Functionalized Nano-MoS2 with Peroxidase Catalytic and Near-Infrared Photothermal Activities for Safe and Synergetic Wound Antibacterial Applications

A Shape-Restorable hierarchical polymer membrane composite system for enhanced antibacterial and antiadhesive efficiency

Intelligent shape memory polymer can be potentially used in manufacturing implantable devices that enables a benign variation of implant dimensions with the external stimuli, thus effectively lowering insertion forces and evading associated risks. However, in surgical implantation, biomaterials-associated infection has imposed a huge burden to healthcare system that urgently requires an efficacious replacement of antibiotic usages. Preventing the initial attachment and harvesting a biocidal function upon native surfaces may be deemed as a preferable strategy to tackle the issues of bacterial infection. Herein, a functionalized polylactic acid (PLA) composite membrane assembled with graphene (GE, a widely used photothermal agent) was fabricated through a blending process and then polydimethylsiloxane utilized as binders to pack hydrophobic SiO2 tightly onto polymer surface (denoted as PLA-GE/SiO2). Such an active platform exhibited a moderate shape-memory performance upon near-infrared (NIR) light stimulation, which was feasible for programmed deformation and shape recovery. Particularly stirring was that PLA-GE/SiO2 exerted a pronounced bacteria-killing effect under NIR illumination, 99.9 % of E. coli and 99.8 % of S. aureus were effectively eradicated in a lean period of 5 min. Furthermore, the obtained composite membrane manifested excellent antiadhesive properties, resulting in a bacteria-repelling efficacy of up to 99 % for both E. coli and S. aureus species. These findings demonstrated the potential value of PLA-GE/SiO2 as a shape-restorable platform in "kill&repel" integration strategy, further expanding its applications for clinical anti-infective treatment.

Stimuli-Responsive NO Delivery Platforms for Bacterial Infection Treatment

The prevalence of drug-resistant bacterial infections has emerged as a grave threat to clinical treatment and global human health, presenting one of the foremost challenges in medical care. Thus, there is an urgent imperative to develop safe and efficacious novel antimicrobial strategies. Nitric oxide (NO) is a recognized endogenous signaling molecule, which plays a pivotal role in numerous pathological processes. Currently, NO has garnered significant interest as an antibacterial agent due to its capability to eradicate bacteria, disrupt biofilms, and facilitate wound healing, all while circumventing the emergence of drug resistance. However, the inherently unstable characteristic of NO therapeutic gas renders the controlled administration of NO gases exceedingly challenging. Hence, in this review, the current challenge of bacterial infection is discussed; then it is briefly elucidated the antibacterial mechanism of NO and comprehensively delineate the recent advancements in stimulus-responsive NO delivery platforms, along with their merits, obstacles, and prospective avenues for clinical application. This review offers guidance for future advancements in NO-medicated anti-infection therapy is hoped.

Targeted mitochondrial nanomaterials in biomedicine: Advances in therapeutic strategies and imaging modalities

Mitochondria, pivotal organelles crucial for energy generation, apoptosis regulation, and cellular metabolism, have spurred remarkable advancements in targeted material development. This review surveys recent breakthroughs in targeted mitochondrial nanomaterials, illuminating their potential in drug delivery, disease management, and biomedical imaging. This review approaches from various application perspectives, introducing the specific applications of mitochondria-targeted materials in cancer treatment, probes and imaging, and diseases treated with mitochondria as a therapeutic target. Addressing extant challenges and elucidating potential therapeutic mechanisms, it also outlines future development trajectories and obstacles. By comprehensively exploring the diverse applications of targeted mitochondrial nanomaterials, this review aims to catalyze innovative treatment modalities and diagnostic approaches in medical research. STATEMENT OF SIGNIFICANCE: This review presents the latest advancements in mitochondria-targeted nanomaterials for biomedical applications, covering diverse fields such as cancer therapy, bioprobes, imaging, and the treatment of various systemic diseases. The novelty and significance of this work lie in its systematic analysis of the intricate relationship between mitochondria and different diseases, as well as the ingenious design strategies employed to harness the therapeutic potential of nanomaterials. By providing crucial insights into the development of mitochondria-targeted nanomaterials and their applications, this review offers a valuable resource for researchers working on innovative treatment modalities and diagnostic approaches. The scientific impact and interest to the readership lie in the identification of promising avenues for future research and the potential for clinical translation of these cutting-edge technologies.

LSPR-enhanced photoresponsive antibacterial efficiency of Bi/MoS2-loaded fibrin gel for management of diabetic wounds

Chronic diabetic wounds present formidable challenges, marked by uncontrolled bacterial infections, prolonged inflammation, and impaired angiogenesis. The evolving landscape of photo-responsive antibacterial therapy holds great promise in addressing these multifaceted issues, with a particular focus on leveraging the distinctive properties of 2D heterojunction materials. In this investigation, we engineered composite sprayed hydrogels, seamlessly integrating Bi/MoS2 nano-heterojunctions. Capitalizing on the synergistic interplay between photocatalytic antibacterial and photothermal antibacterial mechanisms, the Bi/MoS2 heterojunction, guided by its localized surface plasmon resonance, demonstrated outstanding antibacterial efficacy within a mere 10-minute exposure to 808 nm near-infrared light. This accelerated sterilization both in vitro and in vivo, consequently expediting wound healing. The sprayed composite gel not only furnishes protective shielding for skin tissues but also fosters endothelial cell proliferation, vascularization, and angiogenesis. This safe and ultrafast sterilizing hydrogel presents immense potential for application in antimicrobial dressings, thereby offering a promising avenue for diabetic wound healing.

Metastable FeSe2 nanosheets as a one-for-all platform for stepwise synergistic tumor therapy

The urgent need to curb the rampant rise in cancer has impelled the rapid development of nanomedicine. Under the above issue, transition metal compounds have received special attention considering their physicochemical and biochemical properties. However, how to take full advantage of the valuable characteristics of nanomaterials based on their spatial structures and chemical components for synergistic tumor therapy is a worthwhile exploration. In this work, a tailored two-dimensional (2D) FeSe2 nanosheet (NS) platform is proposed, which integrates enzyme activity and drug efficacy through the regulation of itsstability. Specifically, metastable FeSe2 NSs can serve as dual nanozymes in an intact state, depleting GSH and increasing ROS to induce oxidative stress in the tumor microenvironment (TME). With the gradual degradation of the FeSe2 in TME, its degraded products can amplify the Fenton reaction and GSH consumption, enhance the expression of inflammatory factors, and achieve effective near-infrared (NIR)-light irradiation-enhanced synergistic photothermal therapy (PTT) and chemodynamic therapy (CDT). Our exploration further confirmed such a strategy that may integrate carrier activity and drug action into a metastable nanoplatform for tumor synergistic therapy. These results prompt the consideration of the rational design of a one-for-all carrier that can exhibit multifunctional properties and nanomedicine efficacy for versatile therapeutic applications in the future.

Microenvironment-triggered cascade metal-polyphenolic nanozyme for ROS/NO synergistic hyperglycemic wound healing

Wound infection of hyperglycemic patient often has extended healing period and increased probability due to the high glucose level. However, achieving precise and safe therapy of the hyperglycemic wound with specific wound microenvironment (WME) remains a major challenge. Herein, a WME-activated smart L-Arg/GOx@TA-Fe (LGTF) nanozymatic system composed of generally recognized as safe (GRAS) compound is engineered. The nanozymatic system combining metal-polyphenol nanozyme (tannic acid-Fe3+, TA-Fe) and natural enzyme (glucose oxidase, GOx) can consume the high-concentration glucose, generating reactive oxygen species (ROS) and nitric oxide (NO) in situ to synergistically disinfect hyperglycemia wound. In addition, glucose consumption and gluconic acid generation can lower glucose level to promote wound healing and reduce the pH of WME to enhance the catalytic activities of the LGTF nanozymatic system. Thereby, low-dose LGTF can perform remarkable synergistic disinfection and healing effect towards hyperglycemic wound. The superior biosafety, high catalytic antibacterial and beneficial WME regulating capacity demonstrate this benign GRAS nanozymatic system is a promising therapeutic agent for hyperglycemic wound.

