Electron Lock Manipulates the Catalytic Selectivity of Nanozyme

Co-assembly of antimicrobial polypeptoids/carbon dots for internal-external cooperated sterilization

Bacterial infections have emerged as a significant global public health challenge that requires urgent attention. In the research of popular antimicrobial agents, antimicrobial peptide mimics with good properties have the disadvantage of high toxicity, and nanomaterials with metal-doped carbon dots as the most representative have the problems of easy agglomeration and insufficient bactericidal effect. Herein, combined therapeutic strategy was proposed to reach the best compromise and sterilization effects. We employed an electrostatic co-assembly strategy to combine nanomaterials iron-doped carbon dots (Fe-CDs) and antimicrobial polypeptoids Poly(N-allylglycine) modified with thiol-terminated amines (PNAG66-NH2), resulting in the creation of the antimicrobial composite Fe-CDs-PNAG66-NH2. Through electrostatic adsorption, the composite disrupts the electrostatic environment of the bacterial outer membrane, alters its permeability, and triggers an increase in intracellular reactive oxygen species (ROS) to rapidly kill 99.999% of Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) within 10 min. It exhibited negligible cytotoxicity to normal cells. Furthermore, in vivo experiments demonstrated that Fe-CDs-PNAG66-NH2 accelerated the healing of infected wounds, reduced inflammation. The present study demonstrates that the efficient bactericidal properties of the complexes are triggered by the synergistic action of nanomaterials and antimicrobial polypeptoids, which provides a new strategy to achieve safe and efficient broad-spectrum bactericidal activity in antimicrobial aspects.

Multifunctional nanozymes for sonodynamic-enhanced immune checkpoint blockade therapy by inactivating PI3K/AKT signal pathway

Insufficient activation efficacy and tumor immunosuppressive microenvironments hinder the infiltration of cytotoxic T lymphocytes (CTLs) for effective immunotherapy. Herein, the pH-selective multienzyme-mimetic nanozymes have been developed based on Pd-hemoporfin (Pd0/Pd2+‒H) nanoagents for tumor sono-immunotherapy via the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway inactivation. The Pd0/Pd2+‒H is capable of catalase-mimetic, peroxidase-mimetic, and sonodynamic effects, creating an O2-rich environment and elevating the reactive oxygen species (ROS) levels. The elevated ROS levels down-regulate the expression of PI3K and p-AKT on both gene and protein levels, leading to PI3K/AKT pathway inactivation. Subsequently, the augmented immunogenic cell death effectively recruits dendritic cells, presents tumor-associated antigens, and activates antitumor T-cell immunity. As a result, the combination of Pd0/Pd2+‒H and anti-programmed cell death protein ligand 1 results in growth restraints of primary and precaution of tumor metastases. This work offers insights into developing multienzyme-mimetic nanozymes in signaling pathway regulation and antitumor strategy.

Acid-Triggered Charge-Switchable Antibacterial Hydrogel for Accelerated Healing of Gastric Mucosal Wounds

Infection with Helicobacter pylori (H. pylori) is a primary etiological factor for chronic gastritis, peptic ulcers, and gastric cancer. The limited specificity of antibiotics against H. pylori, combined with the risk of severe adverse events from endoscopic submucosal dissection (ESD), presents a major global health challenge in treating gastric mucosal injuries. To address this issue, we developed a targeted antibacterial hydrogel based on a charge-reversal amphiphilic molecule, designed for the harsh gastric acid environment and capable of immediate and strong adhesion. The hydrogel is composed of acryl aspartate (AASP) and cysteine-grafted carboxymethyl chitosan (CMCS-NAC) as the base matrix, integrated with gastric acid-responsive charge-reversal antibacterial molecules (C16N-DCA). Simulated studies show that C16N-DCA undergoes charge reversal under acidic conditions (pH 3), enabling targeted H. pylori eradication mediated by gastric acid, with 98% efficacy and sustained antibacterial activity for up to 36 h. In vitro and in vivo experiments in rodent and porcine models confirmed its safety and efficacy in acidic gastric conditions. This hydrogel offers strong tissue protection and effectively modulates the gastric wound microenvironment, facilitating wound healing and presenting an easily adoptable solution for gastric wound management.

