OH Production Research Articles

Effect of gas components on the post-discharge temporal behavior of OH and O of a non-equilibrium atmospheric pressure plasma driven by nanosecond voltage pulses

OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma (NAPP), which plays an important role in applications such as plasma medicine. However, experimental studies on how the gas content affects the post-discharge temporal evolutions of OH and O in the noble gas ns-NAPP are very limited. In this work, the effect of the percentages of O2, N2, and H2O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence (LIF) method. The results show that the productions of OH and O increase and then decrease with the increase of O2 percentage. Both OH and O densities reach their maximum when about 0.8% O2 is added. Further increase of the O2 concentration results in a decrease of the initial densities of both OH and O, and leads to their faster decay. The increase of N2 percentage also results in the increase and then decrease of the OH and O densities, but the change is smaller. Furthermore, when the H2O concentration is increased from 100 to 3000 ppm, the initial OH density increases slightly, but the OH density decays much faster, while the initial density of O decreases with the increase of the H2O concentration. After analysis, it is found that OH and O are mainly produced through electron collisional dissociation. O(1D) is critical for OH generation. O3 accelerates the consumption processes of OH and O at high O2 percentage. The addition of H2O in the NAPP considerably enhances the electronegativity, while it decreases the overall plasma reactivity, accelerates the decay of OH, and reduces the O atom density.

The influence of Mn(II) on transformation of Cr-absorbed Schwertmannite: Mineral phase transition and elemental fate

Schwertmannite (Sch) is considered as an effective remover of Chromium (Cr) due to its strong affinity for toxic Cr species. Since the instability of Sch, the environmental fate of Cr deserves attention during the transformation of Sch into a more stable crystalline phase. The ubiquitous manganese(II) (Mn(II)) probably affects the transformation of Sch and thus the environmental fate of Cr. Therefore, this study investigated the impact of Mn(II) on the transformation of Cr-absorbed Sch (Cr-Sch) and the associated behavior of SO42− and Cr. We revealed that the transformation products of Cr-Sch at pH 3.0 and 7.0 were goethite and Sch, respectively. The presence of Mn(II) weakened the crystallinity of the transformation products, and the trend was positively correlated with the concentration of Mn(II). However, Mn(II) changed the transformation products of Cr-Sch from hematite to goethite at pH 10.0. Mn(II) replaced Fe(III) in the mineral structures or formed Mn-O complexes with surface hydroxyl groups (-OH), thereby affecting the transformation pathways of Sch. The presence of Mn(II) enhanced the immobilization of Cr on minerals at pH 3.0 and 7.0. Sch is likely to provide an channel for electron transfer between Mn(II) and Cr(VI), which promotes the reduction of Cr(VI). Meanwhile, Mn(Ⅱ) induced more -OH production on the surface of secondary minerals, which played an important role in increasing the Cr fixation. In addition, part of the Mn(Ⅱ) was oxidized to Mn(Ⅲ)/Mn(Ⅳ) at pH 3.0 and pH 7.0. This study helps to predict the role of Mn(II) in the transformations of Cr-Sch in environments and design remediation strategies for Cr contamination.

Trends and Interannual Variability of the Hydroxyl Radical in the Remote Tropics During Boreal Autumn Inferred From Satellite Proxy Data

AbstractDespite its importance for the global oxidative capacity, spatially resolved trends and variability of the hydroxyl radical (OH) are poorly constrained. We demonstrate the utility of a tropospheric column OH (TCOH) product, created from machine learning and satellite proxy data, in determining the spatial variability in trends of tropical OH over the oceans during September through November. While OH increases domain‐wide by 2.1%/decade from 2005–2019, we find significant spatial heterogeneity in regional trends, with decreases in some areas of 2.5%/decade. Our analysis of the trends in the proxy data indicate anthropogenic‐driven changes in emissions of OH drivers as well as increasing temperatures cause these trends. This OH product is potentially a significant advance in constraining OH spatial variability and serves as a useful complement to existing tools in understanding the atmospheric oxidative capacity. Comprehensive observations of TCOH are required to assess the fidelity of this method.

