Generation Of Hydroxyl Radicals Research Articles

Crucial role of the surface hydroxyl groups induced by oxygen vacancies on α-Fe0.9Zn0.1OOH during interfacial peroxymonosulfate activation for meclofenamic acid degradation

The role of H2O molecule during the PMS activation has been rarely followed, although the interfacial mechanism was inseparable from its adsorption and dissociation on catalysts. An efficient catalyst (α-Fe0.9Zn0.1OOH) was synthesized via Zn2+ isomorphous substitution of Fe3+ in α-FeOOH to trigger peroxymonosulfate (PMS) for distinguishing the overlooked interfacial process. The α-Fe0.9Zn0.1OOH/PMS system showed high performance for meclofenamic acid (MCF) degradation (97.0%) owing to the generation of powerful sulfate radicals (SO4•−) and hydroxyl radicals (•OH). Characterization of α-Fe0.9Zn0.1OOH via EDS, ESR and XPS spectra confirmed that Zn2+ doping induced the formation of oxygen vacancy (OV) in the structure. The OV-rich structure promoted the adsorption (Eads = -1.49 eV) and dissociation of H2O to form surface hydroxyl groups (-OHdiss), which was different from the structure -OHlatt. By ATR-FTIR tests in heavy water (D2O), the -OHdiss could be exchanged by PMS, and forming surface complexed ≡Fe(III)-(HO)-OSO3−, which enlarged the O-O bond (from 1.317 Å to 1.506 Å). The electron transfer inner ≡Fe(III)-(HO)-OSO3− benefited O-O cleavage thus inducing SO4•− generation. Overall, the presence of OV in α-Fe1-xZnxOOH greatly promoted this spontaneous process.

High efficiency manganese cobalt spinel structure catalytic ozonation ceramic membrane for in situ BPA degradation and membrane fouling elimination

In recent years, micropollutants contamination in aquatic environments has received increasing attention. Bisphenol A (BPA), an endocrine-disrupting compound, has emerged as a substantial threat to water safety owing to its widespread presence in various aquatic environments. To address this issue, this study focused on the development of ceramic membranes incorporating manganese-cobalt oxides (MCOs) to catalyze the ozone-based degradation of BPA. The catalytic layer was prepared by hydrothermal in-situ growth method, which enhanced BPA degradation during water treatment and improved the ceramic membrane’s resistance to contamination. Moreover this study investigated the synergistic effect of catalytic ozone oxidation in mitigating ceramic membrane pollution and degrading micropollutants. The catalytic mechanism and the contamination modeling were examined systematically to determine the mechanism of micropollutant contamination on ceramic membranes. The experimental results showed that the modified ceramic membrane exhibited a higher BPA removal efficiency (90.6%) and flux recovery (99.5%) than the unmodified membrane (64.2% and 79%, respectively). Furthermore, the MCOs-modified ceramic membrane (CCM) effectively enhanced the generation of hydroxyl radicals during ozonolysis. This enhancement resulted in better degradation of organic pollutants in water, thus improving the quality of the treated water. The combination of ceramic membrane catalytic separation with ozone oxidation technology offers a potential solution for the degradation of emerging pollutants and the mitigation of ceramic membrane pollution.

Enhancing non-radical peroxydisulfate activation by single-atom Fe-N-C catalyst through boron doping

Atomically dispersed transition metal-nitrogen-carbon (M-N-C) is regarded as one of the prospective materials to eliminate organic pollutants in water. However, manipulating the coordination sphere of the center metal to achieve the highest catalytic performance remains a challenge. Herein, a Fe-BNC catalyst with Fe atom decorated B,N-codoped hierarchical porous carbon was synthesized for peroxydisulfate (PDS) activation, which exhibits superb and highly selective degradation of model aqueous pollutants within a wide pH scope (2.63–10.36). The experiments and theoretical simulation indicate that the high activity of Fe-BNC origins from novel dual-pathway activation, involving PDS oxidation at the electron-poor B atoms for the formation of singlet oxygen (1O2) and PDS reduction over electron-rich Fe atoms for the generation of hydroxyl and sulfate radicals, where 1O2 was the primary active species. Moreover, the B atoms introduces point defects and optimizes the distribution of Fe 3d orbitals, which simultaneously facilitates PDS chemical adsorption and activation. We further loaded Fe-BNC on the widely used polyvinylidene fluoride (PVDF) microfiltration membrane and proved the stable performance for removing model pollutants when they pass through the filter, advancing the applications of M-N-C materials in actual practice.

