Heterogeneous Fenton-like discoloration of methyl orange using Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/MWCNTs as catalyst: kinetics and Fenton-like mechanism

The kinetics and Fenton-like mechanism are two challenging tasks for heterogeneous Fenton-like catalytic oxidation of organic pollutants. In this study, three kinetic models were used for the kinetic studies of Fe₃O₄/MWCNTs-H₂O₂ Fenton-like reaction for MO degradation. The results indicated that this reaction followed the first-order kinetic model. The relationship of reaction rate constant and temperature followed the Arrhenius equation. The activation energy and frequency factor of this system were calculated as 8.2 kJ·mol^-1 and 2.72 s^-1, respectively. The quantifications of Fe ions dissolution and ?OH radicals generation confirmed that the homogeneous and heterogeneous catalyses were involved in Fe₃O₄/MWCNTs-H₂O₂ Fenton-like reaction. The reaction rate constant was closely related with Fe ions dissolution and ?OH radicals generation. Fe₃O₄/MWCNTs nanocomposites had typical ferromagnetic property and could be easily separated from solution by an external magnet after being used. Furthermore, Fe₃O₄/MWCNTs nanocomposites exhibited good stability and recyclability. Finally, the Fenton-like mechanisms on homogeneous and heterogeneous catalyses were described.     

Bulk and surface structures of iron doped zirconium oxide systems: Influence of preparation method

Three different Fe-Zr oxide systems were prepared using firstly classical impregnation of iron nitrates on calcined ZrO₂ (Fe_x/ZrO₂, x represents Fe/Zr ratio = 0.01 and 0.11), secondly impregnation of iron nitrates on dried zirconium hydroxide ZrO(OH)₂ (Fe_x/ZrO(OH)₂) and finally hydrolysis of aqueous suspension of iron and zirconium salts to coprecipitate iron and zirconium hydroxides (Fe_x-Zr). Thermal decomposition study of dried samples evidenced a delay in the temperature crystallization of zirconia for Fe_x-Zr and Fe_x/ZrO(OH)₂, the more the iron content in the sample, the more important the delay. For these samples, the formation and the stabilization of different phases were evidenced by several characterization techniques : X-Ray Diffraction (XRD), Raman spectroscopy and Electron Paramagnetic Resonance (EPR).The interaction of iron species with zirconia was different in accordance with different preparations. A bulk dispersion of the coprecipitated sample was observed and as a consequence Zr^{3 +} defects in the solid were not produced. In the case of Fe_x/ZrO₂ sample, production of surface Zr^{3 +} ions was established at low temperature of calcination (up to 600^∘C) and explained by the reaction of NO₃⁻ with Zr^{4 +} on the zirconia surface. However such interaction did not occur for Fe_x/ZrO(OH)₂ since a low dispersion of iron species was observed by X-ray Photoelectron Spectroscopy (XPS), deposited phase (Fe₂O₃) forming preferentially blocks. Temperature Programmed Reduction (TPR) showed that the reduction of small particles of Fe₂O₃ and bulk Fe₂O₃ present in the impregnated samples was easier than that of iron species well dispersed in the bulk of the coprecipitated solid.     

Photodecomposition of 4-chlorophenol by reactive oxygen species in UV/air system

In this article, the photo-degradation of 4-chlorophenol (4-CP) under UV irradiation was studied with focus on the photodecomposition of 4-CP by reactive oxygen species (ROS). 4-CP underwent much faster and more complete degradation in UV/air system than in UV/N₂ system. In UV/air system, the addition of t-butanol, a well-known ^•OH scavenger, significantly impeded the degradation of 4-CP. In the presence of t-butanol, the tendencies for the degradation of 4-CP and the formation of intermediates in UV/air system were very similar to those in UV/N₂ system. In UV/air system, 4-CP was degraded by two pathways, direct photolysis by absorbing the photons and the oxidation via ^•OH. The contribution of direct photolysis and the oxidation via ^•OH to 4-CP decomposition were 17.2% and 82.8%, respectively based on the apparent kinetic constants. Hydrogen peroxide, which could produce ^•OH through photolysis, was formed in UV/air system. It was shown that dissolved oxygen, organic matter in excited state and hydrogen ion are all necessary for the formation of hydrogen peroxide. The formation mechanism of H₂O₂ was proposed based on experimental evidence.     

cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX), its properties and initiation reactivity

Pre-treatment of simulated industrial wastewaters (SIM1, SIM2 and SIM3) containing organic and inorganic compounds (1,2-dichloroethane, sodium formate, sodium hydrogen carbonate, sodium carbonate and sodium chloride) by oxidative degradation using homogeneous Fenton type processes (Fe²⁺/H₂O₂ and Fe³⁺/H₂O₂) has been evaluated. The effects of initial Fe²⁺ and Fe³⁺ concentrations, [Fe^2+/3+], type of iron salt (ferrous sulfate vs. ferric chloride), initial hydrogen peroxide concentration, [H₂O₂], on mineralization extent, i.e., total organic content (TOC) removal, were studied. Response surface methodology (RSM), particularly Box–Behnken design (BBD) was used as modelling tool, and obtained predictive function was used to optimize the overall process by the means of desirability function approach (DFA). Up to 94% of initial TOC was removed after 120 min. Ferrous sulfate was found to be the most appropriate reagent, and the optimal doses of Fe²⁺ and H₂O₂ for reducing the pollutant content, in terms of final TOC and sludge production were assessed.     

Synergistic Amplification of Oxidative Stress–Mediated Antitumor Activity via Liposomal Dichloroacetic Acid and MOF‐Fe2+

Cancer cells are susceptible to oxidative stress; therefore, selective elevation of intracellular reactive oxygen species (ROS) is considered as an effective antitumor treatment. Here, a liposomal formulation of dichloroacetic acid (DCA) and metal–organic framework (MOF)‐Fe²⁺ (MD@Lip) has been developed, which can efficiently stimulate ROS‐mediated cancer cell apoptosis in vitro and in vivo. MD@Lip can not only improve aqueous solubility of octahedral MOF‐Fe²⁺, but also generate an acidic microenvironment to activate a MOF‐Fe²⁺‐based Fenton reaction. Importantly, MD@Lip promotes DCA‐mediated mitochondrial aerobic oxidation to increase intracellular hydrogen peroxide (H₂O₂), which can be consequently converted to highly cytotoxic hydroxyl radicals (?OH) via MOF‐Fe²⁺, leading to amplification of cancer cell apoptosis. Particularly, MD@Lip can selectively accumulate in tumors, and efficiently inhibit tumor growth with minimal systemic adverse effects. Therefore, liposome‐based combination therapy of DCA and MOF‐Fe²⁺ provides a promising oxidative stress–associated antitumor strategy for the management of malignant tumors.     

Studies on photocatalytic removal of antibiotics,ciprofloxacin and sulfamethoxazole,by Fe3O4-ZnO-Chitosan/Alginate nanocomposite in aqueous systems

An ultraviolet-light-induced antibiotic degradation system based on nano-ZnO and Fe₃O₄ and chitosan/alginate nanocomposite bead assembly has been developed using a facile green-synthesis approach. In this study Camellia sinensis extract was used as reducing agent to facilitate the formation of the nanoparticles. The Fe₃O₄-ZnO-CS/SA nanocomposite was employed to degrade ciprofloxacin (CIP) and sulfamethoxazole (SMX) under UV-C light irradiation, and 94.77% and 93.31% degradation was achieved respectively within 180 min with the optimized conditions [pH of 4.0, antibiotic concentration of 10 mg/L, and Fe₃O₄-ZnO-CS/SA nanocomposite weight of 10 g and 15 g for CIP and SMX respectively]. For both the antibiotics, the pseudo-first-order model fitted well with the reaction kinetics data, while the Langmuir isotherm model showed a better fit compared to the Freundlich and Temkin models. Analyzing various characterization data reaction mechanism for CIP and SMX degradation was proposed. In addition, possible degradation pathways of CIP and SMX were proposed based on the intermediates detected by HR-LCMS analysis. Furthermore, the trapping experiments showed that superoxide (¹O₂) and hydroxyl (OH) radicals play major role in the photodegradation of CIP and SMX. The effects of ionic strength, natural organics and various natural water systems on degradation efficacy was investigated. The degraded products were found to show less toxicity to a model organism, a fresh water alga, compared to the parent compounds. This work provides a simple strategy to integrate CS/SA with nano-ZnO and Fe₃O₄ to construct effective nanocomposite photocatalyst for the degradation of different classes of antibiotics.     

