Development of Novel Immobilized Copper-Ligand Complex for Click Chemistry of Biomolecules.

Copper-catalyzed azide-alkyne cycloaddition click (CuAAC) reaction is widely used to synthesize drug candidates and other biomolecule classes. Homogeneous catalysts, which consist of copper coordinated to a ligand framework, have been optimized for high yield and specificity of the CuAAC reaction, but CuAAC reaction with these catalysts requires the addition of a reducing agent and basic conditions, which can complicate some of the desired syntheses. Additionally, removing copper from the synthesized CuAAC-containing biomolecule is necessary for biological applications but inconvenient and requires additional purification steps. We describe here the design and synthesis of a PNN-type pincer ligand complex with copper (I) that stabilizes the copper (I) and, therefore, can act as a CuAAC catalyst without a reducing agent and base under physiologically relevant conditions. This complex was immobilized on two types of resin, and one of the immobilized catalyst forms worked well under aqueous physiological conditions. Minimal copper leaching was observed from the immobilized catalyst, which allowed its use in multiple reaction cycles without the addition of any reducing agent or base and without recharging with copper ion. The mechanism of the catalytic cycle was rationalized by density functional theory (DFT). This catalyst's utility was demonstrated by synthesizing coumarin derivatives of small molecules such as ferrocene and sugar.

A highly stable electrochemical sensor with antifouling and antibacterial capabilities for mercury ion detection in seawater.

The monitoring of heavy metal ions in ocean is crucial for environment protection and assessment of seawater quality. However, the detection of heavy metal ions in seawater with electrochemical sensors, especially for long-term monitoring, always faces challenges due to marine biofouling caused by the nonspecific adsorption of microbial and biomolecules. Herein, an electrochemical aptasensor, integrating both antifouling and antibacterial properties, was developed for the detection of Hg2+ in the ocean. In this electrochemical aptasensor, eco-friendly peptides with superior hydrophilicity served as anti-biofouling materials, preventing nonspecific adsorption on the sensing interface, while silver nanoparticles were employed to eliminate bacteria. Subsequently, a ferrocene-modified aptamer was employed for the specific recognition of Hg2+, leveraging the aptamer's ability to fold into a thymine-Hg2+-thymine (T-Hg2+-T) structure upon interaction, and bringing ferrocene nearer to the sensor surface, significantly amplifying the electrochemical response. The prepared electrochemical aptasensor significantly reduced the nonspecific adsorption in seawater while maintaining sensitive electrochemical response. Furthermore, the biosensor exhibited a linear response range of 0.01-100 nM with a detection limit of 2.30 pM, and realized the accurate monitoring of mercury ions in real marine environment. The research results offer new insights into the preparation of marine antifouling sensing devices, and it is expected that sensors with antifouling and antimicrobial capabilities will find broad applications in the monitoring of marine pollutants.

Insight into the mechanism of chlorinated nitroaromatic compounds anaerobic reduction with mackinawite (FeS) nanoparticles.

Anaerobic biotechnology for wastewaters treatment can nowadays be considered as state of the art methods. Nonetheless, this technology exhibits certain inherent limitations when employed for industrial wastewater treatment, encompassing elevated substrate consumption, diminished electron transfer efficiency, and compromised system stability. To address the above issues, increasing interest is being given to the potential of using conductive non-biological materials, e,g., iron sulfide (FeS), as a readily accessible electron donor and electron shuttle in the biological decontamination process. In this study, Mackinawite nanoparticles (FeS NPs) were studied for their ability to serve as electron donors for p-chloronitrobenzene (p-CNB) anaerobic reduction within a coupled system. This coupled system achieved an impressive p-CNB removal efficiency of 78.3 ± 2.9% at a FeS NPs dosage of 1 mg/L, surpassing the efficiencies of 62.1 ± 1.5% of abiotic and 30.6 ± 1.6% of biotic control systems, respectively. Notably, the coupled system exhibited exclusive formation of aniline (AN), indicating the partial dechlorination of p-CNB. The improvements observed in the coupled system were attributed to the increased activity in the electron transport system (ETS), which enhanced the sludge conductivity and nitroaromatic reductases activity. The analysis of equivalent electron donors confirmed that the S2- ions dominated the anaerobic reduction of p-CNB in the coupled system. However, the anaerobic reduction of p-CNB would be adversely inhibited when the FeS NPs dosage exceeded 5 g/L. In a continuous operation, the p-CNB concentration and HRT were optimized as 125 mg/L and 40 h, respectively, resulting in an outstanding p-CNB removal efficiency exceeding 94.0% after 160 days. During the anaerobic reduction process, as contributed by the predominant bacterium of Thiobacillus with a 6.6% relative abundance, a mass of p-chloroaniline (p-CAN) and AN were generated. Additionally, Desulfomonile was emerged with abundances ranging from 0.3 to 0.7%, which was also beneficial for the reduction of p-CNB to AN. The long-term stable performance of the coupled system highlighted that anaerobic technology mediated by FeS NPs has a promising potential for the treatment of wastewater containing chlorinated nitroaromatic compounds, especially without the aid of organic co-substrates.

