Plasmonic Nanozymes: Leveraging Localized Surface Plasmon Resonance to Boost the Enzyme-Mimicking Activity of Nanomaterials

Cascade enzyme-mimicking with spatially separated gold-ceria for dual-mode detection of superoxide anions

Metal-semiconductor nanozyme of dumbbell Au-CeO2 with spatially separated heterostructure has cascade superoxide dismutase (SOD)-like and peroxidase (POD)-like activities for superoxide anions detection. It was synthesized by selective growth of CeO2 at the ends of Au nanorod (Au NR). Taking advantage of the excellent local surface plasmon resonance (LSPR) effect of Au NR, the spatially separated Au-CeO2 has a higher photothermal effect than the continuously growing core-shell structure of Au@CeO2. Meanwhile, the hot electrons of Au NR could transfer to CeO2 under 808 nm laser irradiation, changing the ratio of Ce3+/Ce4+ redox couples over CeO2 and facilitating H2O2 decomposition thus enhancing POD-like activity. Based on the SOD-like activity of Au-CeO2, superoxide anion (O2·-) can be transformed into hydrogen peroxide (H2O2). Dual-mode including absorbance and temperature sensing detection of O2·-, with the detection range from nM to μM i.e., 0.1-150 μM and LOD of 0.033 μM (S/N = 3) was achieved through the cascade catalysis and photothermal effect. The as-proposed method was applicable to both cancer and normal cell samples with satisfactory accuracy and recovery.

Penetrative Ionic Organic Molecular Cage Nanozyme for the Targeted Treatment of Keratomycosis

Keratomycosis, caused by pathogenic fungi, is an intractable blinding eye disease. Corneal penetration is an essential requirement for conventional antifungal medications to address keratomycosis. Due to the distinctive anatomical and physiological structure of the cornea, the therapeutic efficacy is hampered by the inadequate penetration capacity. Despite the emergence of diverse antifungal drug delivery systems and advanced antifungal nanomaterials, it has remained challenging to achieve corneal penetration over the past decade. This study fabricates a penetrative ionic organic molecular cage-based nanozyme (OMCzyme) for treating keratomycosis. The synthesis of OMCzyme involved two steps. Initially, the ionic OMC is synthesized by a [2+3] cycloimination reaction of triformylphloroglucinol and 2,3-diaminopropionic acid. Subsequently, OMCzyme is fabricated by coordination of Fe2⁺ with carboxyl anions and phenolic hydroxyls in the organic cage, and further deposition of silver nanoparticles on the surface of OMC-Fe complex. The as-prepared OMCzyme demonstrates excellent water dispersion, peroxidase-like activity, in vitro and in vivo biocompatibility, and corneal penetration. Notably, the nanozyme displays targeted antifungal activity, effectively combating Fusarium solani with negligible cytotoxicity toward human corneal epithelial cells. The hybrid mimic is further demonstrated to be effective in treating keratomycosis in mice, indicating the potential of OMCzyme for curing fungal infectious diseases.

Point-of-care testing of Pseudomonas aeruginosa using PCN-222(Pt) prepared by nanoconfinement-guided protocol to catalyze gas generation reaction

BACKGROUND

Pathogenic bacteria are keeping threatening global public health since they can cause many infectious diseases. The traditional microorganism identification and molecular diagnostic techniques are insufficiently sensitive, time-consuming, or expensive. Thus it is of great interest to establish pressure signal-based sensing platforms for point-of-care testing of pathogenic bacteria to achieve timely diagnosis of infectious diseases. Rational design and synthesis of nano-sized probes with high peroxidase-mimicking activity have been a long-term cherished goal for improving the sensitivity of pressure signal-based sensing methods.

RESULTS

Guided by nanoconfinement effect, PCN-222(Pt) was prepared by confining Pt clusters within the channels of a zirconium porphyrin MOFs material termed as PCN-222. In comparison to regular platinum nanoparticles, palladium@platinum core-shell nanodendrites, and platinum-coated gold nanoparticles, the prepared PCN-222(Pt) displayed superior peroxidase-mimicking activity with outstanding efficiency for catalyzing the decay of H2O2 to produce O2. Thus it was used as a pressure signal probe to establish a sensitive method on a hydrogel pellets platform for analyzing Pseudomonas aeruginosa (P. aeruginosa), for which polymyxin B and a phage termed as JZ1 were used as recognition agents for the target pathogen. P. aeruginosa was quantified with a handheld pressure meter within a broad range of 2.2 × 102-2.2 × 107 cfu mL-1. This method was used to quantify P. aeruginosa in various biological and food samples with acceptable accuracy and reliability.

