Generation Of Superoxide Radicals Research Articles

Artificial Light-Harvesting Systems with a Three-Step Sequential Energy Transfer Mechanism for Efficient Photocatalytic Minisci-Type Late-Stage Functionalization.

The natural process of photosynthesis involves a series of consecutive energy transfers, but achieving more steps of efficient energy transfer and photocatalytic organic conversion in artificial light-harvesting systems (ALHSs) continues to pose a significant challenge. In the present investigation, a range of ALHSs showcasing a sophisticated three-step energy transfer mechanism is designed, which are meticulously crafted using pillar[5]arene (WP[5]) and p-phenylenevinylene derivative (PPTPy), utilizing host-guest interactions as energy donors. Three distinct types of fluorescent dyes, namely Rhodamine B (RhB), Sulforhodamine 101 (SR101), and Cyanine 5 (Cy5), are employed as acceptors of energy. Starting from PPTPy-2WP[5], energy is sequentially transferred to RhB, SR101, and Cy5, successfully constructing a multi-step continuous energy transfer system with high energy transfer efficiency. More interestingly, as energy is progressively transferred, the efficiency of superoxide anion radical (O2 •-) generation gradually increased, while the efficiency of singlet oxygen (1O2) generation decreased, achieving the transformation from type II photosensitizer to type I photosensitizer. Furthermore, in order to fully utilize the energy harvested and reactive oxygen species (ROS) obtained, the ALHSs employ a multi-step sequential energy transfer process to enhance Minisci-type alkylation reactions with aldehydes through photocatalysis for late-stage functionalization in an aqueous environment, achieving a 91% yield.

Degradation of Rhodamine B by Visible Light Driven MoO3@TiO2 Core-Shell Photocatalyst.

In this study, a MoO3@TiO2 composite core-shell material was developed to remove Rhodamine B (RhB) dye through synergistic adsorption and photocatalytic degradation. n-n heterostructures were formed by coupling n-type semiconductors to enhance the efficiency of photocarrier separation and photocatalytic performance. MoO3, which possesses strong adsorption capacity, was primarily used as a dye adsorbent. Additionally, the formation of an n-n heterojunction with TiO2 enabled MoO3 to expand the photocorresponding range of TiO2, leading to the generation of superoxide (O2•) and hydroxyl (•OH) free radicals for dye degradation. The experimental results demonstrate that the MoO3@TiO2 core-shell composite exhibits excellent performance for RhB dye removal, with adsorption and degradation rates reaching 35.7 and 70.3%, respectively, even at low catalyst concentrations. This approach offers new insights into the development of MoO3 core-shell photocatalysts.

Antioxidant Effects of Tryptanthrin Oxime.

We studied the radical-binding and antioxidant activities of the alkaloid tryptanthrin (TR) and its new synthetic derivative tryptanthrin oxime (TR-Ox), as well as the cytoprotective activity of TR-Ox under conditions of oxidative stress. The antiradical activity of TR-Ox was revealed in the test of binding with stable chromogen radical 2,2-diphenyl-1-picrylhydrazyl and in the superoxide radical generation test (riboflavin photoreduction reaction with detection by NBT reduction). TR-Ox was inferior to ionol and dihydroquercetin by the antiradical activity. In these tests, TR did not exhibit antiradical activity. TR-Ox did not show iron-chelating activity (in the test with the formation of the o-phenanthroline-Fe2+ complex and its destruction in the presence of chelating agents). In brain homogenate, TR-Ox significantly reduced the increase in spontaneous chemiluminescence. Under conditions of oxidative stress induced by 15 mM H2O2 in the SH-SY5Y neuroblastoma cell culture, TR-Ox exhibited cytoprotective activity and increased the number of viable cells.

