Copper single-atom catalysts with photothermal performance and enhanced nanozyme activity for bacteria-infected wound therapy

Nanozymes have become a new generation of antibiotics with exciting broad-spectrum antibacterial properties and negligible biological toxicity.However,their inherent low catalytic activity limits their antibacterial properties.Herein,Cu single-atom sites/N doped porous carbon(Cu SASs/NPC)is successfully constructed for photothermal-catalytic antibacterial treatment by a pyrolysis-etching-adsorption-pyrolysis(PEAP)strategy.Cu SASs/NPC have stronger peroxidase-like catalytic activity,glutathione(GSH)-depleting function,and photothermal property compared with non-Cu-doped NPC,indicating that Cu doping significantly improves the catalytic performance of nanozymes.Cu SASs/NPC can effectively induce peroxidase-like activity in the presence of H2O2,thereby generating a large amount of hydroxyl radicals(•OH),which have a certain killing effect on bacteria and make bacteria more susceptible to temperature.The introduction of near-infrared(NIR)light can generate hyperthermia to fight bacteria,and enhance the peroxidase-like catalytic activity,thereby generating additional•OH to destroy bacteria.Interestingly,Cu SASs/NPC can act as GSH peroxidase(GSH-Px)-like nanozymes,which can deplete GSH in bacteria,thereby significantly improving the sterilization effect.PTT-catalytic synergistic antibacterial strategy produces almost 100%antibacterial efficiency against Escherichia coli(E.coli)and methicillin-resistant Staphylococcus aureus(MRSA).In vivo experiments show a better PTT-catalytic synergistic therapeutic performance on MRSA-infected mouse wounds.Overall,our work highlights the wide antibacterial and anti-infective bio-applications of Cu single-atom-containing catalysts.

Tiny 2D silicon quantum sheets:a brain photonic nanoagent for orthotopic glioma theranostics

We report that atomically thin two-dimensional silicon quantum sheets(2D Si QSs),prepared by a scalable approach coupling chemical delithiation and cryo-assisted exfoliation,can serve as a highperformance brain photonic nanoagent for orthotopic glioma theranostics.With the lateral size of approximately 14.0 nm and thickness of about 1.6 nm,tiny Si QSs possess high mass extinction coefficient of 27.5 Lg^(-1)cm^(-1)and photothermal conversion efficiency of 47.2%at 808 nm,respectively,concurrently contributing to the best photothermal performance among the reported 2 D mono-elemental materials(Xenes).More importantly,Si QSs with low toxicity maintain the trade-off between stability and degradability,paving the way for practical clinical translation in consideration of both storage and action of nanoagents.In vitro Transwell filter experiment reveals that Si QSs could effectively go across the b End.3 cells monolayer.Upon the intravenous injection of Si QSs,orthotopic brain tumors are effectively inhibited under the precise guidance of photoacoustic imaging,and the survival lifetime of brain tumor-bearing mice is increased by two fold.Atomically thin Si QSs with strong light-harvesting capability are expected to provide an effective and robust 2D photonic nanoplatform for the management of brain diseases.

Cryptobiosis-inspired assembly of “AND” logic gate platform for potential tumor-specific drug delivery

Developing tumor-specific drug delivery systems with minimized off-target cargo leakage remains an enduring challenge.In this study,inspired from the natural cryptobiosis explored by certain organisms and stimuli-responsive polyphenol-metal coordination chemistry,doxorubicin(DOX)-conjugated gelatin nanoparticles with protective shells formed by complex of tannic acid and FeⅢ(DG@TA-FeⅢNPs)were successfully developed as an"AND"logic gate platform for tumor-targeted DOX delivery.Moreover,benefiting from the well-reported photothermal conversion ability of TA-FeⅢcomplex,a synergistic tumor inhibition effect was confirmed by treating 4 T1 tumor-beaing mice with DG@TA-FeⅢNPs and localized near-infrared(NIR)laser irradiation.As a proof of concept study,this work present a simple strategy for developing"AND"logic gate platforms by coating enzyme-degradable drug conjugates with detachable polyphenol-metal shells.

