Singlet Oxygen 1O2 Research Articles

Dual Porphyrin-Loaded Scintillating Nanoparticles Enhanced Photodynamic Therapy in Hypoxic Cancer Cells under X-ray Irradiation.

Tumor hypoxia represents a major challenge to achieving successful therapy outcomes with photodynamic therapy (PDT). We hypothesized that systemic loading of dual porphyrins, protoporphyrin IX (PPIX) as a photosensitizer (PS) and hemin (Fe3+-PPIX) as an oxygen generator, onto Eu-doped NaYF4 scintillator (Sc), collectively terms as Eu-PPIX@Hemin, could enhance the activity of X-ray mediated PDT. Catalase-like property of hemin in the presence of H2O2 facilitated the production of oxygen molecules (3O2) in hypoxic cancer cells. The produced 3O2 reacts with nearby excited PPIX molecules (PPIX*) in the Sc-PS pairs to produce singlet oxygen (1O2), as cytotoxic reactive oxygen species (ROS) under X-ray irradiation. Eu-PPIX@Hemin nanoparticles (NPs) with a diameter of ~60 nm efficiently produced oxygen in the presence of H2O2, which its concentration in tumor cells is higher than that in normal cells. Eu-PPIX@Hemin generated similar amounts of ROS in hypoxic cultured cancer cells under low dose X-ray irradiation (0.5 Gy), compared to those in normoxic cancer cells. Notably, Eu-PPIX@Hemin exhibited similar cytotoxic effects in both hypoxic and normoxic cancer cells under X-ray irradiation. Overall, the mutual Sc-PS performance between PPIX and Eu was synergistically enhanced by hemin in Eu-PPIX@Hemin, which relieved hypoxia in the cancer cells under X-ray irradiation.

Insights into the Removal of Organic Contaminants by Co-CeO2 Nanocatalysts via CaCO3 Activation: Performance, Kinetic, and Mechanism.

The advanced oxidation process based on S(IV) has garnered increasing attention, owing to its efficiency in degrading contaminants. Here, a cobalt-doped cerium oxide catalyst (Co-CeO2) was employed to activate calcium sulfite (CaSO3) for imidacloprid degradation. The Co-CeO2 catalyst was characterized by using SEM, BET, XRD, and XPS techniques to analyze its structural and chemical properties. XPS analysis revealed the presence of Co0, Co2+, and Co3+ species in the Co-CeO2 catalyst. Compared to the CeO2/CaSO3 system, the Co-CeO2/CaSO3 system significantly enhanced the degradation rate of imidacloprid from 5.00% to 94.01%. Scavenging experiments, in conjunction with electron paramagnetic resonance spectroscopy, identified hydroxyl radicals (•OH), sulfate radicals (SO4•-), superoxide radicals (O2•-), sulfite radicals (SO3•-), and singlet oxygen (1O2) as the primary reactive species responsible for the degradation of imidacloprid within the Co-CeO2/CaSO3 system. Density functional theory calculation analysis was employed to investigate the specific sites of imidacloprid attacked by reactive oxygen species, proposing four potential degradation pathways. Furthermore, the Ecological Structure Activity Relationships (ECOSAR) program predicted a significant diminution in the toxicity of intermediate products compared to imidacloprid. Even after five cycles, Co-CeO2 maintained an excellent removal efficiency of 86.35%.

Efficient degradation of emerging organic pollutants via activation of peroxymonosulfate over Fe-N co-doped carbon materials: Singlet oxygen and electron-transfer mechanisms

Singlet oxygen (1O2) is widely recognized as an effective reactive species for the targeted oxidation of organic contaminants. However, producing 1O2 with high selectivity and efficiency remains a significant challenge. This study describes the synthesis of a N-C-loaded Fe catalyst (Fe/NC) loaded with nitrogen-doped carbon materials. The Fe/NC catalyst efficiently produces 1O2 via the activation of peroxymonosulfate (PMS), demonstrating exceptional degradation capabilities for p-chlorophenol (4-CP). Compared to the control samples of nitrogen-doped carbon (NC) and Fe/NC-x under identical conditions, the Fe/NC/PMS produced a significantly greater degradation rate (0.794min-1) for 4-CP (50mg⋅L-1) within 14min. The content of zinc was regulated to enhance the degradation of 4-CP. The durability of the catalyst was tested with a fixed-bed flow reactor, maintaining almost 100% removal efficiency over 36h on stream. The 4-CP degradation within this system was shown to be a non-radical process predominated by 1O2 and electron transfer, as shown by electrochemical methods, quenching studies, and electron paramagnetic resonance test (EPR). Moreover, Fe/NC demonstrated exceptional resistance to pH changes (3-10), natural organics, and inorganic ions while degrading organic contaminants. The degradation process of 4-CP over the Fe/NC catalyst was examined using liquid chromatography-mass spectrometer. The results of the phytotoxicity evaluation indicated a significant decrease in their toxicity within the Fe/NC/PMS/4-CP system. The satisfactory activity, stability, and universality enabled Fe/NC to serve as a promising candidate for PMS activation. This study presents a novel approach for the selective production of 1O2, enabling targeted pollutant degradation in wastewater treatment.