Design of dual-defective polymeric carbon nitride with compact interlayer stacking for boosting photocatalytic H2O2 production: Insight of various configurations

Polymeric carbon nitride (PCN) is an environmentally friendly photocatalyst for solar-driven H2O2 production, but the activity of original PCN is still not satisfactory. The main limitation is the sluggish exciton dissociation leading to slow generation and conversion of superoxide radical (•O2−) intermediate. Herein, the PCN with dual defect sites and compact interlayer is rationally designed for H2O2 photosynthesis with an ultrahigh rate of 3930.9 μmol g−1h−1 and rapid •O2− yield rate of 1.92 min−1. The enhanced activity is attributed to effective exciton dissociation during interlayer and intralayer process. Moreover, nitrogen vacancies change the oxygen adsorption configuration (formation of C − O − O − C bridge mode), thus promoting O2 adsorption and activation. A well-matched linear relationship was established between the concentration of nitrogen vacancies and •O2−/H2O2 production. This work not only provides in-depth insights for the photocatalytic H2O2 generation mechanism, but also offers a new paradigm for designing efficient PCN-based photocatalysts for energy conversion.

Synergetic Effect of Heterojunction and Sulfur Vacancy on ZnIn2S4/CeO2 to Enhance the Photocatalytic Performance of 5‐Hydroxymethylfurfural into 2,5‐Diformylfuran

AbstractThe efficient separation of photocarriers and facile generation of superoxide radicals are crucial for enhancing the performance of photocatalysts in the selectively photo‐oxidizing 5‐hydroxymethylfurfural (HMF) into 2,5‐diformylfuran (DFF). Herein, a ZnIn2S4/CeO2 composite with S‐scheme heterojunction and sulfur vacancies (SV) is successfully developed through a one‐step hydrothermal method. The optimal catalyst (SV‐ZnIn2S4/CeO2) exhibits excellent catalytic activity with 100% conversion of HMF and 96.1% selectivity of DFF in 80 min under ambient conditions, the production rate of DFF is up to 952.6 µmol g−1 h−1. Intriguingly, the performance remains significant even when the concentration of HMF is increased from 8 to 100 mм. Experimental and theoretical investigations discover that the synergistic effect of S‐scheme heterojunction and sulfur vacancies contribute to the separation of photocarriers and the activation of oxygen, which facilitate the generation of superoxide radicals, thus boosting the catalytic oxidation reactions.

Generation and Clearance of Superoxide Radicals at Buried Interfaces of Perovskites with Different Crystal Structures.

One of the most notorious issues with classic perovskite (MAPbI3) is its rapid degradation caused by generating superoxide radicals (O2 •-) on its surface under light and oxygen environments (light/O2). The differences in O2 •- generation rate and tolerance to O2 •- among perovskite with different structures are pending. For the first time it is validated through solid-electron paramagnetic resonance (EPR) that MAPbI3 and Cs0.175FA0.75MA0.075PbI3 (PVSK) crystals can generate O2 •- in an air atmosphere. The rapid degradation of perovskite buried interfaces caused by O2 •- dominates the nonexposed air aging process of SnO2-based perovskite film, and the degradation rate of MAPbI3 film is faster than that of PVSK film. The fullerene pyridine derivatives (C60OPD), which function as a buffer layer between SnO2 and PVSK to scavenge O2 •- and prevent degradation at the buried interface of the PVSK film, reduce the density of defect states, and accelerate the transmission of photogenerated electrons. The photoelectric conversion efficiency (PCE) of perovskite solar cells (PSCs) optimizes with C60OPD increased from 21.15% to 23.11% while significantly improving the stability in light/O2. This work reveals the hidden degradation of perovskite-buried interfaces caused by O2 •- and explores efficient ways for perovskite to resist O2 •-.

Donor-Acceptor Type Supra-Carbon-Dots with Long Lifetime Photogenerated Radicals Boosting Tumor Photodynamic Therapy.

Carbon dots (CDs) have gained significant interest because of their potential in biomedical applications. Nevertheless, developing CDs with efficient photoinduced charge separation for tumor photodynamic therapy (PDT) remains a challenge. This study presents a novel class of supra-carbon-dots (supra-CDs) developed by fusing red emissive CDs with 2,3-dicyanohydroquinone (DCHQ) via post-solvothermal treatment. In supra-CDs, the core, acting as electron donors, is formed by assembled CDs with substantial sp2 domains, the fused interface originating from DCHQ with electron-withdrawing groups functions as the electron acceptor. This configuration creates the unique donor-acceptor nanostructure. Upon white light irradiation, the excited electrons from the assembled CDs were transferred to the electron-withdrawing interface, whereas the photogenerated holes were retained within the assembled CDs as radicals, leading to effective photoinduced charge separation. The separated photogenerated electrons then react with oxygen to generate superoxide radicals. Simultaneously, the photogenerated holes undergo oxidation of crucial cellular substrates. This dual action underscores the exceptional cell-killing efficacy of supra-CDs. Moreover, the increased particle sizes (~20 nm) ensure supra-CDs to exhibit a notable capacity for tumor accumulation via the improved permeability and retention effect, thereby achieving satisfactory anti-tumor PDT efficacy in a mouse subcutaneous tumor model.