SIGNIFICANCE

The proposed nanoconfinement-guided protocol provides a novel approach for rational design and preparation of nano-sized probes with high peroxidase-mimicking activity for catalyzing gas-generation reaction. Thus this study opens an avenue for establishment of sensitive pressure signal-based sensing methods for pathogenic bacteria, which shows broad application prospects in medical diagnosis of infectious diseases.

NIR-II-Responsive Versatile Nanozyme Based on H2O2 Cycling and Disrupting Cellular Redox Homeostasis for Enhanced Synergistic Cancer Therapy

Disturbing cellular redox homeostasis within malignant cells, particularly improving reactive oxygen species (ROS), is one of the effective strategies for cancer therapy. The ROS generation based on nanozymes presents a promising strategy for cancer treatment. However, the therapeutic efficacy is limited due to the insufficient catalytic activity of nanozymes or their high dependence on hydrogen peroxide (H2O2) or oxygen. Herein, we reported a nanozyme (CSA) based on well-defined CuSe hollow nanocubes (CS) uniformly covered with Ag nanoparticles (AgNPs) to disturb cellular redox homeostasis and catalyze a cascade of intracellular biochemical reactions to produce ROS for the synergistic therapy of breast cancer. In this system, CSA could interact with the thioredoxin reductase (TrxR) and deplete the tumor microenvironment-activated glutathione (GSH), disrupting the cellular antioxidant defense system and augmenting ROS generation. Besides, CSA possessed high peroxidase-mimicking activity toward H2O2, leading to the generation of various ROS including hydroxyl radical (•OH), superoxide radicals (•O2-), and singlet oxygen (1O2), facilitated by the Cu(II)/Cu(I) redox and H2O2 cycling, and plentiful catalytically active metal sites. Additionally, due to the absorption and charge separation performance of AgNPs, the CSA exhibited excellent photothermal performance in the second near-infrared (NIR-II, 1064 nm) region and enhanced the photocatalytic ROS level in cancer cells. Owing to the inhibition of TrxR activity, GSH depletion, high peroxidase-mimicking activity of CSA, and abundant ROS generation, CSA displays remarkable and specific inhibition of tumor growth.

Applications of Nanozymes in Chiral-Molecule Recognition through Electrochemical and Ultraviolet-Visible Analysis

Chiral molecules have similar physicochemical properties, which are different in terms of physiological activities and toxicities, rendering their differentiation and recognition highly significant. Nanozymes, which are nanomaterials with inherent enzyme-like activities, have garnered significant interest owing to their high cost-effectiveness, enhanced stability, and straightforward synthesis. However, constructing nanozymes with high activity and enantioselectivity remains a significant challenge. This review briefly introduces the synthesis methods of chiral nanozymes and systematically summarizes the latest research progress in enantioselective recognition of chiral molecules based on electrochemical methods and ultraviolet-visible absorption spectroscopy. Moreover, the challenges and development trends in developing enantioselective nanozymes are discussed. It is expected that this review will provide new ideas for the design of multifunctional chiral nanozymes and broaden the application field of nanozymes.

Elucidating the catalytic mechanism of Prussian blue nanozymes with self-increasing catalytic activity

Although Prussian blue nanozymes (PBNZ) are widely applied in various fields, their catalytic mechanisms remain elusive. Here, we investigate the long-term catalytic performance of PBNZ as peroxidase (POD) and catalase (CAT) mimetics to elucidate their lifespan and underlying mechanisms. Unlike our previously reported Fe3O4 nanozymes, which exhibit depletable POD-like activity, the POD and CAT-like activities of PBNZ not only persist but slightly enhance over prolonged catalysis. We demonstrate that the irreversible oxidation of PBNZ significantly promotes catalysis, leading to self-increasing catalytic activities. The catalytic process of the pre-oxidized PBNZ can be initiated through either the conduction band pathway or the valence band pathway. In summary, we reveal that PBNZ follows a dual-path electron transfer mechanism during the POD and CAT-like catalysis, offering the advantage of a long service life.