Recent Advances in the Field of Amino Acid-Conjugated Aminoferrocenes-A Personal Perspective.

The development of turn-based inhibitors of protein-protein interactions has attracted considerable attention in medicinal chemistry. Our group has synthesized a series of peptides derived from an amino-functionalized ferrocene to investigate their potential to mimic protein turn structures. Detailed DFT and spectroscopic studies (IR, NMR, CD) have shown that, for peptides, the backbone chirality and bulkiness of the amino acid side chains determine the hydrogen-bond pattern, allowing tuning of the size of the preferred hydrogen-bonded ring in turn-folded structures. However, their biological potential is more dependent on their lipophilicity. In addition, our pioneering work on the chiroptical properties of aminoferrocene-containing peptides enables the correlation of their geometry with the sign of the CD signal in the absorption region of the ferrocene chromophore. These studies have opened up the possibility of using aminoferrocene and its derivatives as chirooptical probes for the determination of various chirality elements, such as the central chirality of amino acids and the helicity of peptide sequences.

A new strategy for improving the energy efficiency of electro-Fenton: Using N-doped activated carbon cathode with strong Fe(III) adsorption capacity to promote Fe(II) regeneration.

Fe(II) regeneration plays a crucial role in the electro-Fenton process, significantly influencing the rate of ·OH formation. In this study, a method is proposed to improve Fe(II) regeneration through N-doping aimed at enhancing the adsorption capacity of the activated carbon cathode for Fe(III). N-doping not only enriched the pore structure on the surface of activated carbon, providing numerous adsorption sites, but also significantly increased the adsorption energy for Fe(III). Among the types of nitrogen introduced, pyridine-N exhibited the most substantial enhancement effect, followed by pyrrole-N, while graphite-N showed a certain degree of inhibition. Furthermore, N-doping facilitated the adsorption of all forms of Fe(III) by activated carbon. The adsorption and electrosorption rates of the NAC-900 electrode for Fe(III) were 30.33% and 42.36%, respectively. Such modification markedly enhanced the Fe3+/Fe2+ cycle within the electro-Fenton system. The NAC-900 system demonstrated an impressive phenol degradation efficiency of 93.67%, alongside the lowest electricity consumption attributed to the effective "adsorption-reduction" synergy for Fe(III) on the NAC-900 electrode. Compared to the AC cathode electro-Fenton system, the degradation efficiency of the NAC-900 cathode electro-Fenton system at pH = levels ranging from 3 to 5 exceeded 90%; thus, extending the pH applicability of the electro-Fenton process. The degradation efficiency of phenol using the NAC-900 cathode electro-Fenton system in various water matrices approached 90%, indicating robust performance in real wastewater treatment scenarios. This research elucidates the impact of cathodic Fe(III) adsorption on Fe(II) regeneration within the electro-Fenton system, and clarifies the influence of different N- doping types on the cathodic adsorption of Fe(III).

Two Iron(II), α-Ketoglutarate-Dependent Enzymes Encoded by the PPZ Gene Cluster of Metarhizium majus Enable Production of 8-Hydroxyperamine.

Entomopathogenic fungus Metarhizium majus contains the nine-gene PPZ cluster, with ppzA, encoding a peramine-producing nonribosomal peptide synthetase, as the central component. In this work, the roles of two α-ketoglutarate, iron-dependent oxygenases encoded by the PPZ genes ppzC and ppzD were elucidated. PpzD was found to produce both trans-4-hydroxy-l-proline and trans-3-hydroxy-l-proline in a 13.1:1 ratio, yielding a key precursor for peramine biosynthesis. PpzC was found to act directly on peramine, yielding the novel analogue 8-hydroxyperamine.

