Ligand recognition and G-protein coupling of trace amine receptor TAAR1.

Trace-amine-associated receptors (TAARs), a group of biogenic amine receptors, have essential roles in neurological and metabolic homeostasis1. They recognize diverse endogenous trace amines and subsequently activate a range of G-protein-subtype signalling pathways2,3. Notably, TAAR1 has emerged as a promising therapeutic target for treating psychiatric disorders4,5. However, the molecular mechanisms underlying its ability to recognize different ligands remain largely unclear. Here we present nine cryo-electron microscopy structures, with eight showing human and mouse TAAR1 in a complex with an array of ligands, including the endogenous 3-iodothyronamine, two antipsychotic agents, the psychoactive drug amphetamine and two identified catecholamine agonists, and one showing 5-HT1AR in a complex with an antipsychotic agent. These structures reveal a rigid consensus binding motif in TAAR1 that binds to endogenous trace amine stimuli and two extended binding pockets that accommodate diverse chemotypes. Combined with mutational analysis, functional assays and molecular dynamic simulations, we elucidate the structural basis of drug polypharmacology and identify the species-specific differences between human and mouse TAAR1. Our study provides insights into the mechanism of ligand recognition and G-protein selectivity by TAAR1, which may help in the discovery of ligands or therapeutic strategies for neurological and metabolic disorders.

New dechlorination products and mechanisms of tris(2-chloroethyl) phosphate by an anaerobic enrichment culture from a vehicle dismantling site.

End-of-life vehicles (ELVs) dismantling sites are the notorious hotspots of chlorinated organophosphate esters (Cl-OPEs). However, the microbial-mediated dechlorination of Cl-OPEs at such sites has not yet been explored. Herein, the dechlorination products, pathways and mechanisms of tris(2-chloroethyl) phosphate (TCEP, a representative Cl-OPE) by an anaerobic enrichment culture (ZNE) from an ELVs dismantling plant were investigated. Our results showed that dechlorination of TCEP can be triggered by reductive transformation to form bis(2-chloroethyl) phosphate (BCEP), mono-chloroethyl phosphate (MCEP) and by hydrolytic dechlorination to form bis(2-chloroethyl) 2-hydroxyethyl phosphate (TCEP-OH), 2-chloroethyl bis(2-hydroxyethyl) phosphate (TCEP-2OH), 2-chloroethyl (2-hydroxyethyl) hydrogen phosphate (BCEP-OH). The combination of 16S rRNA gene amplicon sequencing, quantitative real-time PCR (qPCR) and metagenomics revealed that the Dehalococcoides played an important role in the reductive transformation of TCEP to BCEP and MCEP. A high-quality metagenome-assembled genome (completeness >99% and contamination <1%) of Dehalococcoides was obtained. The sulfate-reducing bacteria harboring haloacid dehalogenase genes (had) may be responsible for the hydrolytic dechlorination of TCEP. These findings provide insights into microbial-mediated anaerobic transformation products and mechanisms of TCEP at ELVs dismantling sites, having implications for the environmental fate and risk assessment of Cl-OPEs at those sites.

Orthosteric ligand selectivity and allosteric probe dependence at Hydroxycarboxylic acid receptor HCAR2.

Hydroxycarboxylic acid receptor 2 (HCAR2), a member of Class A G-protein-coupled receptor (GPCR) family, plays a pivotal role in anti-lipolytic and anti-inflammatory effects, establishing it as a significant therapeutic target for treating dyslipidemia and inflammatory diseases. However, the mechanism underlying the signaling of HCAR2 induced by various types of ligands remains elusive. In this study, we elucidate the cryo-electron microscopy (cryo-EM) structure of Gi-coupled HCAR2 in complex with a selective agonist, MK-6892, resolved to a resolution of 2.60 Å. Our structural analysis reveals that MK-6892 occupies not only the orthosteric binding pocket (OBP) but also an extended binding pocket (EBP) within HCAR2. Pharmacological assays conducted in this study demonstrate that the OBP is a critical determinant for ligand selectivity among the HCARs subfamily. Moreover, we investigate the pharmacological properties of the allosteric modulator compound 9n, revealing its probe-dependent behavior on HCAR2 in response to varying orthosteric agonists. Collectively, our findings provide invaluable structural insights that contribute to a deeper understanding of the regulatory mechanisms governing HCAR2 signaling transduction mediated by both orthosteric and allosteric ligands.