Molybdenum Disulfide-Supported Cuprous Oxide Nanocomposite for Near-Infrared-I Light-Responsive Synergistic Antibacterial Therapy

Drug-resistant bacterial infections pose a serious threat to human health; thus, there is an increasingly growing demand for nonantibiotic strategies to overcome drug resistance in bacterial infections. Mild photothermal therapy (PTT), as an attractive antibacterial strategy, shows great potential application due to its good biocompatibility and ability to circumvent drug resistance. However, its efficiency is limited by the heat resistance of bacteria. Herein, Cu2O@MoS2, a nanocomposite, was constructed by the in situ growth of Cu2O nanoparticles (NPs) on the surface of MoS2 nanosheets, which provided a controllable photothermal therapeutic effect of MoS2 and the intrinsic catalytic properties of Cu2O NPs, achieving a synergistic effect to eradicate multidrug-resistant bacteria. Transcriptome sequencing (RNA-seq) results revealed that the antibacterial process was related to disrupting the membrane transport system, phosphorelay signal transduction system, oxidative stress response system, as well as the heat response system. Animal experiments indicated that Cu2O@MoS2 could effectively treat wounds infected with methicillin-resistant Staphylococcus aureus. In addition, satisfactory biocompatibility made Cu2O@MoS2 a promising antibacterial agent. Overall, our results highlight the Cu2O@MoS2 nanocomposite as a promising solution to combating resistant bacteria without inducing the evolution of antimicrobial resistance.

Zinc-Based ROS Amplifiers Trigger Cancer Chemodynamic/Ion Interference Therapy Through Self-Cascade Catalysis

Nanozyme-mediated chemodynamic therapy has emerged as a promising strategy due to its tumor specificity and controlled catalytic activity. However, the poor efficacy caused by low hydrogen peroxide (H2O2) levels in the tumor microenvironment (TME) poses challenges. Herein, an H2O2 self-supplying nanozyme is constructed through loading peroxide-like active platinum nanoparticles (Pt NPs) on zinc peroxide (ZnO2) (denoted as ZnO2@Pt). ZnO2 releases H2O2 in response to the acidic TME. Pt NPs catalyze the hydroxyl radical generation from H2O2 while reducing the mitigation of oxidative stress by glutathione, serving as a reactive oxygen (ROS) amplifier through self-cascade catalysis. In addition, Zn2+ released from ZnO2 interferes with tumor cell energy supply and metabolism, enabling ion interference therapy to synergize with chemodynamic therapy. In vitro studies demonstrate that ZnO2@Pt induces cellular oxidative stress injury through enhanced ROS generation and Zn2+ release, downregulating ATP and NAD+ levels. In vivo assessment of anticancer effects showed that ZnO2@Pt could generate ROS at tumor sites to induce apoptosis and downregulate energy supply pathways associated with glycolysis, resulting in an 89.7% reduction in tumor cell growth. This study presents a TME-responsive nanozyme capable of H2O2 self-supply and ion interference therapy, providing a paradigm for tumor-specific nanozyme design.

Recent advances in reactive oxygen species scavenging nanomaterials for wound healing

Reactive oxygen species play a crucial role in cell signaling pathways during wound healing phases. Treatment strategies to balance the redox level in the deep wound tissue are emerging for wound management. In recent years, reactive oxygen species scavenging agents including natural antioxidants, reactive oxygen species (ROS) scavenging nanozymes, and antioxidant delivery systems have been widely employed to inhibit oxidative stress and promote skin regeneration. Here, the importance of reactive oxygen species in different wound healing phases is critically analyzed. Various cutting-edge bioactive ROS nanoscavengers and antioxidant delivery platforms are discussed. This review also highlights the future directions for wound therapies via reactive oxygen species scavenging. This comprehensive review offers a map of the research on ROS scavengers with redox balancing mechanisms of action in the wound healing process, which benefits development and clinical applications of next-generation ROS scavenging-based nanomaterials in skin regeneration.

Preparation of SnS2/MoS2with p-n heterojunction for NO2sensing

Conventional metal sulfide (SnS2) gas-sensitive sensing materials still have insufficient surface area and slow response/recovery times. To increase its gas-sensing performance, MoS2nanoflower was produced hydrothermally and mechanically combined with SnS2nanoplate. Extensive characterization results show that MoS2was effectively integrated into SnS2. Four different concentrations of SnS2-MoS2composites were evaluated for their NO2gas sensitization capabilities. Among them, SnS2-15% MoS2at 170 °C demonstrated the greatest response values to NO2, 7.3 for 1 ppm NO2, which is about three times greater than the SnS2sensor at 170 °C (2.58). The creation of pn junctions following compositing with SnS2was determined to be the primary reason for the composite's faster recovery time, while the heterojunction allowed for the rapid separation of hole-electron pairs. Because the MoS2surface has multiple vacancy defects, the adsorption energy of these vacancies is significantly higher than that of other places, resulting in increased NO2adsorption. Furthermore, MoS2can serve as active adsorption sites for SnS2micrometer sheets during gas sensing. This study may help to build new NO2gas sensors.

Phytic Acid-Promoted Deposition of Gold Nanoparticles with Grafted Cationic Polymer Brushes for the Construction of Synergistic Contact-Killing and Photothermal Bactericidal Coatings

Medical implants are constantly facing the risk of bacterial infections, especially infections caused by multidrug resistant bacteria. To mitigate this problem, gold nanoparticles with alkyl bromide moieties (Au NPs-Br) on the surfaces were prepared. Xenon light irradiation triggered the plasmon effect of Au NPs-Br to induce free radical graft polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA), leading to the formation of poly(DMAEMA) brush-grafted Au NPs (Au NPs-g-PDM). The Au NPs-g-PDM nanocomposites were conjugated with phytic acid (PA) via electrostatic interaction and van der Waals interaction. The as-formed aggregates were deposited on the titanium (Ti) substrates to form the PA/Au NPs-g-PDM (PAP) hybrid coatings through surface adherence of PA and the gravitational effect. Synergistic bactericidal effects of contact-killing caused by the cationic PDM brushes, and local heating generated by the Au NPs under near-infrared irradiation, conferred strong antibacterial effects on the PAP-deposited Ti (Ti-PAP) substrates. The synergistic bactericidal effects reduced the threshold temperature required for the photothermal sterilization, which in turn minimized the secondary damage to the implant site. The Ti-PAP substrates exhibited 97.34% and 99.97% antibacterial and antiadhesive efficacy, respectively, against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), compared to the control under in vitro antimicrobial assays. Furthermore, the as-constructed Ti-PAP surface exhibited a 99.42% reduction in the inoculated S. aureus under in vivo assays. In addition, the PAP coatings exhibited good biocompatibility in the hemolysis and cytotoxicity assays as well as in the subcutaneous implantation of rats.

Enhanced Chemoradiotherapy for MRSA-Infected Osteomyelitis Using Immunomodulatory Polymer-Reinforced Nanotherapeutics

The eradication of osteomyelitis caused by methicillin-resistant Staphylococcus aureus (MRSA) poses a significant challenge due to its development of biofilm-induced antibiotic resistance and impaired innate immunity, which often leads to frequent surgical failure. Here, the design, synthesis, and performance of X-ray-activated polymer-reinforced nanotherapeutics that modulate the immunological properties of infectious microenvironments to enhance chemoradiotherapy against multidrug-resistant bacterial deep-tissue infections are reported. Upon X-ray radiation, the proposed polymer-reinforced nanotherapeutic generates reactive oxygen species and reactive nitrogen species. To robustly eradicate MRSA biofilms at deep infection sites, these species can specifically bind to MRSA and penetrate biofilms for enhanced chemoradiotherapy treatment. X-ray-activated nanotherapeutics modulate the innate immunity of macrophages to prevent the recurrence of osteomyelitis. The remarkable anti-infection effects of these nanotherapeutics are validated using a rat osteomyelitis model. This study demonstrates the significant potential of a synergistic chemoradiotherapy and immunotherapy method for treating MRSA biofilm-infected osteomyelitis.