Ligand-Engineering MoS2-Osmium Heterostructure as Highly Active and Specific Peroxidase-Mimic Nanozyme for Interference-Free and Multimode Biosensing

It is still a challenge to fabricate nanozymes with both of high catalytic activity and specificity. Herein, a ligand engineering method is developed to fabricate osmium (Os) nanocluster-Molybdenum disulfide (MoS2) heterostructure with superior peroxidase-specific activity. It has been verified that polyvinylpyrrolidone (PVP) as ligands can confine amorphous Os nanoclusters growing on the MoS2 nanosheet, mechanism studies indicated that PVP acts as appropriate size-limiting reagent and electronic transmission bridge between of Os and MoS2 which can synergistically improve the peroxidase-specific activity. Moreover, the ligand engineering will not affect the peroxidase-mimic specificity of MoS2-Os. Further, it is found that MoS2-Os possessed superior photothermal conversion efficiency, therefore, MoS2-Os can be used as colorimetric and photothermal dual-mode tags. MoS2-Os combined lateral flow strip is established for breast cancer HER2+ exosomes colorimetric and photothermal detection with superior sensitivity and broader liner range, MoS2-Os based interference-free salivary glucose biosensor is also established with a LOD of 0.1 µM, almost 100-fold sensitivity than that of Glucose Assay Kit. Therefore, this work developed a ligand-engineering strategy to regulate Os nanocluster on MoS2 and improve the peroxidase-specific activity, the multifunctional MoS2-Os nanozyme can be used for accurate and multimode biosensing in varies scenes.

Amino-Acid-Engineered Bionanozyme Selectivity for Colorimetric Detection of Human Serum Albumin

Nanozymes are emerging nanomaterials owing to their superior stability and enzyme-mimicking catalytic functions. However, unlike natural enzymes with inherent amino-acid-based recognition motifs for target interactions, manipulating nanozyme selectivity toward specific targets remains a major challenge. In this study, we introduce the de novo strategy using the supramolecular assembly of l-tryptophan (l-Trp) as the recognition amino acid with copper (Cu) ions for creating a human serum albumin (HSA)-responsive bionanozyme. This amino-acid-engineered bionanozyme enables selective colorimetric detection of HSA, a critical urinary biomarker for kidney diseases, overcoming the challenge that HSA is neither a typical substrate nor an inhibitor for most nanozymes. Kinetic studies and competitive tests reveal that HSA subdomain IIIA binding to l-Trp sites limits the electron-transfer-induced structural changes of l-Trp-Cu chelate rings, resulting in noncompetitive inhibition. This inhibition effect is significantly stronger than that observed for canonical amino acids, common proteins, and urinary interference species. Colorimetric monitoring of bionanozyme activity enables sensitive HSA detection with a detection limit of 1.3 nM and a quantification range of 2 nM to 10 μM. This approach is exceptionally more sensitive and offers a broader detection range compared to conventional colorimetric and fluorescent methods, suitable for diagnostics across various clinical stages of disease. This innovative rational strategy to designing and manipulating selective nanozyme-target interactions not only addresses the limitations of nanozymes but also expands their precise applications in complex biological systems.

Facile One-Pot Assembly of a Versatile Photoactive Nanozyme for Highly Efficient Antibacterial Therapy