Investigation of the photolysis process of benzo(a)anthracene (BaA) on polyvinyl chloride (PVC) and polystyrene (PS) microplastics: Plastics aging effect, transformation products and toxicity assessment

Microplastics (MPs) and persistent pollutants (POPs) are new pollutants that are extensively studied worldwide. To fill the gaps that the degradation processes and mechanisms of polycyclic aromatic hydrocarbons (PAHs) on the surface of most MPs are still unclear, the photochemical transformation of benzo(a)anthracene (BaA) on polyvinyl chloride (PVC) MPs and polystyrene (PS) MPs in water were investigated and compared. The photolysis of BaA on the surface of PS in water proceeded easier than that on PVC within the 48 h irradiation period, with the pseudo-first-order rate constant of 0.0489 min−1 and 0.0181 min−1, respectively, which can be ascribed to the smaller particle size and more OH production of PS MPs. Due to the light competition between the chromophore and BaA as well as the light-shielding effect, aged MPs showed an inhibitory effect on the degradation of BaA compared with pristine MPs. For BaA/PVC MPs system, the degradation of BaA in real water was not significantly affected by coexisting ions and humic acid (HA) (p < 0.05), while slight inhibitory effect on the degradation of BaA appeared for PS MPs in different water matrices (UP: 86.97 %, YR: 84.47 %, PR: 81.42 % and HR: 83.21 %). According to the electron paramagnetic resonance (EPR) test, quenching experiment and probe experiment, the relative contribution of direct photolysis (PVC: 82.02 %; PS: 69.54 %) and indirect photolysis (PVC: 17.98 %; PS: 30.46 %) was confirmed. A total of 14 products were identified, and the product types were not affected by plastics aging. The results of the toxicity assessment indicated that although some intermediate products remained toxic to aquatic organisms, the toxicity of most products was lower than that of BaA. This study provides new insights into the environmental fate of PAHs and the role of MPs in the photolysis process of contaminants in surface water.

Characterizing Hydroxyl Radical Formation from the Light-Driven Fe(II)-Peracetic Acid Reaction, a Key Process for Aerosol-Cloud Chemistry.

The reaction of peracetic acid (PAA) and Fe(II) has recently gained attention due to its utility in wastewater treatment and its role in cloud chemistry. Aerosol-cloud interactions, partly mediated by aqueous hydroxyl radical (OH) chemistry, represent one of the largest uncertainties in the climate system. Ambiguities remain regarding the sources of OH in the cloud droplets. Our research group recently proposed that the dark and light-driven reaction of Fe(II) with peracids may be a key contributor to OH formation, producing a large burst of OH when aerosol particles take up water as they grow to become cloud droplets, in which reactants are consumed within 2 min. In this work, we quantify the OH production from the reaction of Fe(II) and PAA across a range of physical and chemical conditions. We show a strong dependence of OH formation on ultraviolet (UV) wavelength, with maximum OH formation at λ = 304 ± 5 nm, and demonstrate that the OH burst phenomenon is unique to Fe(II) and peracids. Using kinetics modeling and density functional theory calculations, we suggest the reaction proceeds through the formation of an [Fe(II)-(PAA)2(H2O)2] complex, followed by the formation of a Fe(IV) complex, which can also be photoactivated to produce additional OH. Determining the characteristics of OH production from this reaction advances our knowledge of the sources of OH in cloudwater and provides a framework to optimize this reaction for OH output for wastewater treatment purposes.

Impact of soil–atmosphere HONO exchange on concentrations of HONO and O3 in the North China Plain