Efficient activation of peroxymonosulfate by N-doped waste herb senna obtusifolia biochar for degrading NPX: Synergistic effect of carbonyl and nitrogen sites

In this work, waste herb senna obtusifolia was utilized as the biochar precursor, and a N-doped biochar (NSOBC-6) was prepared to activate peroxymonosulfate (PMS) for degrading Naproxen (NPX). NSOBC-6 exhibited superior catalytic performance in activating PMS, which could degrade NPX completely within 60 min. The NSOBC-6/PMS system also had good reusability and effectiveness under a wide range of pH values and high salinity conditions. The significant contribution of singlet oxygen (1O2) and superoxide radicals (O2•−) in NPX degradation was revealed. The results of XPS and DFT calculations indicated C=O, pyridinic-N and graphite-N participated as catalytic sites in the degradation of NPX. The differences in electron density and the ELUMO-EHOMO (ΔELUMO-HOMO) gap were induced by N doping, enhancing the PMS activation capacity of NSOBC-6. This work presented a strategy to convert waste herbal into functional biochar materials, which was of great significance for the development of green and efficient catalysts.

Robust degradation of tetracycline hydrochloride by electro-assisted activation of peroxymonosulfate over porous cobalt-manganese oxide nanowire array in situ grown on nickel foam

The electro-assisted activation of peroxymonosulfate (PMS) with transition metals for treating antibiotics in water environment has become a research hotspot. In this work, porous cobalt-manganese oxide nanowire array was successfully in situ fabricated on nickel foam (Co2.5Mn0.5O4/NF), and the degradation efficiency of tetracycline hydrochloride (TC) by PMS activation over Co2.5Mn0.5O4/NF in the presence of an electric field (defined as E-Co2.5Mn0.5O4/NF-PMS) was further studied. The E-Co2.5Mn0.5O4/NF-PMS system showed an unexpectedly high catalytic performance for TC degradation, achieving a removal efficiency of 98.71% in 20min with a rate constant of 0.2092min−1. Thereinto, the electric field ensured a rapid redox cycle of Co(II)/Co(III) and Mn(II)/Mn(III)/Mn(IV), which activated PMS continuously and guaranteed the robustness of TC degradation process. Specifically, the catalytic system exhibited outstanding stability after ten consecutive cycles. Electron paramagnetic resonance (EPR) analysis and quenching experiments illuminated that non-radical pathway involved singlet oxygen (1O2) was dominant in TC oxidation degradation in E-Co2.5Mn0.5O4/NF-PMS system, and furthermore possible degradation routes of TC were revealed. Of note, the degradation system exhibited relatively low level of energy consumption (0.51 kWh m−3 order−1), widespread applicability in treating wastewater contaminated with different organic pollutants, and excellent resistance toward the interference from background anions.

Oxygen vacancy-dominated activation of peroxydisulfate and removal of tetracycline：The synergistic contribution of dual-metal cycling and the prominent role of non-radical pathway