Conventional combinational antibacterial therapy requires the complicated assembly of multiple components that might cause a premature leak of therapeutic agents. Thus the one-pot assembly of highly integrated multifunctional antibacterial agents is highly desirable for treating multidrug-resistant (MDR) bacteria. Herein, the vancomycin-derived carbon dots (Van-CDs) are facilely developed as a compact and powerful multifunctional photodynamic nanozyme platform that achieves the augmented reactive oxygen species (ROS) generation for accelerating bacterial elimination. By residual recognition groups of vancomycin, the red emissive Van-CDs gain a specific affinity toward bacteria with a high binding constant of 20 L g-1, manifesting a superior bacteria-imaging ability. Meanwhile, Van-CDs are encoded with an excellent peroxidase-mimicking (POD) activity for mediating the H2O2-activated evolvement of •OH, and also endowed with intrinsic photodynamic property for simultaneously producing singlet oxygen (1O2). Surprisingly, the photodynamic Van-CDs nanozyme possesses an auxiliary photothermal feature, which enables the photothermal imaging-guided hyperthermia-reinforced antibacterial therapy in vivo. Furthermore, a subcutaneous abscess model is established to validate their pronounced biofilm eradication and wound healing acceleration in vivo through the Van-CDs-promoted collagen deposition. Taken together, the present all-in-one compact photodynamic carbon-derived nanozyme with multiple intrinsic therapeutic functions represents a promising and competitive candidate for treating diabetic infections of clinical research.

Single-Atom Cu Anchored on Carbon Nitride as a Bifunctional Glucose Oxidase and Peroxidase Nanozyme for Antibacterial Therapy

A very promising strategy to avoid bacterial drug resistance is to replace antibiotics with artificial nanozymes, but this has not yet been translated to the clinic. Here, we construct a single-atom nanozyme using graphitic carbon nitride nanosheets modified by copper (Cu-g-C3N4). This Cu-g-C3N4 nanosheet possesses both glucose oxidase-like and peroxidase-like activities responsible for reactive-oxygen-species generation by a cascade reaction to eradicate Gram-positive and Gram-negative multidrug-resistant bacteria. Cu-g-C3N4 is introduced into polycaprolactone (PCL) by electrospinning to obtain (Cu-g-C3N4/PCL) nanofibers, which can be used as a dressing for bacterially infected wounds. It is demonstrated that Cu-g-C3N4/PCL nanofiber dressings can eradicate bacterial infections and accelerate wound healing in a mouse model with a skin wound.

Fine-Tuning Electron Transfer for Nanozyme Design

Nanozymes, with their versatile composition and structural adaptability, present distinct advantages over natural enzymes including heightened stability, customizable catalytic activity, cost-effectiveness, and simplified synthesis process, making them as promising alternatives in various applications. Recent advancements in nanozyme research have shifted focus from serendipitous discovery toward a more systematic approach, leveraging machine learning, theoretical calculations, and mechanistic explorations to engineer nanomaterial structures with tailored catalytic functions. Despite its pivotal role, electron transfer, a fundamental process in catalysis, has often been overlooked in previous reviews. This review comprehensively summarizes recent strategies for modulating electron transfer processes to fine-tune the catalytic activity and specificity of nanozymes, including electron-hole separation and carrier transfer. Furthermore, the bioapplications of these engineered nanozymes, including antimicrobial treatments, cancer therapy, and biosensing are also introduced. Ultimately, this review aims to offer invaluable insights for the design and synthesis of nanozymes with enhanced performance, thereby advancing the field of nanozyme research.

Recent Advances of Carbon Dots: Synthesis, Plants Applications, Prospects, and Challenges

Nanomaterials and nanotechnology have garnered significant attention in the realm of agricultural production. Carbon dots (CDs), as a class of nanomaterials, play a crucial role in the field of plant growth due to their excellent properties. This review aims to summarize recent achievements on CDs, focusing on their methods of preparation and applications in plants systems. The effects of CDs on seed germination, growth, photosynthesis, nutritional quality, and stress resistance were studied. It has been demonstrated that CDs can promote seed germination and growth, as well as improve photosynthetic efficiency, ultimately leading to increase plants yield. The nutritional quality of the plants treated with CDs was significantly improved. Specifically, the levels of essential mineral elements, vitamins, amino acids, and other constituents that are beneficial to human health increased notably. Additionally, CDs show positive effects on augmenting plant resistance against environmental stresses, such as drought conditions, heavy metal toxicity, and high salinity. Finally, the prospects and challenges of the application of CDs in plant systems are also discussed, which provide a scientific basis for the future application of CDs in agricultural production.