Organic-Inorganic Heterointerface-Expediting Electron Transfer Realizes Efficient Plasmonic Catalytic Sterilization via a Carbon-Dot Nanozyme

Plasmonic nanozymes bring enticing prospects for catalytic sterilization by leveraging plasmon-engendered hot electrons. However, the interface between plasmons and nanozymes as the mandatory path of hot electrons receives little attention, and the mechanisms of plasmonic nanozymes still remain to be elucidated. Herein, a plasmonic carbon-dot nanozyme (FeCG) is developed by electrostatically assembling catalytic iron-doped carbon dots (Fe-CDs) with plasmonic gold nanorods. The energy harvesting and hot-electron migration are remarkably expedited by a spontaneous organic-inorganic heterointerface holding a Fermi level-induced interfacial electric field. The accumulated hot electrons are then fully utilized by conductive Fe-CDs to boost enzymatic catalysis toward overproduced reactive oxygen species. By synergizing with localized heating from hot-electron decay, FeCG achieves rapid and potent disinfection with an antibacterial efficiency of 99.6% on Escherichia coli within 5 min and is also effective (94.2%) against Staphylococcus aureus. Our work presents crucial insights into the organic-inorganic heterointerface in advanced plasmonic biocidal nanozymes.

Nanozyme-Based Regulation of Cellular Metabolism and Their Applications

Metabolism is the sum of the enzyme-dependent chemical reactions, which produces energy in catabolic process and synthesizes biomass in anabolic process, exhibiting high similarity in mammalian cell, microbial cell, and plant cell. Consequently, the loss or gain of metabolic enzyme activity greatly affects cellular metabolism. Nanozymes, as emerging enzyme mimics with diverse functions and adjustable catalytic activities, have shown attractive potential for metabolic regulation. Although the basic metabolic tasks are highly similar for the cells from different species, the concrete metabolic pathway varies with the intracellular structure of different species. Here, the basic metabolism in living organisms is described and the similarities and differences in the metabolic pathways among mammalian, microbial, and plant cells and the regulation mechanism are discussed. The recent progress on regulation of cellular metabolism mainly including nutrient uptake and utilization, energy production, and the accompanied redox reactions by different kinds of oxidoreductases and their applications in the field of disease therapy, antimicrobial therapy, and sustainable agriculture is systematically reviewed. Furthermore, the prospects and challenges of nanozymes in regulating cell metabolism are also discussed, which broaden their application scenarios.

Advanced nanozymes possess peroxidase-like catalytic activities in biomedical and antibacterial fields: review and progress

Infectious diseases caused by bacterial invasions have imposed a significant global health and economic burden. More worryingly, multidrug-resistant (MDR) pathogenic bacteria born under the abuse of antibiotics have further escalated the status quo. Nowadays, at the crossroads of multiple disciplines such as chemistry, nanoscience and biomedicine, nanozymes, as enzyme-mimicking nanomaterials, not only possess excellent bactericidal ability but also reduce the possibility of inducing resistance. Thus, nanozymes are promising to serve as an alternative to traditional antibiotics. Nanozymes that mimic peroxidase (POD) activity are also known as POD nanozymes. In recent years, POD nanozymes have become one of the most frequently reported and effective nanozymes due to their broad-spectrum bactericidal properties and unique sterilization mechanism. In this review, we introduce the mechanism as well as the classification of POD nanozymes. More importantly, to further improve the antibacterial efficacy of POD nanozymes, we elaborate on three aspects: (1) improving the physicochemical properties; (2) regulating the catalytic microenvironment; and (3) designing multimodel POD nanozymes. In addition, we review the nanosafety of POD nanozymes for discussing their potential toxicity. Finally, the remaining challenges of POD nanozymes and possible future directions are discussed. This work provides a systematic summary of POD nanozymes and hopefully contributes to the early clinical translation.