In this study, a nitrogen-rich porous carbon substrate (NC) doped with NiO and Mo2N-γ was prepared using zeolitic imidazolate framework-8 (ZIF-8) through processes of acid etching and calcination to create a bimetallic catalyst with optimized oxygen vacancies (NiMo-NC/A(2)). This catalyst displayed remarkable peroxydisulfate (PDS) activation, achieving a 90.9% of tetracycline (TC) removal in 60min. The NiMo-NC/A(2)/PDS system showed superior resilience to various interferences, performing well over a wide range of pH levels (3-11) and in wastewater with different background ions and organic substances. This research revealed that the strategic incorporation of OVs into the catalyst not only could substantially amplify its PDS adsorptive affinity, consequently lowering the PDS activation energy threshold and bolstering the production of singlet oxygen (1O2) and some superoxide anions (O2·-), but was also able to propel the redox cycling of the Ni and Mo constituents, thereby invigorating the PDS activation to yield a series of reactive oxygen species (ROS). The Ni-Mo metal sites on the catalyst's surface were capable of adsorbing PDS molecules, forming metastable complexes (PDS*), which hastened the electron transfer-mediated TC adsorption. Meanwhile, the pyrrolic and graphitic N embedded within the carbon matrix accelerated the PDS activation by adsorbing both TC and PDS, assisting the TC's removal. In summary, this work highlighted the critical impact of optimal OVs content on enhancing the catalytic efficiency of the bimetallic catalyst, elucidated the mechanism of PDS activation for effective TC removal, and offered a new direction for developing eco-friendly catalysts for PDS-based contaminant removal.

Concentrated solar energy-driven photothermal efficient degradation and mineralization of fluoroquinolone antibiotics in various water bodies

Sunlight-driven advanced oxidation process has promising applications and is increasingly receiving attention for the removal of emerging pollutants. This study describes a concentrated solar energy-driven photothermal (CSEP) system for the efficient degradation of fluoroquinolone antibiotics in wastewater. The operation of concentrating light degradation was not only a simple combination of thermal degradation and sunlight degradation, but the complex photothermal synergies that occurred to achieve degrading fluoroquinolones (FQs) more thoroughly. In the degradation processes, singlet oxygen (1O2), superoxide anion (O2·−), and hydroxyl radical (·OH) play pivotal roles. Additionally, the CSEP system exhibits outstanding defluorination capability (e.g., achieving 100 % defluorination for ciprofloxacin (CIP)). The photodegradation pathways of CIP were investigated using liquid chromatography/tandem mass spectrometry (LC/MS/MS), ion chromatography (IC) analysis, and density functional theory (DFT). Additionally, the aquatic ecological toxicity of CIP was assessed through ecological structure–activity relationship (ECOSAR) modeling and antimicrobial activity testing. Furthermore, this system demonstrates strong adaptability in addressing various natural water bodies, achieving an average degradation rate of over 98.00 % within a short time (3 min, 2 mg·L−1 CIP). In addition, it enhances the potential for synergistic removal of algae and degradation of FQs in complex water ecosystems. The adoption of this CSEP system holds considerable promise in furnishing robust technical support for the treatment and removal of FQs in water and wastewater.

Construction of multifunctional hydrogel containing pH-responsive gold nanozyme for bacteria-infected wound healing

Nanozymes have become promising alternative antibacterial agents for bacteria-infected wounds. In this study, fucoidan-confined gold nanoparticles (Fuc@AuNPs) are developed by in situ reduction, and stabilized by sulfate groups of fucoidan. Fuc@AuNPs exhibit pH-responsive catalytic activity that can mimic oxidase (OXD) under acidic bacterial infection conditions and mimic superoxide dismutase (SOD) under normal physiological conditions. The OXD-like catalytic activity of Fuc@AuNPs generates active singlet oxygen (1O2), exhibiting effective antibacterial properties against both Gram-negative E. coli and Gram-positive S. aureus. Fuc@AuNPs and aldehyde grafted saponin incorporate with chitosan to form a hybrid hydrogel. This hydrogel exhibits superior mechanical, adhesive, and self-healing properties due to electrostatic complex coacervation networks and dynamic covalent Schiff base reactions. Animal experiments show that the hydrogel aids S. aureus-infected skin wound healing by reducing bacterial infection and promoting granulation tissue formation without causing excessive ROS-induced inflammation. This study presents the design of multifunctional nanozymes and bioactive hydrogels as a promising wound healing dressing for biomedical applications.

Moderately Heavy Atom-Substituted BODIPY Photosensitizer with Mitochondrial Targeting Ability for Imaging-Guided Photodynamic Therapy.