Design of acidic activation-responsive charge-switchable carbon dots and validation of their antimicrobial activity

Bacterial biofilms play a crucial role in the emergence of antibiotic resistance and the persistence of chronic infections. The challenge of effectively eradicating bacterial biofilms while ensuring minimal toxicity to normal cells persists. Carbon-based artificial nanoenzymes have attracted considerable attention as emerging nanotheranostic agents, owing to their biocompatibility, cost-effectiveness, and straightforward synthesis. In this study, we have developed a multifunctional carbon dots (CDs) system, specifically CDs functionalized with 1-(3-aminopropyl) imidazole (API), termed CDs-API. This system demonstrates acid-activated antibiofilm activity. The CDs-API were synthesized from chlorogenic acid (ChA), a bioactive compound naturally occurring in coffee, and subsequently functionalized with API to achieve charge-switchable properties under acidic conditions. This distinctive feature enables CDs-API to efficiently penetrate bacterial biofilms and selectively target the colonized bacteria. The enzyme-like activity of CDs-API effectively consumes high levels of glutathione (GSH) within the biofilm, leading to the accumulation of reactive oxygen species (ROS). Consequently, this process degrades the extracellular polymeric substance (EPS) matrix, damages bacterial DNA and protein structures, and disrupts the redox balance, ultimately leading to bacterial cell death. Experimental results demonstrated that CDs-API effectively inhibited the growth of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAE) while promoting wound healing with minimal damage to healthy tissues. The acid-activated charge-switchable capability of CDs-API provides superior antibacterial efficacy compared to traditional antibiotics, rendering it a promising candidate for the treatment of bacterial biofilm infections.

Donkey-Hide Gelatin-Derived Carbon Dots Activate Erythropoiesis and Eliminate Oxidative Stress for Aplastic Anemia Treatment

Aplastic anemia (AA) is a life-threatening hematologic disease with limited therapeutic options. Stalled erythropoiesis and oxidative stress-induced hemocyte apoptosis are the main pathological features of AA, yet therapeutic agents that address these issues remain elusive. In this study, we report distinctive donkey-hide gelatin-derived carbon dots (G-CDs) that enable erythropoiesis activation and oxidative stress elimination to tackle refractory AA. We demonstrate that G-CDs can promote the proliferation and erythroid differentiation of hematopoietic stem cells as well as erythrocyte maturation, activating the whole process of erythropoiesis. Moreover, G-CDs display multienzyme-like activities and dramatically alleviate the oxidative stress of bone marrow and peripheral blood via catalytic scavenging of multiple reactive oxygen species, reconstructing the hematopoietic microenvironment. Intravenously or orally administered to AA mice induced by chemotherapy drugs, G-CDs significantly boost the level of red blood cells and hemoglobin and lead to the complete recovery of hematopoietic function, showing better therapeutic performance than clinically approved erythropoietin (EPO) without adverse effects. By collaboratively addressing the issues of stalled erythropoiesis and oxidative stress, the G-CDs-based intervention strategy may offer a powerful paradigm for clinical AA management.

Interface-Engineered CuxO@Bi2MoO6 Heterojunctions to Inhibit Piezoelectric Screening Effect and Promote Double-Nanozyme Catalysis for Antibacterial Treatment

