Antibacterial agents with high antibacterial efficiency and bacteria-binding capability are highly desirable. Herein, we describe the successful preparation of Cu2WS4 nanocrystals (CWS NCs) with excellent antibacterial activity. CWS NCs with small size (∼20 nm) achieve more than 5 log (>99.999%) inactivation efficiency of both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) at low concentration (<2 μg mL–1) with or without ambient light, which is much better than most of the reported antibacterial nanomaterials (including Ag, TiO2, etc.) and even better than the widely used antibiotics (vancomycin and daptomycin). Antibacterial mechanism study showed that CWS NCs have both enzyme-like (oxidase and peroxidase) properties and selective bacteria-binding ability, which greatly facilitate the production of reactive oxygen species to kill bacteria. Animal experiments further indicated that CWS NCs can effectively treat wounds infected with methicillin-resistant Staphylococcus aureus (MRSA). This work demonstrates that CWS NCs have the potential as effective antibacterial nanozymes for the treatment of bacterial infection.

instead of CMS NPs dispersion for the saline and saline + NIR-II groups. 10 min later, infected site of the mice was irradiated by 1064 nm laser (1 W cm −2) for 5 min for saline + NIR-II and CMS + NIR-II groups. The infected area was monitored and photographed daily. At the therapeutic day 16, the infected tissues were homogenized and diluted in saline by ultrasonication. Then, these dilutions (100 µL) were plated on LB agar plates. The number of CFU was counted after incubation for 18 h at 37 °C. At the therapeutic day 16, the infected tissues were harvested, fixed in paraformaldehyde solution (4%), paraffined, sectioned, and observed after H&E staining by an Olympus IX-71 microscope.

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.201903746. Lactic acid (LA) is a powerful molecule as the metabolic driver in tumor microenvironments (TMEs). Inspired by its high intratumoral level(5-20 µmol g −1 ), a novel treatment paradigm via the cascade release of H 2 O 2 and ·OH from the LA generated by tumor metabolism is developed for catalytic and pH-dependent selective tumor chemotherapy. By utilizing the acidity and overexpression of LA within the TME, the constructed lactate oxidase (LOD)-immobilized Ce-benzenetricarboxylic acid (Ce-BTC) metal organic framework enables the intratumoral generation of ·OH via a cascade reaction: 1) the in situ catalytic release of H 2 O 2 from LA by LOD, and 2) the catalytic production of ·OH from H 2 O 2 by Ce-BTC with peroxidase-like activity. Highly toxic ·OH effectively induces tumor apoptosis/death. A new strategy for selective tumor chemotherapy is provided herein.

Bacterial biofilm related infections are ever growing issues for global medical community. Traditional antibiotic therapy is usually ineffective for treating them because the bacteria inside biofilms have evolved with multiple mechanisms to evade antibiotic challenge. Hence, effective therapeutic strategy with novel antibiofilm mode of action is highly desired. In this context, nanomedicine has drawn great attentions and has been proven promising to prevent and eliminate bacterial biofilms. In this review, we focus on the recent advance of nanotechnology‐based strategies and nanoagents for combating bacterial biofilm infections. First, typical antibiofilm nanotechnologies utilized different chemical, physical, and biological properties of nanomaterials are discussed. Second, smart nanoagents that can responsive to biofilm microenvironment, including pH, H2O2, and enzymes, are shown. Third, some promising antibiofilm approaches, such as theranostics, biofilm structure destruction, and quorum sensing inhibition, are also demonstrated. Finally, we conclude the current antibiofilm nanotechnologies and discuss the challenges and future directions in this field.

Traditional antibiotic treatment has limited efficacy for the drug-tolerant bacteria present in biofilms because of their unique metabolic conditions in the biofilm infection microenvironment. Modulating the biofilm infection microenvironment may influence the metabolic state of the bacteria and provide alternative therapeutic routes. In this study, photodynamic therapy is used not only to eradicate methicillin-resistant Staphylococcus aureus biofilms in the normoxic condition, but also to potentiate the hypoxic microenvironment, which induces the anaerobic metabolism of methicillin-resistant Staphylococcus aureus and activates the antibacterial activity of metronidazole. Moreover, the photodynamic therapy-activated chemotherapy can polarize the macrophages to a M2-like phenotype and promote the repair of the biofilm infected wounds in mice. This biofilm infection microenvironment modulation strategy, whereby the hypoxic microenvironment is potentiated to synergize photodynamic therapy with chemotherapy, provides an alternative pathway for efficient treatment of biofilm-associated infections.

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Backlash is a key internal excitation on the dynamic response of planetary gear transmission. After the gear transmission running for a long time under load torque, due to tooth wear accumulation, the backlash between the tooth surface of two mating gears increases, which results in a larger and irregular backlash. However, the increasing backlash generated by tooth accumulated wear is generally neglected in lots of dynamics analysis for epicyclic gear trains. In order to investigate the impact of backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set, in this work, first a static tooth surface wear prediction model is incorporated with a dynamic iteration methodology to get the increasing backlash generated by tooth accumulated wear for one pair of mating teeth under the condition that contact ratio equals to one. Then in order to introduce the tooth accumulated wear into dynamic model of compound planetary gear set, the backlash excitation generated by tooth accumulated wear for each meshing pair in compound planetary gear set is given under the condition that contact ratio equals to one and does not equal to one. Last, in order to investigate the impact of the increasing backlash generated by tooth accumulated wear on dynamic response of compound planetary gear set, a nonlinear lumped-parameter dynamic model of compound planetary gear set is employed to describe the dynamic relationships of gear transmission under the internal excitations generated by worn profile, meshing stiffness, transmission error, and backlash. The results indicate that the introduction of the increasing backlash generated by tooth accumulated wear makes a significant influence on the bifurcation and chaotic characteristics, dynamic response in time domain, and load sharing behavior of compound planetary gear set.

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