Advanced photodynamic therapy requires photosensitizers with targeting, diagnostic, and therapeutic properties. To fulfill this multifunctionality, we report the synthesis of two triphenylphosphonium (TPP)-functionalized boron-dipyrromethene (BODIPY) dyes, TPPB-H and TPPB-Br, which incorporate a hydrogen atom and dibrominated vinyl moiety at the 6-position of the BODIPY core, respectively. The heavy-atom effect of the moderately heavy bromine atoms allowed TPPB-Br to achieve a proper balance between the toxic singlet oxygen (1O2) production and fluorescence efficiencies. In this dye, the bromine atom-induced stimulation of the singlet-to-triplet intersystem crossing dynamics resulted in an approximately 45-fold increase in the 1O2 quantum yield with respect to that of the nonbrominated counterpart (0.0059 and 0.28 for TPPB-H and TPPB-Br, respectively). This increase was accompanied only a 2-fold reduction in the fluorescence quantum yield (0.54 and 0.22 for TPPB-H and TPPB-Br, respectively). During multicolor confocal laser scanning microscopy observations conducted using two carcinomas, MCF-7 and HeLa, both BODIPY dyes exhibited high targeting specificity toward cancer cell mitochondria owing to the TPP cation functionalization. The two dyes also showed the feasibility of fluorescence cell imaging; however, only the dibrominated BODIPY TPPB-Br manifested pronounced photocytotoxicity with half-maximal inhibitory concentrations of 0.12 and 0.77 μM obtained for MCF-7 and HeLa cells, respectively. These findings demonstrate the potential applicability of TPPB-Br as an imaging-guided photodynamic therapy agent with mitochondrial specificity.

Electronically regulated Mn-N site-loaded MXenes for highly efficient and selective singlet oxygen generation via PMS activation

In this study, a novel catalyst featuring dual-reactive sites of transition metal and nonmetal is presented, which modifies electronic polarization to enhance the selective generation of singlet oxygen (1O2), resulting in effective degradation of antibiotics. Using MXenes as a substrate, a structurally stable Mn-N@MXenes catalyst with controllable reactive sites was synthesized via a hydrothermal method by adjusting the content of the Mn-N precursor. The study revealed that the loading of Mn-N active sites changes the electronic structure and polarization of MXenes, resulting in asymmetric electronic structures and the generation of numerous oxygen vacancies. These characteristics enable the Mn-N@MXenes/PMS system to selectively generate 1O2 and superoxide radicals (O2∙-), with a synergistic index of 5.77. Compared to the MXenes/PMS system, the Mn-N@MXenes/PMS system significantly boosts the degradation efficiency of ofloxacin (OFL) from 71.32% to 96.07% under optimal conditions. The results demonstrate that during PMS activation, the catalyst maintains a nearly constant degradation rate after four cycles, exhibiting excellent stability and recyclability. Furthermore, the system shows superior performance and environmental adaptability in degrading actual water matrices and other pollutants. This study reveals electronic regulation mechanisms in catalyst design that facilitate pollutant degradation via both radical and non-radical pathways, offering new strategies for efficient degradation.

Carboxymethyl cellulose assisted hydrothermal synthesis of litchi-like zinc ferrite nanoparticles for water remediation through visible photo-Fenton-like catalysis

The conventional methods for the synthesis of zinc ferrite (ZnFe2O4) basically require high temperature calcination oxidation step, which produces environmentally unfriendly high energy consumption and may produce harmful gases that pollute the atmosphere, as well as the calcination synthesis limits the application of ZnFe2O4 such as preparation of organic composite materials. To end this, by adding carboxymethyl cellulose (CMC) to the reaction system, homogeneous litchi-like ZnFe2O4/CMC nanoparticles were successfully synthesized without alkali and calcination in this paper. The rich carboxyl group of CMC is conducive to the chelation and fixation of metal ions in the reaction precursor, which greatly promotes the synthesis of ZnFe2O4. The synthesized particle size is ~100 nm, with obvious ZnFe2O4 diffraction peaks and good crystallinity. The photocatalytic performance of the synthesized photocatalyst was evaluated by visible light-Fenton-like method. With the activation of peroxymonosulfate (PMS), 80.27 % of tetracycline hydrochloride (TC) was degraded in just 18 min, suggesting that the synthesized catalyst had an excellent photocatalytic performance. After four cycles, the catalyst still could degrade 64.52 % TC. And the same behavior in XRD and FTIR spectra confirms the stability of the photocatalyst. In addition, it was determined that singlet oxygen (1O2) dominated the visible light catalytic degradation.

