Catalytic Peroxide Research Articles

Probe on the pivotal role of green rust in improving the enzymatic activity and facilitating the formation of 1O2 in Fenton-like process for degradation of 4-chlorophenol

Iron-based materials have demonstrated significant efficacy in catalyzing hydrogen peroxide (H2O2) for the removal of antibiotics from aquatic environments. Green rust (GR), a hybrid valence state iron-based catalyst, was synthesized. By exploiting the catalytic properties of glucose oxidase (GOx) to generate H2O2 from glucose (Glu), a GR-GOx/Glu system for the removal of recalcitrant organic compound 4-chlorophenol (4-CP) was constructed. In terms of pollutant degradation efficiency, an increase of 30% was observed compared to Fe2+/H2O2 system. Utilizing density functional theory (DFT), we calculated the electrostatic potential energy and charge density distribution, demonstrating the existence of active electron transfer between GR and flavin adenine dinucleotide (FAD), which subsequently enhanced the activity of GOx. The enhancement was pivotal for the sustained generation of preferred oxidative species and rapid degradation of pollutants within the system. Furthermore, the acids and H2O2 generated during enzyme catalysis not only neutralized the alkalinity released by the Fenton-like reaction but also promoted the conversion of superoxide radical (·O2-) to singlet oxygen (1O2). Overall, this study elucidates the fundamental motivation underlying the enhancement of enzymatic activity and highlights the critical role of 1O2 within the system, providing valuable insights into the potential mechanisms by which metal hydroxides catalyze the H2O2 process.

Peroxidase-like activity of widely-used commercial inorganic pigments induces oxidative stress and antibiotic degradation: Implications for health risks.

Inorganic pigments, which often contain significant amounts of nanoparticles, are crucial chemicals for human life. They are produced in massive quantities and widely used in consumer products, food, and pharmaceuticals. Herein, we reported that a variety of commonly used commercial inorganic pigments possess peroxidase-like activity, catalyzing hydrogen peroxide (H2O2) decomposition into reactive oxygen species, primarily hydroxyl radical (OH) and superoxide radical anion (O2-). The catalytic activity of inorganic pigments exhibits saturation kinetics as described by the Michaelis-Menten model, with optimal pH and temperature conditions that can be found in the human body. The enzyme-mimicking activity is strongly correlated with the formation of OH (R2=0.98), indicating the radical-mediated reaction pathway. The peroxidase-like activity of inorganic pigments can induce significant oxidative stress at health-relevant H2O2 concentrations (3-30μM), as demonstrated by the ascorbic acid assay. Additionally, the peroxidase-like activity of inorganic pigments is able to mediate the oxidation of tetracycline, with oxidation rate constants positively correlated with the pigments' peroxidase-like activity. The discovery of peroxidase-like activity of commercial inorganic pigments sheds light on the reported oxidative stress exerted by these pigments and has important implications for the health risk assessment of inorganic food and pharmaceutical colorants, as well as colored consumer products.

Thermoelectric Nanoheterojunction-Mediated Multiple Energy Conversion for Enhanced Cancer Therapy.

Electron-hole recombination and exogenous local hypoxia both impede the effectiveness of thermoelectric tumor catalytic therapy. Here, a thermoelectric heterojunction (Pt-TiO2-x/Ti3C2Tx-PEG) was developed to enhance charge carrier separation and alleviate tumor hypoxia. By incorporating titanium oxide with oxygen vacancies and platinum single atoms onto Ti3C2Tx MXene, we not only improve the charge separation efficiency but also prevent the recombination of positive and negative charges generated by the thermoelectric effect, leading to an increased production of reactive oxygen species (ROS). Furthermore, the Pt SAs exhibited excellent catalase-mimicking (CAT-mimicking) activity, catalyzing hydrogen peroxide to generate oxygen and alleviating the hypoxic tumor microenvironment. Titanium oxide with oxygen vacancies also serves as a sonosensitizer for sonodynamic therapy (SDT), enhancing ROS generation in collaboration with thermoelectric catalytic therapy. Moreover, the photothermal conversion efficiency of Pt-TiO2-x/Ti3C2Tx-PEG is augmented by Pt SAs with a surface plasmon resonance effect, further boosting CAT-mimicking activity and thermoelectric catalytic therapy efficacy. This tumor-specific thermoelectric heterojunction integrates thermoelectric therapy, SDT, and photothermal therapy, demonstrating excellent tumor suppression efficacy both in vitro and in vivo. Therefore, this study offers highly valuable and promising insights into utilizing photothermoelectric/ultrasound-mediated methods for cancer treatment.

