Generation Of Superoxide Radicals Research Articles

Novel angiogenesis inhibitors with superoxide anion radical amplification effect: Surmounting the Achilles’ heels of angiogenesis inhibitors and photosensitizers

Angiogenesis inhibitors and photosensitizers are pivotal in tumor clinical treatment, yet their utilization is constrained. Herein, eleven novel angiogenesis inhibitors were developed through hybridization strategy to overcome their clinical limitations. These title compounds boast excitation wavelengths within the “therapeutic window”, enabling deep tissue penetration. Notably, they could generate superoxide anion radicals via the Type I mechanism, with compound 36 showed the strongest superoxide anion radical generating capacity. Biological evaluation demonstrated remarkable cellular activity of all the title compounds, even under hypoxic conditions. Among them, compound 36 stood out for its superior anti-proliferative activity in both normoxic and hypoxic environments, surpassing individual angiogenesis inhibitors and photosensitizers. Compound 36 induced cell apoptosis via superoxide anion radical generation, devoid of dark toxicity. Molecular docking revealed that the target-recognizing portion of compound 36 was able to insert into the ATP binding pocket of the target protein similar to sorafenib. Collectively, our results suggested that hybridization of angiogenesis inhibitors and photosensitizers was a potential strategy to address the limitations of their clinical use.

Enhancing the Photocatalytic Activity of Halide Perovskite Cesium Bismuth Bromide/Hydrogen Titanate Heterostructures for Benzyl Alcohol Oxidation.

Halide perovskite Cs3Bi2Br9 (CBB) has excellent potential in photocatalysis due to its promising light-harvesting properties. However, its photocatalytic performance might be limited due to the unfavorable charge carrier migration and water-induced properties, which limit the stability and photocatalytic performance. Therefore, we address this constraint in this work by synthesizing a stable halide perovskite heterojunction by introducing hydrogen titanate nanosheets (H2Ti3O7-NS, HTiO-NS). Optimizing the weight % (wt%) of CBB enables synthesizing the optimal CBB/HTiO-NS, CBHTNS heterostructure. The detailed morphology and structure characterization proved that the cubic shape of CBB is anchored on the HTiO-NS surface. The 30 wt% CBB/HTiO-NS-30 (CBHTNS-30) heterojunction showed the highest BnOH photooxidation performance with 98% conversion and 75% benzoic acid (BzA) selectivity at 2 h under blue light irradiation. Detailed optical and photoelectrochemical characterization showed that the incorporating CBB and HTiO-NS widened the range of the visible-light response and improved the ability to separate the photo-induced charge carriers. The presence of HTiO-NS has increased the oxidative properties, possibly by charge separation in the heterojunction, which facilitated the generation of superoxide and hydroxyl radicals. A possible reaction pathway for the photocatalytic oxidation of BnOH to BzH and BzA was also suggested. Furthermore, through scavenger experiments, we found that the photogenerated h+, e- and •O2- play an essential role in the BnOH photooxidation, while the •OH have a minor effect on the reaction. This work may provide a strategy for using HTiO-NS-based photocatalyst to enhance the charge carrier migration and photocatalytic performance of CBB.

Synergistic oxidation of humic acid treated by H2O2/O3 activated by CuCo/C with high efficiency and wide pH range