Modulating the electronic structure of Mn promotes singlet oxygen generation from electrochemical oxidation of H2O via O-O coupling

Selectively catalytic conversion H2O into singlet oxygen (1O2) without additional oxidants is considered as an economic-efficient method for organic pollutants degradation. However, H2O are more consistent with the spin state of 1O2 than common oxygen (O2), retarding the kinetics of spin transition-induced reaction between O2 and 1O2. Herein, we report an unprecedented 1O2 mediated electrocatalytic oxidation process, which allows O–O coupling for 1O2 evolution from H2O over CrMn@C anode. The electron occupancy (eg) of CrMn@C (0.89) is very close to the optimal eg (0.95) of manganese-based materials reported in the literature, which facilitates the activation of H2O on surface. Mn(Mn0.193Cr1.808)O4-Mn in CrMn@C electrode significantly promotes the activation of H2O to produce *O, followed by coupling of *O at adjacent sites to produce *OO, which further spontaneously forms 1O2. And H218O isotope experiments provide direct evidence for the production of 1O2 directly from H2O. Consequently, the production of 1O2 is enhanced with the yield of 785.6 μmol·L−1. Such 1O2-dominated electrocatalytic oxidation system can achieve efficient removal of electron-rich pollutant (bisphenol A) and improve the biodegradability of pharmaceutical wastewater (from 0.17 to 0.39).

Juxtaposing the antibacterial activities of different ZIFs in photodynamic therapy and their oxidative stress approach

Instigating oxidative stress is a crucial aspect of antibacterial therapy. Yet, its behavior is poorly understood in the context of zeolitic imidazolate frameworks (ZIFs) – a group of highly promising antibacterial agents. To address this gap, a series of ZIF@Ce6 particles were synthesized to investigate the impact of particle shape, size, and metal ion type on oxidative stress and bactericidal activity. For the first time, the interplay between the physicochemical properties and antibacterial activities of different ZIF@Ce6 particles is demonstrated, while unearthing their oxidative stress strategy in photodynamic therapy. Notably, the incorporation of chlorin e6 (Ce6), combined with light irradiation, amplified the bactericidal effect of the ZIFs and achieved a rare minimum inhibition concentration (MIC) of 12.5 µgmL−1 for ZIF-8. We discovered that singlet oxygen (1O2) production varies with particle shape and size, while photodynamic activity reshuffles the antibacterial performance sequence from pristine to modified ZIF-8. Interestingly, reactive oxygen species (ROS) accumulation and glutathione depletion tests revealed that oxidative stress in pristine ZIF-8 is predominantly induced by ROS, whereas both ROS and glutathione contribute to the oxidative stress in ZIF@Ce6 and pristine ZIF-67. When bacteria are preincubated with the antioxidant N-acetyl cysteine, the bactericidal activity of ZIF@Ce6 increases while the activity of pristine ZIF-8 is reduced and that of ZIF-67 remains unchanged. This study deepens our understanding of the antibacterial properties of ZIFs and their oxidative stress paths, paving way for the fabrication of ZIF-based materials with enriched and targeted antibacterial properties.

Photocatalytic Achmatowicz Rearrangement on Triphenylbenzene-Dimethoxyterephthaldehyde-Covalent Organic Framework-Mo for Converting Biomass-Derived Furfuryl Alcohol to Hydropyranone.

The conversion of biomass-based feedstocks into high-value platform compounds remains a fundamental but challenging topic. Studies on such transformations are sparse due to the complex nature of biomass and limited upgrading strategies. Photocatalytic aerobic oxidation is a promising pathway for making pharmaceutical precursors from biomass-derived chemicals. In this study, we demonstrate the transformation of furfuryl alcohol into dihydropyranone acetyl by using a molybdenum-incorporated triphenylbenzene-dimethoxyterephthaldehyde-covalent organic framework via a singlet oxygen (1O2)-mediated photocatalytic Achmatowicz reaction. The COF-Mo photocatalyst exhibits exceptional selectivity up to 98% in producing hydroxy-2H-pyran-3(6H)-one, a complex synthone crucial for synthesizing anti-AIDS drugs. Mo incorporation enhances the generation rate by 3.9 times, primarily due to the synergistic effect between Mo active sites and the COF backbone. More importantly, Mo clusters create a superfast charge tunnel for photogenerated electron transfer from COF to adsorbed O2. The metallic state and hexavalent of Mo facilitate the generation of superoxide anions and 1O2, respectively, facilitating photocatalytic reactions.