Hemoglobin Nanocrystals for Drugs Free,Synergistic Theranostics of Colon Tumor (Small 8/2023)

The conventional approach in cancer nanomedicine involves advanced drug nanocarriers delivering preloaded therapeutics to targeted tumor sites to maximize drug efficiency. However, both cancer drugs and nanocarriers inevitably produce side effects and systemic toxicity. Herein, hemoglobin nanocrystals (HbC) as drug-free theranostic nanoformulations with the tumor microenvironment (TME) activated diagnostic and therapeutic abilities towards colon tumors are introduced. HbC can release Fe²⁺ oxidized to Fe³⁺ in the Fenton reaction with tumor endogenous H₂O₂, concurrently with the generation of cytotoxic hydroxyl radicals (•OH) that allow for chemodynamic therapy (CDT). Furthermore, in situ-produced Fe³⁺ reacts with colon tumor-abundant H₂S, resulting in the production of Fe_1−xS, which provides magnetic resonance imaging (MRI) contrast and allows for NIR light-inducible photothermal therapy (PTT). In vitro and in vivo studies revealed that HbC produced CDT towards 4T1 tumors, and MRI-guided, synergistically enhanced combination of CDT and PTT against H₂S abundant colon tumors (CT26), with negligible toxicity towards normal tissues, enlightening HbC as highly efficient and biocompatible TME activated theranostic nanoplatform specific against colon cancer without any traditional drugs and drug carriers.     

Novel nanoparticle-assembled tetrakaidekahedron Bi25FeO40 as efficient photo-Fenton catalysts for Rhodamine B degradation

In this study, nanoparticle-assembled Bi₂₅FeO₄₀ materials were synthesized by a novel and simple process, and their microstructure was regulated by different methods of adding Bi³⁺ and Fe³⁺. The novel nanoparticle-assembled tetrakaidekahedron Bi₂₅FeO₄₀ materials exhibited more oxygen vacancy and larger specific surface area than irregular or cubic-like Bi₂₅FeO₄₀ microcrystals and revealed better photo-Fenton catalytic oxidation activity toward degrading Rhodamine B (RhB) pollutants. These novel materials activated H₂O₂ in visible light to produce non-free radicals ¹O₂ and hole (h⁺) active oxidative species that dominated the catalytic degradation of RhB. Complete degradation of RhB was achieved after 1 h. The possible reaction mechanisms of the photo-Fenton catalytic system are discussed in detail by radical scavenging tests, X-ray phosphorescence analysis, and electron paramagnetic resonance spectroscopy. The results provided a way to rationally explore and construct photo-Fenton catalysts for wastewater treatment.     