Engineering exciton dissociation and intermolecular charge transfer to boost superoxide radical in conjugated microporous polymers for simultaneous elimination of coexisting contaminants

Simultaneous photocatalytic elimination of coexisting contaminants with polymeric semiconductors are highly urgent for environmental purification. Nevertheless, the insufficient exciton dissociation and charge transfer in polymeric photocatalysts results in unsatisfactory photocatalytic performance. Herein, we proposed a sulfur-contained linkages engineering strategy via regulating donor–acceptor interactions to boost exciton dissociation and intermolecular charge transfer for efficient generation of superoxide radical. With the low exciton binding energy (50.11 meV) and short average lifetime (τavg‑TAS) of the photoinduced exciton (478.1 ps), the resultant BDT-Tr deriving from BDT and 2,4,6-tris(4-bromophenyl)-1,3,5-triazine exhibited efficient exciton dissociation and charge transfer, enabling superior photocatalytic degradation of ofloxacin (∼94.0 % in 2 h) than that of TTP-Tr (∼87 %) and DTT-Tr (∼76 %) when coupled with the uranium (VI) reduction (∼96.0 % in 1 h). This is the first work highlights the photocatalytic removal of coexisting aqueous pollutants with CMPs-based photocatalysts, which might facilitate the exploration of polymeric semiconductors for wastewater purification.

High-yield preparation of 1T-MoS2 with excellent piezo-catalytic activity via W6+ doping for antibiotics degradation and Cr(VI) reduction: Mechanistic insights from characterizations to DFT calculations

Molybdenum disulfide (MoS2) is a promising piezoelectric material. Herein, a simple method is reported for the high-yield production of metallic (1 T) phase MoS2 which exhibits excellent piezo-catalytic activity by in-situ doping of trace amounts of W6+. At 1 wt% W6+ doping, the 1 T phase of the obtained MoS2 reaches a concentration as high as 85.56 % and the piezoelectric coefficient and piezoelectric response current increase by 1.67 and 1.18 times, respectively, as compared to pristine MoS2. Consequently, W1.0-MoS2 can remove more than 99.8 % of tetracycline and 97.3 % of Cr(VI) in 10 min. Experimental characterization and theoretical calculations indicate that the enhanced piezoelectric catalytic activity is attributed to the strong synergistic effect between 1T-MoS2 and W6+ doping, which facilitates the rapid generation of hydroxyl radicals and superoxide radicals. This new strategy of doping 1 T/2H-MoS2 with W6+ can significantly enhance the piezoelectric catalytic performance, providing important insights for the removal of pollutants.

Novel Indirect Antioxidant Activity Independent of Nrf2 Exerted by Lactic Acid Bacteria.

In recent years, the health benefits of lactic acid bacteria have garnered attention, but their antioxidant activity remains relatively underexplored. We have been analyzing the antioxidant activities of various dietary phytochemicals by assessing their ability to mitigate oxidative stressor-induced toxicity in zebrafish larvae through pretreatment. In this study, the antioxidant activities of 24 strains of heat-killed lactic acid bacteria from various origins were examined using this zebrafish assay system. The results revealed that all 24 strains possessed antioxidant activity that reduces hydrogen peroxide toxicity. Further detailed analysis using the H61 strain, which exhibited the strongest activity, showed that no direct antioxidant activity was observed in the assay system, suggesting that the detected antioxidant activity was entirely indirect. Moreover, it was found that pretreatment of zebrafish larvae with the H61 strain for more than 6 h was required to exert its antioxidant activity. This duration was similar to that required by dietary antioxidants that activate the Keap1-Nrf2 pathway, suggesting potential involvement of this pathway. However, analysis using Nrf2-knockout zebrafish revealed that the antioxidant activity of strain H61 is independent of Nrf2, indicating that it represents a novel indirect antioxidant activity that does not involve the Keap1-Nrf2 pathway. To further characterize this activity, the ability to mitigate the toxicity of oxidative stressors other than hydrogen peroxide was examined. The results indicated that while the toxicity of tert-butyl hydroperoxide was reduced, unlike with the Keap1-Nrf2 pathway, it was not effective in counteracting the toxicity of paraquat or arsenite, which generate superoxide radicals. In conclusion, we have identified a novel indirect antioxidant activity in lactic acid bacteria.