From Lithium and Sodium Superoxides to Singlet-Oxygen - Insights into the Mechanism of Dissociation Using SHARC-MD.

The formation of highly reactive singlet oxygen from alkaline superoxides presents an important reactivity of this component class. Investigations of the reaction paths such as disproportionation of LiO2 and NaO2 have been presented. Furthermore, the dissociation of these superoxide systems have been discussed as an alternative reaction channel that also allows the formation of singlet oxygen. Here, we present a fundamental study of the electronic nature and dissociation behaviour of the alkali superoxides. The molecular systems were calculated at the CASSCF/CASPT2-level of theory. We determined the minimum energy crossing points along the dissociation required to form triplet oxygen 3O2 and singlet oxygen 1O2. Building on these results, a surface-hopping AIMD-simulation was performed employing the SHARC program package to follow the electronic transitions along the minimum energy crossing points during the dissociation. The feasibility of populating the electronic state corresponding to the formation of singlet oxygen during dissociation was demonstrated. For LiO2, 6.85 % of the trajectories were found to terminate under formation of 1O2, whereas for NaO2 only 1.68 % of the trajectories ended up in 1O2 formation. This represents an inverse trend to that reported in the literature. This observation suggests that the dissociation is a viable, monomolecular reaction path to 1O2 that complements the disproportionation pathway.

Near-infrared AIE chemiluminescence probe for monitoring and evaluating singlet oxygen in vivo

The incorporation a “singlet oxygen (1O2) battery” into photodynamic therapy (PDT) could overcome the deficiency of tumor hypoxia in PDT and enhance its effect. However, real-time monitoring the 1O2 release efficiency of the 1O2 battery still presents a significant challenge in vivo. To address this issue, we have developed a bright aggregation-induced emission (AIE) chemiluminescence (CL) probe (DTLum), which conjugates a luminol unit with a donor-acceptor structured diketopyrrolopyrrole fluorophore, for the specific detection of 1O2. Subsequently, the DTLum nanoparticles (DTLum NPs) were prepared using PEO100-PPO65-PEO100 (Pluronic F127) as the surfactant. The DTLum NPs can detect 1O2 in aqueous solution with a bright near-infrared (NIR) CL signal (651 nm) and great tissue penetration (12.5 mm), making them suitable for the detection of 1O2 both in vitro (quantitative) and in vivo (qualitative). Notably, by utilizing the DTLum NPs, the process of 1O2 release in 1O2 batteries with different release rates can be visually monitored in cells and in vivo. This NIR CL probe provides a powerful platform for real-time monitoring and evaluating the release efficiency of 1O2 battery.

Enhanced peroxymonosulfate activation by MnOOH/CoOOH composites for efficient phenol degradation: Mechanistic insights and practical implications

The strong electronic interactions between metal oxide components are crucial for the activation of peroxymonosulfate (PMS) in pollutant degradation. In this study, an innovative MnOOH/CoOOH composite material (labeled as B-MCo-0.1) was synthesized through mesoscale chemical coupling, serving as an efficient PMS activator for phenol degradation. Experimental findings suggest that CoOOH nanosheets incorporated on MnOOH surface prevent CoOOH aggregation, increase specific surface area, and enhance the synergistic interaction between components, thereby improving activation and degradation efficiency. Under optimal conditions, a 50 mL phenol solution (25 mg/L) can achieve 100 % degradation within 10 minutes. XPS analysis reveals that the robust electronic interaction between CoOOH and MnOOH facilitates PMS activation, generating reactive oxygen species (ROS) that effectively degrade phenol through both non-radical and radical pathways. Experiments, including quenching tests, electrochemical analysis, electron paramagnetic resonance (EPR) measurements, and sulfoxide method experiments for identifying high-valent metal oxides confirm that singlet oxygen (1O2) and superoxide anion (·O2−) play major roles in this process. Additionally, high-valent manganese oxides and electron transfer complexes on the catalyst surface, generated under strong electronic interactions, also contribute significantly to phenol degradation. By exploring the pivotal role of robust electronic interactions in activating PMS, this study extends the potential applications of MnOOH-based materials in environmental remediation.