Chondroitin sulphate modified MoS2 nanoenzyme with multifunctional activities for treatment of Alzheimer's disease

Nano-MoS2 exhibit oxidoreductase-like activities, and has been shown to effectively eliminate excessive intracellular ROS and inhibit Aβ aggregation, thus demonstrating promising potential for anti-Alzheimer's disease (anti-AD) intervention. However, the low water dispersibility and high toxicity of nano-MoS2 limits its further application. In this study, we developed a chondroitin sulphate (CS)-modified MoS2 nanoenzyme (CS@MoS2) by harnessing the excellent biocompatibility of CS and the exceptional activities of nano-MoS2 to explore its potential in anti-AD research. Promisingly, CS@MoS2 significantly inhibited Aβ1-40 aggregation and prevented toxic injury in SH-SY5Y cells caused by Aβ1-40. In addition, CS@MoS2 protected these cells from oxidative stress damage by regulating ROS production, as well as promoting the activities of SOD and GSH-Px. CS@MoS2 also modulated the intracellular Ca2+ imbalance and downregulated Tau hyperphosphorylation by activating GSK-3β. CS@MoS2 suppressed p-NF-κB (p65) translocation to the nucleus by inhibiting MAPK phosphorylation, and modulated the expression of downstream anti- and proinflammatory cytokines. Owing to its multifunctional activities, CS@MoS2 effectively improved spatial learning, memory, and anxiety in D-gal/AlCl3-induced AD mice. Taken together, these results indicate that CS@MoS2 has significant potential for improving the therapeutic efficacy of the prevention and treatment of AD, while also presenting a novel framework for the application of nanoenzymes.

Study on synergistic mechanism of molybdenum disulfide/sodium carboxymethyl cellulose composite nanofiber mats for photothermal/photodynamic antibacterial treatment

Innovative antibacterial therapies using nanomaterials, such as photothermal (PTT) and photodynamic (PDT) treatments, have been developed for treating wound infections. However, creating secure wound dressings with these therapies faces challenges. The primary focus of this study is to prepare an antibacterial nanofiber dressing that effectively incorporates stable loads of functional nanoparticles and demonstrates an efficient synergistic effect between PTT and PDT. Herein, a composite nanofiber mat was fabricated, integrating spherical molybdenum disulfide (MoS2) nanoparticles. MoS2 was deposited onto polylactic acid (PLA) nanofiber mats using vacuum filtration, which was further stabilized by sodium carboxymethyl cellulose (CMC) adhesion and glutaraldehyde (GA) cross-linking. The composite nanofibers demonstrated synergistic antibacterial effects under NIR light irradiation, and the underlying mechanism was explored. They induce bacterial membrane permeability, protein leakage, and intracellular reactive oxygen species (ROS) elevation, ultimately leading to >95 % antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), which is higher than that of single thermotherapy (almost no antibacterial activity) or ROS therapy (about 80 %). In addition, the composite nanofiber mats exhibited promotion effects on infected wound healing in vivo. This study demonstrates the great prospects of composite nanofiber dressings in clinical treatment of bacterial-infected wounds.

Acetylcholine triggered enzymatic cascade reaction based on Fe7S8 nanoflakes catalysis for organophosphorus pesticides visual detection

BACKGROUND

Organophosphorus pesticides (OPs) play important roles in the natural environment, agricultural fields, and biological prevention. The development of OPs detection has gradually become an effective strategy to avoid the dangers of pesticides abuse and solve the severe environmental and health problems in humans. Although conventional assays for OPs analysis such as the bulky instrument required analytical methods have been well-developed, it still remains the limitation of inconvenient, inefficient and lab-dependence analysis in real samples. Hence, there is an urgent demand to develop efficient detection methods for OPs analysis in real scenarios.

RESULTS

Here, by virtue of the highly efficient catalytic performance in Fe7S8 nanoflakes (Fe7S8 NFs), we propose an OPs detection method that rationally integrated Fe7S8 NFs into the acetylcholine (ACh) triggered enzymatic cascade reaction (ATECR) for proceeding better detection performances. In this method, OPs serve as the enzyme inhibitors for inhibiting ATECR among ACh, acetylcholinesterase (AChE), and choline oxidase (CHO), then reduce the generation of H2O2 to suppress the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) that catalyzed by Fe7S8 NFs. Benefiting from the integration of Fe7S8 NFs and ATECR, it enables a sensitive detection for OPs (e.g. dimethoate). The proposed method has presented good linear ranges of OPs detection ranging from 0.1 to 10 μg mL-1. Compared to the other methods, the comparable limits of detection (LOD) of OPs are as low as 0.05 μg mL-1.

SIGNIFICANCE

Furthermore, the proposed method has also achieved a favorable visual detection performance of revealing OPs analysis in real samples. The visual signals of OPs can be transformed into RGB values and gathered by using smartphones, indicating the great potential in simple, sensitive, instrument-free and on-site analysis of pesticide residues in environmental monitoring and biosecurity research.

Exudate-Induced Gelatinizable Nanofiber Membrane with High Exudate Absorption and Super Bactericidal Capacity for Bacteria-Infected Wound Management

Invasion of bacteria and continuous oozing of exudate are significant causes of interference with the healing of infected wounds. Therefore, an exudate-induced gelatinizable and near-infrared (NIR)-responsive nanofiber membrane composed of polyvinyl alcohol (PVA), carboxymethyl chitosan (CMC), and Fe-doped phosphomolybdic acid (Fe-PMA) with exceptional exudate absorption capacity and potent bactericidal efficacy is developed and denoted as the PVA-FP-CMC membrane. After absorbing exudate, the fiber membrane can transform into a hydrogel membrane, forming coordination bonds between the Fe-PMA and CMC. The unique exudate-induced gelation process imparts the membrane with high exudate absorption and retention capability, and the formed hydrogel also traps the bacteria that thrive in the exudate. Moreover, it is discovered for the first time that the Fe-PMA exhibits an enhanced photothermal conversion capability and photocatalytic activity compared to the PMA. Therefore, the presence of Fe-PMA provides the membrane with a photothermal and photodynamic therapeutic effect for killing bacteria. The PVA-FP-CMC membrane is proven with a liquid absorption ratio of 520.7%, a light-heat conversion efficiency of 41.9%, high-level generation of hydroxyl radical (•OH) and singlet oxygen (1O2), and a bacterial killing ratio of 100% for S. aureus and 99.6% for E. coli. The treatment of infected wounds on the backs of rats further confirms the promotion of wound healing by the PVA-FP-CMC membrane with NIR irradiation. Overall, this novel functional dressing for the synergistic management of bacteria-infected wounds presents a promising therapeutic strategy for tissue repair and regeneration.

Metal-Phenolic Nanocapsules with Photothermal Antibacterial and Ros Scavenging Ability for Diabetic Wound Healing

The presence of bacteria in diabetic wounds not only leads to the formation of biofilms but also triggers oxidative stress and inflammatory responses, which hinder the wound-healing process. Therefore, it is imperative to formulate a comprehensive strategy that can proficiently eliminate bacteria and enhance the wound microenvironment. Herein, this work develops multifunctional metal-phenolic nanozymes (TA-Fe/Cu nanocapsules), wherein the one-pot coordination of tannic acid (TA)and Fe3+/Cu2+ using a self-sacrificial template afforded hollow nanoparticles (NPs) with exceptional photothermal and reactive oxygen species scavenging capabilities. After photothermal disruption of the biofilms, TA-Fe/Cu NPs autonomously capture bacteria through hydrogen bonding interactions with peptidoglycans (the bacterial cell wall component), ultimately bolstering the bactericidal efficacy. Furthermore, these NPs exhibit peroxidase-like enzymatic activity, efficiently eliminating surplus hydrogen peroxide in the vicinity of the wound and mitigating inflammatory responses. As the wound transitions into the remodeling phase, the presence of Cu2+ stimulates vascular migration and regeneration, expediting the wound-healing process. This study innovatively devises a minimalist approach to synthesize multifunctional metal-phenolic nanozymes integrating potent photothermal antibacterial activity, bacterial capture, anti-inflammatory, and angiogenesis properties, showcasing their great potential for diabetic wound treatment.