Nitrous acid (HONO) is an important precursor of the hydroxyl radical (OH) and plays a vital role in atmospheric photochemistry and nitrogen cycling. Soil emissions have been considered as a potential source of HONO. Lately, the HONO emission via soil-atmosphere exchange (ESA-exchange) from soil nitrite has been validated and quantified through chamber experiments, but has not been assessed in the real atmosphere. We coupled ESA-exchange and the other seven potential sources of HONO (i.e., traffic, indoor and soil bacterial emissions, heterogeneous reactions on ground and aerosol surfaces, nitrate photolysis, and acid displacement) into the Weather Research and Forecasting model with Chemistry (WRF-Chem), and found that diurnal variations of the soil emission flux at the Wangdu site were well simulated. During the non-fertilization period, ESA-exchange contributed ∼28 % and ∼35 % of nighttime and daytime HONO, respectively, and enhanced the net ozone (O3) production rate by ∼8 % across the North China Plain (NCP). During the preintensive/intensive fertilization period, the maximum ESA-Exchange contributions attained ∼70 %/83 % of simulated HONO in the afternoon across the NCP, definitely asserting its dominance in HONO production. ESA-Exchange enhanced the OH production rate via HONO photolysis by ∼3.5/7.0 times, and exhibited an increase rate of ∼13 %/20 % in the net O3 production rate across the NCP. The total enhanced O3 due to the eight potential HONO sources ranged from ∼2 to 20 ppb, and ESA-exchange produced O3 enhancements of ∼1 to 6 ppb over the three periods. Remarkably, the average contribution of ESA-exchange to the total O3 enhancements remained ∼30 %. This study suggests that ESA-exchange should be included in three-dimensional chemical transport models and more field measurements of soil HONO emission fluxes and soil nitrite levels are urgently required.

Microwave assisted plastic waste derived O vacancies enriched cobalt oxide/porous carbon material for highly efficient carbamazepine degradation via peroxymonosulfate activation

In this study, porous carbon catalytic materials prepared by a simple microwave pyrolysis of waste plastic polyethyleneterephthalate (PET) were used to degrade carbamazepine (CBZ) through peroxymonosulfate (PMS) activation. Microwave absorbers cobalt nitrate and initially carbonized α-cellulose were employed to assist the waste plastic PET carbonization. The cobalt oxide formation, cobalt sulfide generation, oxygen vacancies introduction and specific surface area enlargement were all conducive to the improvement of catalytic performance. The optimal catalyst S0.3-Co@P2C could achieve 100.0 % CBZ degradation in 15 min, with the rate constant of 0.7445 min−1. Compared to traditional pyrolysis, the microwave-treated carbon materials were more conducive to the formation and exposure of active sites (CoS and CoO) in the catalytic materials for SO4•- and·OH production via PMS activation. In addition, the introduction of PET was conducive to the formation of C = O in the catalytic materials for the PMS activation to accelerate non-radical CBZ degradation pathway. This study provides new insights into the antibiotic degradation in water with the concept of using waste to deal with waste.

Isomer-resolved unimolecular dynamics of the hydroperoxyalkyl intermediate (•QOOH) in cyclohexane oxidation

The oxidation of cycloalkanes is important in the combustion of transportation fuels and in atmospheric secondary organic aerosol formation. A transient carbon-centered radical intermediate (•QOOH) in the oxidation of cyclohexane is identified through its infrared fingerprint and time- and energy-resolved unimolecular dissociation dynamics to hydroxyl (OH) radical and bicyclic ether products. Although the cyclohexyl ring structure leads to three nearly degenerate •QOOH isomers (β-, γ-, and δ-QOOH), their transition state (TS) barriers to OH products are predicted to differ considerably. Selective characterization of the β-QOOH isomer is achieved at excitation energies associated with the lowest TS barrier, resulting in rapid unimolecular decay to OH products that are detected. A benchmarking approach is employed for the calculation of high-accuracy stationary point energies, in particular TS barriers, for cyclohexane oxidation (C6H11O2), building on higher-level reference calculations for the smaller ethane oxidation (C2H5O2) system. The isomer-specific characterization of β-QOOH is validated by comparison of experimental OH product appearance rates with computed statistical microcanonical rates, including significant heavy-atom tunneling, at energies in the vicinity of the TS barrier. Master-equation modeling is utilized to extend the results to thermal unimolecular decay rate constants at temperatures and pressures relevant to cyclohexane combustion.