Smart Enzyme-Like Polyphenol-Copper Spray for Enhanced Bacteria-Infected Diabetic Wound Healing.

Developing functional medical materials is urgent to treat diabetic wounds with a high risk of bacterial infections, high glucose levels and oxidative stress. Here, a smart copper-based nanocomposite acidic spray has been specifically designed to address this challenge. This copper-based nanocomposite is pH-responsive and has multienzyme-like properties. It enables the spray to effectively eliminate bacteria and alleviate tissue oxidative pressure, thereby accelerating the healing of infected diabetic wounds. The spray works by generating hydroxyl radicals through catalysing H2O2, which has a high sterilization efficiency of 97.1%. As alkaline micro-vessel leakage neutralizes the acidic spray, this copper-based nanocomposite modifies its enzyme-like activity to eliminate radicals. This reduces the level of reactive oxygen species in diabetic wounds by 45.3%, leading to a similar wound-healing effect between M1 diabetic mice and non-diabetic ones by day 8. This smart nanocomposite spray provides a responsive and regulatedmicroenvironment for treating infected diabetic wounds. It also offers a convenient and novel approach to address the challenges associated with diabetic wound healing.

Difunctional AuNPs@PVP with oxidase-like activity for SERRS detection of total antioxidant capacity

Assessing the total antioxidant capacity (TAC) of foods plays a significant role in dietary guidance and disease risk reduction. Therefore, building a simple, rapid, and sensitive sensing method for detecting TAC possesses broad application prospects. Herein, we constructed a novel nanozyme catalyzed‒surface-enhanced Raman resonance scattering (SERRS) sensing strategy for analysis of TAC based on polyvinylpyrrolidone coated gold nanoparticles (AuNPs@PVP) that was synthesized by one step reduction method. AuNPs@PVP not only served as the SERRS substrate but also possessed high oxidase activity which can catalyze 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation by generating hydroxyl radicals (•OH) and superoxide anion free radical (•O2−). According to the inhibiting effect of antioxidants, ascorbic acid (AA) was selected as the representative for TAC detection. The linear range and limit of detection (LOD) were determined to be 10−8‒10−5 M and 0.6 nM, respectively. More importantly, the proposed nanozyme catalyzed‒SERRS strategy has been successfully applied to the detection of TAC in fruit juices, demonstrating promising potential in the field of food supervision and healthcare applications.

Exudate-Induced Gelatinizable Nanofiber Membrane with High Exudate Absorption and Super Bactericidal Capacity for Bacteria-Infected Wound Management.

Invasion of bacteria and continuous oozing of exudate are significant causes of interference with the healing of infected wounds. Therefore, an exudate-induced gelatinizable and near-infrared (NIR)-responsive nanofiber membrane composed of polyvinyl alcohol (PVA), carboxymethyl chitosan (CMC), and Fe-doped phosphomolybdic acid (Fe-PMA) with exceptional exudate absorption capacity and potent bactericidal efficacy is developed and denoted as the PVA-FP-CMC membrane. After absorbing exudate, the fiber membrane can transform into a hydrogel membrane, forming coordination bonds between the Fe-PMA and CMC. The unique exudate-induced gelation process imparts the membrane with high exudate absorption and retention capability, and the formed hydrogel also traps the bacteria that thrive in the exudate. Moreover, it is discovered for the first time that the Fe-PMA exhibits an enhanced photothermal conversion capability and photocatalytic activity compared to the PMA. Therefore, the presence of Fe-PMA provides the membrane with a photothermal and photodynamic therapeutic effect for killing bacteria. The PVA-FP-CMC membrane is proven with a liquid absorption ratio of 520.7%, a light-heat conversion efficiency of 41.9%, high-level generation of hydroxyl radical (•OH) and singlet oxygen (1O2), and a bacterial killing ratio of 100% for S. aureus and 99.6% for E. coli. The treatment of infected wounds on the backs of rats further confirms the promotion of wound healing by the PVA-FP-CMC membrane with NIR irradiation. Overall, this novel functional dressing for the synergistic management of bacteria-infected wounds presents a promising therapeutic strategy for tissue repair and regeneration.