FeS2 nanosheets-luminol-O2 chemiluminescence method for determination of venlafaxine hydrochloride, imipramine hydrochloride, and cefazolin sodium.

This study introduces a novel chemiluminescence (CL) approach utilizing FeS2 nanosheets (NSs) catalyzed luminol-O2 CL reaction for the measurement of three pharmaceuticals, namely venlafaxine hydrochloride (VFX), imipramine hydrochloride (IPM), and cefazolin sodium (CEF). The CL method involved the phenomenon of quenching induced by the pharmaceuticals in the CL reaction. To achieve the most quenching efficacy of the pharmaceuticals in the CL reaction, the concentrations of reactants comprising luminol, NaOH, and FeS2 NSs were optimized accordingly. The calibration curves demonstrated exceptional linearity within the concentration range spanning from 4.00 × 10-7 to 1.00 × 10-3 mol L-1, 1.00 × 10-7 to 1.00 × 10-4 mol L-1, and 4.00 × 10-6 to 2.00 × 10-4 mol L-1 with detection limits (3σ) of 3.54 × 10-7, 1.08 × 10-8, and 2.63 × 10-6 mol L-1 for VFX, IPM, and CEF, respectively. This study synthesized FeS2 NSs using a facile hydrothermal approach, and then the synthesized FeS2 NSs were subjected to a comprehensive characterization using a range of spectroscopic methods. The proposed CL method was effective in measuring the aforementioned pharmaceuticals in pharmaceutical formulations as well as different water samples. The mechanism of the CL system has been elucidated.

Structural, Spectroscopic, and Computational Insights from Canavanine-Bound and Two Catalytically Compromised Variants of the Ethylene-Forming Enzyme.

The ethylene-forming enzyme (EFE) is an Fe(II), 2-oxoglutarate (2OG), and l-arginine (l-Arg)-dependent oxygenase that either forms ethylene and three CO2/bicarbonate from 2OG or couples the decarboxylation of 2OG to C5 hydroxylation of l-Arg. l-Arg binds with C5 toward the metal center, causing 2OG to change from monodentate to chelate metal interaction and OD1 to OD2 switch of D191 metal coordination. We applied anaerobic UV-visible spectroscopy, X-ray crystallography, and computational approaches to three EFE systems with high-resolution structures. The ineffective l-Arg analogue l-canavanine binds to the EFE with O5 pointing away from the metal center while promoting chelate formation by 2OG but fails to switch the D191 metal coordination from OD1 to OD2. Substituting alanine for R171 that interacts with 2OG and l-Arg inactivates the protein, prevents metal chelation by 2OG, and weakens l-Arg binding. The R171A EFE had electron density at the 2OG binding site that was identified by mass spectrometry as benzoic acid. The substitution by alanine of Y306 in the EFE, a residue 12 Å away from the catalytic metal center, generates an interior cavity that leads to multiple local and distal structural changes that reduce l-Arg binding and significantly reduce the enzyme activity. Flexibility analyses revealed correlated and anticorrelated motions in each system, with important distinctions from the wild-type enzyme. In combination, the results are congruent with the currently proposed enzyme mechanism, reinforce the importance of metal coordination by OD2 of D191, and highlight the importance of the second coordination sphere and longer range interactions in promoting EFE activity.

Cr(VI) Reduction and Sequestration by FeS Nanoparticles Formed in situ as Aquifer Material Coating to Create a Regenerable Reactive Zone.

Remediation of large and dilute plumes of groundwater contaminated by oxidized pollutants such as chromate is a common and difficult challenge. Herein, we show that in situ formation of FeS nanoparticles (using dissolved Fe(II), S(-II), and natural organic matter as a nucleating template) results in uniform coating of aquifer material to create a regenerable reactive zone that mitigates Cr(VI) migration. Flow-through columns packed with quartz sand are amended first with an Fe2+ solution and then with a HS- solution to form a nano-FeS coating on the sand, which does not hinder permeability. This nano-FeS coating effectively reduces and immobilizes Cr(VI), forming Fe(III)-Cr(III) coprecipitates with negligible detachment from the sand grains. Preconditioning the sand with humic or fulvic acid (used as model natural organic matter (NOM)) further enhances Cr(VI) sequestration, as NOM provides additional binding sites of Fe2+ and mediates both nucleation and growth of FeS nanoparticles, as verified with spectroscopic and microscopic evidence. Reactivity can be easily replenished by repeating the procedures used to form the reactive coating. These findings demonstrate that such enhancement of attenuation capacity can be an effective option to mitigate Cr(VI) plume migration and exposure, particularly when tackling contaminant rebound post source remediation.