Cinnamaldehyde affects the storage quality of freshly cut water chestnuts through the regulation of reactive oxygen species and the AsA-GSH cycle

The quality of fresh-cut Chinese water chestnuts (CWCs) rapidly deteriorates with prolonged storage time, thus affecting its commercial value. This study aimed to investigate the effect of cinnamaldehyde (CA) treatment on the quality of fresh-cut CWCs and its mechanism of action. CA treatment maintained good appearance and higher total soluble solids content (TSS) of fresh-cut CWCs and also significantly inhibited microbial proliferation, respiration, phenylalanine ammonia-lyase activity (PAL) and enzymatic browning substance content. Moreover, CA treatment increased the antioxidant capacity and defense function-related enzyme activities (PPO and POD) of fresh-cut CWCs, and suppressed ·OH production rate and MDA content. Meanwhile, CA treatment significantly increased the content of antioxidant compounds and enzyme activities of the AsA-GSH cycle system. In conclusion, CA can inhibit surface discoloration of fresh-cut CWCs and extend their shelf life, thus increasing their commercial value.

Humic substance mitigated the microplastic-induced inhibition of hydroxyl radical production in riparian sediment

Hydroxyl radicals (·OH) generated during the flooding-drought transformation process play a vital role in affecting nutrient cycles at riparian zone. However, information on the processes and mechanisms for ·OH formation under the influence of microplastics (MPs) remains unclear. In this study, the effects of MPs on ·OH production from riparian sediments with different biomass [e.g., vegetation lush (VL) and vegetation barren (VB)] were studied. The results showed that presence of MPs inhibited the production of ·OH by 27 % and 7.5 % for VB and VL sediments, respectively. The inhibition was mainly resulted from the MP-induced reduction of the biotic and abiotic mediated Fe redox processes. Spectral analysis revealed that VL sediments contained more high-molecular-weight humic-like substances. Presence of MPs increased the abundances and activities of Proteobacteria, Acidobacteria and Actinobacteria, which were conducive to the changes in humification and polar properties of organic matters. The reduced humic- and fulvic-like substances were accumulated in the flooding period and substantially oxidized during flooding/drought transformation due to the enhanced MP-mediated electron transfer abilities, thus mitigated the MP-induced inhibition effects. Therefore, in order to better understanding the biogeochemical cycling of contaminants as influenced by ·OH and MPs in river ecosystems, humic substances should be considered systematically.

Novel photoelectrocatalytic system of oxygen vacancy-rich black TiO2-x nanocones photoanode and natural air diffusion cathode for efficient water purification and simultaneous H2O2 production

Photoelectrocatalytic (PEC) system harnesses solar energy for chemical reactions, representing a highly promising renewable energy-based technology for water purification. Herein, we design a novel separated PEC system that integrates water purification on an oxygen vacancy-rich black TiO2 nanocones (b-TiO2-x) photoanode with two-electron O2 reduction reaction for H2O2 production on a natural air diffusion cathode. This integration benefits from thermodynamic advantages, synergy effects and enhanced •OH production, thus exhibiting superior water purification (98.32%, 0.064 min−1) and H2O2 production (6.83 μmol/h/cm2) at ultra-low applied cell voltage of 0.5 V, with the energy consumption of only 0.034 kWh/m3 wastewater treated, where the simultaneous production of value-added H2O2 could fully compensate for the electric cost of the system. Notably, even under real sunlight irradiation, this system achieves efficient water purification and H2O2 production without additional energy consumption, offering a cost-effective and environmental-benign strategy for the dual purpose of water purification and resourcization.

Fabrication of a carbon-coated Fe3O4 for ozone catalysis to facilitate HO2− formation during ozonation

In the O3 self-decomposition process, the poor HO2− formation efficiency limits O3 decomposition and •OH production. Although the addition of Fenton’s reagent facilitates this process, H2O2 consumption and Fe(III) sedimentation must be addressed. In this study, carbon-coated Fe3O4 (Fe3O4@C) samples were prepared using the metal–organic frameworks (MOFs) modification method for the catalytic ozonation of aromatics, which effectively solved the above challenges. The fabricated 4-Fe3O4@C catalyst not only exhibited a yolk-shell structure, but also increased •OH production by 9-fold, resulting in optimal target removal, mineralization, and O3 decomposition efficiency. Further investigation confirmed that the activity of 4-Fe3O4@C was owing to the combined action of Fe(II) on the catalyst surface and the H2O2 produced from aromatic degradation. Furthermore, the outer carbon layer with reducing properties regenerated Fe(II) in a timely manner, ensuring catalyst durability. Finally, a clear pathway for enhancing O3 decomposition and •OH generation is proposed.