Combination of oxidation processes are one of the most promising humic acid treatment technologies. Single oxidant or even two oxidants in advance oxidation process can hardly achieve satisfactory removal efficiency of refractory organic matter, mainly humic acid, in the treatment process of reverse osmosis concentrates from landfill leachate. To solve this problem, this study investigated the synergistic degradation of Humic acid (HA) using a Cu and Co supported on carbon catalyst (CuCo/C) in a Hydrogen peroxide (H2O2) with ozone (O3) system. The catalyst was characterized by performing SEM, XRD, BET, XPS and FTIR technologies. UV–vis spectra, 3D Excitation Emission Matrix Spectra (3D-EEM) and gas chromatography-mass spectrometry (GC–MS) were applied for exploring degradation mechanism of HA. To further understand the oxidation mechanism, electron paramagnetic resonance (EPR) was used to evaluate the generation of hydroxyl (·OH) and superoxide radicals (O2·-). As a result, CuCo/C catalyst possessed stable catalytic performance for HA degradation with a wide pH range from 5 to 8, while T = 40 °C，catalyst dosage of 2.4 g/L，O3 intake rate of 0.15 g/min and H2O2 dosage of 1.92 mL/L, the degradation rate of total organic carbon (TOC) achieved 40–46.5 mg·L−1min−1. As affirmed by the EPR, ·OH and O2·- were effectively generated with addition of the CuCo/C catalyst. Degradation performance of UV254 proved that the catalytic activity can still be maintained above 95% with removal rate of 82% after 5 cycles reuse. GC-MS shows that the oxidation products mainly consist of amide, benzoheterocyclic ring and carboxylic acid. This work promotes an effective method for degrading HA, which has the potential for satisfactory application in landfill leachate.

Regulating Reactive Oxygen Species over M-N-C Single-Atom Catalysts for Potential-Resolved Electrochemiluminescence.

The development of potential-resolved electrochemiluminescence (ECL) systems with dual emitting signals holds great promise for accurate and reliable determination in complex samples. However, the practical application of such systems is hindered by the inevitable mutual interaction and mismatch between different luminophores or coreactants. In this work, for the first time, by precisely tuning the oxygen reduction performance of M-N-C single-atom catalysts (SACs), we present a dual potential-resolved luminol ECL system employing endogenous dissolved O2 as a coreactant. Using advanced in situ monitoring and theoretical calculations, we elucidate the intricate mechanism involving the selective and efficient activation of dissolved O2 through central metal species modulation. This modulation leads to the controlled generation of hydroxyl radical (·OH) and superoxide radical (O2·-), which subsequently trigger cathodic and anodic luminol ECL emission, respectively. The well-designed Cu-N-C SACs, with their moderate oxophilicity, enable the simultaneous generation of ·OH and O2·-, thereby facilitating dual potential-resolved ECL. As a proof of concept, we employed the principal component analysis statistical method to differentiate antibiotics based on the output of the dual-potential ECL signals. This work establishes a new avenue for constructing a potential-resolved ECL platform based on a single luminophore and coreactant through precise regulation of active intermediates.

Analysis of microbial community evolution, autolysis phenomena, and energy metabolism pathways in Pholiota nameko endophytes.

Pholiota nameko is a widely consumed edible fungus. This study focuses on two crucial developmental stages of Pholiota nameko, namely, mycelium and ascospores. The objectives of this research were to investigate changes in microbial diversity and community structure during the growth of Pholiota nameko and to analyze the adaptability of the dominant strains to their respective habitats through metabolic. Specifically, we conducted second-generation sequencing of the 16S rRNA gene (Illumina) on samples obtained from these stages. In addition, we isolated and characterized endophytes present in Pholiota nameko, focusing on examining the impact of dominant endophyte genera on autolysis. We also conducted a metabolic pathway analysis. The results unveiled 578,414 valid sequences of Pholiota nameko endophytic fungi. At the phylum level, the dominant taxa were Basidiomycota, Ascomycota, Zoopagomycota, and Mucoromycota. At the genus level, the dominant taxa observed were Pholiota, Inocybe, Fusarium, and Hortiboletus. For endophytic bacteria, we obtained 458,475 valid sequences. The dominant phyla were Proteobacteria, TM6, Firmicutes, and Bacteroidetes, while the dominant genera were Edaphobacter, Xanthomonas, Burkholderia, and Pseudomonas. Moreover, we identified the isolated strains in Pholiota nameko using 16S rDNA, and most of them were found to belong to the genus Pseudomonas, with Pseudomonas putida being the most prevalent strain. The findings revealed that the Pseudomonas putida strain has the ability to slow down the breakdown of soluble proteins and partially suppress the metabolic processes that generate superoxide anion radicals in Pholiota nameko, thereby reducing autolysis. Additionally, our results demonstrated that molybdenum enzyme-mediated anaerobic oxidative phosphorylation reactions were the primary energy metabolism pathway in the Pseudomonas putida strain. This suggests that the molybdenum cofactor synthesis pathway might be the main mechanism through which Pholiota nameko adapts to its complex and diverse habitats.