Post-vulcanization combined with magnetic modification of sulfonated biochar as heterogeneous fenton catalyst for tetracycline degradation

Although the Fenton reaction has shown remarkable effectiveness in degrading antibiotic contamination in water bodies, its strict pH dependence has limited its wide practical application. In this study, a novel magnetic biochar material with dual functions of adsorption and catalysis was successfully synthesized by carbonization of the shell of blue flower blue with concentrated sulfuric acid through sulfide and magnetic modification. The innovation of this material is its ability to overcome the recycling limitations of traditional catalysts while achieving efficient reactions in the pH range of 3–11. In particular, the introduction of sulfur promotes a stable cycle of Fe(II)/Fe(III) in the material, thereby enhancing its catalytic properties. The porous structure of the sulphonated jacaranda hull and its successful loading of sulfur and iron were revealed by SEM, FTIR, XRD, and XPS analysis. The experimental results showed that under the conditions of S-Fe3O4@JSS dosage of 0.2 g/L, hydrogen peroxide concentration of 10 mM, initial pH value of 5, and initial tetracycline concentration of 50 mg/L, the optimal degradation rate of tetracycline was as high as 85.85 %. The mechanism analysis shows that hydroxyl radical plays a key role in this reaction system because S-Fe3O4@JSS not only releases Fe(II) but also catalyzes hydrogen peroxide with the introduction of surface acidic sites and sulfur elements, which increases the free radical yield and accelerates the tetracycline degradation process. This study provides a new efficient and stable method to solve the problem of antibiotic pollution treatment in water.

Nickel manganese oxide catalyst made in glycerol solvent via a tubular furnace in a batch reactor for the CWPO process of phenol oxidation

The process of catalytic wet peroxide oxidation (CWPO) of phenol has been investigated in a batch reactor employing (Al2O3/NiMnO3) made from nickel and manganese salts. The sol-gel method was utilized to create the nanocatalyst locally using Al(NO3)3 hydrate as the active ingredient and glycerol as the solvent. In addition to the standard FTIR, XRD, TEM, and SEM characteristics, nanocatalyst's surface area and adsorption capacity were measured. They then used a batch reactor running at various reaction temperatures (40, 50, 60, and 70 °C), concentrations of phenol (200, 300, 400, and 500 ppm), and batch times (60, 80, 100, and 120 min) to check for CWPO. The findings demonstrated that at the best reaction temperature (70°C), batch duration (120 min), and starting concentration (200 ppm), the greatest conversion was (98.37%) for the (8% Al2O3/NiMnO3). An effective ANN model is developed in this study using Python to predict the magnitude of this effect. Phenol removal studies in a wet catalytic peroxide oxidation batch reactor were used to validate the model's output and training data. The dataset is separated into three groups based on temperature, time, and concentration. Phenol was eliminated in order for the ANN model to forecast performance. The data nearly closely matched the projected yield values. 0.99 was the regression coefficient (R2).

50 Years of Organoselenium Chemistry, Biochemistry and Reactivity: Mechanistic Understanding, Successful and Controversial Stories.

In 1973, two major discoveries changed the face of selenium chemistry: the identification of the first mammal selenoenzyme, glutathione peroxidase 1, and the discovery of the synthetic utility of the so-called selenoxide elimination. While the chemical mechanism behind the catalytic activity of glutathione peroxidases appears to be mostly unveiled, little is known about the mechanisms of other selenoproteins and, for some of them, even the function lies in the dark. In chemistry, the capacity of organoselenides of catalyzing hydrogen peroxide activation for the practical manipulation of organic functional groups has been largely explored, and some mechanistic details have been clearly elucidated. As a paradox, despite the long-standing experience in the field, the nature of the active oxidant in various reactions still remains matter of debate. While many successes characterize these fields, the pharmacological use of organoselenides still lacks any true application, and while some organoselenides were found to be non-toxic and safe to use, to date no therapeutically approved use was granted. In this review, some fundamental and chronologically aligned topics spanning organoselenium biochemistry, chemistry and pharmacology are discussed, focusing on the current mechanistic picture describing their activity as either bioactive compounds or catalysts.