High-efficiency metal-free electro-Fenton system on oxygenated graphene-based floating electrodes

Metal-free electro-Fenton (EF) are a promising technology for environmental remediation. This paper reports a novel EF modified with oxygenated graphene aerogel used as a floating electrode for efficient degradation of bisphenol A (BPA) through improved H2O2 yield combined with activation of hydroxyl radical (·OH) production. Impressively, the floating configuration of the electrodes allowed oxygen from the air to diffuse naturally into the reaction interface, reducing additional aeration energy consumption. The current efficiency of the floating system for H2O2 production was 40 times higher than the conventional vertical mode. The pollutant degradation trend exhibited a positive correlation with the ·OH production performance of the electrode. The modified catalyst system achieved the highest ·OH yield of 76.48 μM within 60 min, which was 2.72 times greater than that of the catalyst-free (28.10 μM) and 2.06 times higher than that of the unmodified catalyst (37.19 μM). Experiments and theoretical calculations indicated that the oxygen-containing functional groups introduced the graphene skeleton created new sites for in situ activation of electrogenerated H2O2, resulting in increased ·OH production. The primary activation sites were identified as the = O and –COOH groups, with the = O edges playing a particularly significant role. This system offers long-lasting stability and avoids secondary pollution, making it ideal for green environmental remediation compared to the traditional EF process.

High-performance pyrite nano-catalyst driven photothermal/chemodynamic synergistic therapy for Osteosarcoma

Osteosarcoma (OS) is an aggressive bone tumor with strong invasiveness, rapid metastasis, and dreadful mortality. Chemotherapy is a commonly used approach for OS treatment but is limited by the development of drug resistance and long-term adverse effects. To date, OS still lacks the curative treatment. Herein, we fabricated pyrite-based nanoparticles (FeS2@CP NPs) as synergetic therapeutic platform by integrating photothermal therapy (PTT) and chemo-dynamic therapy (CDT) into one system. The synthetic FeS2@CP NPs showed superior Fenton reaction catalytic activity. FeS2@CP NPs-based CDT efficaciously eradicated the tumor cells by initiating dual-effect of killing of apoptosis and ferroptosis. Furthermore, the generated heat from FeS2@CP under near-infrared region II (NIR-II) laser irradiation could not only inhibit tumor’s growth, but also promote tumor cell apoptosis and ferroptosis by accelerating •OH production and GSH depletion. Finally, the photothermal/NIR II-enhanced CDT synergistic therapy showed excellent osteosarcoma treatment effects both in vitro and in vivo with negligible side effects. Overall, this work provided a high-performance and multifunctional Fenton catalyst for osteosarcoma synergistic therapy, which provided a pathway for the clinical application of PTT augmented CDT.

Photoproduction of Hydroxyl Radicals Under Sunlight by Fe-Zn Oxides for Partial Oxidation Applications

Iron-zinc oxide (FZ) photocatalysts with activity in the visible region were designed for the partial oxidation of organic molecules with the least loss of raw material. The FZ materials were synthesized using the sol-gel method with citric acid as a stabilizing agent. From TGA results, 400 °C was observed as the minimum temperature for precursors degradation, then two thermal treatment times were assessed at 60 and 180 min. The powder photocatalysts were comprehensively characterized by TGA, DSC, FTIR, XRD, Raman, Mössbauer, XPS, UV-Vis, and SEM. The production of hydroxyl radicals (•OH) was followed by the fluorescence emission of 2-hydroxy-terephthalic acid (OHTA). The absorbance decrease of methylene blue (MB) and disodium terephthalate (NaTA) was measured by UV-Vis spectroscopy to calculate the total degradation degree. The photocatalytic activity of FZ materials was quantified after 2 h under simulated sunlight radiation at room temperature conditions. All FZ oxides treated for 60 min presented no •OH detection, in which photocatalytic blanks showed an adsorption phenomenon of the probe molecules. FZ7 and FZ8 materials showed the best •OH production and the least MB/NaTA degradation, making them the best candidates for partial oxidation applications.