Role of reactive carbonyls and superoxide radicals in protein damage by cigarette smoke extracts: Comparison of Heat-not-Burn e-cigarettes to conventional cigarettes

Oxidative protein damage involving carbonylation of respiratory tract proteins typically accompanies exposure to tobacco smoke. Such damage can arise via multiple mechanisms, including direct amino acid oxidation by reactive oxygen species or protein adduction by electrophilic aldehydes. This study investigated the relative importance of these pathways during exposure of a model protein to fresh cigarette emission extracts. Briefly, protein carbonyl adducts were estimated in bovine serum albumin following incubation in buffered solutions with whole cigarette emissions extracts prepared from either a single 1R6F research cigarette or a single “Heat-not-Burn” e-cigarette. Although both extracts caused concentration-dependent protein carbonylation, conventional cigarette extracts produced higher adduct yields than e-cigarette extracts. Superoxide radical generation by conventional and e-cigarette emissions was assessed by monitoring nitro blue tetrazolium reduction and was considerably lower in extracts made from “Heat-Not-Burn” e-cigarettes. The superoxide dismutase/catalase mimic EUK-134 strongly suppressed radical production by whole smoke extracts from conventional cigarettes, however, it did not diminish protein carbonyl adduction when incubating smoke extracts with the model protein. In contrast, edaravone, a neuroprotective drug with strong carbonyl-trapping properties, strongly suppressed protein damage without inhibiting superoxide formation. Although these findings require extension to appropriate cell-based and in vivo systems, they suggest reactive aldehydes in tobacco smoke make greater contributions to oxidative protein damage than smoke phase radicals.

Involvement of ROS and calcium ions in developing heat resistance and inducing antioxidant system of wheat seedlings under melatonin's effects.

The stress-protective effect of melatonin (N-acetyl-5-methoxytryptamine) on plant cells is mediated by key signaling mediators, in particular calcium ions and reactive oxygen species (ROS). However, the links between changes in calcium and redox homeostasis and the formation of adaptive responses of cultivated cereals (including wheat) to the action of high temperatures have not yet been studied. In the present study, we investigated the possible involvement of ROS and calcium ions as signaling mediators in developing heat resistance in wheat (Triticum aestivum L.) seedlings and activating their antioxidant system. Treatment of 3-day-old etiolated seedlings with melatonin solutions at concentrations 0.01-10µM increased their survival after exposure to 45°C for 10min. The most significant stress-protective effect was exerted by melatonin treatment at 1µM concentration. Under the influence of melatonin, a transient enhancement of superoxide anion radical (O2•-) generation and an increase in hydrogen peroxide content were observed in roots, with a maximum at 1h. Four hours after treatment with melatonin, the activity of catalase and guaiacol peroxidase increased in roots, while the activity of superoxide dismutase did not change significantly. After exposure to 45°C, the activity of catalase and guaiacol peroxidase was higher in the roots of melatonin-treated wheat seedlings, and the indices of ROS generation, content of the lipid peroxidation product malonic dialdehyde, and cell membrane damage were lower than in control seedlings. Melatonin-induced changes in root ROS generation and antioxidant enzyme activities were eliminated by pretreatment with the hydrogen peroxide scavenger dimethylthiourea (DMTU), NADPH oxidase inhibitor imidazole, and calcium antagonists (the extracellular calcium chelator EGTA and phospholipase C inhibitor neomycin). Treatment with DMTU, imidazole, EGTA, and neomycin also abolished the melatonin-induced increase in survival of wheat seedlings after heat stress. The role of calcium ions and ROS, generated with the participation of NADPH oxidase, as signaling mediators in the melatonin-induced antioxidant system and heat stress resistance of wheat seedlings have been demonstrated.