A Mechanism Underpinning the Bioenergetic Metabolism-Regulating Function of Gold Nanocatalysts

Bioenergetic deficits are known to be significant contributors to neurodegenerative diseases. Nevertheless, identifying safe and effective means to address intracellular bioenergetic deficits remains a significant challenge. This work provides mechanistic insights into the energy metabolism-regulating function of colloidal Au nanocrystals, referred to as CNM-Au8, that are synthesized electrochemically in the absence of surface-capping organic ligands. When neurons are subjected to excitotoxic stressors or toxic peptides, treatment of neurons with CNM-Au8 results in dose-dependent neuronal survival and neurite network preservation across multiple neuronal subtypes. CNM-Au8 efficiently catalyzes the conversion of an energetic cofactor, nicotinamide adenine dinucleotide hydride (NADH), into its oxidized counterpart (NAD+ ), which promotes bioenergy production by regulating the intracellular level of adenosine triphosphate. Detailed kinetic measurements reveal that CNM-Au8-catalyzed NADH oxidation obeys Michaelis-Menten kinetics and exhibits pH-dependent kinetic profiles. Photoexcited charge carriers and photothermal effect, which result from optical excitations and decay of the plasmonic electron oscillations or the interband electronic transitions in CNM-Au8, are further harnessed as unique leverages to modulate reaction kinetics. As exemplified by this work, Au nanocrystals with deliberately tailored structures and surfactant-free clean surfaces hold great promise for developing next-generation therapeutic agents for neurodegenerative diseases.

Electron Lock Manipulates the Catalytic Selectivity of Nanozyme

Nanomaterials with enzyme-mimicking functions, termed nanozymes, offer attractive opportunities for biocatalysis and biomedicine. However, manipulating nanozyme selectivity poses an insurmountable hurdle. Here, we propose the concept of an energy-governed electron lock that controls electron transfer between nanozyme and substrates to achieve selectivity manipulation of enzyme-like catalysis. An electron lock can be constructed and opened, via modulating the nanozyme's electron energy to match the energy barrier of enzymatic reactions. An iron-doped carbon dot (FeCD) nanozyme with easy-to-regulate electron energy is selected as a proof of concept. Through regulating the conduction band which dominates electron energy, activatable oxidase and selective peroxidase (POD) with substrate affinity 123-fold higher than that of natural horseradish peroxidase (HRP) is achieved. Furthermore, while maintaining selectivity, FeCDs exhibit catalytic kinetics comparable to that of HRP upon transforming photons into electrons. Superior selectivity, efficient catalysis, and undetectable biotoxicity energize FeCDs as potent targeted drugs on antibiotic-resistant bacterial abscesses. An electron lock provides a robust strategy to manipulate selectivity toward advanced nanozymes.

Accumulation of Ag(0) Single Atoms at Water/Mineral Interfaces during Sunlight-Induced Reduction of Ionic Ag by Phenolic DOM

Silver (Ag) undergoes a complex and dynamic Ag+/Ag0 cycle under environmental conditions. The Ag+ → Ag nanoparticles (AgNPs) transformation due to the combined actions of sunlight, O2, and dissolved organic matter has been a well-known environmental phenomenon. In this study, we indicate that this process may be accompanied by a pronounced accumulation of Ag(0) single atoms (Ag-SAs) on the minerals' surfaces. According to spherical aberration-corrected scanning transmission electron microscopy and high-energy-resolution X-ray adsorption fine structure analyses, humic acid (HA) and phenol (PhOH) can induce Ag-SAs accumulation, whereas oxalic acid causes only AgNPs deposition. Ag-SAs account for more than 20 wt % of total Ag(0) on the γ-Al2O3 surfaces during HA- and PhOH-mediated photolysis processes. HA also causes Ag-SAs to accumulate on two other prevalent soil minerals, SiO2 and Fe2O3, and the fractions of Ag-SAs are about 15 wt %. Our mechanism studies suggest that a phenolic molecule acts as a reducing agent of Ag+ and a stabilizer of Ag-SAs, protecting Ag-SAs against autocatalytic nucleation.

Plasmonic nanobipyramids with photo-enhanced catalytic activity under near-infrared II window for effective treatment of breast cancer

