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Pathogenic bacteria pose a devastating threat to public health. However, because of the growing bacterial antibiotic resistance, there is an urgent need to develop alternative antibacterial strategies to the established antibiotics. Herein, iron-doped carbon dots (Fe-CDs, ∼3 nm) nanozymes with excellent photothermal conversion and photoenhanced enzyme-like properties are developed through a facile one-pot pyrolysis approach for synergistic efficient antibacterial therapy and wound healing. In particular, Fe doping endows CDs with photoenhanced peroxidase (POD)-like activity, which lead to the generation of heat and reactive oxygen species (ROS) for Gram-positive and Gram-negative bacteria killing. This study demonstrates Fe-CDs have significant wound healing efficiency of Fe-CDs by preventing infection, promoting fibroblast proliferation, angiogenesis, and collagen deposition. Furthermore, the ultrasmall size of Fe-CDs possesses good biocompatibility favoring clinical translation. We believe that the nanozyme-mediated therapeutic platform presented here is expected to show promising applications in antibacterial.

Palladium nanosheets (Pd NSs) are well-investigated photothermal therapy agents, but their catalytic potential for tumor therapy has been underexplored owing to the inactive dominant (111) facets. Herein, lattice tensile strain is introduced by surface reconstruction to activate the inert surface, endowing the strained Pd NSs (SPd NSs) with photodynamic, catalase-like, and peroxidase-like properties. Tensile strain promoting the photodynamic and enzyme-like activities is revealed by density functional theory calculations. Compared with Pd NSs, SPd NSs exhibit lower photothermal effect, but approximately five times higher tumor inhibition rate. This work calls for further study to activate nanomaterials by strain engineering and surface reconstruction for catalytic therapy of tumors.

Sonodynamic therapy (SDT) offers an efficient noninvasive strategy for cancer treatment. However, the efficiency of SDT is limited by the structural and physicochemical properties of ultrasound (US)-sensitive agents. Here, we discover the combination of bioactivity and sonodynamic properties of zeolite imidazolium framework-8 nanocrystals (ZIF-8 NCs) for efficient tumor therapy. ZIF-8 NCs are susceptible to biodegradation to release zinc ions (Zn2+) triggered by the weakly acidic tumor microenvironment, demonstrating the bioactivity to induce apoptosis in cancer cells. Density functional theory calculations combined with experiments revealed that the unsaturated zinc-nitrogen (Zn-N) active sites on the surface of ZIF-8 NCs allow an enhanced electron transfer via ligand to metal charge transfer bands from the highest occupied molecular orbitals to the lowest unoccupied molecular orbitals. This process is critical for the generation of reactive oxygen species by metal-organic frameworks (MOFs) under US irradiation. In vivo experiments show that ZIF-8 NCs exhibit high tumor inhibition efficiency (84.6%) as both a bioactive anticancer agent and a sonosensitizer. We believe that this study can expand the application of MOFs and contribute to a better understanding of the mechanism of action of sonosensitizers.

Single-atom catalysts (SACs), as homogeneous catalysts, have been widely explored for chemical catalysis. However, few studies focus on the applications of SACs in enzymatic catalysis. Herein, we report that a zinc-based zeolitic-imidazolate-framework (ZIF-8)-derived carbon nanomaterial containing atomically dispersed zinc atoms can serve as a highly efficient single-atom peroxidase mimic. To reveal its structure-activity relationship, the structural evolution of the single-atom nanozyme (SAzyme) was systematically investigated. Furthermore, the coordinatively unsaturated active zinc sites and catalytic mechanism of the SAzyme are disclosed using density functional theory (DFT) calculations. The SAzyme, with high therapeutic effect and biosafety, shows great promises for wound antibacterial applications.