Exploring the modulatory influence on the antimalarial activity of amodiaquine using scaffold hybridisation with ferrocene integration.

Amodiaquine (AQ) is a potent antimalarial drug used in combination with artesunate as part of artemisinin-based combination therapies (ACTs) for malarial treatment. Due to the rising emergence of resistant malaria parasites, some of which have been reported for ACT, the usefulness of AQ as an efficacious therapeutic drug is threatened. Employing the organometallic hybridisation approach, which has been shown to restore the antimalarial activity of chloroquine in the form of an organometallic hybrid clinical candidate ferroquine (FQ), the present study utilises this strategy to modulate the biological performance of AQ by incorporating ferrocene. Presently, we have conceptualised ferrocenyl AQ derivatives and have developed facile, practical routes for their synthesis. A tailored library of AQ derivatives was assembled and their antimalarial activity evaluated against chemosensitive (NF54) and multidrug-resistant (K1) strains of the malaria parasite, Plasmodium falciparum. The compounds generally showed enhanced or comparable activities to those of the reference clinical drugs chloroquine and AQ, against both strains, with higher selectivity for the sensitive phenotype, mostly in the double-digit nanomolar IC50 range. Moreover, representative compounds from this series show the potential to block malaria transmission by inhibiting the growth of stage II/III and V gametocytes in vitro. Preliminary mechanistic insights also revealed hemozoin inhibition as a potential mode of action.

[Fe(NCMe)6](BF4)2 is a bifunctional catalyst for styrene aziridination by nitrene transfer and heterocycle expansion by subsequent dipolar insertion.

The solvated iron(II) salt [Fe(NCMe)6](BF4)2 (Me = methyl) is shown to be a bifunctional catalyst with respect to aziridination of styrene. The salt serves as an active catalyst for nitrene transfer from PhINTs to styrene to form 2-phenyl-N-tosylaziridine (Ph = phenyl; Ts = tosyl, -S{O}2-p-C6H4Me). The iron(II) salt also acts as a Lewis acid in non-coordinating CH2Cl2 solution, to catalyze heterolytic CN bond cleavage of the aziridine and insertion of dipolarophiles. The 1,3-zwitterionic intermediate is presumably supported by interaction of the metal dication with the anion, and by resonance stabilization of the carbocation. Nucleophilic dipolarophiles then insert to give a five-membered heterocyclic ring. The result is a two-step cycloaddition, formally [2 + 1 + 2], that is typically regiospecific, but not stereospecific. This reaction mechanism was confirmed by conducting a series of one-step, [3 + 2] additions of unsaturated molecules into pre-formed 2-phenyl-N-tosylaziridine, also catalyzed by [Fe(NCMe)6](BF4)2. Relevant substrates include styrenes, carbonyl compounds and alkynes. These yield five-membered heterocylic rings, including pyrrolidines, oxazolidines and dihydropyrroles, respectively. The reaction scope appears limited only by the barrier to formation of the dipolar intermediate, and by the nucleophilicity of the captured dipolarophile. The bifunctionality of an inexpensive, earth-abundant and non-toxic catalyst suggests a general strategy for one-pot construction of heterocyclic rings, as demonstrated specifically for pyrrolidine ring formation.

Degradation of methylmercury into Hg(0) by the oxidation of iron(II) minerals.

Mercury contamination is a global concern, and the degradation and detoxification of methylmercury have gained significant attention due to its neurotoxicity and biomagnification within the food chain. However, the currently known pathways of abiotic demethylation are limited to light-induced photodegradation process and little is known about light-independent abiotic demethylation of methylmercury. In this study, we reported a novel abiotic pathway for the degradation of methylmercury through the oxidation of both mineral structural iron(II) and surface-adsorbed iron(II) in the absence of light. Our findings reveal that methylmercury can be oxidatively degraded by reactive oxygen species, specifically hydroxyl and superoxide radicals, which are generated from the oxidation of iron(II) minerals under dark conditions. Surprisingly, Hg(0) trapping experiments demonstrated that inorganic Hg(II) resulting from the oxidative degradation of methylmercury was rapidly reduced to gaseous Hg(0) by iron(II) minerals. The demethylation of methylmercury, coupled with the generation of Hg(0), suggests a potential natural attenuation process for methylmercury. Our results highlight the underappreciated roles of iron(II) minerals in the abiotic degradation of methylmercury and the release of gaseous Hg(0) into the atmosphere.