Biased allosteric activation of ketone body receptor HCAR2 suppresses inflammation.

Hydroxycarboxylic acid receptor 2 (HCAR2), modulated by endogenous ketone body ß-hydroxybutyrate and exogenous niacin, is a promising therapeutic target for inflammation-related diseases. HCAR2 mediates distinct pathophysiological events by activating Gi/o protein or ß-arrestin effectors. Here, we characterize compound 9n as a Gi-biased allosteric modulator (BAM) of HCAR2 and exhibit anti-inflammatory efficacy in RAW264.7 macrophages via a specific HCAR2-Gi pathway. Furthermore, four structures of HCAR2-Gi complex bound to orthosteric agonists (niacin or monomethyl fumarate), compound 9n, and niacin together with compound 9n simultaneously reveal a common orthosteric site and a unique allosteric site. Combined with functional studies, we decipher the action framework of biased allosteric modulation of compound 9n on the orthosteric site. Moreover, co-administration of compound 9n with orthosteric agonists could enhance anti-inflammatory effects in the mouse model of colitis. Together, our study provides insight to understand the molecular pharmacology of the BAM and facilitates exploring the therapeutic potential of the BAM with orthosteric drugs.

Mechanism of activation and biased signaling in complement receptor C5aR1.

The complement system plays an important role in the innate immune response to invading pathogens. The complement fragment C5a is one of its important effector components and exerts diverse physiological functions through activation of the C5a receptor 1 (C5aR1) and associated downstream G protein and ß-arrestin signaling pathways. Dysfunction of the C5a-C5aR1 axis is linked to numerous inflammatory and immune-mediated diseases, but the structural basis for activation and biased signaling of C5aR1 remains elusive. Here, we present cryo-electron microscopy structures of the activated wild-type C5aR1-Gi protein complex bound to each of the following: C5a, the hexapeptidic agonist C5apep, and the G protein-biased agonist BM213. The structures reveal the landscape of the C5a-C5aR1 interaction as well as a common motif for the recognition of diverse orthosteric ligands. Moreover, combined with mutagenesis studies and cell-based pharmacological assays, we deciphered a framework for biased signaling using different peptide analogs and provided insight into the activation mechanism of C5aR1 by solving the structure of C5aR1I116A mutant-Gi signaling activation complex induced by C089, which exerts antagonism on wild-type C5aR1. In addition, unusual conformational changes in the intracellular end of transmembrane domain 7 and helix 8 upon agonist binding suggest a differential signal transduction process. Collectively, our study provides mechanistic understanding into the ligand recognition, biased signaling modulation, activation, and Gi protein coupling of C5aR1, which may facilitate the future design of therapeutic agents.

Effect of butachlor on Microcystis aeruginosa: Cellular and molecular mechanisms of toxicity.

The rapid development of agriculture increases the release of butachlor into aquatic environments. As a dominant species causing cyanobacterial blooms, Microcystis aeruginosa (M. aeruginosa) can produce microcystin and poses threats to aquatic ecosystems and human health. However, the impact of butachlor on M. aeruginosa remains unclarified. Therefore, the physiochemical responses of M. aeruginosa to butachlor were investigated, and the relevant underlying molecular mechanism was highlighted. There were no significant changes (P > 0.05) in the growth and physiology of M. aeruginosa at the low concentrations of butachlor (0-0.1 mg/L), which evidenced a high level of butachlor tolerance in Microcystis aeruginosa. For the high concentrations of butachlor (4-30 mg/L), the inhibition of photosynthetic activity, disruption of cell ultrastructure, and oxidative stress were dominant toxic effects on M. aeruginosa. Additionally, the impaired cellular integrity and lipid peroxidation may be attributed to the substantial elevations of extracellular microcystin-LR concentration. Downregulation of genes associated with photosynthesis, energy metabolism, and oxidative stress was inferred to be responsible for the growth suppression of M. aeruginosa in 30 mg/L butachlor treatment. The upregulation of gene sets involved in nitrogen metabolism may illustrate the specific effort to sustain the steady concentration of intracellular microcystin-LR. These findings dissect the response mechanism of M. aeruginosa to butachlor toxicity and provide valuable reference for the evaluation of potential risk caused by butachlor in aquatic environments.