Role of low-molecular-weight organic compounds on photochemical formation of Mn(III)-ligands in aqueous systems: Implications for BPA removal

Aqueous trivalent manganese [Mn(III)], an important reactive intermediate, is ubiquitous in natural surface water containing humic acid (HA). However, the effect of low-molecular-weight organic acids (LMWOAs) on the formation, stability and reactivity of Mn(III) intermediate is still unknown. In this study, six LMWOAs, including oxalic acid (Oxa), salicylic acid (Sal), catechol (Cat), caffeic acid (Caf), gallic acid (Gal) and ethylene diamine tetraacetic acid (EDTA), were selected to investigate the effects of LMWOAs on the degradation of BPA induced by in situ formed Mn(III)-L in the HA/Mn(II) system under light irradiation. The chromophoric constituents of HA could absorb light radiation and generate superoxide radical to promote the oxidation of Mn(II) to form Mn(III), which was further involved in transformation of BPA. Our results implied that different LMWOAs did significantly impact on Mn(III) production and its degradation of BPA due to their different functional group. EDTA, Oxa and Sal extensively increased the Mn(III) concentration from 50 to 100 μM compared to the system without LMWOAs, following the order of EDTA > Oxa > Sal, and also enhanced the degradation of BPA with the similar patterns. In contrast, Cat, Caf and Gal had an inhibitory effect on the formation of Mn(III), which is likely because they consumed the superoxide radicals generated from irradiated HA, resulting in the inhibition of Mn(II) oxidation and further BPA removal. The product identification and theoretical calculation indicated that a single electron transfer process occurred between Mn(III)-L and BPA, forming BPA radicals and subsequent self-coupling products. Our results demonstrated that the LMWOAs with different structures could alter the cycling process of Mn via complexation and redox reactions, which would provide new implications for the removal of organic pollutants in surface water.

Highly efficient electrochemiluminescence based on Lu@Ov-ZMO as an ECL emitter for ultrasensitive detection of CA242

An effective electrochemiluminescence (ECL) emitter, luminol@oxygen vacancies-ZnMn2O4 (Lu@Ov-ZMO), was prepared to fabricate a novel luminol/H2O2-O2/Ov-ZMO ECL system for ultrasensitive detection of carbohydrate antigen 242 (CA242). The integrated design of co-reaction accelerator ZMO and luminol effectively shortened the electron transfer distance in the ECL system. Meanwhile, the abundant oxygen vacancies in ZMO further promoted the generation of more superoxide anion radicals (O2.-), which further improved the ECL luminescence efficiency. The resonance energy transfer (RET) strategy was used to construct the signal-off ECL immunesensor with PDA@SiO2 as the quencher. The fabricated immunosensor showed a good linear range of 0.01 mU/mL to 100 U/mL with a detection limit of 3.3 μU/mL (S/N = 3) under the optimum experimental conditions. This work put forward a new method of integrating luminophore and OVs enriched accelerator with wonderful signal-amplification strategy to formulate a functional immunosensor for early disease diagnostics.

Enhanced degradation of Direct Red 80 dye via Fenton-like process mediated by cobalt ferrite: generated superoxide radicals and singlet oxygen.