Cuprorivaite/hardystonite/alginate composite hydrogel with thermionic effect for the treatment of peri-implant lesion

Peri-implant lesion is a grave condition afflicting numerous indi-viduals with dental implants. It results from persistent periodontal bacteria accumulation causing inflammation around the implant site, which can primarily lead to implant loosening and ultimately the implant loss. Early-stage peri-implant lesions exhibit symptoms akin to gum disease, including swelling, redness and bleeding of the gums surrounding the implant. These signs indicate infection and inflammation of the peri-implant tissues, which may result in bone loss and implant failure. To address this problem, a thermionic strategy was applied by designing a cuprorivaite-hardystonite bioceramic/alginate composite hydrogel with photothermal and Cu/Zn/Si multiple ions releasing property. This innovative approach creates a thermionic effect by the release of bioactive ions (Cu2+ and Zn2+ and SiO 3 2 - ) from the composite hydrogel and the mild heat environment though the photothermal effect of the composite hydrogel induced by near-infrared light irradiation. The most distinctive advantage of this thermionic effect is to substantially eliminate periodontal pathogenic bacteria and inhibit inflammation, while simultaneously enhance peri-implant osseointegration. This unique attribute renders the use of this composite hydrogel highly effective in significantly improving the survival rate of implants after intervention in peri-implant lesions, which is a clinical challenge in periodontics. This study reveals application potential of a new biomaterial-based approach for peri-implant lesion, as it not only eliminates the infection and inflammation, but also enhances the osteointegration of the dental implant, which provides theoretical insights and practical guidance to prevent and manage early-stage peri-implant lesion using bioactive functional materials.

A magnetic nanozyme platform for bacterial colorimetric detection and chemodynamic/photothermal synergistic antibacterial therapy

Rapid, convenient, and sensitive detection of bacteria and development of novel antibacterial materials are conducive to accurate treatment of bacterial infection and reducing the generation of drug-resistant bacteria caused by overuse of antibiotics. A dual-function magnetic nanozyme, Fc-MBL@rGO@Fe3O4, has been constructed with broad-spectrum bacterial affinity and good peroxidase-like activity. Detection signal amplification was realized in the presence of 3,3',5,5'-tetramethylbenzidine (TMB) with a detection limit of 26 CFU/mL. In addition, the excellent photothermal properties of Fc-MBL@rGO@Fe3O4 could realize synergistic chemodynamic/photothermal antibacterial therapy. Furthermore, the good bacterial affinity of Fc-MBL@rGO@Fe3O4 enhances the accurate and rapid attack of hydroxyl radical (·OH) on the bacterial membrane and achieves efficient sterilization (100%) at low concentration (40 µg/mL) and mild temperature (47℃). Notably, Fc-MBL@rGO@Fe3O4 has a broad spectrum of antibacterial activity against Gram-negative, Gram-positive, and drug-resistant bacteria. The magnetic nanoplatform integrating detection-sterilization not only meets the need for highly sensitive and accurate detection in different scenarios, but can realize low power density NIR-II light-responsive chemodynamic/photothermal antibacterial therapy, which has broad application prospects.

Current Advances on the Single-Atom Nanozyme and Its Bioapplications

Nanozymes, a class of nanomaterials mimicking the function of enzymes, have aroused much attention as the candidate in diverse fields with the arbitrarily tunable features owing to the diversity of crystalline nanostructures, composition, and surface configurations. However, the uncertainty of their active sites and the lower intrinsic deficiencies of nanomaterial-initiated catalysis compared with the natural enzymes promote the pursuing of alternatives by imitating the biological active centers. Single-atom nanozymes (SAzymes) maximize the atom utilization with the well-defined structure, providing an important bridge to investigate mechanism and the relationship between structure and catalytic activity. They have risen as the new burgeoning alternative to the natural enzyme from in vitro bioanalytical tool to in vivo therapy owing to the flexible atomic engineering structure. Here, focus is mainly on the three parts. First, a detailed overview of single-atom catalyst synthesis strategies including bottom-up and top-down approaches is given. Then, according to the structural feature of single-atom nanocatalysts, the influence factors such as central metal atom, coordination number, heteroatom doping, and the metal-support interaction are discussed and the representative biological applications (including antibacterial/antiviral performance, cancer therapy, and biosensing) are highlighted. In the end, the future perspective and challenge facing are demonstrated.

Natural Extracts for Antibacterial Applications

Bacteria-induced epidemics and infectious diseases are seriously threatening the health of people around the world. In addition, antibiotic therapy has been inducing increasingly more serious bacterial resistance, which makes it urgent to develop new treatment strategies to combat bacteria, including multidrug-resistant bacteria. Natural extracts displaying antibacterial activity and good biocompatibility have attracted much attention due to greater concerns about the safety of synthetic chemicals and emerging drug resistance. These antibacterial components can be isolated and utilized as antimicrobials, as well as transformed, combined, or wrapped with other substances by using modern assistive technologies to fight bacteria synergistically. This review summarizes recent advances in natural extracts from three kinds of sources-plants, animals, and microorganisms-for antibacterial applications. This work discusses the corresponding antibacterial mechanisms and the future development of natural extracts in antibacterial fields.

An integrated electrochemical immunosensor based on Pd-Ir cubic nanozyme and Ketjen black for ultrasensitive detection of circulating tumor cells

Ultrasensitive detection of circulating tumor cells (CTCs) holds significant clinical importance in monitoring metastasis and therapeutic outcomes. In this study, we have developed a novel electrochemical sensing model based on nanomaterials for highly sensitive and specific determination of CTCs. A gold electrode co-modified with Ketjin black (KB) and Au nanoparticles (AuNPs) exhibits exceptional conductivity. By conjugating palladium-iridium cubic nanozyme (Pd-Ir CNE) with antibodies, we have created a detection probe capable of catalyzing hydrogen peroxide (H2O2), thereby amplifying the output signal and resulting in significantly enhanced current on the electrode for detecting CTCs. The constructed immunosensor has achieved a detection limit of 2 cell mL-1 for model MCF-7 cells. Furthermore, the as-constructed electrochemical immunosensor can accurately detect whole blood-spiked target CTCs, showing great promise for clinical applications in early cancer diagnosis and prognosis.

Nanozyme-based inulin@nanogold for adhesive and antibacterial agent with enhanced biosafety

Nanozymes with oxidase or peroxidase-mimicking activity have emerged as a promising alternative for disinfecting resistant pathogens. However, further research and clinical applications of nanozymes are hampered by their low in vivo biosafety and biocompatibility. In this study, inulin-confined gold nanoparticles (IN@AuNP) are synthesized as an antibacterial agent via a straightforward in situ reduction of Au3+ ions by the hydroxyl groups in inulin. The IN@AuNP exhibits both peroxidase-mimicking and oxidase-mimicking catalytic activities, of which the maximum reaction velocity (Vmax) for H2O2 is 2.66 times higher than that of horseradish peroxidase. IN@AuNP can catalyze the production of reactive oxygen species (ROS), resulting in effective antibacterial behavior against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Abundant hydroxyl groups retained in inulin endow the nanozyme with high adhesion to bacteria, reducing the distance between the captured bacteria and ROS, achieving an antibacterial ratio of 100 % within 1 h. Importantly, due to the natural biosafety and non-absorption of the dietary fiber inulin, as well as the inability of inulin-trapped AuNP to diffuse, the IN@AuNP exhibits high biosafety and biocompatibility under physiological conditions. This work is expected to open a new avenue for nanozymes with great clinical application value.