Sonodynamic therapy is confronted with the low acoustic efficiency of sonosensitizers, and nanozymes are accompanied by intrinsic low catalytic activity. Herein, to increase the piezopotential of N-type piezoelectric semiconductors, the P-N heterojunction is designed to inhibit the piezoelectric screening effect (PSE) and increase electron utilization efficiency to enhance nanozyme activity. P-type CuxO nanoparticles are in situ grown on N-type piezoelectric Bi2MoO6 (BMO) nanoflakes (NFs) to construct heterostructured CuxO@BMO by interface engineering. CuxO deposition leads to lattice distortion of BMO NFs to improve piezoelectric response, and the strong interface electric field (IEF) suppresses PSE and increases piezopotential. The nonlocal piezopotential, local IEF, and glutathione (GSH) inoculation enhances electron-hole separation and increases peroxidase (POD)-like activity of BMO and GSH oxidase (GSHOx)-like activity of CuxO with high selectivity. The heterojunction formation causes the transfer and rearrangement of interface electrons, and the increased piezopotential accelerates electron transfer at interfaces with bacteria, thus increasing the production of reactive oxidative species and interfering with adenosine triphosphate synthesis. The heterostructured nanozymes produce abundant intracellular ·OH and achieve 4log magnitude reductions in viable bacteria and effective biofilm dispersion. This study elucidates integral mechanisms of nanozyme and acoustic catalysis and opens up a new way to synergize high piezopotential and nanozyme-catalyzed therapy.

Kinetic Profiling of Oxidoreductase-Mimicking Nanozymes: Impact of Multiple Activities, Chemical Transformations, and Colloidal Stability

In contrast to homogeneous enzyme catalysis, nanozymes are nanosized heterogeneous catalysts that perform reactions on a rigid surface. This fundamental difference between enzymes and nanozymes is often overlooked in kinetic studies and practical applications. In this article, using 14 nanozymes of various compositions (core@shell, metal-organic frameworks, metal, and metal oxide nanoparticles), we systematically demonstrate that nontypical features of nanozymes, such as multiple catalytic activities, chemical transformations, and aggregation, need to be considered in nanozyme catalysis. Ignoring these features results in the inaccurate quantification of catalytic activity. Neglecting the multiple activities led to a six-time underestimation of Mn2O3 oxidation activity and mischaracterization of this material as a low-active peroxidase-mimicking nanozyme. Additionally, overlooking chemical stability during catalytic reactions led to the reporting of high peroxidase-mimicking activity for Au@Ag nanoparticles, which, in reality, exhibited no intrinsic activity and oxidized the substrate through the leakage of Ag+ ions. Ignoring the chemical stability of Au@Prussian Blue nanoparticles may lead to more than four times overestimation of peroxidase-mimicking activity after just 24 h of storage. Finally, disregarding the colloidal stability of nanozymes led to a five-time inaccuracy in catalytic activity. These findings underscore the necessity of optimizing procedures to account for these factors in nanozyme kinetic measurements, which will in turn ensure more reliable biosensors and the success of other practical applications.

A bioinspired sulfur-Fe-heme nanozyme with selective peroxidase-like activity for enhanced tumor chemotherapy

Iron-based nanozymes, recognized for their biocompatibility and peroxidase-like activities, hold promise as catalysts in tumor therapy. However, their concurrent catalase-like activity undermines therapeutic efficacy by converting hydrogen peroxide in tumor tissues into oxygen, thus diminishing hydroxyl radical production. Addressing this challenge, this study introduces the hemin-cysteine-Fe (HCFe) nanozyme, which exhibits exclusive peroxidase-like activity. Constructed through a supramolecular assembly approach involving Fmoc-L-cysteine, heme, and Fe²⁺ coordination, HCFe distinctly incorporates heme and [Fe-S] within its active center. Sulfur coordination to the central Fe atom of Hemin is crucial in modulating the catalytic preference of the HCFe nanozyme towards peroxidase-like activity. This unique mechanism distinguishes HCFe from other bifunctional iron-based nanozymes, enhancing its catalytic selectivity even beyond that of natural peroxidases. This selective activity allows HCFe to significantly elevate ROS production and exert cytotoxic effects, especially against cisplatin-resistant esophageal squamous cell carcinoma (ESCC) cells and their xenografts in female mice when combined with cisplatin. These findings underscore HCFe's potential as a crucial component in multimodal cancer therapy, notably in augmenting chemotherapy efficacy.