Oxidation of polyvinyl alcohol by persulfate activated with heat,Fe, and zero-valent iron

The oxidation of polyvinyl alcohol (PVA) by persulfate (S₂O₈²⁻) activated with heat, Fe²⁺, and zero-valent iron (Fe(0)) was investigated via batch experiments. It was hypothesized that elevated temperature and the addition of Fe²⁺ or Fe(0) into a persulfate-water system could enhance the oxidation of PVA by activated persulfate. Increasing the temperature from 20 to 60 °C or 80 °C accelerated the oxidation rate of PVA, which achieved complete oxidation in 30 and 10 min, respectively. At 20 °C, the addition of Fe²⁺ or Fe(0) to the persulfate-water system significantly enhanced the oxidation of PVA. The optimal persulfate-to-Fe²⁺ or Fe(0) molar ratio was found to be 1:1. Complete oxidation of PVA was obtained by Fe(0)-activated persulfate in 2 h. Synergistic activation of persulfate by heat and Fe²⁺ or Fe(0) was also shown to enhance the oxidation of PVA in the persulfate-water system. By using GC–MS analysis, an oxidation product of PVA was identified as vinyl acetic acid (C₄H₆O₂), which is readily biodegradable. Our results suggest that the oxidative treatment of PVA by activated persulfate is a viable option for the pretreatment of PVA-laden wastewater to enhance its biodegradability.     

Hydrophilic and photocatalytic properties of the SiO2/TiO2 double layers

The hydrophilic and photocatalytic properties of the SiO₂/TiO₂ double layers composed of a 20-nm-thick porous SiO₂ layer on the 200-nm-thick columnar anatase TiO₂ layer were studied. The hydrophilicity of the double layers was strictly determined by the relative coverage of organic contaminants. The intrinsic hydrophilicity of 0° of SiO₂ in terms of the water contact angle was restored by the photocatalytic decomposition of organic contaminants under the UV light irradiation.Electron spin resonance measurements revealed the generation of OH radicals under the UV light irradiation onto the SiO₂/TiO₂ double layers. Photoconductivity measurements showed that the current decay in O₂ gas atmosphere was remarkably fast in comparison with that in H₂O vapor. These observations support our view that the generation of OH radicals effective for decomposing organic contaminants on the surface begins with the reaction between O₂ molecules and the photoexcited electrons. We propose together with other experimental facts herein that OH radicals would be generated via O₂⁻ and H₂O₂ in the double layer system.     

Dechlorination of 3,3′,4,4′-tetrachlorobiphenyl in aqueous solution by hybrid Fe0/Fe3O4 nanoparticle system

The kinetics and efficiency of 3,3′,4,4′-tetrachlorobiphenyl (PCB77) degradation in aqueous solution by hybrid Fe⁰/Fe₃O₄ nanoparticle system were investigated. The results showed that nano-sized Fe⁰ and Fe₃O₄ could efficiently degrade PCB77, and the residual rate of PCB77 by nano-sized Fe⁰ and Fe₃O₄ were 67.70% ± 0.42% and 82.26% ± 2.96%, respectively after 240 min of reaction (for 5 mg·L^?1 PCB77 and 5 g·L^?1 nanoparticles). The combined use of nanoscale Fe⁰ and Fe₃O₄ could enhance the degradation of PCB77. The dose ratios of nano-sized Fe⁰ and Fe₃O₄ significantly affected the PCB77 degradation rate. At Fe⁰/Fe₃O₄ ratios of 1:0.1, 1:0.2 and 1:1, the residual rates of PCB77 were 6.46%, 10.23% and 38.20%, respectively. The PCB77 degradation efficiency was also greatly affected by solution pH, and was maximised at pH 6.8. The degradation of PCB77 by Fe⁰/Fe₃O₄ nanoparticle was a dechlorination process, and the chlorion concentration increased with the decreasing residual rate of PCB77 accordingly. Fe₃O₄ provided Fe²⁺ and Fe³⁺ for enhancing the PCB77 degradation by nanoscale Fe⁰, suggesting a synergy between Fe⁰ and Fe₃O₄.     