Despite the remarkable number of investigations on the potential risks of the engineered nanomaterials (ENMs) to terrestrial plants, there was limited knowledge regarding the effects of mesoporous carbon nanoparticles (MCNs) with different sizes on crops. The objective of our study was to evaluate the toxicity of MCNs to rice (Oryza sativa L.) seedlings. Two novel MCNs with different particle sizes (MCN1: 150 and MCN2: 80 nm) were synthesized using the high-temperature pyrolysis method and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and Raman spectra. Phytotoxicity of two MCNs was then comparatively evaluated using rice as a model plant. The rice seedlings were hydroponically exposed to both MCN suspensions with concentrations of 0, 10, 50, 150 mg/L for 20 days. Exposure to 150 mg/L MCN1 resulted in more than 21% and 29% decrease in root length and in shoot length, respectively. MCN2 significantly reduced the root and shoot lengths by approximately 70% and 57% at the concentration of 150 mg/L. Additionally, the concentrations of three endogenous phytohormones, including brassinolide (BR), indole propionic acid (IPA), and dihydrozeatinriboside (DHZR) in plant shoots were increased significantly compared with the control. Our findings illustrated that size-effects of MCNs contributed greatly in causing phytotoxicity to plants, which should have drawn our attention to the use of these novel ENMs in agriculture given the evidence of their potential risks to crops. More importantly, this is the first study on assessment of the phytotoxicity of MCNs to rice seedlings from the perspective of plant hormones.

Metal-organic frameworks (MOFs)-based yolk-shell nanostructures have drawn enormous attention recently due to their multifunctionality. However, the regulations of the size and morphology of yolk-shell nanostructures are still limited by the unclear formation mechanism. Herein, we first demonstrated a solvent-dependent adsorption-driven mechanism for synthesizing yolk-shelled MOFs-based nanostructures coated with mesoporous SiO2 shells (ZIF-8@mSiO2 ) with tunable size and morphology. The selective and competitive adsorption of methanol (CH3 OH) and water (H2 O) on ZIF-8 core were found to have decisive effects on inducing the morphology evolution of yolk-shell nanostructures. The obtained yolk-shelled ZIF-8@mSiO2 nanostructures show great promise in generating acoustic cavitation effect for sonodynamic cancer therapy in vitro. We believe that this work will not only help us to design novel MOFs-based yolk-shell nanostructures, but also promote the widespread application of MOFs materials.

Engineered DNA frameworks have been extensively exploited as affinity scaffolds for drug delivery. However, few studies focus on the rational design to comprehensively improve their stability, internalization kinetics, and drug loading efficiency. Herein, DNA framework-based hybrid nanomaterials are rationally engineered by using a molecular docking tool, where the framework acts as a template to support conjugated polymers. The hybrid materials exhibit high stability in biofluids owning to the multiple interactions between DNA and cationic conjugated polymer. Through molecular docking, it is found that a specific structure of the conjugated polymer at major grooves of DNA gives rise to a unique pocket for small-molecular drug doxorubicin (DOX) yielding lower binding energy than conventional DOX binding sites. This increases the binding affinity of DOX, allowing for high drug loading content and efficiency, and preventing drug leakage under physiological condition. As a proof of concept, the hybrid nanomaterials equipped with aptamer are used to carry DOX and antisense oligonucleotide G3139, which effectively inhibits solid tumor growth and shows negligible side effects on mice. It is anticipated that this approach would find broad applications in hybrid materials design and precise medicine.

Pd nanosheets (Pd NSs) have attracted extensive attention due to their promising application in photothermal therapy. However, their photodynamic properties have rarely been reported. Herein, holey Pd NSs (H-Pd NSs) with intrinsic photodynamic and hypoxia-resistant capacities are fabricated for the first time using an anisotropic oxidative etching strategy, which introduces one-dimensional nanoholes with active (100) facets on the hole walls. Gradual degradation of H-Pd NSs is observed in simulated physiological media due to the oxidative etching. In vitro and in vivo studies indicate that the single-component H-Pd NSs can act as a photothermal/photodynamic agent for imaging-guided hypoxic tumor therapy, with a high tumor inhibition rate of 99.7%. This work provides ideas for introducing active facets in metallic pore walls, broadening the application of Pd NSs and the design of biodegradable noble metal nanotheranostic agents for cancer therapy.