Aerobic Oxidation of 5-Hydroxymethylfurfural (HMF) in Aqueous Medium over Fe-Doped-Poly(heptazine imide) Photocatalysts: Unveiling the Bad Role of Hydroxyl Radical Generation on the Catalytic Performance.

5-hydroxymethylfurfural (HMF) oxidation in aqueous media using visible photocatalysis is a green and sustainable route for the valorization of lignocellulosic biomass derivatives. Several semiconductors have already been applied for this purpose; however, the use of Poly(heptazine imides), which has high crystallinity and a special cation exchange property that allows the replacement of the cation held between the layers of C3N4 structure by transition metal ions (TM), remains scarce. In this study, PHI(Na) was synthesized using a melamine/NaCl method and used as precursor to prepare metal (Fe, Co, Ni, or Cu)-doped PHI catalysts. The catalysts were tested for selective oxidation of HMF to 2,5-diformylfuran (DFF) in water and O2 atmosphere under blue LED radiation. The catalytic results revealed that the 0.1 wt% PHI(Fe) catalyst is the most efficient photocatalyst while higher Fe loading (1 and 2 wt%) favors the formation of Fe3+ clusters, which are responsible for the drop in HMF oxidation. Moreover, the 0.1 wt% PHI(Fe) photocatalyst has strong oxidative power due to its efficiency in H2O2 production, thus boosting the generation of nonselective hydroxyl radicals (●OH) via different pathways that can destroy HMF. We found that using 50 mM, the highest DFF production rate (393 μmol·h-1·g-1) was obtained in an aqueous medium under visible light radiation.

Photothermal-promoted O2/[rad]OH generation of gold nanotetrapod @ platinum nano-islands for enhanced catalytic/photodynamic therapy

Ultrasmall platinum (Pt) nanozymes are used for catalytic therapy and oxygen (O2)-dependent photodynamic therapy (PDT) by harnessing the dual-enzyme activities of catalase (CAT) and peroxidase (POD). However, their applications as nanocatalysts are limited due to their low catalytic activity. Herein, we constructed a photothermal-promoted bimetallic nanoplatform (AuNTP@Pt-IR808) by depositing ultrasmall Pt nano-islands and modifying 1-(5-Carboxypentyl)-2-(2-(3-(2-(1-(5-carboxypentyl)-3,3-dimethylindolin-2-ylidene)ethylidene)-2-chlorocyclohex-1-en-1-yl)vinyl)-3,3-dimethyl-3H-indol-1-ium bromide (IR808) on gold nanotetrapod (AuNTP) with CAT/POD activities to enhance PDT/catalytic therapy. In the tumor microenvironment, the ultrasmall Pt can catalyze endogenous hydrogen peroxide (H2O2) to produce O2, relieving tumor hypoxia and enhancing the PDT performance. Moreover, AuNTP integration into the bimetallic nanoplatform showed good electron transfer properties and promoted the POD activity of ultrasmall Pt. Importantly, AuNTP@Pt-IR808 possessed higher photothermal conversion performance than single AuNTPs, which enhanced photothermal therapy (PTT). It also accelerated the CAT/POD dual-enzyme activities, and promoted the generation of singlet oxygen (1O2) and hydroxyl radical (OH). By enhancing the performances of PTT/PDT/catalytic therapy, the developed AuNTP@Pt-IR808 nanoplatform demonstrated good antitumor efficacy against breast cancer.