Two-dimensional ternary chalcogenide nanodots with spatially controlled catalytic activity for bacteria infected wound treatment

Nanozymes hold great prospects for bacteria-infected wound management, yet the spatial control of their catalytic activity in infected area and normal tissues remains mired by the heterogeneity of tissue microenvironment. Here, we develop a novel two-dimensional ternary chalcogenide nanodots (Cu2MoS4, CMS NDs) with renal clearable ability and controlled catalytic activity for bacteria-infected wound treatment. The two-dimensional CMS NDs (∼4 nm) are prepared by a simple microwave-assisted chemical synthetic route. Our results show that CMS NDs not only have peroxidase-like activity in a pH-dependent manner (pH < 5.5). Based on the generation of hydroxyl radical (OH) by adding H2O2, CMS NDs show > 2 log bacterial inactivation for both Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative Escherichia coli (E. coli) under the acidic condition. Moreover, CMS NDs show good biocompatibility and can be excreted by the kidney in mice. In vivo results display that CMS NDs show good therapeutic effect against bacteria infected wound in the presence of H2O2, but no damage for normal tissues. Taken together, this work provides a renal clearable two-dimensional nanozyme with spatially controlled catalytic activity for the treatment of wounds and bacterial infections on the skin surface.

Research progress of metal-organic framework nanozymes in bacterial sensing, detection, and treatment

The high efficiency and specificity of enzymes make them play an important role in life activities, but the high cost, low stability and high sensitivity of natural enzymes severely restrict their application. In recent years, nanozymes have become convincing alternatives to natural enzymes, finding utility across diverse domains, including biosensing, antibacterial interventions, cancer treatment, and environmental preservation. Nanozymes are characterized by their remarkable attributes, encompassing high stability, cost-effectiveness and robust catalytic activity. Within the contemporary scientific landscape, metal-organic frameworks (MOFs) have garnered considerable attention, primarily due to their versatile applications, spanning catalysis. Notably, MOFs serve as scaffolds for the development of nanozymes, particularly in the context of bacterial detection and treatment. This paper presents a comprehensive review of recent literature pertaining to MOFs and their pivotal role in bacterial detection and treatment. We explored the limitations and prospects for the development of MOF-based nanozymes as a platform for bacterial detection and therapy, and anticipate their great potential and broader clinical applications in addressing medical challenges.

Photoacid Generators for Biomedical Applications

Photoacid generators (PAGs) are compounds capable of producing hydrogen protons (H+ ) upon irradiation, including irreversible and reversible PAGs, which have been widely studied in photoinduced polymerization and degradation for a long time. In recent years, the applications of PAGs in the biomedical field have attracted more attention due to their promising clinical value. So, an increasing number of novel PAGs have been reported. In this review, the recent progresses of PAGs for biomedical applications is systematically summarized, including tumor treatment, antibacterial treatment, regulation of protein folding and unfolding, control of drug release and so on. Furthermore, a concept of water-dependent reversible photoacid (W-RPA) and its antitumor effect are highlighted. Eventually, the challenges of PAGs for clinical applications are discussed.

Unveiling the antibacterial strategies and mechanisms of MoS2: a comprehensive analysis and future directions

Antibiotic resistance is a growing problem that requires alternative antibacterial agents. MoS2, a two-dimensional transition metal sulfide, has gained significant attention in recent years due to its exceptional photocatalytic performance, excellent infrared photothermal effect, and impressive antibacterial properties. This review presents a detailed analysis of the antibacterial strategies and mechanism of MoS2, starting with its morphology and synthesis methods and focusing on the different interaction stages between MoS2 and bacteria. The paper summarizes the main antibacterial mechanisms of MoS2, such as photocatalytic antibacterial, enzyme-like catalytic antibacterial, physical antibacterial, and photothermal-assisted antibacterial. It offers a comprehensive discussion focus on recent research studies of photocatalytic antibacterial mechanisms and categorizes them, guiding the application of MoS2 in the antibacterial field. Overall, the review provides an in-depth understanding of the antibacterial mechanisms of MoS2 and presents the challenges and future directions for the improvement of MoS2 in the field of high-efficiency antibacterial materials.

Co-, N-doped carbon dot nanozymes based on an untriggered ROS generation approach for anti-biofilm activities and in vivo anti-bacterial treatment

Bacterial infections originating from food, water, and soil are widely recognized as significant global public health concerns. Biofilms are implicated in approximately two-thirds of bacterial infections. In recent times, nanomaterials have emerged as potential agents for combating biofilms and bacteria, with many of them being activated by light and H2O2 to generate reactive oxygen species (ROS). However, this energy-consuming and extrinsic substrate pattern poses many challenges for practical application. Consequently, there is a pressing need to develop methods for the untriggered generation of ROS to effectively address biofilm and bacterial infections. In this study, we investigated the oxidase-like activity of the Co,N-doped carbon dot (CoNCD) nanozyme, which facilitated the oxidation of ambient O2 to generate 1O2 in the absence of light and H2O2 supplementation; this resulted in effective biofilm cleavage and enhanced bactericidal effects. CoNCDs could become a potential candidate for wound healing and treatment of acute peritonitis in vivo, which can be primarily attributed to the spontaneous production of ROS. This study presents a convenient ROS generator that does not necessitate any specific triggering conditions. The nanozyme properties of CoNCDs exhibit significant promise as a potential remedy for diseases, specifically as an anti-biofilm and anti-bacterial agent.

Construction of Mn-N-C nanoparticles with multienzyme-like properties and photothermal performance for the effective treatment of bacterial infections

In this work, we successfully constructed Mn-coordinated nitrogen-carbon nanoparticles (Mn-N-C NPs) exhibiting multienzyme-like activities. In a bacterial infectious microenvironment, the POD-like and OXD-like activities of Mn-N-C NPs could synergistically trigger the generation of ROS (˙OH and O2˙-), causing oxidative damage to the bacterial cell membrane for killing bacteria. Alternatively, in neutral or weak alkaline normal tissues, the excessive O2˙- could be converted into O2 and H2O2via the SOD-like ability of Mn-N-C NPs, and subsequently their CAT-like activity catalyzed excess H2O2 into H2O and O2 for protecting normal cells through the antioxidant defense. Mn-N-C NPs also possessed a good NIR-photothermal performance, which could enhance their POD-like and OXD-like activities. Furthermore, Mn-N-C NPs could facilitate the GSH oxidation process and disrupt the intrinsic balance in the bacterial protection microenvironment with the assistance of H2O2, which is beneficial for rapid bacterial death. Undoubtedly, the Mn-N-C NPs + H2O2 system showed the highest antibacterial activity when irradiated with an 808 nm laser, destroying the bacterial membrane and causing the efflux of proteins. Moreover, the Mn-N-C NPs + H2O2 system was immune to the development of bacterial resistance and could efficiently disrupt the formation of a bacterial biofilm with negligible cytotoxicity and low hemolysis ratio. Finally, Mn-N-C NPs exhibited an excellent antibacterial performance in vivo and could accelerate wound healing without cellular inflammation production. Therefore, due to their significant therapeutic effects, Mn-N-C NPs show great potential in fighting antibiotic-resistant bacteria.

Regulating Lewis Acidic Sites of 1T-2H MoS2 Catalysts for Solar-Driven Photothermal Catalytic H2 Production from Lignocellulosic Biomass

Solar-driven photothermal catalytic H2 production from lignocellulosic biomass was achieved by using 1T-2H MoS2 with tunable Lewis acidic sites as catalysts in an alkaline aqueous solution, in which the number of Lewis acidic sites derived from the exposed Mo edges of MoS2 was successfully regulated by both the formation of an edge-terminated 1T-2H phase structure and tunable layer number. Owing to the abundant Lewis acidic sites for the oxygenolysis of lignocellulosic biomass, the 1T-2H MoS2 catalyst shows high photothermal catalytic lignocellulosic biomass-to-H2 transformation performance in polar wood chips, bamboo, rice straw corncobs, and rice hull aqueous solutions, and the highest H2 generation rate and solar-to-H2 (STH) efficiency respectively achieves 3661 μmol·h-1·g-1 and 0.18% in the polar wood chip system under 300 W Xe lamp illumination. This study provides a sustainable and cost-effective method for the direct transformation of renewable lignocellulosic biomass to H2 fuel driven by solar energy.