Single-atom nanozymes (SAzymes) represent a new research frontier in the biomedical fields. The rational design and controllable synthesis of SAzymes with well-defined electronic and geometric structures are essential for maximizing their enzyme-like catalytic activity and therapeutic efficacy but remain challenging. Here, a melamine-mediated pyrolysis activation strategy is reported for the controllable fabrication of iron-based SAzyme containing five-coordinated structure (FeN

As one of the diseases with high morbidity and low cure rate in the world, cancer has always threatened the health of the public. However, due to the complexity, diversity and heterogeneity of the tumor, it is difficult to inhibit tumor recurrence and metastasis by relying on surgery, radiotherapy or chemotherapy. Photothermal therapy (PTT) is a cancer treatment by laser irradiation, which converts light energy into heat energy mediated by photothermal agents, and induces local tissue hyperthermia to treat cancer. And it has attracted widespread attention because of its non-specificity, high tumor ablation efficiency, and low toxic side effects on normal cells. However, the clinical transformation process of PTT is also severely limited by some disadvantages including the inconvenience of the delivery, distribution and metabolic process of the photothermal agent and the inaccurate and incomplete evaluation of the results of cancer treatment. The researchers have designed a variety of photothermal agents with multimodal imaging capabilities for cancer diagnosis and treatment. These imaging methods include thermal imaging (TI), photoacoustic (PA) imaging, photoluminescence (PL) imaging, magnetic resonance imaging (MRI), X-ray computed tomography (CT) imaging, and positron emission tomography (PET) imaging. And the imaging-guided cancer treatments have improved the accuracy of tumor visual treatments and greatly facilitated the clinical transformation of PTT. At present, the trend of cancer treatment development has gradually changed from monotherapy to combination therapy. Other therapies in combination with PTT include photodynamic therapy (PDT), chemotherapy, immunotherapy, radiotherapy (RT), sonodynamic therapy (SDT), and other PTT-related therapies. These combination therapies overcome tumor heterogeneity and complexity, reversing multidrug resistance, and reduce unnecessary side effects, and can more effectively achieve cancer diagnosis and treatment. This review summarizes the recent advances in multimodal imaging-guided PTT and multitherapies in combination with PTT for cancer diagnosis and treatment. For a single photothermal treatment, it is often difficult for researchers to effectively monitor the delivery, distribution, metabolism, and excretion of photothermal agents, and to accurately and dynamically track and evaluate the real-time therapeutic effects of tumors. Various strategies have been developed to solve the problems of single photothermal therapy. The new nano-platforms based on PTT-based multimodal imaging methods or therapies reviewed in this paper combine cancer diagnosis and treatment, and effectively overcome the shortcomings of single photothermal anti-tumor therapy, which is difficult to visualize tumors and lack of therapeutic efficiency to provide the development of new cancer diagnosis and treatment technologies new opportunities. Whether it is a single photothermal therapy or a combination of photothermal therapy and other methods, there is still a long way to go to study its therapeutic mechanism and further applications. The ultimate goal of these studies is to go to the clinic, cure the tumor, and benefit mankind. It is believed that with the rapid development of nanotechnology and nanomedicine, these problems will be gradually solved, and the photothermal anti-tumor combination therapy based on multimodal imaging will surely make new breakthroughs.