Stable Isotopic and Metagenomic Analyses Reveal Microbial-Mediated Effects of Microplastics on Sulfur Cycling in Coastal Sediments.

Microplastics are readily accumulated in coastal sediments, where active sulfur (S) cycling takes place. However, the effects of microplastics on S cycling in coastal sediments and their underlying mechanisms remain poorly understood. In this study, the transformation patterns of different S species in mangrove sediments amended with different microplastics and their associated microbial communities were investigated using stable isotopic analysis and metagenomic sequencing. Biodegradable poly(lactic acid) (PLA) microplastics treatment increased sulfate (SO42-) reduction to yield more acid-volatile S and elementary S, which were subsequently transformed to chromium-reducible S (CRS). The S isotope fractionation between SO42- and CRS in PLA treatment increased by 9.1‰ from days 0 to 20, which was greater than 6.8‰ in the control. In contrast, recalcitrant petroleum-based poly(ethylene terephthalate) (PET) and polyvinyl chloride (PVC) microplastics had less impact on the sulfate reduction, resulting in 7.6 and 7.7‰ of S isotope fractionation between SO42- and CRS from days 0 to 20, respectively. The pronounced S isotope fractionation in PLA treatment was associated with increased relative abundance of Desulfovibrio-related sulfate-reducing bacteria, which contributed a large proportion of the microbial genes responsible for dissimilatory sulfate reduction. Overall, these findings provide insights into the potential impacts of microplastics exposure on the biogeochemical S cycle in coastal sediments.

Impacts of high-quality coal mine drainage recycling for replenishment of aquatic ecosystems in arid regions of China: Bacterial community responses.

Coal mine water is usually recycled as supplementary water for aquatic ecosystems in arid and semiarid mining regions of China. To ensure ecosystem health, the coal mine water is rigorously treated using several processes, including reverse osmosis, to meet surface water quality standards. However, the potential environmental impacts of this management pattern on the ecological function of receiving water bodies are unclear. In this study, we built several microcosm water ecosystems to simulate the receiving water bodies. High-quality treated coal mine drainage was mixed into the model water bodies at different concentrations, and the sediment bacterial community response and functional changes were systematically investigated. The results showed that the high-quality coal mine drainage could still shape bacterial taxonomic diversity, community composition and structure, with a concentration threshold of approximately 50%. Moreover, both the Mantel test and the structural equation model indicated that the salinity fluctuation caused by the receiving of coal mine drainage was the primary factor shaping the bacterial communities. 10 core taxa in the molecular ecological network influenced by coal mine drainage were identified, with the most critical taxa being patescibacteria and g_Geothermobacter. Furthermore, the pathway of carbohydrate metabolism as well as signaling molecules and interactions was up-regulated, whereas amino acid metabolism showed the opposite trend. All results suggested that the complex physical-chemical and biochemical processes in water ecosystems may be affected by the coal mine drainage. The bacterial community response and underlying functional changes may accelerate internal nutrient cycling, which may have a potential impact on algal bloom outbreaks.

Research on the Impact of Entrepreneurship Education on Employee Creativity from the Perspective of Career Environment Based on an Intermediary Model.

Based on the human capital theory and creativity component theory, this study empirically examines the direct effect of entrepreneurship education on employees' environment protection creativity in the workplace and the dual mediating effect of boundary-free mental model and organizational mobility preference based on 266 valid sample data. The results show that entrepreneurship and environmental protection education received in colleges and universities can significantly promote the improvement of employees' environment protection creativity. Borderless mental model and organizational mobility preference play an intermediary role between them. The impact of entrepreneurship education on creativity is expanded from college students to employees through the bridge of borderless career attitude, which effectively verifies the lag effect of entrepreneurship education in colleges and universities and the dual intermediary effect of borderless mental model and organizational mobility preference. It further expands the research on the impact of entrepreneurship education in colleges and universities and has certain theoretical value.