Tumor Necrosis Factor Receptors and C-C Chemokine Receptor-2 Positive Cells Play an Important Role in the Intraerythrocytic Death and Clearance of Babesia microti.

Babesia microti is an Apicomplexan parasite that infects erythrocytes and causes the tick-transmitted infection, babesiosis. B. microti can cause a wide variety of clinical manifestations ranging from asymptomatic to severe infection and death. Some risk factors for severe disease are well-defined, an immune compromised state, age greater than 50, and asplenia. However, increasing cases of severe disease and hospitalization in otherwise healthy individuals suggests that there are unknown risk factors. The immunopathology of babesiosis is poorly described. CD4+ T cells and the spleen both play a critical role in parasite clearance, but few other factors have been found that significantly impact the course of disease. Here, we evaluated the role of several immune mediators in B. microti infection. Mice lacking TNF receptors 1 and 2, the receptors for TNFα and LTα, had a higher peak parasitemia, reduced parasite killing in infected red blood cells (iRBCs), and delayed parasite clearance compared to control mice. Mice lacking CCR2, a chemokine receptor involved in the recruitment of inflammatory monocytes, and mice lacking NADPH oxidase, which generates superoxide radicals, demonstrated reduced parasite killing but had little effect on the course of parasitemia. These results suggest that TNFR-mediated responses play an important role in limiting parasite growth, the death of parasites in iRBCs, and the clearance of iRBCs, and that the parasite killing in iRBCs is being primarily mediated by ROS and inflammatory monocytes/macrophages. By identifying factors involved in parasite killing and clearance, we can begin to identify additional risk factors for severe infection and newer therapeutic interventions.

A hexanuclear Iridium(III) cluster for histidine-induced singlet oxygen and superoxide radicals generation

Photosensitizers (PSs) play key roles in photodynamic therapy (PDT). PDT is typically reliant on the local concentration of oxygen. A big challenge for PSs is to develop oxygen-independent photosensitizers, which can work well in hypoxic tumor microenvironment. In this piece of work, a hexanuclear Ir(III) cluster (Ir6) is highly selective towards histidine and histidine-rich (His-rich) proteins to form mononuclear Ir(III) complexes of [Ir(bpy)2(His)]. After the selective response to histidine or his-rich proteins, [Ir(bpy)2(His)] generates both singlet oxygen(1O2) and superoxide (O2−). This work opens an avenue for the potential application of Ir6 for type Ι and ΙΙ synergic photodynamic therapy.

Ternary photocatalyst Bi5O7I/Bi2O2CO3/Ag2CO3 with double Z-scheme heterojunction for the degradation of levofloxacin under visible light: Practical application and DFT calculation

A novel double Z-scheme heterojunction Bi5O7I/Bi2O2CO3/Ag2CO3 was constructed by a simple hydrothermal calcination and one-step in-situ growth technique, demonstrating efficient levofloxacin degradation (86.9 % in 60 min). The degradation rates of the system are 1.5, 4.1, 1.3 and 1.4 times faster than those of pure Bi5O7I, Bi2O2CO3, Ag2CO3 and binary Bi5O7I/Bi2O2CO3, respectively. The method enhances the photocatalyst performance through improving the separation efficiency of electron-hole pairs (e-/h+) and the production of various free radicals in the double Z-scheme system. The generation of hydroxyl radicals (•OH), superoxide radicals (•O2–) and holes (h+) species were directly confirmed by Electron Spin Resonance test, and their contributions on the degradation of Levofloxacin follow the order of h+ > •OH > •O2–. The band structure, density of states, work function and potential sites of contaminant vulnerability in the material were determined by Density Functional Theory (DFT), which provides additional evidence for the formation of double Z-scheme heterojunction. Besides, the degradation experiment was conducted with four real surface water bodies, including lake water, river water, tap water and effluent of sewage treatment plant. The results show that the degradation rate for Levofloxacin reaches 60∼80 %. Moreover, Levofloxacin and its intermediate products were identified and their toxicity was predicted with Quantitative Structure-Activity Relationship (QSAR) modelling, which can be useful in the future for the actual design of a double Z-scheme heterojunction photocatalyst to efficiently remove pollutants under visible light irradiation.