Gold complexes can serve as efficient photothermal converters for cancer therapy, but their non-biodegradability hinders clinical bioapplications. Although enormous effort has been devoted, the conventionally adopted synthetic methods of biodegradation are characterized by high cost and complicated procedures, which delay the process of further clinical translation of gold complexes. Here, we report a multifunctional poly(amino acid)-gold-magnetic complex with self-degradation properties for synergistic chemo-photothermal therapy via simple and green chemistry methods. Nanoparticles of ∼3 nm in the biodegradation product were observed in simulated body fluid in 4 days. The biodegradability mainly benefits from the weakened internal electrostatic interaction of the poly(amino acid) by the ions in simulated body fluid. It is demonstrated that the poly(amino acid)-gold-magnetic complex has great cellular endocytosis by taking advantage of the guanidine group in arginine and possesses multimodal imaging and efficient tumor ablation (94%). This study reports a possibility for gold-magnetic complexes composed of poly(amino acid) to serve as a biodegradable nanotherapeutic for clinical applications.

Nanozymes have attracted extensive interest owing to their high stability, low cost and easy preparation, especially in the field of cancer therapy. However, the relatively low catalytic activity of nanozymes in the tumor microenvironment (TME) has limited their applications. Herein, we report a novel nanozyme (PtFe@Fe3 O4 ) with dual enzyme-like activities for highly efficient tumor catalytic therapy. PtFe@Fe3 O4 shows the intrinsic photothermal effect as well as photo-enhanced peroxidase-like and catalase-like activities in the acidic TME, thereby effectively killing tumor cells and overcoming the tumor hypoxia. Importantly, a possible photo-enhanced synergistic catalytic mechanism of PtFe@Fe3 O4 was first disclosed. We believe that this work will advance the development of nanozymes in tumor catalytic therapy.

Dual phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has shown a great prospect in cancer treatment. However, its therapeutic effect is restricted by the depth of light penetration in tissue and tumor hypoxia environment. Herein, inspired by the specific response of nanozymes to the tumor microenvironment (TME), a simple and versatile nanozyme-mediated synergistic dual phototherapy nanoplatform (denoted as FePc/HNCSs) is constructed using hollow nitrogen-doped carbon nanospheres (HNCSs) and iron phthalocyanine (FePc). FePc/HNCSs simultaneously exhibit peroxidase (POD)- and catalase (CAT)-like activities, which not only can convert endogenous hydrogen peroxide (H2 O2 ) into highly toxic hydroxyl radicals (•OH) for catalytic therapy, but also decompose H2 O2 to oxygen (O2 ) to enhance O2 -dependent PDT. In addition, their enzyme-like activities are significantly enhanced under light irradiation. Combining with the excellent photothermal effect, FePc/HNCSs realize a high tumor inhibition rate of 96.3%. This strategy opens a new horizon for exploring a more powerful tumor treatment nanoplatform.

The performances of catalysts are highly dependent on their crystallinities. It is a significant challenge to successively manipulate the crystallinities of noble metal nanocatalysts due to the strong metallic bonds, especially under ambient conditions. Herein, a post-crystallization approach is developed for successive control of the crystallinity of Pd nanosheets via selective oxidation etching of the amorphous domains. This strategy can be extended to crystallize other Pd and Ru nanomaterials. By carefully modulating the crystallinity of Pd nanosheets, the time for the complete conversion of 4-nitrostyrene via hydrogenation is reduced by 20 times. Also, crystallization can turn the selectivity of the products and improve the stability of Pd nanosheets. These findings may advance the crystal engineering of metal nanomaterials for wide applications.

Nanozyme is defined as a nanomaterial‐based artificial enzyme. It has rapidly attracted interest and been regarded as a promising alternative to natural enzymes due to its low cost, high stability, and high activity. Many researchers have recently paid attention to the optical properties of nanozymes and have found a variety of nanozymes with excellent photoactivity, called photo‐responsive nanozymes. In this minireview, we briefly introduce the mechanisms of photo‐responsive nanozymes, especially for the relationship between the enzyme‐like activity and photoactivity. Some activity regulation strategies for improving the performance of photo‐responsive nanozymes are also summarized. Moreover, the synergy of enzyme‐like activity and photoactivity in biomedical applications will also be discussed, including cancer therapy, antibacteria, and biological detection. We believe this minireview will be of great significance for understanding the optical properties of nanozymes and applying them in biomedicine.