Visible light-promoted, catalyst-free synthesis of isoniazid azomethines: In vitro antioxidant activity, molecular docking, ADME and toxicity prediction

Green synthesis of biologically active molecules is essential for environmental sustainability, resource efficiency, reduced environmental impact, and compliance with regulations. It ensures a safer working environment, and fosters innovation in sustainable chemistry practices. In this context, we introduce an electron donor-acceptor (EDA)-mediated visible light-promoted, catalyst-free (VLCF) scalable synthesis of isoniazid azomethines. This synthesis encompasses the drug salizide and its analogues, which were subsequently evaluated for their antioxidant activities. Isoniazid azomethines 3e demonstrated superior activity compared to salizide and ascorbic acid, with an IC50 of 0.078 mg/mL in the hydrogen peroxide antioxidant assay. Specifically, 3e exhibited greater antioxidant properties (79.02 %) than isoniazid azomethine 3b (75.82 %), isoniazid azomethine 3d (62.2 %), isoniazid azomethine 3c (59.86 %), and isoniazid azomethine 3a (54.62 %). In the superoxide dismutase antioxidant assay, 3e was also identified as the most active, with a SOD activity level of 650 U/mg of protein, surpassing other compounds (3a-d) with SOD activity levels of 330, 560, 350, and 420 U/mg of protein, respectively. Molecular docking against horseradish peroxidase (1W4Y) showed compound 3e with the best binding energy (-6.561 kcal/mol), forming key hydrogen bonds (Asn135, Pro139) and a π-cation interaction with Arg38. These interactions suggest 3e may effectively inhibit hydrogen peroxide catalysis. The in silico assessment of the physicochemical properties, pharmacokinetics, and toxicology of synthesized compounds suggests that these compounds exhibit promising ADMET characteristics, with no identified toxicological concerns.

Augment of Ferroptosis with Photothermal Enhanced Fenton Reaction and Glutathione Inhibition for Tumor Synergistic Nano-Catalytic Therapy.

Ferroptosis-driven tumor ablation strategies based on nanotechnology could be achieved by elevating intracellular iron levels or inhibiting glutathione peroxidase 4 (GPX4) activity. However, the intracellular antioxidative defense mechanisms endow tumor cells with ferroptosis resistance capacity. The purpose of this study was to develop a synergistic therapeutic platform to enhance the efficacy of ferroptosis-based tumor therapy. In this study, a multifunctional nano-catalytic therapeutic platform (mFeB@PDA-FA) based on chemodynamic therapy (CDT) and photothermal therapy (PTT) was developed to effectively trigger ferroptosis in tumor. In our work, iron-based mesoporous Fe3O4 nanoparticles (mFe3O4 NPs) were employed for the encapsulation of L-buthionine sulfoximine (BSO), followed by the modification of folic acid-functionalized polydopamine (PDA) coating on the periphery. Then, the antitumor effect of mFeB@PDA-FA NPs was evaluated using Human OS cells (MNNG/HOS) and a subcutaneous xenograft model of osteosarcoma. mFe3O4 harboring multivalent elements (Fe2+/3+) could catalyze hydrogen peroxide (H2O2) into highly cytotoxic ˙OH, while the tumor microenvironment (TME)-responsive released BSO molecules inhibit the biosynthesis of GSH, thus achieving the deactivation of GPX4 and the enhancement of ferroptosis. Moreover, thanks to the remarkable photothermal conversion performance of mFe3O4 and PDA shell, PTT further synergistically enhanced the efficacy of CDT and facilitated ferroptosis. Both in vivo and in vitro experiments confirmed that this synergistic therapy could achieve excellent tumor inhibition effects. The nanotherapeutic platform mFeB@PDA-FA could effectively disrupted the redox homeostasis in tumor cells for boosting ferroptosis through the combination of CDT, PTT and GSH elimination, which provided a new perspective for the treatment of ferroptosis sensitive tumors.