Safety Landscape of Therapeutic Nanozymes and Future Research Directions

Oxidative stress and inflammation are at the root of a multitude of diseases. Treatment of these conditions is often necessary but current standard therapies to fight excessive reactive oxygen species (ROS) and inflammation are often ineffective or complicated by substantial safety concerns. Nanozymes are emerging nanomaterials with intrinsic enzyme-like properties that hold great promise for effective cancer treatment, bacterial elimination, and anti-inflammatory/anti-oxidant therapy. While there is rapid progress in tailoring their catalytic activities as evidenced by the recent integration of single-atom catalysts (SACs) to create next-generation nanozymes with superior activity, selectivity, and stability, a better understanding and tuning of their safety profile is imperative for successful clinical translation. This review outlines the current applied safety assessment approaches and provides a comprehensive summary of the safety knowledge of therapeutic nanozymes. Overall, nanozymes so far show good in vitro and in vivo biocompatibility despite considerable differences in their composition and enzymatic activities. However, current safety investigations mostly cover a limited set of basic toxicological endpoints, which do not allow for a thorough and deep assessment. Ultimately, remaining research gaps that should be carefully addressed in future studies are highlighted, to optimize the safety profile of therapeutic nanozymes early in their pre-clinical development.

Fine-Tuning 2D Heterogeneous Channels for Charge-Lock Enhanced Lithium Separation from Brine

The extraction of lithium (Li) from complex brines presents significant challenges due to the interference of competing ions, particularly magnesium (Mg2⁺), which complicates the selective separation process. Herein, a strategy is introduced employing charge-lock enhanced 2D heterogeneous channels for the rapid and selective uptake of Li⁺. This approach integrates porous ZnFe2O4/ZnO nanosheets into Ag+-modulated sub-nanometer interlayer channels, forming channels optimized for Li⁺ extraction. The novelty lies in the charge-lock mechanism, which selectively captures Mg2⁺ ions, thereby facilitating the effective separation of Li from Mg. This mechanism is driven by a charge transfer during the formation of ZnFe2O4/ZnO, rendering O atoms in Fe-O bonds more negatively charged. These negative charges strongly interact with the high charge density of Mg2⁺ ions, enabling the charge-locking mechanism and the targeted capture of Mg2⁺. Optimization with Ag⁺ further improves interlayer spacing, increasing ion transport rates and addressing the swelling issue typical of 2D membranes. The resultant membrane showcases high water flux (44.37 L m⁻2 h⁻¹ bar⁻¹) and an impressive 99.8% rejection of Mg2⁺ in real brine conditions, achieving a Li⁺/Mg2⁺ selectivity of 59.3, surpassing existing brine separation membranes. Additionally, this membrane demonstrates superior cyclic stability, highlighting its high potential for industrial applications.

Nanozybiotics: Advancing Antimicrobial Strategies Through Biomimetic Mechanisms

Infectious diseases caused by bacterial, viral, and fungal pathogens present significant global health challenges. The rapid emergence of antimicrobial resistance exacerbates this issue, leading to a scenario where effective antibiotics are increasingly scarce. Traditional antibiotic development strategies are proving inadequate against the swift evolution of microbial resistance. Therefore, there is an urgent need to develop novel antimicrobial strategies with mechanisms distinct from those of existing antibiotics. Nanozybiotics, which are nanozyme-based antimicrobials, mimic the catalytic action of lysosomal enzymes in innate immune cells to kill infectious pathogens. This review reinforces the concept of nanozymes and provides a comprehensive summary of recent research advancements on potential antimicrobial candidates. Initially, nanozybiotics are categorized based on their activities, mimicking either oxidoreductase-like or hydrolase-like functions, thereby highlighting their superior mechanisms in combating antimicrobial resistance. The review then discusses the progress of nanozybiotics in treating bacterial, viral, and fungal infections, confirming their potential as novel antimicrobial candidates. The translational potential of nanozybiotic-based products, including hydrogels, nanorobots, sprays, bandages, masks, and protective clothing, is also considered. Finally, the current challenges and future prospects of nanozybiotic-related products are explored, emphasizing the design and antimicrobial capabilities of nanozybiotics for future applications.