Synergistic catalysis of immobilized enzyme and peroxymonosulfate activation: CuFe2O4/kaolin-CTS-Laccase for enhanced performance of reactive blue 19 degradation

This work constructed an immobilized laccase - peroxymonosulfate (PMS) activation synergistic catalytic system for enhancing the efficient removal of reactive blue 19 (RB19). Superparamagnetic CuFe2O4/kaolin (CF/K) composites were prepared by one-step solvothermal and calcination methods and then modified with chitosan as immobilized carriers for laccase. The enzyme activity of CuFe2O4/kaolin-CTS-Laccase (CF/K-CTS-Lac) could reach 316.3 U/g under optimal immobilization conditions of 3 h and 2.6 mg/mL. CF/K-CTS-Lac exhibited improved pH stability and thermal stability in comparison to free laccase. The CF/K-CTS-Lac/PMS synergistic catalytic system achieved 98.4 % decolourization of RB19 within 90 min, which was 1.7 and 1.9 times higher than that of the CF/K-CTS-Lac system and CF/K-CTS/PMS system, respectively. Enhanced RB19 degradation efficiency attributed to synergistic catalysis by immobilized laccase and PMS activation. Free radical quenching experiments showed that hydroxyl radicals (•OH), sulfate radicals (SO4•-), superoxide radicals (•O2-) and singlet oxygen (1O2) were involved in the synergistic catalytic system, with •O2- and 1O2 playing a major role. Our investigations are expected to provide new insights into the construction of synergistic catalytic systems for pollutants.

Hypoxia-Activated Biodegradable Porphyrin-Based Covalent Organic Frameworks for Photodynamic and Photothermal Therapy of Wound Infection.

Wound infections have gradually become a major threat to human health. Recently, covalent organic frameworks (COFs) have shown great potential in antibacterial and wound healing; however, difficult biodegradability and long-time in vivo retention limit their further application. Herein, biodegradable COFs containing porphyrin backbones and hypoxia-sensitive azobenzene group, namely, HRCOFs, are fabricated for photodynamic therapy (PDT) and photothermal therapy (PTT) of wound infection. Due to the introduction of a porphyrin molecule, HRCOFs can produce singlet oxygen (1O2) under 660 nm laser irradiation. The prepared HRCOFs can also generate thermal energy under 808 nm NIR laser irradiation. HRCOFs show excellent synergetic antibacterial ability against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in vitro. The in vivo experiments also demonstrate synergistic PDT and PTT effects of HRCOFs against wound infection. Importantly, HRCOFs are response to wound microenvironment, can be degraded for clearance, and avoid some adverse effects caused by long-time retention in vivo, exhibiting good biocompatibility. In general, the obtained biodegradable HRCOFs with both photodynamic and photothermal effects can be used for antibacterial infections and provide great value for promoting wound healing.

Enhanced organic pollutant degradation in a two-dimensional Fe-doped crystalline carbon nitride membrane with near 100 % singlet oxygen generation through the Fe–O–N configuration

The singlet oxygen (1O2)-based nonradical AOP process, realized in carbon materials after nitrogen and metal doping, has drawn much attention in recent years. However, the exclusive generation of 1O2 in the specialized two-dimensional (2D) catalytic membranes and the associated contaminant degradation mechanisms remain unclear. Herein, a Fe-doped crystalline carbon nitride (Fe-CCN) material without additional nitrogen doping was developed to preferentially initiate 1O2-based nanoconfined oxidation of organic pollutants in the 2D Fe-CCN membrane/PMS system. Density functional theory calculation revealed that the Fe-O-N configuration formed after Fe doping altered the electronic structure of Fe centers, enhancing PMS adsorption and promoting the thermodynamically favorable generation of the –O* intermediate, leading to fast and highly selective 1O2 generation. EPR characterization and ROS quenching experiment also confirmed that the Fe-CCN activated PMS, generating nearly 100 % 1O2. The Fe-CCN membrane/PMS system exhibited excellent resistance to natural organic matter (NOM) interference and dramatically increased Bisphenol A (BPA) degradation kinetics, approximately 590 times faster than in conventional batch systems. Enhanced 1O2 exposure concentration within the Fe-CCN membrane nanochannels was supported by EPR data and 1O2 exposure simulations. Furthermore, The Fe-CCN membrane/PMS system showed wide pH tolerance, excellent pollutant degradation performance, and high stability. This work underscores the practical significance of 1O2-based oxidation reactions in membrane-confined AOPs for the rapid and efficient removal of organic contaminants from water.