Piezoelectric-mediated two-dimensional copper-based metal–organic framework for synergistic sonodynamic and cuproptosis-driven tumor therapy

Sonodynamic therapy (SDT) is a minimally invasive therapeutic approach that utilizes sonosensitizers to catalyze substrates and generate reactive oxygen species (ROS) under ultrasound stimulation, ultimately inducing tumor cell death. Enhancing the piezoelectric properties of nanomaterials and modulating the semiconductor energy band are effective strategies to improve the catalytic efficiency of sonosensitizers. In this study, we developed a two-dimensional (2D) copper-based piezoelectric metal–organic framework (MOF) sonosensitizer, denoted as CM, through the coordination of copper and dimethylimidazole. The unique 2D MOF structure imparts CM with piezoelectric characteristics, enabling it to enhance SDT efficacy by modulating the semiconductor bandgap and carrier mobility. Upon ultrasound irradiation, CM catalyzes oxygen to undergo a cascade reaction, producing highly toxic singlet oxygen. Additionally, cupric ions in CM can be reduced by glutathione, facilitating the spontaneous catalysis of hydrogen peroxide in tumors to generate hydroxyl radicals and deplete glutathione, thereby inducing oxidative damage. Moreover, cupric ions in CM can trigger tumor cell cuproptosis, which, in combination with the generated ROS, accelerates cell death. Thus, this study establishes a MOF-based system for controllably inducing multi-pathway cancer cell death and provides a foundation for enhancing ultrasound-catalyzed tumor therapy through the optimization of piezoelectric properties.

Hollow Copper Sulfide Nanocubes Loaded with Pt(IV) Complexes for Cancer Multimodal Therapy.

Chemotherapy (CT) can significantly inhibit tumor growth, metastasis, and recurrence during cancer therapy. People have widely used platinum drugs in cancer treatment. However, as most chemotherapeutic drugs, platinum drugs still have shortcomings such as poor solubility, low cell uptake, nonspecific distribution, multidrug resistance, and adverse side effects. Therefore, we synthesized hollow copper sulfide (CuS) nanocubes with photothermal and photodynamic properties as carriers for Pt(IV) drugs. Hollow CuS nanocubes have attracted considerable interest in the field of cancer photothermal therapy (PTT) using multiple biological windows. Under near-infrared (NIR) laser irradiation, Cu2+ can be reduced into Cu+ in the presence of hydrogen peroxide in the tumor microenvironment. The resulting Cu+ can be used for photodynamic therapy (PDT), which can perform a Fenton-like reaction under acidic conditions (pH 5.5-6.5) and catalyze hydrogen peroxide to produce ·OH in the tumor microenvironment. In addition, compared with Pt(II) drugs, Pt(IV) drugs not only have lower systemic toxicity but also consume glutathione (GSH), thereby increasing reactive oxygen species (ROS) levels in tumor cells and effectively promoting PDT. In this study, we oxidized ethylenediamine platinum chloride to its tetravalent state, loaded the Pt(IV) complexes using hollow CuS nanocubes, and modified the surfaces of the nanoparticles with PEG to improve the EPR effect. The Pt(IV)-loaded hollow CuS nanocubes modified with PEG (Pt(IV)-CuS@PEG) are expected to be used for tumor chemo/photothermal/photodynamic therapy.

An Intelligent Triple Assisted Gold Cluster‐Based Nanosystem for Enhanced Tumor Photodynamic Therapy

Comprehensive SummaryPhotodynamic therapy (PDT) has been attracted a surge of research interest. However, there are several obstacles to limit the efficacy of PDT, such as hypoxic tumor microenvironment (TME), overexpressed glutathione (GSH), inefficient reactive oxygen species (ROS) generation, and so on. Herein, a smart responsive nanosystem was constructed, which was composed of Au25 modified with triphenylphosphine (Au25‐TPP), catalase (CAT) and GSH‐responsive diselenide‐bridged mesoporous silica nanoparticles (Se‐MSN). When the nanosystem arrived at tumor site, Se‐MSN was degraded by the intracellular overexpressed GSH to release Au25‐TPP and CAT. The Au25‐TPP was targeted to mitochondria and generated ROS under the 808 nm NIR laser irradiation to kill tumor cells. Simultaneously, CAT could catalyze hydrogen peroxide to provide oxygen for relieving the hypoxia of TME. Besides, GSH was consumed by the diselenide bond to diminish the ROS loss. The above tactics (mitochondria targeting, hypoxia relieving and GSH consuming) jointly enhanced the PDT efficacy. The nanosystem showed distinct in vitro anticancer effect significantly stronger than other groups containing one or two assistance. Moreover, the in vivo results suggested that the tumors could be restrained obviously. The current study provides a new inspiration for constructing novel inorganic nanomedicines with multiple enhancement effect of PDT efficacy.