Approach of a small protein to the biomimetic bis-(μ-oxo) dicopper active-site installed in MOF-808 pores with restricted access perturbs substrate selectivity of oxidase nanozyme

Advances in nanozymes have taken shape over the past few years in several domains. However, persisting challenging limitations of selectivity, specificity, and efficiency necessitate careful attention to aid in the development of next-generation artificial enzymes. Despite nanozymes having significant therapeutic and biotechnological prospects, the multienzyme mimetic activities can compromise their intended applications. Furthermore, the lack of substrate selectivity can hamper crucial biological pathways. While working on addressing the challenges of nanozymes, in this work, we aim to highlight the interplay between the substrates and bis-(μ-oxo) dicopper active site-installed MOF-808 for selectively mimicking oxidase. This oxidase mimetic with a small pore-aperture (1.4 nm), similar to the opening of enzyme binding pockets, projects a tight control over the dynamics and the reactivity of substrates, making it distinct from the general oxidase nanozymes. Interestingly, the design and the well-regulated activity of this nanozyme effectively thwart DNA from approaching the active site, thereby preventing its oxidative damage. Crucially, we also show that despite these merits, the oxidase selectivity is compromised by small proteins such as cytochrome c (Cyt c), having dimensions larger than the pore aperture of MOF-808. This reaction lucidly produces water molecules as a result of four electron transfer to an oxygen molecule. Such unintended side reactivities warrant special attention as they can perturb redox processes and several cellular energy pathways. Through this study, we provide a close look at designing next-generation artificial enzymes that can address the complex challenges for their utility in advanced applications.

Enzyme-loaded manganese-porphyrin metal-organic nanoframeworks for oxygen-evolving photodynamic therapy of hypoxic cells

Photodynamic therapy (PDT) is attracting great attention for cancer treatments, while its therapeutic efficacy is limited by unsatisfactory photosensitizers and hypoxic tumor microenvironment (TME). To address these problems, we have developed catalase-loaded manganese-porphyrin frameworks (CAT@MnPFs) for catalytically-assisted PDT of cancer cells. CAT@MnPFs were constructed by the assembly of Mn2+ ions and PpIX into MnPFs and the subsequent loading of catalase. Under 650 nm light irradiation, the porphyrin (Protoporphyrin IX) within the structure of CAT@MnPFs can convert oxygen (O2) into singlet oxygen (1O2), showing the photodynamic effect. Importantly, the loaded catalase can decompose hydrogen peroxide (H2O2) into O2 with a huge elevation of O2 level (13.22 mg L-1) in 600 s, thus promoting 1O2 generation via PDT. As a result, CAT@MnPFs combined with 650 nm light can effectively ablate cancer cells due to the catalase-assisted oxygen-evolving PDT, showing a high therapeutic efficacy. Meanwhile, after the incubation with CAT@MnPFs, unobvious damage can be found in normal and red blood cells. Thus, the obtained CAT@MnPFs integrate the advantage of photosensitizers and catalase for oxygen-evolving PDT, which can provide some insight for treating hypoxic cells.

"Three-in-One" Plasmonic Au@PtOs Nanocluster Driven Lateral Flow Assay for Multimodal Cancer Exosome Biosensing

Exploiting the multiple properties of nanozymes for the multimode lateral flow assay (LFA) is urgently required to improve the accuracy and versatility. Herein, we developed a novel plasmonic Au nanostar@PtOs nanocluster (Au@PtOs) as a multimode signal tag for LFA detection. Based on the PtOs bimetallic nanocluster doping strategy, Au@PtOs can indicate both excellent SERS enhancement and nanozyme catalytic activity. Meanwhile, Au@PtOs displays a better photothermal effect than that of Au nanostars. Therefore, catalytic colorimetric/SERS/temperature three-mode signals can be read out based on the Au@PtOs nanocomposite. The Au@PtOs was combined with LFA and applied for breast cancer exosome detection. The detection limit for the colorimetric/SERS/temperature mode was 2.6 × 103/4.1 × 101/4.6 × 102 exosomes/μL, respectively, which was much superior to the common Au nanoparticles LFA (∼105 exosomes/μL). Moreover, based on the fingerprint molecular recognition ability of the SERS mode, exosome phenotypes derived from different breast cancer cell lines can be discriminated easily. Based on the convenient visual colorimetric mode and sensitive SERS/temperature quantitative modes, Au@PtOs driven LFA can satisfy the requirements of accurate and flexible multimodal sensing in different application scenarios.