Azo dyes, widely used in the textile industry, contribute to effluents with significant organic content. Therefore, the aim of this work was to synthesize cobalt ferrite (CoFe2O4) using the combustion method and assess its efficacy in degrading the azo dye Direct Red 80 (DR80). TEM showed a spherical structure with an average size of 33 ± 12nm. Selected area electron diffraction and XRD confirmed the presence of characteristic crystalline planes specific to CoFe2O4. The amount of Co and Fe metals were determined by ICP-OES, indicating an n(Fe)/n(Co) ratio of 2.02. FTIR exhibited distinct bands corresponding to Co-O (455cm-1) and Fe-O (523cm-1) bonds. Raman spectroscopy detected peaks associated with octahedral and tetrahedral sites. For the first time, the material was applied to degrade DR80 in an aqueous system, with the addition of persulfate. Consistently, within 60min, these trials achieved nearly 100% removal of DR80, even after the material had undergone five cycles of reuse. The pseudo-second-order model was found to be the most fitting model for the experimental data (k2 = 0.07007 L mg-1min-1). The results strongly suggest that degradation primarily occurred via superoxide radicals and singlet oxygen. Furthermore, the presence of UV light considerably accelerated the degradation process (k2 = 1.54093 L mg-1min-1). The material was applied in a synthetic effluent containing various ions, and its performance consistently approached 100% in the photo-Fenton system. Finally, two degradation byproducts were identified through HPLC-MS/MS analysis.

Samarium doped carbon dots for near-infrared photo-therapy

Photo-assisted tumor therapy, encompassing photodynamic therapy (PDT) and photothermal therapy (PTT), has garnered considerable attention as a promising approach for tumor treatment owing to its stimuli-responsive nature and noninvasive characteristics. Carbon dots (CDs) have recently emerged as a novel type of nanomaterial with great potential in the field of anticancer therapy. However, the development of multifunctional CDs nano-platforms that integrate multiple therapeutic performance remains a challenge, especially in near-infrared (NIR) window. In this study, we synthesized samarium-doped carbon dots (Sm/CDs) via a one-step hydrothermal process for fluorescence imaging guided PTT/PDT in NIR-II window. Sm/CDs demonstrated remarkable absorption and emission properties in the NIR region, enabling efficient generation of heat energy, superoxide (•O2–) and hydroxyl radicals (•OH) under NIR irradiation. The photothermal conversion efficiencies of Sm/CDs reached up to 34.12 % and 24.38 % when exposed to 808 nm and 1060 nm wavelengths, respectively. Moreover, long-term toxicity experiments conducted in vivo as well as fluorescence experiments confirmed the potential of such functional CDs for fluorescence imaging and excellent biocompatibility. It is noteworthy that the tumor is nearly eradicated when exposed to either 808 nm or 1060 nm, demonstrating significant efficacy in both scenarios. This study provides a multifunctional CDs nano-platform that offers a promising bimodal phototherapeutic strategy to enhance the synergistic treatment of tumors through PDT and PTT.

β particles enhance the modulating lattice distortion of Mn-doped BiFeO3 and photo-responsive catalyzing of As(III) and Sb(III)

In this work, metal Mn was doped into BiFeO3(BFO) to modulate the lattice, and a high-energy β electron beam was used to irradiate the Mn-BiFeO3(BFMO) to produce lattice distortions, resulting in reducing the photogenerated carrier complexation rate of the material and improving the photocatalytic activity for arsenic and antimony. The physical properties of the BFMO with lattice distortion also produced some changes, with the Bi: O ratio on the surface decreasing from 1.0: 3.0–1.0: 1.6 and the band gap decreasing from 1.5 eV to 1.3 eV. In addition, the experiment results show that the structure of Bi-Mn-Fe-O can efficiently enhance the photocatalytic oxidation of As(III) and Sb(III) at different initial pH values, and the elimination rates of As(III) and Sb(III) can reach 100% and 79.9%, respectively. Characterization by PL, Mott-Schottky, transient photocurrent response, and DFT calculations demonstrated that BFMO-450 (irradiated at a dose of 450 KGy) has excellent charge mobility, which is conducive to the separation and transfer of photogenerated carriers. The XPS results showed that the BFMO-450 surface has optimal Mn4+/Mn2+ and Fe2+/Fe3+ ion pairs, and the formation of the Fe-Mn structure is favorable for the generation of superoxide radicals (·O2−, whereas the most prominent radicals in the photocatalytic process are the ·O2−, which was proved by the electron paramagnetic resonance (EPR) and bursting experiments. This study provides a novel approach to modifying BFMO composites and demonstrates that materials possessing lattice distortion have advantages in treating heavy metal-contaminated water.