Nanozyme-Shelled Microcapsules for Targeting Biofilm Infections in Confined Spaces.

Bacterial infections in irregular and branched confinements pose significant therapeutic challenges. Despite their high antimicrobial efficacy, enzyme-mimicking nanoparticles (nanozymes) face difficulties in achieving localized catalysis at distant infection sites within confined spaces. Incorporating nanozymes into microrobots enables the delivery of catalytic agents to hard-to-reach areas, but poor nanoparticle dispersibility and distribution during fabrication hinder their catalytic performance. To address these challenges, a nanozyme-shelled microrobotic platform is introduced using magnetic microcapsules with collective and adaptive mobility for automated navigation and localized catalysis within complex confinements. Using double emulsions produced from microfluidics as templates, iron oxide and silica nanoparticles are assembled into 100-µm microcapsules, which self-organize into multi-unit, millimeter-size assemblies under rotating magnetic fields. These microcapsules exhibit high peroxidase-like activity, efficiently catalyzing hydrogen peroxide to generate reactive oxygen species (ROS). Notably, microcapsule assemblies display remarkable collective navigation within arched and branched confinements, reaching the targeted apical regions of the tooth canal with high accuracy. Furthermore, these nanozyme-shelled microrobots perform rapid catalysis in situ and effectively kill biofilms on contact via ROS generation, enabling localized antibiofilm action. This study demonstrates a facile method of integrating nanozymes onto a versatile microrobotic platform to address current needs for targeted therapeutic catalysis in complex and confined microenvironments.

Polyvalent copper oxide nanozymes: Co-delivery of ROS and NO for inducing cuproptosis-like bacterial death against MRSA infections

The development of highly effective and low-toxicity antimicrobials is one of the important challenges for combat methicillin-resistant Staphylococcus aureus (MRSA) infections. Recent studies have found that cuproptosis-like bacterial death is an effective strategy to overcome drug resistance. Here, we designed and synthesized a valence in situ conversion of polyvalent copper oxide nanozymes (L-CuxO NPs), which modified L-arginine (L-Arg) to enhance antibacterial ability. In vitro studies showed that L-CuxO NPs can catalyze hydrogen peroxide (H2O2) to produce hydroxyl radical (•OH), mediate NO release, and continuously consume glutathione (GSH) through change of valence state of Cu2+ and Cu+. Importantly, copper overload in bacteria restricts the tricarboxylic acid (TCA) cycle, promoting bacterial cuproptosis-like death. In vivo results confirmed that L-CuxO NPs is not only effective in alleviating acute MRSA lung infection, but also accelerates the healing of MRSA infected wounds. Accordingly, this study provides a new idea for overcoming bacterial resistance and structural innovation of novel nanozymes.

Enhancing the Self-Propelled Motion of Hydrogen Peroxide Fueled Active Particles with Formic Acid and Other Oxygen Scavengers.

We report enhanced active particle motion in hydrogen peroxide-fueled self-diffusiophoretic active particle systems of up to 400% via addition of low concentrations of oxygen scavenging agents such as formic acid (as well as other organic acids, hydrazine, and citric acid), whereas active motion was inhibited at higher concentrations. Control experiments showed that enhanced motion was decoupled from catalytic hydrogen peroxide decomposition rate and insensitive to particle surface chemistry. Experimental results point to bulk oxygen scavenging as the cause for the enhanced active motion, representing a realization of recently predicted promotional effects of product sinks on self-diffusiophoretic motion. Diminished active motion at high oxygen scavenger concentrations was attributed to catalytic site blocking by adsorbed solute.