Rational Design of Guanidinium-Based Bio-MCOF as a Multifunctional Nanocatalyst in Tumor Cells for Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) has emerged as a promising approach to cancer treatment, which can break the intracellular redox state balance and result in severe oxidative damage to biomolecules and organelles with the advantages of being less dependent on external stimulation, having deep tissue-healing abilities, and being resistant to drug resistance. There is considerable interest in developing CDT drugs with high efficiency and low toxicity. In this study, a new guanidinium-based biological metal covalent organic framework (Bio-MCOF), GZHMU-1@Mo, is rationally designed and synthesized as a multifunctional nanocatalyst in tumor cells for enhanced CDT. The DFT calculation and experimental results showed that due to the ability of MoO42- ion to promote electron transfer and increase the redox active site, Cu3 clusters and MoO42- ions in GZHMU-1@Mo can synergistically catalyze the production of reactive oxygen species (ROS) from oxygen and H2O2 in tumor cells, as well as degrade intracellular reducing substances, GSH and NADH, so as to disrupt the redox balance in tumor cells. Moreover, GZHMU-1@Mo exhibits a potent killing effect on tumor cells under both normal oxygen and anaerobic conditions. Further in vitro and in vivo antiproliferation studies revealed that the GZHMU-1@Mo nanoagent displays a remarkable antiproliferation effect and effectively inhibits tumor growth. Taken together, our study provides an insightful reference benchmark for the rational design of Bio-MCOF-based nanoagents with efficient CDT.

Highly Conductive Peroxidase-like Ce-MoS2 Nanoflowers for the Simultaneous Electrochemical Detection of Dopamine and Epinephrine

The accurate and simultaneous detection of neurotransmitters, such as dopamine (DA) and epinephrine (EP), is of paramount importance in clinical diagnostic fields. Herein, we developed cerium-molybdenum disulfide nanoflowers (Ce-MoS2 NFs) using a simple one-pot hydrothermal method and demonstrated that they are highly conductive and exhibit significant peroxidase-mimicking activity, which was applied for the simultaneous electrochemical detection of DA and EP. Ce-MoS2 NFs showed a unique structure, comprising MoS2 NFs with divalent Ce ions. This structural design imparted a significantly enlarged surface area of 220.5 m2 g-1 with abundant active sites as well as enhanced redox properties, facilitating electron transfer and peroxidase-like catalytic action compared with bare MoS2 NFs without Ce incorporation. Based on these beneficial features, Ce-MoS2 NFs were incorporated onto a screen-printed electrode (Ce-MoS2 NFs/SPE), enabling the electrochemical detection of H2O2 based on their peroxidase-like activity. Ce-MoS2 NFs/SPE biosensors also showed distinct electrocatalytic oxidation characteristics for DA and EP, consequently yielding the highly selective, sensitive, and simultaneous detection of target DA and EP. Dynamic linear ranges for both DA and EP were determined to be 0.05~100 μM, with detection limits (S/N = 3) of 28 nM and 44 nM, respectively. This study shows the potential of hierarchically structured Ce-incorporated MoS2 NFs to enhance the detection performances of electrochemical biosensors, thus enabling extensive applications in healthcare, diagnostics, and environmental monitoring.

Preparation of polyvinyl alcohol/chitosan nanofibrous films incorporating graphene oxide and lanthanum chloride by electrospinning method for potential photothermal and chemical synergistic antibacterial applications in wound dressings

Electrospun fibres have been widely used as skin dressings due to their unique structur. However, due to the lack of intrinsic antimicrobial activity, it is easy for the wound to become infected. Bacterial infection, which leads to chronic inflammation, severely hinders the normal process of skin regeneration. In this study, a polyvinyl alcohol/chitosan (PVA/CS) composite films with chemical sterilization and near-infrared (NIR) photothermal antibacterial activity was fabricated by electrospinning. Graphene oxide (GO), a photosensitiser, was incorporated into the films, and lanthanum chloride (Lacl3) as a chemical antibacterial agent was also doped in the electrospun films. The structure, morphology, mechanical properties, wettability, and antimicrobial and photothermal antibacterial activity of the PVA/CS-based fibre films were investigated. The results showed that the addition of Lacl3 to the PVA/CS/GO nanofibres (PVA/CS/GO-La) improved the hydrophilicity, tensile strength and resistance to elastic deformation of the nanofibres. The PVA/CS/GO-La12.5 mM sample exhibited the best antibacterial performance, showing high inhibition against Staphylococcus aureus (82% antibacterial efficacy) and Escherichia coli (99.7% antibacterial efficacy). Furthermore, the antibacterial efficacy of the films surface was further enhanced after exposure to NIR light (808 nm, 0.01 W) for 20 min. In addition, the nanofibre films showed no cytotoxicity against human skin fibroblasts (HSFs), indicating its potential application in the field of broad-spectrum antibacterial materials.

Large-scale production of MXenes as nanoknives for antibacterial application

Antimicrobial resistance of existing antibacterial agents has become a pressing issue for human health and demands effective antimicrobials beyond conventional antibacterial mechanisms. Two-dimensional (2D) nanomaterials have attracted considerable interest for this purpose. However, obtaining a high yield of 2D nanomaterials with a designed morphology for effective antibacterial activity remains exceptionally challenging. In this study, an efficient one-step mechanical exfoliation (ECO-ME) method has been developed for rapidly preparing Ti3C2 MXenes with a concentration of up to 30 mg mL-1. This synthetic pathway involving mechanical force endows E-Ti3C2 MXene prepared by the ECO-ME method with numerous irregular sharp edges, resulting in a unique nanoknife effect that can successfully disrupt the bacterial cell wall, demonstrating better antibacterial activity than the MXenes prepared by conventional wet chemical etching methods. Overall, this study provides a simple and effective method for preparing MXenes on a large scale, and its antibacterial effects demonstrate great potential for E-Ti3C2 in environmental and biomedical applications.

Photocatalytic microbial disinfection under indoor conditions: Prospects and challenges of near IR-photoactive materials

The accumulation of microbes especially in the air and in water bodies is causing the major disease outbreaks. Indoor environment remediation methods are necessary today to clean up these microbes. Among the remediation methods available, in situ generation of highly reactive and oxidizing radical species by advanced oxidation processes (AOPs) inactivate most of the microbes unselectively. Of these AOPs, photocatalytic microbial disinfection especially under indoor conditions is of great interest to maintain microbe-free indoor environment. For efficient microbes' inactivation under indoor conditions, the near IR and IR response of the photocatalysts must be improved. Though the photocatalytic disinfection of microbes using semiconductor-based photocatalysts has been extensively investigated, most of the photocatalysts that have been investigated are either weekly responsive or totally not irresponsive to IR photons due to inappropriate bandgap energies. Several strategies have been investigated to enhance the light harvesting properties of semiconductor based photocatalysts under indoor conditions and make them active to near IR and IR radiations. This review summarizes the recent progress in the field of materials for photocatalysts employed for microbial removal in indoor environments over the past decade as well as outlines key perspectives to enlighten future researches. The paper details the fundamentals of photocatalysis and basic properties of photocatalytic materials in the disinfection of common microbes under indoor conditions. The applications of photocatalytic materials in the disinfection of microbes in indoor environmental conditions are discussed and reviewed. Finally, the remaining challenges and future strategies/prospects in the design and synthesis of IR (and near IR) responsive photocatalysts are discussed.

Celebrating 20 Years of NCNST: Innovation in Nanoscience and Nanotechnology

With the development of nanoscience and technology, it has become an essential part of various research directions, changing our way of life, such as advanced accurate manufacturing in nanotechnology that facilitates reducing chip sizes, progress made in health care via nanoscience that provides hope to patients, and so on. As the nation's flagship institution of nanoscience and technology in China, the National Center for Nanoscience and Technology, China (NCNST), established in December 2003, has played a crucial role in promoting cutting-edge technologies in the field of nanoscience and expediting interdisciplinary fusion. With a strong research team and state-of-the-art research equipment, NCNST currently carries out frontier research and world-class technology innovation, including nanosystems and hierarchical fabrication, biological effects of nanomaterials and nanosafety, standardization and measurements for nanotechnology, as well as theoretical simulations. Serving as one of the most prestigious institutions in nanoscience and nanotechnology in China, NCNST will continue to foster impactful international cooperation, cultivate young talents, and boost inspiring innovation.