Nanozyme-based catalytic therapy is an effective method for cancer treatment, but insufficient catalytic activity presents a challenge in achieving optimal therapeutic outcomes. External light can provide an innovative approach to modulate nanozyme catalytic activity. Herein, we report on plasmonic gold nanobipyramid@cuprous oxide (Au NBP@Cu2O) nanozyme for the effective phototherapy of breast cancer. In the tumor microenvironment, Cu+-mediated Fenton-like reaction catalyzes the generation of toxic hydroxyl radicals (•OH) from endogenous hydrogen peroxide to induce apoptosis. Additionally, the Au NBP@Cu2O nanostructure improves the absorption performance of Au NBPs in the near-infrared II region through near-field enhancement of equipartite exciters and achieves a high photothermal conversion efficiency value of 58%. Remarkably, the Au NBP@Cu2O nanoheterostructure can capture hot electrons induced by equipartition excitations and promote electron-hole separation under 1064 nm laser irradiation, facilitating the production of more reactive oxygen species (ROS). The mechanism behind this enhanced catalytic activity was unraveled using femtosecond transient absorption spectroscopy. Both in vitro and in vivo investigations have demonstrated the efficacious tumor therapeutic potential of Au NBP@Cu2O nanozyme, particularly under 1064 nm laser irradiation. Furthermore, the proposed therapeutic approach has been proved to effectively block tumor metastasis, providing a promising strategy for the development of multifunctional nanotherapeutics to tackle metastatic tumors. STATEMENT OF SIGNIFICANCE: A highly effective plasmonic nanozyme has been developed to improve catalytic therapy for breast cancer. When exposed to 1064 nm laser irradiation, Au NBP@Cu2O nanozyme can promote the separation of hot electrons and holes thereby facilitating the production of reactive oxygen species. Hot electrons transfer behavior is unveiled by femtosecond transient absorption spectroscopy technique. This enhanced catalytic activity, along with the intrinsic photothermal effect, effectively kills tumor cells.

A comprehensive exploration of the latest innovations for advancements in enhancing selectivity of nanozymes for theranostic nanoplatforms

Nanozymes have captured significant attention as a versatile and promising alternative to natural enzymes in catalytic applications, with wide-ranging implications for both diagnosis and therapy. However, the limited selectivity exhibited by many nanozymes presents challenges to their efficacy in diagnosis and raises concerns regarding their impact on the progression of disease treatments. In this article, we explore the latest innovations aimed at enhancing the selectivity of nanozymes, thereby expanding their applications in theranostic nanoplatforms. We place paramount importance on the critical development of highly selective nanozymes and present innovative strategies that have yielded remarkable outcomes in augmenting selectivities. The strategies encompass enhancements in analyte selectivity by incorporating recognition units, refining activity selectivity through the meticulous control of structural and elemental composition, integrating synergistic materials, fabricating selective nanomaterials, and comprehensively fine-tuning selectivity via approaches such as surface modification, cascade nanozyme systems, and manipulation of external stimuli. Additionally, we propose optimized approaches to propel the further advancement of these tailored nanozymes while considering the limitations associated with existing techniques. Our ultimate objective is to present a comprehensive solution that effectively addresses the limitations attributed to non-selective nanozymes, thus unlocking the full potential of these catalytic systems in the realm of theranostics.

Uniform Gold Nanostructure Formation via Weakly Adsorbed Gold Films and Thermal Annealing for Reliable Localized Surface Plasmon Resonance-Based Detection of DNase-I

Deoxyribonuclease-I (DNase-I), a representative endonuclease, is an important biomarker for the diagnosis of infectious diseases and cancer progression. However, enzymatic activity decreases rapidly ex vivo, which highlights the need for precise on-site detection of DNase-I. Here, a localized surface plasmon resonance (LSPR) biosensor that enables the simple and rapid detection of DNase-I is reported. Moreover, a novel technique named electrochemical deposition and mild thermal annealing (EDMIT) is applied to overcome signal variations. By taking advantage of the low adhesion of gold clusters on indium tin oxide substrates, both the uniformity and sphericity of gold nanoparticles are increased under mild thermal annealing conditions via coalescence and Ostwald ripening. This ultimately results in an approximately 15-fold decrease in LSPR signal variations. The linear range of the fabricated sensor is 20-1000 ng mL-1 with a limit of detection (LOD) of 127.25 pg mL-1 , as demonstrated by spectral absorbance analyses. The fabricated LSPR sensor stably measured DNase-I concentrations from samples collected from both an inflammatory bowel disease (IBD) mouse model, as well as human patients with severe COVID-19 symptoms. Therefore, the proposed LSPR sensor fabricated via the EDMIT method can be used for early diagnosis of other infectious diseases.