Novel SnO2-modified hydrozincite photocatalyst: Material design and application in efficient micropollutants degradation in wastewater

In this work novel photocatalysts have been synthesized based on hydrozincite and SnO2 with varying mol% of SnO2 in hydrozincite. The photocatalysts were prepared via chemical co-precipitation using thermal urea hydrolysis, without calcination or activation processes, and were applied in the photodegradation of micropollutants (in this case, several phenolic compounds). Characterization of the materials using various techniques revealed that the generation of hydroxyl radicals, holes, and superoxide radicals played crucial roles in the photodegradation process. The best photocatalyst was achieved with a 10 mol% SnO2 content in hydrozincite, which shows the highest rate in the pollutants degradation (higher than 93% in all the cases), also higher than TiO2-P25This study presents promising insights for developing highly efficient photocatalytic materials for environmental remediation applications.

Functional status of blood neutrophils in congenital defects of antibody production

We evaluated some functional indices of neutrophils in 100 adult patients with a verified diagnosis of primary antibody production deficiency (44 patients with common variable immunodeficiency – CVID, and 56 patients with selective IgA deficiency – SigAD). The diagnosis was made according to the criteria of the Pan-American Group for Immunodeficiency and European Society for Immunodeficiency. The criteria for diagnosis were based on clinical data, medical history and results of laboratory tests. All patients with CVID received regular immunoglobulin replacement therapy, and the SIgAD patients received symptomatic treatment on demand. The examination was performed beyond the infectious episodes, inflammatory events or exacerbation of chronic disorders upon admission for planned hospitalisation, before any therapeutic and diagnostic procedures. In addition to standard clinical and laboratory examination appointed for the mentioned diseases, we assessed fnctional status of neutrophils: superoxide-anion radical production, NETosis, phagocytosis and apoptosis. Taking into account clinical manifestations, the patients with CVID were divided into 6 clinical subgroups: without CVID-related complications (13.6%); with infectious complications, i.e., bronchiectatic disease (15.9%), autoimmune syndromes (22.7%), polyclonal lymphoid infiltration (13.6%), enteropathic syndrome (34.1%), and malignant neoplasms (9.1%). Four phenotypes were identified in the patients with SIgAD: absence of SIgAD-related complications (28.6%); autoimmune syndrome (16.1%), non-malignant lymphoproliferation (3.6%) and enteropathy (28.6%). Higher incidence of non-infectious complications (autoimmune syndrome, non-malignant lymphoproliferation, enteropathies) was found in СVID compared to SIgAD patients (χ2 = 10.27; p = 0.001). Patients from the both groups showed changes in neutrophil reactivity compared to control values expressing higher basal generation of superoxide radicals (p < 0.001), NETosis activity (p = 0.005) and apoptosis (p < 0.001) with decreased phagocytic function (p < 0.001) and lower reserve for reactive oxygen species formation (p < 0.001). The maximal degree of changes in phagocytosis and superoxide-producing activity was observed in СVID; altered NETosis was revealed in SIgAD. The development of non-infectious complications was accompanied by a significant increase in stimulated NETosis indexes, thus suggesting a promising index in order to assess stability of clinical course and to predict development of complications in congenital defects of antibody production.

ROS signaling in innate immunity via oxidative protein modifications.