Iron–molybdenum bimetals incorporated montmorillonite-based catalytic ceramic membrane for heterogenous Fenton reaction towards the degradation of micropollutants in water

This study developed an innovative material approach that integrated Fenton catalysis with membrane filtration in a single system using iron–molybdenum bimetal oxides (FeMoO) incorporated montmorillonite (MMT)-based ceramic membrane (FeMoMMTCM) to achieve continuous Fenton reaction for water purification. The embedded bimetallic FeMoO catalyst created abundant active Fe(II) sites on the external and internal surfaces of the ceramic membrane (CM) for H2O2 activation. Using naproxen (NPX) as a model micropollutant in water, the FeMoMMTCM/H2O2 system achieved a 98.6 % removal of NPX (10 mg/L) within a filtration period of 3.4 min through the membrane, in comparison to a 17.5 % removal by FeMoMMTCM filtration with no H2O2 dosing and a 21.1 % removal by the FeMoO-less MMTCM/H2O2 system. The catalytic membrane demonstrated its high NPX removal efficiency over multiple cycles, retaining its effectiveness even in the presence of co-existing ions and organic matter in the water matrix. Furthermore, the FeMoMMTCM/H2O2 system was able to remove nearly 70 % of residual organic pollutants from the actual secondary wastewater effluent. The quenching tests and electro-paramagnetic resonance (EPR) detection confirmed the generation of hydroxyl (OH) and superoxide (O2−) radicals from H2O2. The excellent catalytic performance can be attributed to the Fe-Mo bimetallic catalyst, in which the active Mo(VI)/Mo(IV) cycle can facilitate the Fe(II)/Fe(III) cycle for continuous Fenton reaction. The cost analysis indicates that the low-cost MMT and its low sintering temperature for ceramics would greatly decrease the cost of MMTCM (243.1 US$/m2 vs. 541.5 US$/m2 of alumina-based CM). Overall, the research presents a technical strategy for the fabrication of highly cost-effective catalytic membranes with Fenton reaction for removing micropollutants from water.

Magnetic biochar-doped g-C3N4/Fe2O3 S-scheme heterojunction with enhanced photocatalytic degradation of tetracycline by addition of persulfate

Graphitic carbon nitride (g-C3N4) exhibits remarkable thermal and chemical stability, enabling effective activation of molecular oxygen and generation of superoxide radicals for photocatalytic pollutant degradation. However, its low surface area and poor photocatalytic activity have limited its development, and the reaction mechanism of pollutant degradation remains unclear. In this study, we synthesized g-C3N4/BC/Fe2O3 catalysts by combining g-C3N4, biochar (BC), and Fe2O3 in intimate contact. The highest photocatalytic degradation efficiency of tetracycline (TC) reached 94.9 % in the g-C3N4/BC/Fe2O3-2/PDS system, which was 3.01, 1.53, and 2.35 times higher than that of pure g-C3N4, BC, and BC/Fe2O3, respectively. The addition of persulfate (PDS) accelerated the formation of reactive oxygen species (ROS), providing more active species and improving photocatalytic performance, thereby enhancing TC degradation. LC-MS analysis and density functional theory (DFT) calculations were used to elucidate possible TC degradation pathways in the g-C3N4/BC/Fe2O3-2/PDS system. Electron paramagnetic resonance (EPR) confirmed the generation of multiple ROS in the reaction system, including h+, •OH, SO4•−, •O2−, and 1O2. This work provides mechanistic insights into TC degradation and offers a theoretical foundation for future studies on advanced oxidation processes for water treatment.