Biochar accelerated Fenton process for roxarsone oxidation, inorganic arsenic adsorption and simultaneous immobilization of arsenic-iron sludge

Complete remediation of organoarsenics from environmental matrix hits the bottleneck, that is, the sluggish efficiency of oxidative degradation towards organoarsenics and unsatisfying immobilization performance towards generated inorganic arsenic. Herein, we establish a biochar accelerated Fenton (BA-Fenton) process to decontaminate water from roxarsone (ROX). In comparison with Fe2+/H2O2 process (10 μΜ/0.2 mM), the incorporation of 0.5 g L-1 biochar promoted ROX degradation from 48.2% to 98.2% and total arsenic elimination from 67.6% to 97.3%, respectively. In BA-Fenton process, •OH as the dominant reactive oxygen species (ROS), exhibited a cumulative concentration of 0.42 mM, three times higher than that in classical Fenton process. Crucially, the presence of biochar in Fenton process significantly enhanced the stability of arsenic-iron sludge, whereas the secondary leaching of total arsenic decreased from 433.8 μg-As L-1 to 13.9 μg-As L-1, meeting the prescribed environmental quality standards for surface water in China (50 μg-As L-1, GB 3838-2002). Mechanistic studies unveiled ROX remediation mechanism by BA-Fenton process, highlighting the dual functionality of biochar. On one hand, biochar efficiently reduced Fe3+ to Fe2+ with a rate constant of 0.225 min-1, overcoming the rate-determining step of classical Fenton process for •OH production, consequently promoting the transformation of ROX to As(V). On the other hand, molecular spectroscopy analysis elucidated that in-situ formed As(V) was adsorbed by ferric hydroxides with the formation of arsenic-iron sludge. Subsequently, biochar immobilized arsenic-iron sludge through hydrogen bonds, electrostatic attraction and surface complexation. Furthermore, real water studies demonstrated the effective remediation of organoarsenics by BA-Fenton process in tap water, lake water and chicken manure leachate. This “Two Birds with One Stone” strategy with low-cost, environmental-friendly and sustainable biochar holds great promise for the ultimate disposal of industrial wastewater containing organoarsenics.

Oxygen-independent organic photosensitizer with ultralow-power NIR photoexcitation for tumor-specific photodynamic therapy

Photodynamic therapy (PDT) is a promising cancer treatment but has limitations due to its dependence on oxygen and high-power-density photoexcitation. Here, we report polymer-based organic photosensitizers (PSs) through rational PS skeleton design and precise side-chain engineering to generate •O2− and •OH under oxygen-free conditions using ultralow-power 808 nm photoexcitation for tumor-specific photodynamic ablation. The designed organic PS skeletons can generate electron-hole pairs to sensitize H2O into •O2− and •OH under oxygen-free conditions with 808 nm photoexcitation, achieving NIR-photoexcited and oxygen-independent •O2− and •OH production. Further, compared with commonly used alkyl side chains, glycol oligomer as the PS side chain mitigates electron-hole recombination and offers more H2O molecules around the electron-hole pairs generated from the hydrophobic PS skeletons, which can yield 4-fold stronger •O2− and •OH production, thus allowing an ultralow-power photoexcitation to yield high PDT effect. Finally, the feasibility of developing activatable PSs for tumor-specific photodynamic therapy in female mice is further demonstrated under 808 nm irradiation with an ultralow-power of 15 mW cm−2. The study not only provides further insights into the PDT mechanism but also offers a general design guideline to develop an oxygen-independent organic PS using ultralow-power NIR photoexcitation for tumor-specific PDT.

The H2O2 Self-Sufficient 3D Printed β-TCP Scaffolds with Synergistic Anti-Tumor Effect and Reinforced Osseointegration.