The innate immune response represents the first-line of defense against invading pathogens. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been implicated in various aspects of innate immune function, which involves respiratory bursts and inflammasome activation. These reactive species widely distributed within the cellular environment are short-lived intermediates that play a vital role in cellular signaling and proliferation and are likely to depend on their subcellular site of formation. NADPH oxidase complex of phagocytes is known to generate superoxide anion radical (O2 •-) that functions as a precursor for antimicrobial hydrogen peroxide (H2O2) production, and H2O2 is utilized by myeloperoxidase (MPO) to generate hypochlorous acid (HOCl) that mediates pathogen killing. H2O2 modulates the expression of redox-responsive transcriptional factors, namely NF-kB, NRF2, and HIF-1, thereby mediating redox-based epigenetic modification. Survival and function of immune cells are under redox control and depend on intracellular and extracellular levels of ROS/RNS. The current review focuses on redox factors involved in the activation of immune response and the role of ROS in oxidative modification of proteins in macrophage polarization and neutrophil function.

One-pot synthesis of BiSCl–Bi6.88S8·64Cl3.36 nanorods for rhodamine B photodegradation in water

In the domain of water treatment, photocatalytic degradation presents a compelling approach. However, the quest for photocatalysts that exhibit superior solar energy absorption and conversion remains a challenge. We explore rod-shaped bismuth-rich chalcohalide photocatalyst BiSCl–Bi6.88S8·64Cl3.36 by simple temperature control and demonstrate the proficiency in degrading organic pollution under visible light. BiSCl–Bi6.88S8.64Cl3.36 nanorods manifest a composition-tailored band gap, effectively spanning the visible spectrum. Remarkably, in the absence of cocatalysts and sacrificial agents, BiSCl–Bi6.88S8·64Cl3.36 exhibit exceptional photocatalytic degradation rate of 99.8%, which is comparable to that of BiSBr (98.6%). Moreover, the photodegradation rate of BiSCl–Bi6.88S8·64Cl3.36 (0.091 min−1) is higher than that of BiSBr (0.048 min−1). The rate position it among the most effective known photocatalysts, with the generation of superoxide anion radicals (•O2−) and photogenerated holes (h+) as the primary active species. Notably, the enhanced photocatalytic activity of BiSCl–Bi6.88S8·64Cl3.36 is attributed to the high number of Bi centers and the higher electronegativity, which induces a more polar crystal structure.

Readily Available Stable Nonquantum Dot CsPbBr3/TiO2 Heterostructure Crystals for Efficient Photocatalyst

The application of perovskites in the field of photocatalyst has been greatly limited due to their poor stability. Herein, the easy‐to‐prepare CsPbBr3/TiO2 heterostructure nanocrystals are employed as photocatalysts. The results confirm that the strong interfacial connection and efficient charge separation can be observed in CsPbBr3/TiO2 heterostructure crystals by natural crystal growth. Consequently, the generation of superoxide radicals, which is beneficial for the photocatalytic properties, is obviously increased. The CsPbBr3/TiO2 heterostructure nanocrystals completely degrade Rhodamine B in just 4 min. In addition, it is also found that the nonquantum dot CsPbBr3 crystals can be naturally encapsulated by the stable and compact TiO2 nanoparticles without complex synthesis process, which finally provides an excellent protection for the stability of CsPbBr3 perovskite. The CsPbBr3/TiO2 heterostructure nanocrystals can exhibit almost no degradation of photocatalytic performance exceeding 8 months in oceanic climate (10 °C ≤ T ≤ 32 °C, 20% ≤ RH ≤ 100%), showing a remarkable stability.