Ultrasound-Augmented Multienzyme-like Nanozyme Hydrogel Spray for Promoting Diabetic Wound Healing

Treatment of diabetic foot ulcers (DFU) needs to reduce inflammation, relieve hypoxia, lower blood glucose, promote angiogenesis, and eliminate pathogenic bacteria, but the therapeutic efficacy is greatly limited by the diversity and synergy of drug functions as well as the DFU microenvironment itself. Herein, an ultrasound-augmented multienzyme-like nanozyme hydrogel spray was developed using hyaluronic acid encapsulated l-arginine and ultrasmall gold nanoparticles and Cu1.6O nanoparticles coloaded phosphorus doped graphitic carbon nitride nanosheets (ACPCAH). This nanozyme hydrogel spray possesses five types of enzyme-like activities, including superoxide dismutase (SOD)-, catalase (CAT)-, glucose oxidase (GOx)-, peroxidase (POD)-, and nitric oxide synthase (NOS)-like activities. The kinetics and reaction mechanism of the sonodynamic/sonothermal synergistic enhancement of the SOD-CAT-GOx-POD/NOS cascade reaction of ACPCAH are fully investigated. Both in vitro and in vivo tests demonstrate that this nanozyme hydrogel spray can be activated by the DFU microenvironment to reduce inflammation, relieve hypoxia, lower blood glucose, promote angiogenesis, and eliminate pathogenic bacteria, thus accelerating diabetic wound healing effectively. This study highlights a competitive approach based on multienzyme-like nanozymes for the development of all-in-one DFU therapies.

Single-Nanoparticle-Level Understanding of Oxidase-like Activity of Au Nanoparticles on Polymer Nanobrush-Based Proton Reservoirs

Enzyme-mimicking nanoparticles play a key role in important catalytic processes, from biosensing to energy conversion. Therefore, understanding and tuning their performance is crucial for making further progress in biological applications. We developed an efficient and sensitive electrochemical method for the real-time monitoring of the glucose oxidase (GOD)-like activity of single nanoparticle through collision events. Using brush-like sulfonate (-SO3-)-doped polyaniline (PANI) decorated on TiO2 nanotube arrays (TiNTs-SPANI) as the electrode, we fabricated a proton reservoir with excellent response and high proton-storage capacity for evaluating the oxidase-like activity of individual Au nanoparticles (AuNPs) via instantaneous collision processes. Using glucose electrocatalysis as a model reaction system, the GOD-like activity of individual AuNPs could be directly monitored via electrochemical tests through the nanoparticle collision-induced proton generation. Furthermore, based on the perturbation of the electrical double layer of SPANI induced by proton injection, we investigated the relationship between the measured GOD-like activities of the plasmonic nanoparticles (NPs) and the localized surface plasmon resonance (LSPR) as well as the environment temperature. This work introduces an efficient platform for understanding and characterizing the catalytic activities of nanozymes at the single-nanoparticle level.

Recent progress in nanozymes for the treatment of diabetic wounds

The slow healing of diabetic wounds has seriously affected human health. Meanwhile, the open wounds are susceptible to bacterial infection. Clinical therapeutic methods such as antibiotic therapy, insulin treatment, and surgical debridement have made great achievements in the treatment of diabetic wounds. However, drug-resistant bacteria will develop after long-term use of antibiotics, resulting in decreased efficacy. To improve the therapeutic effect, increasing drug concentration is a common strategy in clinical practice, but it also brings serious side effects. In addition, hyperglycemia control or surgical debridement can easily bring negative effects to patients, such as hypoglycemia or damage of normal tissue. Therefore, it is essential to develop novel therapeutic strategies to effectively promote diabetic wound healing. In recent years, nanozyme-based diabetic wound therapeutic systems have received extensive attention because they possess the advantages of nanomaterials and natural enzymes. For example, nanozymes have the advantages of a small size and a high surface area to volume ratio, which can enhance the tissue penetration of nanozymes and increase the reactive active sites. Moreover, compared with natural enzymes, nanozymes have more stable catalytic activity, lower production cost, and stronger operability. In this review, we first reviewed the basic characteristics of diabetic wounds and then elaborated on the catalytic mechanism and action principle of different types of nanozymes in diabetic wounds from three aspects: controlling bacterial infection, controlling hyperglycemia, and relieving inflammation. Finally, the challenges, prospects and future implementation of nanozymes for diabetic wound healing are outlined.