Tumor recurrence and massive bone defects are two critical challenges for postoperative treatment of oral and maxillofacial tumor, posing serious threats to the health of patients. Herein, in order to eliminate residual tumor cells and promote osteogenesis simultaneously, the hydrogen peroxide (H2O2) self-sufficient TCP-PDA-CaO2-CeO2 (TPCC) scaffolds are designed by preparing CaO2 or/and CeO2 nanoparticles (NPs)/chitosan solution and modifying the NPs into polydopamine (PDA)-modified 3D printed TCP scaffolds by rotary coating method. CaO2 NPs loaded on the scaffolds can release Ca2+ and sufficient H2O2 in the acidic tumor microenvironment (TME). The generated H2O2 can further produce hydroxyl radicals (·OH) under catalysis effect by peroxidase (POD) activity of CeO2 NPs, in which the photothermal effect of the PDA coating enhances its POD catalytic effect. Overall, NPs loaded on the scaffold chemically achieve a cascade reaction of H2O2 self-sufficiency and ·OH production, while functionally achieving synergistic effects on anti-tumor and bone promotion. In vitro and in vivo studies show that the scaffolds exhibit effective osteo-inductivity, induced osteoblast differentiation and promote osseointegration. Therefore, the multifunctional composite scaffolds not only validate the concept of chemo-dynamic therapy (CDT) cascade therapy, but also provide a promising clinical strategy for postoperative treatment of oral and maxillofacial tumor.

Quantification and Mechanistic Investigation of the Spontaneous H2O2 Generation at the Interfaces of Salt-Containing Aqueous Droplets.

There is now much evidence that OH radicals and H2O2 are spontaneously generated at the air-water interface of atmospheric aerosols. Here, we investigated the effect of halide anions (Cl-, Br-, I-), which are abundant in marine aerosols, on this H2O2 production. Droplets were generated via nebulization of water solutions containing Na2SO4, NaCl, NaBr, and NaI containing solutions, and H2O2 was monitored as a function of the salt concentration under atmospheric relevant conditions. The interfacial OH radical formation was also investigated by adding terephthalic acid (TA) to our salt solutions, and the product of its reaction with OH, hydroxy terephthalic acid (TAOH), was monitored. Finally, a mechanistic investigation was performed to examine the reactions participating in H2O2 production, and their respective contributions were quantified. Our results showed that only Br- contributes to the interfacial H2O2 formation, promoting the production by acting as an electron donor, while Na2SO4 and NaCl stabilized the droplets by only reducing their evaporation. TAOH was observed in the collected droplets and, for the first time, directly in the particle phase by means of online fluorescence spectroscopy, confirming the interfacial OH production. A mechanistic study suggests that H2O2 is formed by both OH and HO2 self-recombination, as well as HO2 reaction with H atoms. This work is expected to enhance our understanding of interfacial processes and assess their impact on climate, air quality, and health.

Boosting Energy Deprivation by Synchronous Interventions of Glycolysis and Oxidative Phosphorylation for Bioenergetic Therapy Synergetic with Chemodynamic/Photothermal Therapy.

Bioenergetic therapy is emerging as a promising therapeutic approach. However, its therapeutic effectiveness is restricted by metabolic plasticity, as tumor cells switch metabolic phenotypes between glycolysis and oxidative phosphorylation (OXPHOS) to compensate for energy. Herein, Metformin (MET) and BAY-876 (BAY) co-loaded CuFe2O4 (CF) nanoplatform (CFMB) is developed to boost energy deprivation by synchronous interventions of glycolysis and OXPHOS for bioenergetic therapy synergetic with chemodynamic/photothermal therapy (CDT/PTT). The MET can simultaneously restrain glycolysis and OXPHOS by inhibiting hexokinase 2 (HK2) activity and damaging mitochondrial function to deprive energy, respectively. Besides, BAY blocks glucose uptake by inhibiting glucose transporter 1 (GLUT1) expression, further potentiating the glycolysis repression and thus achieving much more depletion of tumorigenic energy sources. Interestingly, the upregulated antioxidant glutathione (GSH) in cancer cells triggers CFMB degradation to release Cu+/Fe2+ catalyzing tumor-overexpressed H2O2 to hydroxyl radical (∙OH), both impairing OXPHOS and achieving GSH-depletion amplified CDT. Furthermore, upon near-infrared (NIR) light irradiation, CFMB has a photothermal conversion capacity to kill cancer cells for PTT and improve ∙OH production for enhanced CDT. In vivo experiments have manifested that CFMB remarkably suppressed tumor growth in mice without systemic toxicity. This study provides a new therapeutic modality paradigm to boost bioenergetic-related therapies.