Flower-like boron-doped zinc single-atom nanozymes for colorimetric sensing and smartphone-assisted detection of Cr(VI)

With the development of electronics, electroplating, printing, and dyeing industries, environmental pollution caused by hexavalent chromium (Cr(VI)) has become increasingly prominent. Skin contact with Cr (VI) can cause allergies or genetic defects, and inhalation can cause cancer, which is a lasting danger to the environment and the human body. Developing effective strategies to monitor Cr(VI) in environmental water or industrial wastewater can evaluate the degree of water pollution and risk warning, thus helping to prevent the spread of Cr(VI) pollution, promote the protection of water resources and the ecological environment, and ensure human safety and sustainable development. On the basis of the regulation of dopamine, boron-doped zinc single-atom nanozymes (Zn/B-NC SAzymes) with three-dimensional nanoflower morphology were controlled in this work. The introduction of B in Zn/B-NC SAzymes and the high metal loading of Zn (6.5 wt%) led to the formation of more active sites, resulting in the material showing excellent enzyme-like activity. H2O2 decomposed to generate superoxide radicals under the catalysis of Zn/B-NC SAzymes, which then oxidized the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) to generate blue oxTMB. When Cr(VI) was introduced into the sensor system, the color of blue oxTMB is deepened, and the colorimetric method of Cr(VI) was constructed. The linear range is 0.2–40 μM, LOD is 59 nM, and the visual detection of Cr (VI) is performed with the aid of the smartphone. This work not only provides experimental and theoretical guidance for understanding the active centers of Zn-SAzymes and their catalytic processes, but also provides a promising and alternative detection strategy for the rapid and even visual on-site detection of Cr(VI) in aquatic environments, which is of great significance for the control of Cr(VI) pollution in the environment and industrial wastewater.

Visible‐Light Photocatalytic Activity of a Novel TiO2/g‐C3N4/CuFe2O4 Nanocomposite in Degradation Amoxicillin, Chlorpyrifos and Methylene Blue

AbstractA novel TiO2/g‐C3N4/CuFe2O4 nanocomposite is synthesized via a wet impregnation process and has been evaluated for photocatalytic degradation of organic pollutants such as Amoxicillin (Antibiotic), Chlorpyrifos (Pesticide), and Methylene blue (Dye) under dark and visible light conditions in water. The synthesis and its photocatalytic characterization of nanocomposite are analyzed using XRD, FT‐IR, HR‐SEM, TEM, EDS, XPS, UV‐Vis, DRS, PL, BET, EIS, VSM, and ESR analysis. Among the various organic pollutants analyzed using TiO2/g‐C3N4/CuFe2O4 to serve as a photocatalyst, the degradation of MB pollutant was significantly greater (99.5 %, k=0.0533 min−1) in comparison to the degradation of the AMX (97.6 %, k=0.0346 min−1) and CPF (97.3 %, k=0.0340 min−1) during visible light irradiation for a period of 90 minutes. The recyclability is validated over three cycles, displayed its stability with 76 % degradation of pollutants and the photocatalyst is also easily separated using a simple magnet for further recycling study. As observed in the results of ESR, the formation of O2 significantly accelerated the superoxide radical generation during the photocatalytic degradation of pollutants, enhancing degradation efficiency. It is worth highlighting that the remarkable degradation efficacy, stability and reusability exhibited by the synthesised nanocomposite prove advantageous for subsequent applications.

The synthesis of Bi2MoO6 with metallic and nonmetallic vacancies for degradation of LVF in visible light