Emerging markers for antimicrobial resistance monitoring

The appearance and spread of antibiotic-resistant pathogens known as antimicrobial resistance(AMR)is one of the major worldwide health crises that humanity have to deal with over the next decades.One of the main methods for addressing AMR is the effective screening for antimicrobial insensitivity in clinical and environmental monitoring.Current clinical laboratory procedures use traditional culturebased antibiotic susceptibility testing(AST)methods,which can take up to 24 h to identify which drug is suitable for the infection inhibition.Therefore,it is vital to develop novel strategies that offer quick,simple,affordable,reliable,sensitive and accurate AMR monitoring.Sensors for AMR markers detection could possess the essential qualities for quickly identifying resistant microorganisms and could give vital data for the selection of antibacterial drugs administration.This review offers a summary of the innovative application of these AMR markers detection strategies focusing on healthcare and environmental surveillance for the AMR genotypic or phenotypic assessment.

Emerging 2D pnictogens for biomedical applications

Two-dimensional(2D)materials composed of single pnictogen element,namely,2D pnictogens(e.g.,black phosphorus,arsenene,antimonene and bismuthine),have recently showed remarkable potential for biomedical applications,especially after the rapid development of black phosphorus.With unique optical and electronic properties,2D pnictogens are considered as promising nanoagents for biosensors,diagnosis and therapy.In this review,after brief introduction of the structure,properties,synthesis strategies,and biocompatibility of 2D pnictogens,their biomedical applications including anti-tumor,anti-inflammation,anti-bacterial,neurodegenerative treatment and tissue repairing are reviewed.The major obstacles and opportunities of 2D pnictogens are also discussed.This review provides a short yet timely summary on the synthesis and biomedical applications of emerging 2D pnictogens.

Anti-inflammatory catecholic chitosan hydrogel for rapid surgical trauma healing and subsequent prevention of tumor recurrence

Although occupying pillar position in clinical cancer treatments,surgery itself and surgical trauma would elicit series of local/systemic inflammation-related responses that resulted in high rate of tumor recurrence.Herein,chitosan with conjugated gallic acid(CSG)molecules were coordinated with Fe3+to form CSG/Fe3+hydrogel for filling the tumo r-resected cavity with considerable wet-adhesion ability and anti-inflammatory performance.With the assistance of doxorubicin hydrochloride(DOX·HCl),CSG/Fe3+/DOX hydrogel exhibited syne rgistic photothermal-chemo tumo r-inhibited performance under near-infrared(NIR)light irradiation for eradicating residual and/or surgical trauma-recruited cancer cells.Thus,our study attempts to show a paradigm that realizes quick surgical trauma healing,inflammation inhibition and prevention of postsurgical tumor recurrence.

Liquid exfoliation of stanene as degradable nanoagents for NIR-II photothermal therapy

Stanene,the two-dimensional form of elemental tin(Sn),is easily oxidized in the ambient environ-ment,significantly hindering its applications in biomedical fields.However,the degradation mechanism of stanene remains unclear.Herein,combined DFT calculations and proof-of-concept experiments were conducted to elucidate the underlying degradation mechanism of stanene.The results reveal that the degradation of stanene in an oxygenated water environment is a water-accelerated oxidation process.H_(2) O molecules could not only facilitate the electron transfer from stanene to O_(2) because of the polarization effect of H_(2) O,but also directly react with the defect sites of stanene due to enhanced absorption energy.Moreover,several protective strategies like alcohol protection were proposed to avoid or mitigate the oxidation of stanene for further applications.Finally,stanene was explored as the second near-infrared(NIR-II)photonic agents for ablation of 4T1 tumor,depicting a tumor-growth inhibition ratio up to 96.7%,much better than that of the first near-infrared(NIR-I)group(65.5%).This work reveals the degradation mechanism of stanene and demonstrates its biomedical applications in the NIR-II region.

Cell membrane-coated nanoparticles for immunotherapy

Nanoparticle-based disease detection, prevention and therapies have gained increased interests in biomedical applications, owing to their significant advantages in therapeutic efficacy and safety. Nonetheless, suffering from the challenges including fast recognition and clearance of foreign nanoparticles by innate immune system before arriving at diseased regions, clinical applications of nanoparticles are usually intercepted. Among various strategies for reducing non-specific phagocytosis and enhancing diseasetargeting efficiency of nanoparticles, membrane coating nanotechnology exhibits great potential in the disease diagnosis and therapeutics due to both the structural and functional preservation of membrane proteins from source cells. Benefiting the inherited immune-regulation capacities, this review mainly summarized the latest development of such biomimetic nanoparticles for immunotherapy in treating immune-related diseases including microbial infections, inflammation, tumor and autoimmune diseases.