Nanozyme-based tumor catalytic therapy has attracted widespread attention in recent years. However, its therapeutic outcomes are diminished by many factors in the tumor microenvironment (TME), such as insufficient endogenous hydrogen peroxide (H2 O2 ) concentration, hypoxia, and immunosuppressive microenvironment. Herein, an immunomodulation-enhanced nanozyme-based tumor catalytic therapy strategy is first proposed to achieve the synergism between nanozymes and TME regulation. TGF-β inhibitor (TI)-loaded PEGylated iron manganese silicate nanoparticles (IMSN) (named as IMSN-PEG-TI) are constructed to trigger the therapeutic modality. The results show that IMSN nanozyme exhibits both intrinsic peroxidase-like and catalase-like activities under acidic TME, which can decompose H2 O2 into hydroxyl radicals (•OH) and oxygen (O2 ), respectively. Besides, it is demonstrated that both IMSN and TI can regulate the tumor immune microenvironment, resulting in macrophage polarization from M2 to M1, and thus inducing the regeneration of H2 O2 , which can promote catalytic activities of IMSN nanozyme. The potent antitumor effect of IMSN-PEG-TI is proved by in vitro multicellular tumor spheroids (MCTS) and in vivo CT26-tumor-bearing mice models. It is believed that the immunomodulation-enhanced nanozyme-based tumor treatment strategy is a promising tool to kill cancer cells.

Sonodynamic therapy (SDT) can overcome the critical issue of depth-penetration barrier of photo-triggered therapeutic modalities. However, the discovery of sonosensitizers with high sonosensitization efficacy and good stability is still a significant challenge. In this study, the great potential of a metal-organic-framework (MOF)-derived carbon nanostructure that contains porphyrin-like metal centers (PMCS) to act as an excellent sonosensitizer is identified. Excitingly, the superior sonosensitization effect of PMCS is believed to be closely linked to the porphyrin-like macrocycle in MOF-derived nanostructure in comparison to amorphous carbon nanospheres, due to their large highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap for high reactive oxygen species (ROS) production. The nanoparticle-assisted cavitation process, including the visualized formation of the cavitation bubbles and microjets, is also first captured by high-speed camera. High ROS production in PMCS under ultrasound is validated by electron spin resonance and dye measurement, followed by cellular destruction and high tumor inhibition efficiency (85%). This knowledge is important from the perspective of understanding the structure-dependent SDT enhancement of a MOF-derived carbon nanostructure.

Environmental exposure and health risk upon engineered nanomaterials are increasingly concerned. The family of mesoporous carbon nanomaterials (MCNs) is a rising star in nanotechnology for multidisciplinary research with versatile applications in electronics, energy and gas storage, and biomedicine. Meanwhile, there is mounting concern on their environmental health risks due to the growing production and usage of MCNs. The lung is the primary site for particle invasion under environmental exposure to nanomaterials. Here, we studied the comprehensive toxicological profile of MCNs in the lung under the scenario of moderate environmental exposure. It was found that at a low concentration of 10μg/mL MCNs induced biophysical inhibition of natural pulmonary surfactant. Moreover, MCNs at similar concentrations reduced viability of J774A.1 macrophages and lung epithelial A549 cells. Incubating with nature pulmonary surfactant effectively reduced the cytotoxicity of MCNs. Regarding the pro-inflammatory responses, MCNs activated macrophages in vitro, and stimulated lung inflammation in mice after inhalation exposure, associated with lung fibrosis. Moreover, we found that the size of MCNs played a significant role in regulating cytotoxicity and pro-inflammatory potential of this nanomaterial. In general, larger MCNs induced more pronounced cytotoxic and pro-inflammatory effects than their smaller counterparts. Our results provided valuable information on the toxicological profile and environmental health risks of MCNs, and suggested that fine-tuning the size of MCNs could be a practical precautionary design strategy to increase safety and biocompatibility of this nanomaterial.