Robust integration of light-driven carbon quantum dots with bacterial cellulose enables excellent mechanical and antibacterial biodegradable yarn

Due to the overuse of antimicrobial drugs, bacterial resistance became an urgent problem to be solved. In this study, carbon quantum dots (CQDs) with high photodynamic antibacterial activity were synthesized by a one-pot hydrothermal method and introduced into bacterial cellulose (BC) dispersion solution. Through a wet-spinning and wet-twisting processing strategy, bionic ordering nanocomposite macrofiber (BC/CQDs-based yarn) based on BC were obtained. The results showed that BC/CQDs-based yarn had excellent tensile strength (226.8 MPa) and elongation (22.2 %). Utilizing the light-driven generation of singlet oxygen (1O2) and hydroxyl radical (·OH), BC/CQDs-based yarn demonstrated remarkable antibacterial efficacy, with 99.9999 % (6 log, P < 0.0001) and 96.54 % (1.46 log, P < 0.0004) effectiveness against E. coli and S. aureus, respectively. At the same time, BC/CQDs-based yarn also displayed the characteristics of photothermal, fluorescent, and biodegradability. In summary, the application potential of BC/CQDs-based yarn is significant, opening up a new strategy for the development of sustainable green weaving and bio-based multi-function yarn.

Damage evolution and plastic deformation mechanism of passivation layer during shear rheological polishing of polycrystalline tungsten

Aiming at the problems of low processing efficiency and uneven material removal during shear rheological polishing (SRP) of polycrystalline tungsten, this paper introduces the Fenton-like reaction between H2O2 and Cu2+ to enhance the chemical effect on material removal. Passivation behavior and removal mechanisms were investigated using electrochemical tests, scanning electron microscopy, atomic force microscopy, and other characterization methods. Results show that the Fenton-like reaction exhibits excellent activity under the combined action of H2O2 and Cu(NO3)2, obtaining a satisfactory material removal rate of 702.22 Å⋅min−1 and a surface roughness Rq of 7.05 nm. The efficacy of the H2O2+Cu(NO3)2 slurry lies in its superior removal and passivation performance, attributed to the generation of hydroxyl radicals through the Fenton-like reaction. These radicals facilitate the formation of a WO3 passivation layer with good corrosion resistance on the surface, while enabling easy removal through mechanical wear. In addition, the plastic deformation mechanism of passivation layer was also studied by nanoscratch tests and transmission electron microscopy. It is found that a pure plastic flow groove can be obtained in the load range of 3–100 mN, accompanied by the formation of asymmetric deformation and pile-ups in the subsurface of the main plastic zone.

Ultrathin Clay Nanoparticles-Mediated Mutual Reinforcement of Ferroptosis and Cancer Immunotherapy.

Ferroptosis-triggered immunogenic cell death (ICD) is widely adopted to potentiate the body's antitumor immunity by catalyzing the production of toxic reactive oxygen species (ROS). However, the efficacy of ferroptosis and immunotherapy is greatly restricted by intracellular abundant glutathione (GSH) and immunosuppressive tumor microenvironment (TME). Herein, a facile bottom-up method for solvent-free synthesis of ultrathin manganese (Mn)-based layered double hydroxide nanosheets with high loading efficiency for pro-inflammatory cytokine interferon (IFNγ) (IFNγ/uMn-LDHs) is proposed to mutually reinforce the ferroptosis and systemic immunity. The introduction of manganese ions significantly contributes to GSH depletion and hydroxyl radical generation, which can be further enhanced by IFNγ delivery-induced SLC7A11 downregulation. The ICD effect after cell ferroptosis cooperates with the intrinsic immunomodulatory property of IFNγ/uMn-LDHs to facilitate the maturation of dendritic cells (DCs) and the priming of T cells. IFNγ secretion from activated CD8+ T cells in turn involves cascade immunogenic ferroptosis, thus constructing a closed-loop therapy. Remarkably, a potent abscopal effect is observed in the growth inhibition of both primary and distant tumors. Overall, the ultrathin Mn-based clay nanoplatform provides a simple approach for mutual regulation between ferroptosis and antitumor immune response, overcoming the obstacles of current cancer immunotherapy.

PH-Responsive Sorafenib/Iron-Co-Loaded Mesoporous Polydopamine Nanoparticles for Synergistic Ferroptosis and Photothermal Therapy.