Gelatin-coated glutathione depletion and oxygen generators in potentiated chemotherapy for pancreatic cancer

Chemotherapy is generally acknowledged as an effective method for pancreatic cancer (PC). However, its treatment efficacy is often compromised due to inefficient drug delivery and drug resistance propensity of tumor tissues. The purpose of this study is to design and develop a novel drug delivery system (Manganese-doped mesoporous silica nanoparticles, Mn-MSN) in which paclitaxel (PTX), a conventional chemotherapeutic agent used to effectively treat pancreatic cancer clinically. Through cross-linking with glutaraldehyde, gelatin (Ge) was encapsulated on the carrier surface, endowing the nanoparticles (Ge-Mn-MSN@PTX) with excellent biocompatibility, low hemolytic activity, and enzyme-responsive degradation. Mn was added for the following purposes: (1) catalyzing hydrogen peroxide (H2O2) to generate oxygen (O2), thereby alleviating tumor hypoxia and drug resistance; (2) depleting glutathione (GSH), inducing intracellular lipid peroxidation and ferroptosis; (3) enabling real-time monitoring of the therapeutic efficacy of the nanoparticles via magnetic resonance imaging (MRI). The experimental results demonstrated that Ge-Mn-MSN@PTX has satisfactory biosafety, antitumor activity, controlled drug release as well as imaging tracking capabilities. In the SW1990 nude mice model, the Ge-Mn-MSN@PTX effectively inhibited tumor growth by suppressing the expression of the resistance protein P-glycoprotein (P-gp) and inducing ferroptosis. In conclusion, the designed gelatin-coated Mn-MSN shows potential for application in future pancreatic cancer therapy.

Understanding the Role of Corrosion and Reactive Oxygen Species in Electrochemical Ozone Production on Nickel and Antimony Doped Tin Oxide

Electrochemical ozone production (EOP), a six-electron reaction, offers promising green applications for water disinfection and organic synthesis. Nickel and antimony-doped tin oxide (Ni/Sb-SnO2, NATO) electrodes are known to be active for EOP. Still, the mechanism of NATO's selectivity and activity and the origin of its instability need to be clarified. We combine electrochemistry, spectroscopic detection of reactive oxygen species (ROS) using selective chemical probes, oxygen anion chemical ionization mass spectrometry (CIMS), and density-functional theory (DFT) simulations to identify the reaction mechanism and investigate the role of corrosion and homogenous reactive oxygen species in EOP on NATO electrodes. We identify hydrogen peroxide as a critical reaction intermediate. Our results suggest that the presence of nickel in NATO enables the catalysis of hydrogen peroxide to hydroperoxyl radicals, which subsequently undergo oxidation to produce ozone. The isotopic makeup of products shows that water is the primary source of ozone, but it also contains oxygen from the metal oxide lattice. The change in the isotopic generation pattern of ozone suggests that NATO catalysts corrode irreversibly, and the lattice oxygen is not regenerated, explaining NATO's instability.

Polyoxometalate-based iron-organic complex nanozymes with peroxidase-like activities for colorimetric detection of hydrogen peroxide and ascorbic acid.

As a new type of artificial enzyme, ananozyme is an ideal substitute for natural enzymes and has been successfully applied in many fields. However, in the application of biomolecular detection, most nanozymes have the disadvantages of long reaction times or high detection limits, prompting researchers to search for new efficient nanozymes. In this work, the enzyme-like activities of three polyoxometalate-based iron-organic complexes ([Fe(bpp)2](Mo6O19), [Fe(bpp)2]2(Mo8O26)·2CH3OH, and [Fe(bpp)2]4H[Na(Mo8O26)]3), namely, FeMo6, Fe2Mo8, and Fe4Mo8Na, were analyzed. All three polyoxometalate-based iron-organic complexes were found to be capable of catalyzing hydrogen peroxide (H2O2) to oxidize 3,3',5,5'-tetramethylbenzidine and o-phenylenediamine, resulting in visible color changes, further exhibiting peroxidase-like activity. Results showed that Fe4Mo8Na had more active sites due to its long chain structure, endowing more prominent peroxidase-like activity compared with Fe2Mo8 and FeMo6. A colorimetric sensing platform for H2O2 and ascorbic acid detection based on Fe4Mo8Na was established. The linear response range for H2O2 detection was 0.5-100μM, and the detection limit was 0.143μM. The linear response for ascorbic acid detection ranges from 0 to 750μM with a detection limit of 1.07μM. This study provides a new perspective for developing new nanozymes and expanding the sensing and detection application of nanozymes.