Mechanism of the enhanced degradation of pentachlorophenol by ultrasound in the presence of elemental iron

Ultrasound combined with elemental iron (US/Fe(0)) is effective in oxidizing organic contaminants in water. The sonolysis degradation of pentachlorophenol (PCP) was significantly enhanced by a factor of 4.2 with the addition of elemental iron, mainly via reaction with hydroxyl radicals (OH radicals), and the synergistic mechanism of the enhancement in the combined system was investigated. Experiments were performed with (1) sole ultrasonic treatment; (2) ultrasound in presence of iron; (3) ultrasound combined with copper powder as the same particle size as iron powder; (4) ultrasound in presence of Fe(II). It was observed that PCP degradation and OH radicals production were both enhanced in these combined methods, and the pitting on the sonicated iron surface was apparent. These results indicated that the rate enhancements in US/Fe(0) system were attributed to (1) the iron solid effect and the catalysis of Fe(II) produced from corroded-iron with promoting the production of OH radicals; (2) the increased surface area of iron particles by acoustic cavitation with promoting the adsorption process.     

Nanocatalysts‐Augmented and Photothermal‐Enhanced Tumor‐Specific Sequential Nanocatalytic Therapy in Both NIR‐I and NIR‐II Biowindows

The tumor microenvironment (TME) has been increasingly recognized as a crucial contributor to tumorigenesis. Based on the unique TME for achieving tumor‐specific therapy, here a novel concept of photothermal‐enhanced sequential nanocatalytic therapy in both NIR‐I and NIR‐II biowindows is proposed, which innovatively changes the condition of nanocatalytic Fenton reaction for production of highly efficient hydroxyl radicals (?OH) and consequently suppressing the tumor growth. Evidence suggests that glucose plays a vital role in powering cancer progression. Encouraged by the oxidation of glucose to gluconic acid and H₂O₂ by glucose oxidase (GOD), an Fe₃O₄/GOD‐functionalized polypyrrole (PPy)‐based composite nanocatalyst is constructed to achieve diagnostic imaging‐guided, photothermal‐enhanced, and TME‐specific sequential nanocatalytic tumor therapy. The consumption of intratumoral glucose by GOD leads to the in situ elevation of the H₂O₂ level, and the integrated Fe₃O₄ component then catalyzes H₂O₂ into highly toxic ?OH to efficiently induce cancer‐cell death. Importantly, the high photothermal‐conversion efficiency (66.4% in NIR‐II biowindow) of the PPy component elevates the local tumor temperature in both NIR‐I and NIR‐II biowindows to substaintially accelerate and improve the nanocatalytic disproportionation degree of H₂O₂ for enhancing the nanocatalytic‐therapeutic efficacy, which successfully achieves a remarkable synergistic anticancer outcome with minimal side effects.     

Hydrogen substitutes for the in situ generation of H2O2: an application in the Fenton reaction

This study investigates the ability of formic acid, hydrazine and hydroxylamine to act as H₂ substitutes in conducting phenol degradation by Fenton reaction using in situ generated hydrogen peroxide. The processes were performed with semi-heterogeneous (Pd/Al₂O₃ + soluble Fe²⁺) and fully heterogeneous (FePd/Al₂O₃) catalytic systems under ambient conditions. In contrast to bulk H₂O₂ production conditions, hydrazine is able to produce H₂O₂in situ followed by phenol degradation using Pd/Al₂O₃ + Fe²⁺ at pH 3 without the need for halide ions. However, a degree of mineralization exceeding 37% could not be achieved. The significant production of in situ H₂O₂ at the inherent acidic pH of hydroxylammonium sulfate in the presence of Pd/Al₂O₃ + Fe²⁺ was also found to differ from the bulk production of H₂O₂, in which no H₂O₂ was detected. A remarkable degree of mineralization (ca. 65%) as well as fast phenol degradation during the reaction started at pH 7 over FePd/Al₂O₃ may be an advantage of using hydroxylamine. On the other hand, using formic acid, H₂O₂ was produced at a moderate rate, thereby achieving higher efficiency in the mineralization of phenol. Most importantly, the catalysts were more stable in the presence of formic acid than hydrazine or hydroxylamine.     