Ferroptosis has attracted significant attention as a new mechanism of cell death. Sorafenib (SRF) is widely considered a prototypical ferroptosis-inducing drug, particularly for liver cancer treatment. However, the low solubility and hydrophobic nature of SRF, along with the absence of synergistic therapeutic strategies, still limit its application in cancer treatment. Herein, we report a dual therapeutic method incorporating photothermal therapy and ferroptosis by using Fe-doped mesoporous polydopamine nanoparticles (Fe-mPDA@SRF-TPP) as a carrier for loading SRF and targeting triphenylphosphine (TPP). SRF molecules are efficiently encapsulated within the polydopamine nanospheres with a high loading ratio (80%) attributed to the porosity of Fe-mPDA, and the inherent biocompatibility and hydrophilicity of Fe-mPDA@SRF-TPP facilitate the transport of SRF to the target cancer cells. Under the external stimuli of acidic environment (pH 5.0), glutathione (GSH), and laser irradiation, Fe-mPDA@SRF-TPP shows sustained release of SRF and Fe ions with the ratio of 72 and 50% within 48 h. Fe-mPDA@SRF-TPP nanoparticles induce intracellular GSH depletion, inhibit glutathione peroxidase 4 (GPX4) activity, and generate hydroxyl radicals, all of which are essential components of the therapeutic ferroptosis process for killing MDA-MB-231 cancer cells. Additionally, the excellent near-infrared (NIR) light absorption of Fe-mPDA@SRF-TPP nanoparticles demonstrates their capability for photothermal therapy and further enhances the therapeutic efficiency. Therefore, this nanosystem provides a multifunctional therapeutic platform that overcomes the therapeutic limitations associated with standalone ferroptosis and enhances the therapeutic efficacy of SRF for breast cancer.

Facile synthesis of solar active charcoal passivated Ag3PO4 and their two-channel mechanisms for H2O2 formation in aerated water

This work presents the use of activated charcoal passivated-Ag3PO4 (CAgP) and bare Ag3PO4(AgP) nanoparticles (NPs) as effective photocatalysts for the generation of hydrogen peroxide (H2O2) in air-saturated water containing either formic acid (FA) or silver nitrate (AgNO3). The synthesized CAgP and pristine AgP were characterized using various state-of-the-art optical and electron microscopy techniques. The CAgP composites showed remarkable photocatalyzed H2O2 formation compared to bare AgP NPs. The CAgP photocatalyzed-assisted H2O2 formation from O2-saturated water under sunlight was achieved via two-channel mechanisms. First, in the presence of FA as a hole scavenger, enhanced H2O2 formation was facilitated by the decomposition of FA to produce proton (H+), followed by a spontaneous reduction of dissolved molecular oxygen by the valence band electrons. The second pathway involves the formation of H2O2 in the absence of electrons (using AgNO3 as an electron scavenger) which occurs via the oxidation of H2O by photo-induced holes to generate hydroxyl radicals (•HO) and the combination of •HO radicals to produce H2O2. The most notable feature of CAgP composite as a photocatalyst is the ease of H2O2 formation in O2/H2O and O2/H2O/FA system, as well as the ability to reuse the recovered CAgP catalyst for a few reaction cycles without losing substantial catalytic activity or mass.

The diverse roles of halide ions in the degradation of bisphenol A via UV/peracetic acid process at different pH values: Radical chemistry, and transformation pathways

UV/Peracetic Acid (UV/PAA), as an innovative advanced oxidation process (AOP), is employed to treat bisphenol A (BPA) in water through the generation of hydroxyl radicals (•OH) and carbon-centered radicals (R−C•). The impact of halide ions (Cl−; Br−; I−) on the efficiency of UV/PAA was investigated for the first time under varying pH levels. The presence of halide ions exerted an influence on the reactivity of •OH and R−C•, exhibiting varying degrees of impact across different pH conditions. It was discovered that pH exerts a significant influence on its efficiency, with optimal removal performance observed at a pH 9. The degradation of BPA was inhibited by Cl− through the generation of reactive chlorine species (RCS), which triggers the interconversion between •OH and R−C•. Reactive bromine species (RBS) were produced in the presence of Br−, facilitating BPA degradation and generating HOBr as a supplementary source of •OH radicals. I− primarily generate reactive iodine species (RIS) through photolysis, which facilitates the degradation of BPA. The transformation of BPA involves hydroxylation, demethylation, halogenation, and cleavage reactions to form various products and pathways. The toxicity test demonstrates that the UV/PAA treatment of BPA exhibits lower toxicity, thereby indicating its environmentally friendly.