Tumor microenvironment responsive chitosan-coated W-doped MoOx biodegradable composite nanomaterials for photothermal/chemodynamic synergistic therapy

Chemodynamic therapy (CDT), an approach that eradicates tumor cells through the catalysis of hydrogen peroxide (H2O2) into highly toxic hydroxyl radicals (·OH), possesses distinct advantages in tumor specificity and minimal side effects. However, CDT's therapeutic efficacy is currently hampered by the low production efficiency of ·OH. To address this limitation, this study introduces a water-soluble chitosan-coated W-doped MoOx (WMoOx/CS) designed for the combined application of photothermal therapy (PTT) combined with CDT. The W-doped MoOx (WMoOx) was synthesized in one step by the hydrothermal method, and its surface was modified by water-soluble chitosan (carboxylated chitosan, CS) to enhance its biocompatibility. WMoOx boasts a high near-infrared photothermal conversion efficiency of 52.66 %, efficiently transducing near-infrared radiation into heat. Moreover, the Mo4+/Mo5+ and W5+ ions in WMoOx catalyze H2O2 to produce ·OH for CDT, and the Mo5+/Mo6+ and W6+ ions in WMoOx reduce intracellular glutathione levels and prevent the scavenging of ·OH by glutathione. Crucially, the combination of WMoOx/CS and near-infrared light irradiation demonstrates promising synergistic antitumor effects in both in vitro and in vivo models, highlighting its potential for the combined application of PTT and CDT.

Dual-recognition colorimetric platform based on porous Au@Pt nanozymes for highly sensitive washing-free detection of Staphylococcus aureus.

Adual-recognition strategy is reportedto construct a one-step washing and highly efficient signal-transduction tag system for high-sensitivity colorimetric detection of Staphylococcus aureus (S. aureus). The porous (gold core)@(platinum shell) nanozymes (Au@PtNEs) as the signal labels show highly efficient peroxidase mimetic activity and arerobust. For the sake of simplicity the detection involved the use of a vancomycin-immobilized magnetic bead (MB) and aptamer-functionalized Au@PtNEs for dual-recognition detection in the presence of S. aureus.In addition, we designed a magnetic plate to fit the 96-well microplate to ensure consistent magnetic properties of each well, which can quickly remove unreacted Au@PtNEs and sample matrix while avoiding tedious washing steps. Subsequently, Au@PtNEs catalyze hydrogen peroxide (H2O2) to oxidize 3,3',5,5'-tetramethylbenzidine (TMB) generating a color signal. Finally, the developed Au@PtNEs-based dual-recognition washing-free colorimetric assay displayed a response in the range of S. aureus of 5 × 101-5 × 105 CFU/mL, and the detection limit was 40 CFU/mL within 1.5 h. In addition, S. aureus-fortified samples were analyzed to further evaluate the performance of the proposed method, which yielded average recoveries ranging from 93.66 to 112.44% and coefficients of variation (CVs) within the range 2.72-9.01%. These results furnish a novel horizon for the exploitation of a different mode of recognition and inexpensive enzyme-free assay platforms as an alternative to traditional enzyme-based immunoassays for the detection of other Gram-positive pathogenic bacteria.

MXene/Carbon Dots Nanozyme Composites for Glutathione Detection and Tumor Therapy.

Co-N-CDs-based MXene nanocomposites (MXene@PDA/Co-N-CDs) were constructed by decorating Co-N-CDs on polydopamine-functionalized MXene nanosheets. Both Co-N-CDs and MXene nanosheets have peroxidase-like activity; when the two materials are combined to form MXene@PDA/Co-N-CDs nanocomposites, the peroxide-like activity can be further enhanced. MXene@PDA/Co-N-CDs could oxidize the substrate 3,3'5,5'-tetramethylbenziline (TMB) to form ox-TMB, as confirmed by detecting the absorption of the blue products. A highly selective colorimetric biosensor was developed for the determination of glutathione (GSH) in the concentration range of 0.3 to 20 µM with a lower detection limit (LOD) of 0.12 µM, which realized the accurate detection of GSH in human serum and urine samples. Moreover, in the tumor microenvironment, MXene@PDA/Co-N-CDs could catalyze hydrogen peroxide to produce hydroxyl free radicals and produce a photothermal effect under the exposure of NIR-I irradiation. The catalytic activity of MXene@PDA/Co-N-CD nanocomposites was fully achieved for the death of cancer cells through photothermal/photodynamic synergistic therapy. The MXene@PDA/Co-N-CDs nanozyme offers multiple applications in GSH detection and tumor therapy.