Fe(II)-driven spatiotemporal assembly of heterotrophic and anammox bacteria enhances simultaneous nitrogen and phosphorus removal for low-strength municipal wastewater.

The mainstream anaerobic ammonium oxidation (anammox) faces considerable challenges with low-strength municipal wastewater. A Fe(Ⅱ)-amended partial denitrification coupled anammox (PD/A) process was conducted and achieved a long-term and efficient nitrogen and phosphorus removal, yielding effluent total nitrogen and phosphorus concentrations of 1.97 ± 1.03 mg/L and 0.23 ± 0.13 mg/L, respectively, which could well meet more stringent effluent discharge standard of some wastewater treatment plants in specific geographical locations, e.g., estuaries. Fe(Ⅱ)-driven vivianite formation provided key nucleuses for the optimization of the spatial distribution of heterotrophic and anammox bacteria with enhanced extracellular polymeric substances as key driving forces. Metagenomics analysis further revealed the increase of key genes, enhancing anammox bacteria homeostasis, which also bolstered the resistance to environmental perturbations. This study provided a comprehensive sight into the function of Fe(Ⅱ) in mainstream PD/A process, and explored a promising alternative for synergetic nitrogen and phosphorus removal for low-strength municipal wastewater treatment.

Spin Trapping of Nitric Oxide by Hemoglobin and Ferrous Diethyldithiocarbamate in Model Tumors Differing in Vascularization.

Animal tumors serve as reasonable models for human cancers. Both human and animal tumors often reveal triplet EPR signals of nitrosylhemoglobin (HbNO) as an effect of nitric oxide formation in tumor tissue, where NO is complexed by Hb. In search of factors determining the appearance of nitrosylhemoglobin (HbNO) in solid tumors, we compared the intensities of electron paramagnetic resonance (EPR) signals of various iron-nitrosyl complexes detectable in tumor tissues, in the presence and absence of excess exogenous iron(II) and diethyldithiocarbamate (DETC). Three types of murine tumors, namely, L5178Y lymphoma, amelanotic Cloudman S91 melanoma, and Ehrlich carcinoma (EC) growing in DBA/2 or Swiss mice, were used. The results were analyzed in the context of vascularization determined histochemically using antibodies to CD31. Strong HbNO EPR signals were found in melanoma, i.e., in the tumor with a vast amount of a hemorrhagic necrosis core. Strong Fe(DETC)2NO signals could be induced in poorly vascularized EC. In L5178Y, there was a correlation between both types of signals, and in addition, Fe(RS)2(NO)2 signals of non-heme iron-nitrosyl complexes could be detected. We postulate that HbNO EPR signals appear during active destruction of well-vascularized tumor tissue due to hemorrhagic necrosis. The presence of iron-nitrosyl complexes in tumor tissue is biologically meaningful and defines the evolution of complicated tumor-host interactions.

An enzyme-responsive hydrogel of ferrocene-grafted carboxymethyl chitosan as a soft electrochemical sensor for MMP-9 detection.

Matrix metalloproteinase 9 (MMP-9) plays an important role in wound healing. However, overexpression of MMP-9 leads to the degradation of the newly formed extracellular matrix, which delays wound healing, ultimately leading to chronic wounds. Therefore, timely monitoring of the MMP-9 activity using simple, cost-effective methods is important to prevent the formation of chronic wounds. In this work, ferrocene-modified MMP-9 cleavage peptide (Fc-MG) modified carboxymethyl chitosan hydrogels were prepared as electrochemical biosensors. In the presence of MMP-9, the peptide chain is sheared, and the electrochemically active ferrocene segment is released. Therefore, analyzing the electrochemical activity of hydrogels using differential pulse voltammetry (DPV) can be used to determine MMP-9 activity. The results showed that the DPV peaks were correlated with the MMP-9 concentration in phosphate-buffered saline (PBS, pH 7.4) and Dulbecco's modified Eagle's medium (DMEM). Specifically, the corresponding coefficient of determination (R2) were 0.918 and 0.993. The limit of detections were 73.08 ng/mL and 131.71 ng/mL, respectively. Compared with the enzyme-linked immunosorbent assay, the hydrogel biosensor determined the concentration of MMP-9 in solution with simpler steps. This study demonstrates a novel strategy based on Fc-MG-modified hydrogels to monitor MMP-9 activity in cell secretion samples and shows the potential application in chronic wounds.

