stress, whereas endogenous rhamnolipids played a limited role in alleviating Cd²⁺ stress. Synthesized rhamnolipids exhibited a higher critical micelle concentration (CMC) (674.1 mg/L) and lower emulsification index (4.7%) under high Cd-stress, while these parameters showed no obvious changes. High Cd-stress resulted in high hydrophilic wild-type bacterial surface and lower bioremediation ability. This study could advance a deeper understanding of the mechanism of cadmium resistance and provide a theoretical foundation for the application of biosurfactant and biosurfactant-secreted bacterium in contaminant bioremediation.

Germanene-modified chitosan hydrogel for treating bacterial wound infection: An ingenious hydrogel-assisted photothermal therapy strategy

The elaborate design of an ingenious hydrogel-assisted photothermal therapy (PTT) platform is a promising strategy for treating bacterial wound infections. Herein, a new generation of germanene nanocrystals (Ge NCs) with excellent photothermal performance are prepared via an ice-bath sonication liquid-phase exfoliation technique. Whereafter, by crosslinking interaction between chitosan and zinc acetate, as well as self-assembly property between Ge NCs and chitosan, we successfully construct an innovative germanene-modified chitosan antimicrobial hydrogel (CS/Ge NCs^0.8) integrating capture and killing bacteria performances. When co-cultured with bacteria, CS/Ge NCs^0.8 hydrogel with the positive charge can adsorb and restrict bacteria in the range of PTT destruction. Once the near-infrared laser is introduced, CS/Ge NCs^0.8 hydrogel will effectively convert light energy into localized heat, further inducing bacterial death. By this entirely novel modality, CS/Ge NCs^0.8 hydrogel exhibits marvelous antibacterial property against E. coli and S. aureus in vitro. Furthermore, in vivo studies demonstrate that CS/Ge NCs^0.8 hydrogel possesses the ability to significantly rescue S. aureus-induced skin wound infections, suggesting CS/Ge NCs^0.8 hydrogel can be served as an antibacterial dressing. Strikingly, this is the first-ever report of CS/Ge NCs^0.8 hydrogel in the antibacterial field, which may spur a wave of developing Ge-based biomaterials to benefit biomedical applications.

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.

How to Treat Melanoma? The Current Status of Innovative Nanotechnological Strategies and the Role of Minimally Invasive Approaches like PTT and PDT

Melanoma is the most aggressive type of skin cancer, the incidence and mortality of which are increasing worldwide. Its extensive degree of heterogeneity has limited its response to existing therapies. For many years the therapeutic strategies were limited to surgery, radiotherapy, and chemotherapy. Fortunately, advances in knowledge have allowed the development of new therapeutic strategies. Despite the undoubted progress, alternative therapies are still under research. In this context, nanotechnology is also positioned as a strong and promising tool to develop nanosystems that act as drug carriers and/or light absorbents to potentially improve photothermal and photodynamic therapies outcomes. This review describes the latest advances in nanotechnology field in the treatment of melanoma from 2011 to 2022. The challenges in the translation of nanotechnology-based therapies to clinical applications are also discussed. To sum up, great progress has been made in the field of nanotechnology-based therapies, and our understanding in this field has greatly improved. Although few therapies based on nanoparticulate systems have advanced to clinical trials, it is expected that a large number will come into clinical use in the near future. With its high sensitivity, specificity, and multiplexed measurement capacity, it provides great opportunities to improve melanoma treatment, which will ultimately lead to enhanced patient survival rates.

Arsenic Prodrug-Mediated Tumor Microenvironment Modulation Platform for Synergetic Glioblastoma Therapy

Glioblastoma (GBM) has a distinct internal environment characterized by high levels of glutathione (GSH) and low oxygen partial pressure, which significantly restrict most drugs' effectiveness. Arsenic-based drugs are emerging candidates for treating solid tumors; however, relatively high doses in solo systems and inconsistent complementary systems severely damage the normal tissues. We proposed a novel covalently conjugated strategy for arsenic-based therapy via arsenic-boronic acid complex formation. The boronic acid was modified on silver (AgL) to capture As^V under an alkaline condition named arsenate plasmonic complex (APC) with a distinct Raman response. The APC can precisely release the captured As^V in lysosomal acidic pH that specifically targets TME to initiate a multimodal therapeutic effect such as GSH depletion and reactive oxygen species generation. In addition, GSH activation leads to subconverted As^V into As^III, which further facilitated glutathione peroxidase (GPx) and superoxide dismutase inhibition, whereas the tumor selective etching of the silver core triggered by endogenous H₂O₂ that can oxidize to generate highly toxic Ag ions produces and supplies O₂ to help the alleviated hypoxia. Both in vitro and in vivo data verify the APC-based chemotherapy paving the way for efficient nanomedicine-enabled boronate affinity-based arsenic chemotherapeutics for on demand site-specific cancer combination treatment of GBM tumors.