Research on the Effect of Narcissistic Leadership on Employee Job Embeddedness.

Narcissistic leadership is the synthesis of narcissistic personality traits and leadership behaviors that are motivated mainly by self-interest needs and arrogant beliefs. Such leadership style has multiple effects on organizations and employees. The amplifying influence of narcissistic leadership on their subordinates has become a hot topic in the field of organizational behavior. Based on the social exchange theory and the resource conservation theory, the current study constructs a chain mediation model of narcissistic leadership affecting employees' job embeddedness with 405 corporate employees as survey respondents. The results of data analysis show that narcissistic leadership is significantly and negatively related to employees' job embeddedness; Leader-member exchange (LMX) and perceived insider status not only play a mediating role between narcissistic leadership and job embeddedness but also play a chain mediating roles in the relationship between narcissistic leadership and job embeddedness. Our findings deepen the theoretical exploration of narcissistic leadership and help all types of organizations to improve their leadership practices.

Template Removal and Surface Modification of an SSZ-13 Membrane with Heated Sodium Chloride for CO2/CH4 Gas Separation.

Hydrothermal synthesis with an organic template of N,N,N trimethyl-1-adamantammonium hydroxide (TMAdaOH) is the most commonly used method to prepare an SSZ-13 zeolite membrane. In this paper, the synthesized membrane was treated in heated sodium chloride to remove TMAdaOH instead of calcination in air. The surface of the membrane was modified by the heated NaCl and resulted in an improved CO2/CH4 gas separation selectivity. TMAda+ in the channels of SSZ-13 zeolite decomposed completely, and the treatment time was shortened significantly compared with calcination in air. The recrystallization of zeolite reacting with heated NaCl was the possible reason for the improved gas separation performance of the membrane.

Cucurbitacin E inhibits cellular proliferation and induces apoptosis in melanoma by suppressing HSDL2 expression.

BACKGROUND: Melanoma is among the most aggressive types of skin malignancy and can have an unpredictable clinical course. Exploration of novel therapeutic targets and their regulators remains essential for the prevention and treatment of melanoma. METHODS: HSDL2 protein levels were examined by immunohistochemistry. The roles of HSDL2 in cell proliferation and apoptosis were identified by CCK-8 and colony formation assays. The function of HSDL2 in cell apoptosis was analysed by flow cytometry. Western blotting, cell proliferation and apoptosis and a xenograft tumour model were utilized to explore the inhibitory functions and mechanisms of CuE in melanoma. RESULTS: HSDL2 is overexpressed in melanoma and promotes melanoma progression by activating the ERK and AKT pathways. CuE could inhibit the ERK and AKT pathways by decreasing HSDL2 expression; therefore, CuE could inhibit melanoma growth in vitro and in vivo. CONCLUSION: HSDL2 may be a promising therapeutic target against melanoma, and CuE can inhibit melanoma by downregulating HSDL2 expression.

Dehalococcoides-Containing Enrichment Cultures Transform Two Chlorinated Organophosphate Esters.

Although chlorinated organophosphate esters (Cl-OPEs) have been reported to be ubiquitously distributed in various anoxic environments, little information is available on their fate under anoxic conditions. In this study, we report two Dehalococcoides-containing enrichment cultures that transformed 3.88 ± 0.22 µmol tris(2-chloroethyl) phosphate (TCEP) and 2.61 ± 0.02 µmol tris(1-chloro-2-propyl) phosphate (TCPP) within 10 days. Based on the identification of the transformed products and deuteration experiments, we inferred that TCEP may be transformed to generate bis(2-chloroethyl) phosphate and ethene via one-electron transfer (radical mechanism), followed by C-O bond cleavage. Ethene was subsequently reduced to ethane. Similarly, TCPP was transformed to form bis(1-chloro-2-propyl) phosphate and propene. 16S rRNA gene amplicon sequencing and quantitative polymerase chain reaction analysis revealed that Dehalococcoides was the predominant contributor to the transformation of TCEP and TCPP. Two draft genomes of Dehalococcoides assembled from the metagenomes of the TCEP- and TCPP-transforming enrichment cultures contained 14 and 15 putative reductive dehalogenase (rdh) genes, respectively. Most of these rdh genes were actively transcribed, suggesting that they might contribute to the transformation of TCEP and TCPP. Taken together, this study provides insights into the role of Dehalococcoides during the transformation of representative Cl-OPEs.