Assessment of the catalytic and biological potential of yttrium and samarium-modified copper ferrite nanomaterials.

The present study reports the preparation of crystalline and nanosized copper ferrite (CuFe2O4), Y3+ substituted CuFe2O4 (CuFe1.95Y0.05O4), and Sm3+ substituted CuFe2O4 (CuFe1.95Sm0.05O4) using a simple co-precipitation method. The XRD analysis confirmed the formation of the cubic spinel phase, while XPS studies validated the presence of Cu and Fe in 2+ and 3+ oxidation states respectively. Transmission electron microscopy (TEM) analysis revealed the nanoparticles with a diameter in the range of 10-60 nm. The introduction of fractional amounts of Y3+ and Sm3+ ions in the CuFe2O4 lattice enhanced the reduction of 4-nitrophenol, attributed to decreased particle size facilitating the reduction process. In the case of antimicrobial activity, Candida albican was found to be maximally sensitive to CuFe2O4 and CuFe1.95Y0.05O4, while Pseudomonas aeruginosa was inhibited by CuFe1.95Sm0.05O4. Moreover, a maximum of 61.9 ± 1.91 % anti-Pseudomonas biofilm activity and 75.7 ± 1.28 % DPPH radical scavenging activity was observed for CuFe1.95Y0.05O4 at 200 µg/ml concentration. The improvement in biological activities was attributed to the reduced particle size, crystal structure modification, and increased stability of the CuFe2O4 lattice with substitution. The enhancement in catalytic and biological performance highlighted the effectiveness of minimal Y3+ and Sm3+ concentrations in modulating the properties of CuFe2O4 nanomaterials.

MXene-based composite aerogels with bifunctional ferrous ions for the efficient degradation of phenol from wastewater.

Herein, MXene-based composite aerogel (MXene-Fe2+ aerogel) are constructed by a one-step freeze-drying method, using Ti3C2Tx MXene layers as substrate material and ferrous ion (Fe2+) as crosslinking agent. With the aid of the Fe2+ induced Fenton reaction, the synthesized aerogels are used as the particle electrodes to remove phenol from wastewater with three-dimensional electrode technology. Combined with the dual roles of Fe2+ and the highly conductive MXene, the obtained particle electrode possesses extremely effective phenol degradation. The effects of experiment parameters such as Fe2+ to MXene ratio, particle electrode dosage, applied voltage, and initial pH of solution on the removal of phenol are discussed. At pH = 2.5, phenol with 50 mg/L of initial concentration can be completely removed within 50 min at 10 V with the particle electrode dosage of 0.56 g/L. Finally, the mechanism of degradation is explored. This work provides an effective way for phenol degradation by MXene-based aerogel, which has great potential for the degradation of other organic pollutants in wastewater.

Divergent redistribution behavior of divalent metal cations associated with Fe(II)-mediated jarosite phase transformation.