Copper-Zinc Bimetallic Single-Atom Catalysts with Localized Surface Plasmon Resonance-Enhanced Photothermal Effect and Catalytic Activity for Melanoma Treatment and Wound-Healing

Nanomaterials with photothermal combined chemodynamic therapy (PTT-CDT) have attracted the attention of researchers owing to their excellent synergistic therapeutic effects on tumors. Thus, the preparation of multifunctional materials with higher photothermal conversion efficiency and catalytic activity can achieve better synergistic therapeutic effects for melanoma. In this study, a Cu-Zn bimetallic single-atom (Cu/PMCS) is constructed with augmented photothermal effect and catalytic activity due to the localized surface plasmon resonance (LSPR) effect. Density functional theory calculations confirmed that the enhanced photothermal effect of Cu/PMCS is due to the appearance of a new d-orbital transition with strong spin-orbit coupling and the induced LSPR. Additionally, Cu/PMCS exhibited increased catalytic activity in the Fenton-like reaction and glutathione depletion capacity, further enhanced by increased temperature and LSPR. Consequently, Cu/PMCS induced better synergistic anti-melanoma effects via PTT-CDT than PMCS in vitro and in vivo. Furthermore, compared with PMCS, Cu/PMCS killed bacteria more quickly and effectively, thus facilitating wound healing owing to the enhanced photothermal effect and slow release of Cu2+ . Cu/PMCS promoted cell migration and angiogenesis and upregulated the expression of related genes to accelerate wound healing. Cu/PMCS has potential applications in treating melanoma and repairing wounds with its antitumor, antibacterial, and wound-healing properties.

Single Copper Atom Photocatalyst Powers an Integrated Catalytic Cascade for Drug-Resistant Bacteria Elimination

To address the issue posed by drug-resistant bacteria and inspired by natural antimicrobial enzymes, we report the atomically doped copper on guanine-derived nanosheets (G-Cu) that possess the integrated catalytic cascade property of glucose oxidase and peroxidase, yielding free radicals to eliminate drug-resistant bacteria upon light irradiation. Density functional theory calculations demonstrate that copper could notably promote oxygen activation and H₂O₂ splitting on the G-Cu complexes. Further all-atom simulation and experimental data indicate that the lysis of bacteria is mainly induced by cell membrane damage and the elevation of intracellular reactive oxygen species. Lastly, the G-Cu complexes efficiently eliminate the staphylococci in the infected wounds and accelerate their closure in a murine model, with negligible side effects on the normal tissues. Therefore, our G-Cu complexes may provide an efficient nonantibiotic alternative to the current treatments for bacterial infections.

A peroxidase-like magneto-gold nanozyme AuNC@Fe3O4 with photothermal effect for induced cell apoptosis of hepatocellular carcinoma cells in vitro

Hepatocellular carcinoma (HCC) is one of the most commonly diagnosed and malignant cancers worldwide. Conventional therapy strategies may not completely eradicate the tumor and may cause side effects during treatment. Nano-catalytic therapy, as a novel strategy, has attracted a great deal of attention. This study aimed to synthesize a multifunctional magneto-gold nanozyme AuNC@Fe₃O₄ and evaluate its anti-cancer potential in HepG2 cells in vitro. The characteristics of AuNC@Fe₃O₄ were assessed using a transmission electron microscope, dynamic light scattering, and energy-dispersive X-ray. The photothermal performance and peroxidase (POD)-like activity of AuNC@Fe₃O₄ were detected, using thermal camera and ultraviolet-visible spectrophotometer, respectively. The anti-cancer potential of AuNC@Fe₃O₄ was examined using cell counting kit-8, live/dead cell staining, and apoptosis analysis. Further research on HepG2 cells included the detection of intracellular reactive oxygen species (ROS) and lysosomal impairment. We observed that the AuNC@Fe₃O₄ had a small size, good photothermal conversion efficiency and high POD-like activity, and also inhibited cell proliferation and enhanced cell apoptotic ability in HepG2 cells. Furthermore, the AuNC@Fe₃O₄ enhanced ROS production and lysosomal impairment via the synergistic effect of photothermal and nano-catalytic therapies, which induced cell death or apoptosis. Thus, the magneto-gold nanozyme AuNC@Fe₃O₄ may offer a potential anti-cancer strategy for HCC.