Theranostic gold-in-gold cage nanoparticles enable photothermal ablation and photoacoustic imaging in biofilm-associated infection models

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we described a complex structure of a dextran-coated gold-in-gold cage nanoparticle that enabled photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser could selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observed a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections, respectively. These effects were over 100 times greater than those seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We concluded that photothermal ablation using theranostic nanoparticles is a rapid, precise, and nontoxic method to detect and treat biofilm-associated infections.

Cryptotanshinone-Doped Photothermal Synergistic MXene@PDA Nanosheets with Antibacterial and Anti-Inflammatory Properties for Wound Healing

Humans are threatened by bacteria and other microorganisms, resulting in countless pathogen-related infections and illnesses. Accumulation of reactive oxygen species (ROS) in infected wounds activates strong inflammatory responses. The overuse of antibiotics has led to increasing bacterial resistance. Therefore, effective ROS scavenging and bactericidal capacity are essential and the advanced development of collaborative therapeutic techniques to combat bacterial infections is needed. Here, this work developes an MXene@polydopamine-cryptotanshinone (MXene@PDA-CPT) antibacterial nanosystem with excellent reactive oxygen and nitrogen species scavenging ability, which effectively inactivates drug-resistant bacteria and biofilms, thereby promoting wound healing. In this system, the adhesion of polydopamine nanoparticles to MXene produced a photothermal synergistic effect and free radical scavenging activity, presenting a promising antibacterial and anti-inflammatory strategy. This nanosystem causes fatal damage to bacterial membranes. The loading of cryptotanshinone further expanded the advantages of the system, causing a stronger bacterial killing effect and inflammation mitigatory effect with desired biosafety and biocompatibility. In addition, combining nanomaterials and active ingredients of traditional Chinese medicine, this work provides a new rationale for the future development of wound dressings, which contributes to eliminating bacterial resistance, delaying disease deterioration, and alleviating the pain of patients.

Hollow Cobalt Sulfide Nanospheres with Highly Enzyme-like Antibacterial Activities to Accelerate Infected Wound Healing

The emergence of nanozymes presents a promising alternative to antibiotics for reactive oxygen species-mediated broad-spectrum antimicrobial purposes, but nanozymes still face challenges of low therapeutic efficiency and poor biocompatibility. Herein, we creatively prepared a novel kind of hollow cobalt sulfide (CoS) nanospheres with a unique mesoporous structure that is able to provide numerous active sites for enzyme-like reactions. The results revealed that 50 μg/mL of CoS nanospheres exhibited strong peroxidase- and oxidase-like activities under physiological conditions with the assistance of a low concentration of hydrogen peroxide (H2O2, 100 μM) while possessing highly efficient GSH-depletion ability, which endowed CoS nanospheres with triple enzyme-like properties to combat bacterial infections. The in vitro experiments demonstrated that the CoS nanozyme displayed significant antibacterial effects against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). The in vivo implantation showed that the synthesized CoS effectively eliminated bacteria and promoted the recovery of infected wounds in rats while exhibiting a low cytotoxicity. This study provides a promising treatment strategy to accelerate infected wound healing.

Responses of Phragmites communis and its rhizosphere bacteria to different exposure sequences of molybdenum disulfide and levofloxacin

The effect of the molybdenum disulfide (MoS2)/levofloxacin (LVF) co-exposure was explored on Phragmites communis and rhizosphere soil bacterial communities. The sequence of MoS2/LVF exposure and the different MoS2 dosages (10 mg/kg and 100 mg/kg) contributed to different degrees of effect on the plant after 42 days of exposure. The treatment with priority addition of low dosage MoS2 significantly ameliorated P. communis growth, with root length growing up to 532.22 ± 46.29 cm compared to the sole LVF stress (200.04 ± 29.13 cm). Besides, MoS2 served as an alleviator and reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in P. communis under LVF stress, and activated bacteria in rhizosphere soil. These rhizosphere soil microbes assisted in mitigating toxic pollution in the soil and inducing plant resistance to external stress, such as bacteria genera Bacillus, Microbacterium, Flavihumibacter and altererythrobacter. Potential functional profiling of bacterial community indicated the addition of MoS2 contributed to relieve the reduction in functional genes associated with amino acid metabolism and the debilitation of gram_negative and aerobic phenotypic traits caused by LVF stress. This finding reveals the effect of different exposure sequences of MoS2 nanoparticles and antibiotic for plant-soil systems.

Recent advances in nanomaterial-mediated bacterial molecular action and their applications in wound therapy

Because of the multi-pathway antibacterial mechanisms of nanomaterials, they have received widespread attention in wound therapy. However, owing to the complexities of bacterial responses toward nanomaterials, antibacterial molecular mechanisms remain unclear, making it difficult to rationally design highly efficient antibacterial nanomaterials. Fortunately, molecular dynamics simulations and omics techniques have been used as effective methods to further investigate the action targets of nanomaterials. Therefore, the review comprehensively analyzes the antibacterial mechanisms of nanomaterials from the morphology-dependent antibacterial activity and physicochemical/optical properties-dependent antibacterial activity, which provided guidance for constructing excellently efficient and broad-spectrum antibacterial nanomaterials for wound therapy. More importantly, the main molecular action targets of nanomaterials from the membranes, DNA, energy metabolism pathways, oxidative stress defense systems, ribosomes, and biofilms are elaborated in detail. Furthermore, nanomaterials used in wound therapy are reviewed and discussed. Finally, future directions of nanomaterials from mechanisms to nanomedicine are further proposed.

Effect of fluorine doping on the NO2-sensing properties of MoS2nanoflowers

The somewhat slow recovery kinetics of NO2sensing at low temperatures are still challenging to overcome. To enhance the gas sensing property, fluorine is doped to MoS2nanoflowers by facile hydrothermal method. Extensive characterization data demonstrate that F was effectively incorporated into the MoS2nanoflowers, and that the microstructure of the MoS2nanoflowers did not change upon F doping. The two MoS2doped with varying concentrations of fluorine were tested for their sensing property to NO2gas. Both of them show good repeatability and stability. A smaller recovery time was seen in the F-MoS2-1 sample with a little amount of F loading, which was three times quicker than that of pure MoS2. The key reason for the quicker recovery time of this material was found to be the fluorine ions that had been adsorbed on the surface of F-MoS2-1 would take up some of the NO2adsorption site. Additionally, the sample F-MoS2-2 with a higher F doping level demonstrated increased sensitivity. The F-MoS2-2 sensor's high sensitivity was mostly due to the lattice fluorine filled to the sulfur vacancy, which generated impurity levels and reduced the energy required for its electronic transition. This study might contribute to the development of new molybdenum sulfide based gas sensor.

Reactive oxygen nanobiocatalysts: activity-mechanism disclosures, catalytic center evolutions, and changing states

Benefiting from low costs, structural diversities, tunable catalytic activities, feasible modifications, and high stability compared to the natural enzymes, reactive oxygen nanobiocatalysts (RONBCs) have become dominant materials in catalyzing and mediating reactive oxygen species (ROS) for diverse biomedical and biological applications. Decoding the catalytic mechanism and structure-reactivity relationship of RONBCs is critical to guide their future developments. Here, this timely review comprehensively summarizes the recent breakthroughs and future trends in creating and decoding RONBCs. First, the fundamental classification, activity, detection method, and reaction mechanism for biocatalytic ROS generation and elimination have been systematically disclosed. Then, the merits, modulation strategies, structure evolutions, and state-of-art characterisation techniques for designing RONBCs have been briefly outlined. Thereafter, we thoroughly discuss different RONBCs based on the reported major material species, including metal compounds, carbon nanostructures, and organic networks. In particular, we offer particular insights into the coordination microenvironments, bond interactions, reaction pathways, and performance comparisons to disclose the structure-reactivity relationships and mechanisms. In the end, the future challenge and perspectives for RONBCs are also carefully summarised. We envision that this review will provide a comprehensive understanding and guidance for designing ROS-catalytic materials and stimulate the wide utilisation of RONBCs in diverse biomedical and biological applications.