Effects of hydroxyl radicals oxidation on digestion properties of silver carp myofibrillar protein gel

The generation of hydroxyl radicals from fat oxidation during frozen storage of surimi has been confirmed to induce oxidative cross-linking of proteins, but the further effect on their digestive properties and nutritional qualities is still unclear. In this work, a simulated system composed of the silver carp myofibrillar protein (MP) and Fenton system was used to study their digestive process and activities. Affected by oxidative cross-linking, oxidized MP gels were slowly and incompletely hydrolyzed by gastrointestinal process according to free amino content, particle size and peptide amount. However, the essential amino acid proportion, reduced power and hydroxyl radical chelation of digestion products from slight oxidation group (0.1–0.5 mM H2O2) were found to be generally stronger than over-oxidation group (5.0–10.0 mM H2O2). Furthermore, the in vitro biological evaluations confirmed that there were certain antioxidant activities of digestion products without potential cytotoxicity on HepG2 cells. Oxidation treatment on MP was found to negatively maintain SOD activity and generating GSH. Nevertheless, the slight oxidation group showed great protection effects to keep HepG2 cells from cell membrane damage and release LDH. In conclusion, the slight oxidation of MP is beneficial to improve the nutritional quality and in vitro antioxidant activity of its digested products.

Cascade Catalytic Nanoparticles Selectively Alkalize Cancerous Lysosomes to Suppress Cancer Progression and Metastasis.

Lysosomes are critical in modulating the progression and metastasis for various cancers. There is currently an unmet need for lysosomal alkalizers that can selectively and safely alter the pH and inhibit the function of cancer lysosomes. Here an effective, selective, and safe lysosomal alkalizer is reported that can inhibit autophagy and suppress tumors in mice. The lysosomal alkalizer consists of an iron oxide core that generates hydroxyl radicals (•OH) in the presence of excessive H+ and hydrogen peroxide inside cancer lysosomes and cerium oxide satellites that capture and convert •OH into hydroxide ions. Alkalized lysosomes, which display impaired enzyme activity and autophagy, lead to cancer cell apoptosis. It is shown that the alkalizer effectively inhibits both local and systemic tumor growth and metastasis in mice. This work demonstrates that the intrinsic properties of nanoparticles can be harnessed to build effective lysosomal alkalizers that are both selective and safe.

Targeted modulation and enhancement of macrophages via sonodynamic therapy-driven cupferroptosis-like stress for implant-associated biofilm infections

As the vanguard against implant-associated infections (IAIs), macrophages facilitate the phagocytosis and pro-inflammatory polarization of planktonic and biofilm infections, but indirectly serve as a “Trojan horse” for intracellular bacterial infections. Effective drug delivery and macrophage immunomodulation to eliminate intracellular infections will contribute to the treatment of refractory IAIs and prevention of relapse. Herein, we developed an ultrasound-responsive copper-based nanoparticle targeting macrophages by encapsulating copper in a porphyrin metal-organic framework and surface-grafting D-Mannosamine to synthesize CuTCPP@MOF nanodots@ Mannosamine (CTMM) with macrophage-targeting functionality. Concurrent generation of hydroxyl radicals and singlet oxygen in biofilm microenvironment mediated by ultrasound disrupts the biofilm structure, achieving CTMM overload and interfering with bacterial biofilm growth and metabolism. By regulating macrophage oxidative stress metabolism, CTMM induced a cupferroptosis-like stress, characterized by concurrent cuproptosis and ferroptosis, to eliminate intracellular infections. Transcriptomic analysis verified that the cupferroptosis-like stress based on GPX4 axis modulation further promotes macrophage inflammatory activation. This CTMM+US-mediated bacterial clearance in biofilms and macrophage immunomodulation informs the "Trojan War" strategy to combat IAIs clinically.