Potassium and chlorine co-tuned graphitic carbon nitride for organic pollutants photodegradation: Revealing the effects of cyano groups on O2 evolution

The insufficient active sites and sluggish photogenerated electron migration are hindered the photocatalytic activity of g-C3N4. Herein, we successfully synthesized a K and Cl co-tuned g-C3N4, with cyano groups incorporating (expressed as CN-KCl). The optoelectronic and physicochemical properties of the samples were comprehensively investigated using a combination of characterization techniques and DFT calculations. The results demonstrated that Cl atom replaced sp2-hybridized nitrogen atom, while K atom was doped at the interstitial site. With the synergistic effect of K/Cl atoms, the transfer of photogenerated electrons across layers and lamellae was enhanced. Additionally, the cyano groups not only acted as the most stable adsorption sites for O2, but also served as charge transfer bridge between catalysts and O2, enhancing the activation of O2. This ultimately led to an improvement in the generation of superoxide radicals and contributed to the enhanced photocatalytic activity of CN-KCl.

Dependence of superoxide radical generation on peroxymonosulfate under visible light: Enrofloxacin degradation and mechanism insight

Compared with the pure photocatalytic degradation system, although the sulfate radicals (SO4·-) generated in the peroxymonosulfate-assisted photocatalytic (PMS-photo) system redound to improve degradation activity. However, the degradation mechanism of the PMS-photo system still needs to be improved. For example, the relationship between superoxide radical (O2−) generation and PMS has been overlooked. Herein, the BiVO4/BiOBr photocatalyst was prepared via anion exchange method. Subsequently, the in-situ growth of BiVO4 on the surface of BiOBr nanosheet was confirmed though various characterization techniques. The degradation performance of the PMS-photo system was investigated, in which the 10 wt% BiVO4/BiOBr (BVB) composite exhibited the highest efficiency in degrading enrofloxacin (ENR, 95 %, 90 min) and tetracycline (TC, 94 %, 20 min) under visible light. Moreover, the structure of the intermediate product and the corresponding toxicity were determined by liquid chromatography-mass spectrometry (LC-MS) and Toxicity Estimation Software (T.E.S.T). Photoelectrochemical and fluorescence detection were employed to reveal that 10 wt% BVB has the fastest photogenerated carrier generation, separation and transmission efficiency. In addition, results from radicals quenching experiments, electron paramagnetic resonance (EPR), energy band structure analysis and DFT calculation were combined to substantiate the formation of II-type heterojunction between BiVO4 and BiOBr. More importantly, based on the above results, it was confirmed that the active species in the pure photocatalytic system were holes (h+) and electrons (e−). Due to the introduction of PMS, O2− and singlet oxygen (1O2) were generated, thereby achieving efficient degradation of pollutants. This result revealed the effect of peroxymonosulfate on the generation of O2−, presented a new perspective on the synergy of PMS with photocatalysis and offered a novel avenue for enhancing the performance of underperforming photocatalysts.

MoO3/MIL-125-NH2 with boosted peroxidase-like activity for electrochemical staphylococcus aureus sensing via specific recognition of bacteriophages

Herein, novel nanozyme mimics MoO3/MIL-125-NH2 were reported and conjugated with bacteriophages as a new electrochemical probe for high sensitivity and specific electrochemical detection of staphylococcus aureus. The excellent peroxidase-like activity of MoO3/MIL-125-NH2 composites was attributed to the integration of MIL-125-NH2 with MoO3, which can boost the generation of superoxide radicals (O• 2–) and thus promote the oxidation of TMB in the presence of H2O2. In this work, two bacteriophages named SapYZU04 and SapYZU10 were isolated from sewage samples by using staphylococcus aureus YZUsa12 as the host. In comparison, MoO3/MIL-125-NH2@SapYZU04 was selected as a recognition agent. The DPV current declined linearly with staphylococcus aureus YZUsa12 concentration in the range of 101−108 CFU mL−1, with a low detection limit of 16 CFU mL−1 (S/N = 3). 20 strains including 13 host strains and 7 non-host strains were used to evaluate the selectivity of the proposed sensor. Regardless of the differences in the degrees of lytic performance for phage SapYZU04, all selected host strains can be screened with merely the same DPV current. Host spectrum-oriented bacteriophage sensing is of great importance for the practical application of bacteriophage-based biosensors in the future.