Radical generation on hydroxyapatite by UV irradiation

The radical species generated on hydroxyapatite (HAp) samples by UV irradiation were investigated and compared by electron spin resonance (ESR) with spin trapping reagent. It was recognized that ^·OH and O₂^·− species were produced on HAp after heat treatment at 200 °C (HAp200) by UV irradiation. It was assumed that ^·OH radical was generated from H₂O on HAp200 by photo-induced excitation with UV irradiation as well as O₂^·− from O₂ in air. These radicals were very active. On the other hand, few radical species were produced on HAp after heat treatment at 1150 °C by UV irradiation. The difference of generation of active radical species on HAp by UV irradiation must influence the activity for the photocatalytic decomposition of organic compounds.     

NIR Responsive Doxorubicin-Loaded Hollow Copper Ferrite @ Polydopamine for Synergistic Chemodynamic/Photothermal/Chemo-Therapy

Osteosarcoma (OS) is the most serious bone malignancy, and the survival rate has not significantly improved in the past 40 years. Thus, it is urgent to develop a new strategy for OS treatment. Chemodynamic therapy (CDT) as a novel therapeutic method can destroy cancer cells by converting endogenous hydrogen peroxide (H₂O₂) into highly toxic hydroxyl radicals (·OH). However, the therapeutic efficacy of CDT is severely limited by the low catalytic efficiency and overexpressed glutathione (GSH). Herein, an excellent nanocatalytic platform is constructed via a simple solvothermal method using F127 as a soft template to form the hollow copper ferrite (HCF) nanoparticle, followed by the coating of polydopamine on the surface and the loading of doxorubicin (DOX). The Fe³⁺ and Cu²⁺ released from HCF@polydopamine (HCFP) can deplete GSH through the redox reactions, and then trigger the H₂O₂ to generate ·OH by Fenton/Fenton-like reaction, resulting in enhanced CDT efficacy. Impressively, the photothermal effect of HCFP can further enhance the efficiency of CDT and accelerate the release of DOX. Both in vitro and in vivo experiments reveal that the synergistic chemodynamic/photothermal/chemo-therapy exhibits a significantly enhanced anti-OS effect. This work provides a promising strategy for OS treatment.     

Boosting Photo-Electro-Fenton Process Via Atomically Dispersed Iron Sites on Graphdiyne for InVitro Hydrogen Peroxide Detection

Hydrogen peroxide (H₂O₂) is essential in oxidative stress and signal regulation of organs of animal body. Realizing in vitro quantification of H₂O₂ released from organs is significant, but faces challenges due to short lifetime of H₂O₂ and complex bio-environment. Herein, rationally designed and constructed a photoelectrochemical (PEC) sensor for in vitro sensing of H₂O₂, in which atomically dispersed iron active sites (Hemin) modified graphdiyne (Fe-GDY) serves as photoelectrode and catalyzes photo-electro-Fenton process. Sensitivity of Fe-GDY electrode is enhanced 8 times under illumination compared with dark condition. The PEC H₂O₂ sensor under illumination delivers a wide linear range from 0.1 to 48 160 µm and a low detection limit of 33 nm , while demonstrating excellent selectivity and stability. The high performance of Fe-GDY is attributed to, first, energy levels matching of GDY and Hemin that effectively promotes the injection of photo-generated electrons from GDY to Fe³⁺ for reduced Fe²⁺, which facilitates the Fe³⁺/Fe²⁺ cycle. Second, the Fe²⁺ actively catalyzes H₂O₂ to OH^- through the Fenton process, thereby improving the sensitivity. The PEC sensor demonstrates in vitro quantification of H₂O₂ released from different organs, providing a promising approach for molecular sensing and disease diagnosis in organ levels.     