Adenosine triphosphate-activated prodrug system for on-demand bacterial inactivation and wound disinfection

The prodrug approach has emerged as a promising solution to combat bacterial resistance and enhance treatment efficacy against bacterial infections. Here, we report an adenosine triphosphate (ATP)-activated prodrug system for on-demand treatment of bacterial infection. The prodrug system benefits from the synergistic action of zeolitic imidazolate framework-8 and polyacrylamide hydrogel microsphere, which simultaneously transports indole-3-acetic acid and horseradish peroxidase in a single carrier while preventing the premature activation of indole-3-acetic acid. The ATP-responsive characteristic of zeolitic imidazolate framework-8 allows the prodrug system to be activated by the ATP secreted by bacteria to generate reactive oxygen species (ROS), displaying exceptional broad-spectrum antimicrobial ability. Upon disruption of the bacterial membrane by ROS, the leaked intracellular ATP from dead bacteria can accelerate the activation of the prodrug system to further enhance antibacterial efficiency. In vivo experiments in a mouse model demonstrates the applicability of the prodrug system for wound disinfection with minimal side effects.

Prodrugs are increasingly promising in tackling bacterial resistance and efficacy of treatment. Here, the authors encapsulated horseradish peroxidase and zeolitic imidazolate framework-8 loaded with indole-3-acetic acid in polyacrylamide hydrogel microspheres for ATP-activated wound disinfection.

A dynamic nano-coordination protein hydrogel for photothermal treatment and repair of infected skin injury

In this work, a dynamic photothermal hydrogel based on copper disulfide nanoparticles and thiolated gelatin was reported. The resultant hydrogel enabled rapid photothermal sterilization and the sterilization rate could reach 99.9% after 10 minutes of near-infrared irradiation. In addition, the hydrogel exhibited typical dynamic properties with self-recovery, injectability and photothermal conversion ability, showing great potential as a highly adaptable and antibacterial wound dressing for infected tissue injuries.

Liquid exfoliation of V8C7 nanodots as peroxidase-like nanozymes for photothermal-catalytic synergistic antibacterial treatment

Nanozymes are effective antibiotics that use reactive oxygen species (ROS) produced by Fenton/Fenton-like reactions to kill bacteria. However, its activity is still not satisfactory and requires large amounts of hydrogen peroxide (H₂O₂) with side effects on normal tissues. Herein, ultrasmall V₈C₇ nanodots (NDs) are successfully constructed by the liquid-phase exfoliation method for photothermal-catalytic synergistic antibacterial treatment. The prepared V₈C₇ NDs are horseradish peroxidase (HRP)-like nanozymes that can efficiently catalyze H₂O₂ to produce a large amount of ROS. Unlike traditional HRP-like nanozymes, V₈C₇ NDs can have a good catalytic effect under slightly acidic conditions (pH=5.5). Moreover, V₈C₇ NDs have good near-infrared (NIR) absorption and high photothermal conversion efficiency (PTCE, 50.39%), which can be used for photothermal treatment (PTT) of bacteria. In addition, the mild photothermal effect can further enhance the HRP-like catalytic activity of V₈C₇ NDs, thereby further enhancing the antibacterial performance of V₈C₇ NDs. In vitro results show that V₈C₇ NDs can effectively eradicate Escherichia coli (E. coli, gram-negative) and methicillin-resistant Staphylococcus aureus (MRSA, gram-positive) under laser irradiation and the presence of H₂O₂, possessing spectral antibacterial properties. More importantly, V₈C₇ NDs display satisfactory therapeutic effects on wounds infected by MRSA in vivo, and their toxicity is negligible, suggesting that they may have great potential for application as powerful and safe antibacterial agents. This work presents a practical antibacterial strategy by combining PTT and catalytic therapy to achieve efficient treatment of bacteria-infected wounds. STATEMENT OF SIGNIFICANCE: (1) Ultrasmall V₈C₇ NDs were prepared by the liquid-phase exfoliation method. (2) V₈C₇ NDs showed good photothermal, catalytic properties. (3) V₈C₇ NDs achieved satisfactory photothermal-catalytic synergistic antibacterial treatment.