The Fe(II)/Fe(III) cycle is an important driving force for dissolution and transformation of jarosite. Divalent heavy metals usually coexist with jarosite; however, their effects on Fe(II)-induced jarosite transformation and different repartitioning behavior during mineral dissolution-recrystallization are still unclear. Here, we investigated Fe(II)-induced (1 mM Fe(II)) jarosite conversion in the presence of Cd(II), Mn(II), Co(II), Ni(II) and Pb(II) (denoted as Me(II), 1 mM), respectively, under anaerobic condition at neutral pH. The results showed that all co-existing Me(II) retarded Fe(II)-induced jarosite dissolution. In the Fe(II)-only system, jarosite first rapidly transformed to lepidocrocite (an intermediate product) and then slowly to goethite; lepidocrocite was the main product. In Fe(II)-Cd(II), -Mn(II), and -Pb(II) systems, coexisting Cd(II), Mn(II) and Pb(II) retarded the above process and lepidocrocite was still the dominant conversion product. In Fe(II)-Co(II) system, coexisting Co(II) promoted lepidocrocite transformation into goethite. In Fe(II)-Ni(II) system, jarosite appeared to be directly converted into goethite, although small amounts of lepidocrocite were detected in the final product. In all treatments, the appearance or accumulation of lepidocrocite may be also related to the re-adsorption of released sulfate. By the end of reaction, 6.0 %, 4.0 %, 76.0 % 11.3 % and 19.2 % of total Cd(II), Mn(II), Pb(II) Co(II) and Ni(II) were adsorbed on the surface of solid products. Up to 49.6 %, 44.3 %, and 21.6 % of Co(II), Ni(II), and Pb(II) incorporated into solid product, with the reaction indicating that the dynamic process of Fe(II) interaction with goethite may promote the continuous incorporation of Co(II), Ni(II), and Pb(II).

Haem iron versus ferrous iron salts to treat iron deficiency anaemia in Gambian children: protocol for randomised controlled trial {1}.

BACKGROUND: The World Health Organization recommends universal iron supplementation for children aged 6-23 months in countries where anaemia is seen in over 40% of the population. Conventional ferrous salts have low efficacy due to low oral absorption in children with inflammation. Haem iron is more bioavailable, and its absorption may not be decreased by inflammation. This study aims to compare daily supplementation with haem iron versus ferrous sulphate on haemoglobin concentration and serum ferritin concentration after 12 weeks of supplementation. METHODS: This will be a two-arm, randomised controlled trial. Gambian children aged 6-12 months with anaemia will be recruited within a predefined geographical area and recruited by trained field workers. Eligible participants will be individually randomised using a 1:1 ratio within permuted blocks to daily supplementation for 12 weeks with either 10.0 mg of elemental iron as haem or ferrous sulphate. Safety outcomes such as diarrhoea and infection-related adverse events will be assessed daily by the clinical team (see Bah et al. Additional file 4_Adverse event eCRF). Linear regression will be used to analyse continuous outcomes, with log transformation to normalise residuals as needed. Binary outcomes will be analysed by binomial regression or logistic regression, Primary analysis will be by modified intention-to-treat (i.e., those randomised and who ingested at least one supplement dose of iron), with multiple imputations to replace missing data. Effect estimates will be adjusted for baseline covariates (C-reactive protein, alpha-1-acid glycoprotein, haemoglobin, ferritin, soluble transferrin receptor). DISCUSSION: This study will determine if therapeutic supplementation with haem iron is more efficacious than with conventional ferrous sulphate in enhancing haemoglobin and ferritin concentrations in anaemic children aged 6-12 months. TRIAL REGISTRATION: Pan African Clinical Trial Registry PACTR202210523178727.

Ascorbic acid enhanced the circulation between Fe(II) and Fe(III) in peroxymonosulfate system for fluoranthene degradation.

In this research, ascorbic acid (AA) was used to enhance Fe(II)/Fe(III)-activated permonosulfate (PMS) systems for the degradation of fluoranthene (FLT). AA enhanced the production of ROS in both PMS/Fe(II) and PMS/Fe(III) systems through chelation and reduction and thus improved the degradation performance of FLT. The optimal molar ratio in PMS/Fe(II)/AA/FLT and PMS/Fe(III)/AA/FLT processes were 2/2/4/1 and 5/10/5/1, respectively. In addition, the experimental results on the effect of FLT degradation under different groundwater matrixes indicated that PMS/Fe(III)/AA system was more adaptable to different water quality conditions than the PMS/Fe(II)/AA system. SO4·- was the major reactive oxygen species (ROS) responsible for FLT removal through the probe and scavenging tests in both systems. Furthermore, the degradation intermediates of FLT were analyzed using gas chromatograph-mass spectrometry (GC-MS), and the probable degradation pathways of FLT degradation were proposed. In addition, the removal of FLT was also tested in actual groundwater and the results showed that by increasing the dose and pre-adjusting the solution pH, 88.8 and 100% of the FLT was removed for PMS/Fe(II)/AA and PMS/Fe(III)/AA systems. The above experimental results demonstrated that PMS/Fe(II)/AA and PMS/Fe(III)/AA processes have a great perspective in practice for the rehabilitation of FLT-polluted groundwater.