Amyloid-like nanofibrous network confined and aligned ultrafine bimetallic nanozymes for smart antibacterial therapy

Nanozyme-based antibacterial therapy (NABT) has emerged as a promising strategy to combat bacterial antimicrobial resistance. Engineering the noble metal nanozymes with strong bacterial capture and high catalytic activity for enhanced NABT is highly anticipated but still challenged. Herein, we developed hybrid nanozymes by engineering ultrafine bimetallic Au/Cu nanoparticles confined on the lysozyme amyloid-like nanofibrous networks (LNF). The introduction of copper in the nanozymes facilitates the H2O2 adsorption and reduces the energy barrier for activating the H2O2 decomposition to form •OH, meanwhile displaying the significantly enhanced POD-like activity under NIR irradiation. Taking advantage of the inherent supramolecular networks inspired from human defensin 6-trapping bacteria mechanism, the hybrid nanozymes effectively capture the bacteria and allow the catalytic attack around the bacterial surfaces to improve the antibacterial efficiency. Finally, the as-prepared nanozymes exhibit the preeminent bactericidal efficacy against bacteria, especially for drug-resistant bacteria both in vitro and in vivo, and the effect on wound healing.

Hydrogen-bonded organic framework-stabilized charge transfer cocrystals for NIR-II photothermal cancer therapy

Charge-transfer (CT) cocrystals consisting of an electron donor and acceptor have gained attention for designing photothermal (PT) conversion materials with potential for biomedical and therapeutic use. However, the applicability of CT cocrystals is limited by their low stability and aqueous dispersity in biological settings. In this study, we present the self-assembly of CT cocrystals within hydrogen-bonded organic frameworks (HOFs), which not only allows for the dispersion and stabilization of cocrystals in aqueous solution but also promotes the CT interaction within the confined space of HOFs for photothermal conversion. We demonstrate that the CT interaction-driven self-assembly of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) with PFC-1 HOFs results in the formation of cocrystal-encapsulated TQC@PFC-1 while retaining the crystalline structure of the cocrystal and PFC-1. TQC@PFC-1, in particular, exhibits significant absorption in the second near-infrared region (NIR-II) and excellent photothermal conversion efficiency, as high as 32%. Cellular delivery studies show that TQC@PFC-1 can be internalized in different types of cancer cells, leading to an effective NIR-II photothermal therapy effect both in cultured cells and in vivo. We anticipate that the strategy of self-assembly and stabilization of CT cocrystals in nanoscale HOFs opens the path for tuning their photophysical properties and interfacing cocrystals with biological settings for photothermal therapeutic applications.

Multifunctional nanozyme-reinforced copper-coordination polymer nanoparticles for drug-resistance bacteria extinction and diabetic wound healing

BACKGROUND

Drug-resistant bacterial infections in chronic wounds are a persistent issue, as they are resistant to antibiotics and can cause excessive inflammation due to generation of reactive oxygen species (ROS). An effective solution would be to not only combat bacterial infections but also scavenge ROS to relieve inflammation at the wound site. Scaffolds with antioxidant properties are attractive for their ability to scavenge ROS, and there is medical demand in developing antioxidant enzyme-mimicking nanomaterials for wound healing.

METHODS

In this study, we fabricated copper-coordination polymer nanoparticles (Cu-CPNs) through a self-assembly process. Furthermore, ε-polylysine (EPL), an antibacterial and cationic polymer, was integrated into the Cu-CPNs structure through a simple one-pot self-assembly process without sacrificing the glutathione peroxidase (GPx) and superoxide dismutase (SOD)-mimicking activity of Cu-CPNs.

RESULTS

The resulting Cu-CPNs exhibit excellent antioxidant propertiesin mimicking the activity of glutathione peroxidase and superoxide dismutase and allowing them to effectively scavenge harmful ROS produced in wound sites. The in vitro experiments showed that the resulting Cu-CPNs@EPL complex have superior antioxidant properties and antibacterial effects. Bacterial metabolic analysis revealed that the complex mainly affects the cell membrane integrity and nucleic acid synthesis that leads to bacterial death.

CONCLUSIONS

The Cu-CPNs@EPL complex has impressive antioxidant properties and antibacterial effects, making it a promising solution for treating drug-resistant bacterial infections in chronic wounds. The complex's ability to neutralize multiple ROS and reduce ROS-induced inflammation can help relieve inflammation at the wound site. Schematic illustration of the ROS scavenging and bacteriostatic function induced by Cu-CPNs@EPL nanozyme in the treatment of MRSA-infected wounds.

Application of f-FeNC@GOx cascade enzyme nanomaterials in the healing of infected wounds

AIMS

Bacterial infection is a significant factor contributing to the deterioration of wounds, and the misuse of antibiotics has exacerbated bacterial resistance. Therefore, there is an urgent need to develop a novel antibacterial strategy to replace conventional therapies. This study aims to construct a self-activated cascade reaction nanozyme, f-FeNC@GOx, which triggers a cascade reaction in the presence of glucose. This cascade reaction generates highly toxic hydroxyl radicals (OH), thereby achieving the goal of eliminating bacteria and promoting wound healing.

MATERIAL AND METHODS

In vitro antibacterial experiments, bacterial spread plate method, Live/Dead staining, and crystal violet staining were conducted to analyze the antibacterial ability and mechanism of f-FeNC@GOx. In vivo experiments, a mouse wound model was established, and H&E and Masson staining of wound tissues were performed to assess the antibacterial activity of the f-FeNC@GOx in vivo.

KEY FINDINGS

The in vivo and in vitro experiments confirmed that f-FeNC@GOx exhibited significant antibacterial effect against both Staphylococcus aureus and Escherichia coli in the presence of glucose. Furthermore, it showed optimal wound healing performance in the wound models.

SIGNIFICANCE

These findings suggested that f-FeNC@GOx was a novel and effective antibacterial nanomaterial, which provided a promising antibacterial strategy using nanoenzyme based cascade reaction.

Fluoride-activated photothermal system for promoting bacteria-infected wound healing

Although photothermal therapy (PTT) employing nanozymes has shown excellent antibacterial potential, excessive heating generally harms host cells and hinders recovery. Herein, we report an innovative technique for acquiring the programmed temperature by managing the catalytic activity of nanozymes. The photothermal system of CeO2 + F- + TMB can obtain precise photothermal temperature by adjusting the concentration of fluoride ions under near-infrared irradiation. At the optimized photothermal temperature, the photothermal system affords fine photothermal antibacterial treatment with high-efficiency antibacterial effects against Staphylococcus aureus and Escherichia coli in vitro. In vivo wound healing experiments confirm that the system can effectively promote fibroblast proliferation, angiogenesis and collagen deposition with remarkable wound healing efficiency. This strategy offers a novel design concept for creating a new generation of PTT and opens the way for the creation of alternative antibiotics.

Nano-Biotechnology for Bacteria Identification and Potent Anti-bacterial Properties: A Review of Current State of the Art

Sepsis is a critical disease caused by the abrupt increase of bacteria in human blood, which subsequently causes a cytokine storm. Early identification of bacteria is critical to treating a patient with proper antibiotics to avoid sepsis. However, conventional culture-based identification takes a long time. Polymerase chain reaction (PCR) is not so successful because of the complexity and similarity in the genome sequence of some bacterial species, making it difficult to design primers and thus less suitable for rapid bacterial identification. To address these issues, several new technologies have been developed. Recent advances in nanotechnology have shown great potential for fast and accurate bacterial identification. The most promising strategy in nanotechnology involves the use of nanoparticles, which has led to the advancement of highly specific and sensitive biosensors capable of detecting and identifying bacteria even at low concentrations in very little time. The primary drawback of conventional antibiotics is the potential for antimicrobial resistance, which can lead to the development of superbacteria, making them difficult to treat. The incorporation of diverse nanomaterials and designs of nanomaterials has been utilized to kill bacteria efficiently. Nanomaterials with distinct physicochemical properties, such as optical and magnetic properties, including plasmonic and magnetic nanoparticles, have been extensively studied for their potential to efficiently kill bacteria. In this review, we are emphasizing the recent advances in nano-biotechnologies for bacterial identification and anti-bacterial properties. The basic principles of new technologies, as well as their future challenges, have been discussed.

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

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