Synthesis of granular activated carbon/zero valent iron composites for simultaneous adsorption/dechlorination of trichloroethylene

The coupling adsorption and degradation of trichloroethylene (TCE) through dechlorination using synthetic granular activated carbon and zerovalent iron (GAC-ZVI) composites was studied. The GAC-ZVI composites were prepared from aqueous Fe²⁺ solutions by impregnation with and without the use of a PEG dispersant and then heated at 105 °C or 700 °C under a stream of N₂. Pseudo-first-order rate constant data on the removal of TCE demonstrates that the adsorption kinetics of GAC is similar to those of GAC-ZVI composites. However, the usage of GAC-ZVI composites liberated a greater amount of Cl than when ZVI was used alone. The highest degree of reductive dechlorination of TCE was achieved using a GAC-ZVI700P composite (synthesized using PEG under 700 °C). A modified Langmuir-Hinshelwood rate law was employed to depict the behavior of Cl liberation. As a result, a zero-order Cl liberation reaction was observed and the desorption limited TCE degradation rate constant decreased as the composite dosage was increased. The GAC-ZVI composites can be employed as a reactive GAC that is not subject to the limitations of using GAC and ZVI separately.     

Fe(III)-Naphthazarin Metal–Phenolic Networks for Glutathione-Depleting Enhanced Ferroptosis–Apoptosis Combined Cancer Therapy

Nowadays, Fenton chemistry-based chemodynamic therapy (CDT) is an emerging approach to killing tumor cells by converting endogenous H₂O₂ into cytotoxic hydroxyl radicals (·OH). However, the elimination of ·OH by intracellular overexpressed glutathione (GSH) results in unsatisfactory antitumor efficiency. In addition, the single mode of consuming GSH and undesirable drug loading efficiency cannot guarantee the efficient cancer cells killing effect. Herein, a simple one-step strategy for the construction of Fe³⁺-naphthazarin metal–phenolic networks (FNP MPNs) with ultrahigh loading capacity, followed by the modification of NH₂-PEG-NH₂, is developed. The carrier-free FNP MPNs can be triggered by acid and GSH, and rapidly release naphthazarin and Fe³⁺, which is further reduced to Fe²⁺ that exerts Fenton catalytic activity to produce abundant ·OH. Meanwhile, the Michael addition between naphthazarin and GSH can lead to GSH depletion and thus achieve tumor microenvironment (TME)-triggered enhanced CDT, followed by activating ferroptosis and apoptosis. In addition, the reduced Fe²⁺ as a T₁-weighted contrast agent endows the FNP MPNs with magnetic resonance imaging (MRI) functionality. Overall, this work is the debut of naphthazarin as ligands to fabricate functional MPNs for effectively depleting GSH, disrupting intracellular redox homeostasis, and enhancing CDT effects, which opens new perspectives on multifunctional MPNs for tumor synergistic therapy.     

Comparative electrochemical treatments of two chlorinated aliphatic hydrocarbons. Time course of the main reaction by-products

Acidic aqueous solutions of the chlorinated aliphatic hydrocarbons 1,2-dichloroethane (DCA) and 1,1,2,2-tetrachloroethane (TCA) have been treated by the electro-Fenton (EF) process. Bulk electrolyses were performed at constant current using a BDD anode and an air diffusion cathode able to generate H₂O₂ in situ, which reacts with added Fe²⁺ to yield OH from Fenton's reaction. At 300 mA, almost total mineralization was achieved at 420 min for solutions containing 4 mM of either DCA or TCA. Comparative treatments without Fe²⁺ (anodic oxidation) or with a Pt anode led to a poorer mineralization. The better performance of the EF process with BDD is explained by the synergistic action of the oxidizing radicals, BDD(OH) at the anode surface and OH in the bulk, and the minimization of diffusional limitations. The decay of the initial pollutant accomplished with pseudo first-order kinetics. Chloroacetic and dichloroacetic acids were the major by-products during the degradation of DCA and TCA, respectively. Acetic, oxalic and formic acids were also identified. The proposed reaction pathways include oxidative and reductive (cathodic) dechlorination steps. Chlorine was released as Cl⁻, being further oxidized to ClO₃⁻ and, mostly, to ClO₄⁻, due to the action of the largely generated BDD(OH) and OH.