Two-dimensional ternary chalcogenide nanodots with spatially controlled catalytic activity for bacteria infected wound treatment

Nanozymes hold great prospects for bacteria-infected wound management, yet the spatial control of their catalytic activity in infected area and normal tissues remains mired by the heterogeneity of tissue microenvironment. Here, we develop a novel two-dimensional ternary chalcogenide nanodots (Cu2MoS4, CMS NDs) with renal clearable ability and controlled catalytic activity for bacteria-infected wound treatment. The two-dimensional CMS NDs (∼4 nm) are prepared by a simple microwave-assisted chemical synthetic route. Our results show that CMS NDs not only have peroxidase-like activity in a pH-dependent manner (pH < 5.5). Based on the generation of hydroxyl radical (OH) by adding H2O2, CMS NDs show > 2 log bacterial inactivation for both Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative Escherichia coli (E. coli) under the acidic condition. Moreover, CMS NDs show good biocompatibility and can be excreted by the kidney in mice. In vivo results display that CMS NDs show good therapeutic effect against bacteria infected wound in the presence of H2O2, but no damage for normal tissues. Taken together, this work provides a renal clearable two-dimensional nanozyme with spatially controlled catalytic activity for the treatment of wounds and bacterial infections on the skin surface.

Systematic Fe(II)-EDTA Method of Dose-Dependent Hydroxyl Radical Generation for Protein Oxidative Footprinting.

Correlating the structure and dynamics of proteins with biological function is critical to understanding normal and dysfunctional cellular mechanisms. We describe a quantitative method of hydroxyl radical generation via Fe(II)-ethylenediaminetetraacetic acid (EDTA)-catalyzed Fenton chemistry that provides ready access to protein oxidative footprinting using equipment commonly found in research and process control laboratories. Robust and reproducible dose-dependent oxidation of protein samples is observed and quantitated by mass spectrometry with as fine a single residue resolution. An oxidation analysis of lysozyme provides a readily accessible benchmark for our method. The efficacy of our oxidation method is demonstrated by mapping the interface of a RAS-monobody complex, the surface of the NIST mAb, and the interface between PRC2 complex components. These studies are executed using standard laboratory tools and a few pennies of reagents; the mass spectrometry analysis can be streamlined to map the protein structure with single amino acid residue resolution.

Embedding Atomically Dispersed Manganese/Gadolinium Dual Sites in Oxygen Vacancy-Enriched Biodegradable Bimetallic Silicate Nanoplatform for Potentiating Catalytic Therapy.

Due to their atomically dispersed active centers, single-atom nanozymes (SAzymes) have unparalleled advantages in cancer catalytic therapy. Here, loaded with chlorin e6 (Ce6), a hydrothermally mass-produced bimetallic silicate-based nanoplatforms with atomically dispersed manganese/gadolinium (Mn/Gd) dual sites and oxygen vacancies (OVs) (PMnSA GMSNs-V@Ce6) is constructed for tumor glutathione (GSH)-triggered chemodynamic therapy (CDT) and O2 -alleviated photodynamic therapy. The band gaps of silica are significantly reduced from 2.78 to 1.88eV by doping with metal ions, which enables it to be excited by a 650nm laser to produce electron-hole pairs, thereby facilitating the generation of reactive oxygen species. The Gd sites can modulate the local electrons of the atom-catalyzed Mn sites, which contribute to the generation of superoxide and hydroxyl radicals (• OH). Tumor GSH-triggered Mn2+ release can convert endogenous H2 O2 to • OH and realize GSH-depletion-enhanced CDT. Significantly, the hydrothermally generated OVs can not only capture Mn and Gd atoms to form atomic sites but also can elongate and weaken the O-O bonds of H2 O2 , thereby improving the efficacy of Fenton reactions. The degraded Mn2+ /Gd3+ ions can be used as tumor-specific magnetic resonance imaging contrast agents. All the experimental results demonstrate the great potential of PMnSA GMSNs-V@Ce6 as cancer theranostic agent.