Bacterial lipase-responsive polydopamine nanoparticles for detection and synergistic therapy of wound biofilms infection

Wound biofilms represent an elusive conundrum in contemporary treatment and diagnostic options, accredited to their escalating antibiotic resistance and interference in chronic wound healing processes. Here, we developed mesoporous polydopamine (mPDA) nanoparticles, and grafted with rhodamine B (Rb) as biofilm lipase responsive detection probe, followed by π - π stacking mediated ciprofloxacin (CIP) loading to create mP-Rb@CIP nanoparticles. mPDA NPs with a melanin structure could quench fluorescence emissions of Rb. Once encountering biofilm in vivo, the ester bond in Rb and mPDA is hydrolyzed by elevated lipase concentrations, triggering the liberation of Rb and restore fluorescence emissions to achieve real-time imaging of biofilm-infected wounds. Afterwards, the 808 nm near-infrared (NIR) illumination initiates a spatiotemporal controlled antibacterial photothermal therapy (PTT), boosting its effectiveness through photothermal-triggered CIP release for synergistic biofilm eradication. The mP-Rb@CIP platform exhibits dual diagnostic and therapeutic functions, efficaciously treating biofilm-infected wounds in vivo and in vitro. Particularly, the mP-Rb@CIP/NIR procedure expedites wound-healing by alleviating oxidative stress, modulating inflammatory mediators, boosting collagen synthesis, and promoting angiogenesis. Taken together, the theranostic nanosystem strategy holds significant potential for addressing wound biofilm-associated infections.

Amino acid-based metallo-supramolecular nanoassemblies capable of regulating cellular redox homeostasis for tumoricidal chemo-/photo-/catalytic combination therapy

Nanozymes, as nanomaterials with natural enzyme activities, have been widely applied to deliver various therapeutic agents to synergistically combat the progression of malignant tumors. However, currently common inorganic nanozyme-based drug delivery systems still face challenges such as suboptimal biosafety, inadequate stability, and inferior tumor selectivity. Herein, a super-stable amino acid-based metallo-supramolecular nanoassembly (FPIC NPs) with peroxidase (POD)- and glutathione oxidase (GSHOx)-like activities was fabricated via Pt4+-driven coordination co-assembly of l-cysteine derivatives, the chemotherapeutic drug curcumin (Cur), and the photosensitizer indocyanine green (ICG). The superior POD- and GSHOx-like activities could not only catalyze the decomposition of endogenous hydrogen peroxide into massive hydroxyl radicals, but also deplete the overproduced glutathione (GSH) in cancer cells to weaken intracellular antioxidant defenses. Meanwhile, FPIC NPs would undergo degradation in response to GSH to specifically release Cur, causing efficient mitochondrial damage. In addition, FPIC NPs intrinsically enable fluorescence/photoacoustic imaging to visualize tumor accumulation of encapsulated ICG in real time, thereby determining an appropriate treatment time point for tumoricidal photothermal (PTT)/photodynamic therapy (PDT). In vitro and in vivo findings demonstrated the quadruple orchestration of catalytic therapy, chemotherapeutics, PTT, and PDT offers conspicuous antineoplastic effects with minimal side reactions. This work may provide novel ideas for designing supramolecular nanoassemblies with multiple enzymatic activities and therapeutic functions, allowing for wider applications of nanozymes and nanoassemblies in biomedicine.