Defect engineering advantages include regulating the band structure of photocatalytic materials, inhibiting the recombination of photoelectron-hole pairs, and promoting the conversion of photogenerated electrons into active radicals. In this paper, bismuth molybdate (Bi2MoO6) photocatalysts with double vacancies (VBi-O-BMO) were prepared by solvothermal and ionic eutectic solvent methods. EPR, TEM, and XPS results confirmed the successful construction of oxygen and bismuth vacancies on Bi2MoO6. The photocatalytic performance of the prepared catalysts was investigated by photodegradation of levofloxacin hydrochloride (LVF) under visible light. The double vacancies markedly enhanced the photocatalytic properties of Bi2MoO6, with the photodegradation rate of VBi-O-BMO reaching 88.36 % for 40 mg/L LVF within 60 min. Kinetic studies have demonstrated that the reaction rate constant of VBi-O-BMO can reach 0.0351 min−1, which is 3.2 times higher than that of bulk-BMO. This can be attributed to the favorable synergistic effect of oxygen and bismuth double vacancies. VO not only captures oxygen and electrons, facilitating the generation of superoxide radicals (O2−), but also elevates the conduction band position and boosts the reduction capability of Bi2MoO6. VBi not only captures photogenerated holes (h+) to directly impact LVF degradation, but also promotes interfacial charge transfer and inhibits the recombination of electron-hole pairs. Furthermore, the intermediates and degradation pathways of LVF photodegradation were surmised based on the LC-MS analysis. The reaction mechanism of LVF photodegradation by VBi-O-BMO was elucidated through the application of the free radical pathway. This study demonstrates a methodology for the creation of double vacancies in catalysts and the significant potential of VBi-O-BMO for the remediation of antibiotic residues in water under visible light.

A glutathione-activated bismuth-gallic acid metal-organic framework nano-prodrug for enhanced sonodynamic therapy of breast tumor

Sonodynamic therapy is a promising, noninvasive, and precise tumor treatment that leverages sonosensitizers to generate cytotoxic reactive oxygen species during ultrasound stimulation. Gallic acid (GA), a natural polyphenol, possesses certain anti-tumor properties, but exhibits significant toxicity toward normal cells, limiting its application in cancer treatment. To overcome this issue, we synthesized a bismuth-gallic acid (BGA), coordinated metal–organic framework (MOF) nano-prodrug. Upon encountering glutathione (GSH), BGA gradually dissociated and depleted GSH, releasing GA, which had anti-tumor effects. As an MOF with semiconductor properties, BGA primarily produced superoxide anion radical upon ultrasound excitation. After the release of GA, GA generated superoxide anion radical and further produced high toxic singlet oxygen under ultrasound stimulation, while further oxidizing and consuming GSH, enhancing sonocatalytic performance. Additionally, the released GA induced cell cycle arrest, ultimately leading to apoptosis. Our results revealed that BGA, as a GSH-activated, metal-polyphenol MOF nano-prodrug, showed potential for use in breast tumor sonodynamic therapy, providing a novel strategy for precise tumor treatment.

Built-in electric field mediated S-scheme high-quality charge separation in BiVO4/NiAl-LDH heterojunction for highly efficient photocatalytic degradation of antibiotics

As an up and coming technology for antibiotics removal from water, photocatalysis required well-pleasing charge isolation, migration, and utilization efficiency to come true an efficaciously photocatalytic performance, but developing affordable and high-efficiency photocatalyst remains a great challenging. Herein, an emerging S-scheme BiVO4/NiAl-LDH heterojunction was ingeniously fabricated by mulberry-like BiVO4 microrods immobilized onto the surfaces of flower-like NiAl-LDH microspheres. The physicochemical properties of the BiVO4/NiAl-LDH heterojunctions were analyzed by multiple techniques. Expectedly, the manufactured BiVO4/NiAl-LDH heterojunction endowed a significantly strengthened removal rate of tetracycline compared to mono-component BiVO4 and NiAl-LDH under visible light. Specifically, the optimized BVO-NAL-3 manifested the exceptional tetracycline removal efficiency with an apparent rate constant of up to 0.0409 min−1, which was close to 34.1 and 4.4 times more rapid than those of neat NiAl-LDH and BiVO4, severally. This signal enhancement was centrally related to the creation of S-scheme heterojunction, which accelerated high-quality charge separation and strengthened redox capacity under the force of created a built-in electric field, which was corroborated by experiments results together with density functional theory calculations. Besides, the generation of superoxide radicals and photogenerated holes played an imperative role in the tetracycline degradation over BVO-NAL-3. Noteworthily, BVO-NAL-3 expressed the satisfactory stability and exceptional resistance to environmental interferences. More amazingly, other refractory antibiotics including ciprofloxacin, levofloxacin and amoxicillin were also efficaciously eliminated by BVO-NAL-3. Ultimately, the possible degradation mechanism and pathways of tetracycline were logically inferred. This work unveils a valuable afflatus for the reasonable layout and establishment of S-scheme heterojunction with high-quality charge separation for the eradication of antibiotics.