A comprehensive evaluation of factors affecting the reactivity of FeS towards hexabromocyclododecane diastereoisomers.

Reactivity of iron sulfide (FeS) towards hexabromocyclododecane (HBCD) was explored under conditions of varying temperature, pH, inorganic ion and dissolved organic matter (DOM) in this study. Results show that the reduction of HBCD by FeS has an activation energy of 29.2 kJ mol-1, suggesting that the rate-limiting step in the reduction was a surface-mediated reaction. The reduction of HBCD by FeS was a highly pH-dependent process. The optimal rate for HBCD reduction by FeS was observed at a pH of 6.2. All the tested inorganic ions suppressed the reduction of HBCD by FeS. XPS analysis confirmed that both Fe(II)-S and bulk S(-II) on FeS surface could be impacted by solution pH and inorganic ions and were responsible for the regulation of HBCD reduction. Some DOMs (i.e., fulvic acid, humic acid, salicylic acid, catechol and sodium dodecyl sulfate) were found to hinder the reduction via competing with HBCD for active sites on FeS surface. However, the presence of 2,2'-bipyridine, triton X-100 and cetyltrimethyl ammonium bromide was able to significantly enhance the rate of HBCD reduction by 5.8, 9.0 and 20 times, respectively. Different factors could influence the reduction efficiency of HBCD diastereoisomers to different extent, but not the reaction orders of HBCD diastereoisomers (α-HBCD < γ-HBCD < ß-HBCD). Moreover, FeS could completely remove HBCD diastereoisomers in sediments with multiple factors within 9 d reaction. Our results contribute to give a better understanding on the performance of FeS towards HBCD under real and complex conditions and facilitate the application of FeS in remediation sites.

Monitoring of Fe (II) ions in living cells using a novel quinoline-derived fluorescent probe.

Physiologically, Fe(III) and Fe(II) is the most important redox pairs in a variety of biological and environmental procedures with its capability of transition. The detection of physiological iron, especially Fe(II), has become the recent research focus of investigations on revealing the mechanism of iron-related metabolism. In this work, we exploited a novel quinoline-derived fluorescent probe, YTP, for the detection of Fe(II). It could monitor the level of Fe(II) with a linear range of 0-2.0 equivalent and the detection limit of 0.16 µM. High selectivity from other analytes including Fe(III) and steadiness for over 24 h confirmed the practicability of YTP. YTP was further applied in real buffer systems and in cellular imaging. The probe could achieve the semi-quantitative monitoring of Fe(II) in living cells. This work provided a potential implement for the detection of Fe(II), and raised important information for further researches on the redox pairs of iron, in mechanism and in practice.

Reductive degradation of chlorinated organophosphate esters by nanoscale zerovalent iron/cetyltrimethylammonium bromide composites: Reactivity, mechanism and new pathways.

Chlorinated organophosphate esters (Cl-OPEs), e.g., tris(2-chloroethyl) phosphate (TCEP), tris(2-chloro-2-propyl) phosphate (TCPP) and tris(1,3-dichloro-2-propyl) phosphate (TDCPP), are widely used as additive flame retardants in commercial and building products. They have potential persistent organic pollutant properties and are frequently detected in various waters, especially in wastewaters. Nanoscale zerovalent iron (nZVI)-based method is an efficient reductive technology for treating waters polluted by halogenated organic pollutants (HOCs). Cetyltrimethylammonium bromide (CTAB) is a ubiquitous surfactant in wastewaters and can favorably affect the interaction between HOCs and nZVI. However, its effect on the Cl-OPEs removal by nZVI-based materials still remains unknown. Herein, the adsorption and degradation efficiencies of Cl-OPEs by nZVI and sulfidated nZVI (S-nZVI) in the presence or absence of CTAB were quantified based on the decreasing concentrations of Cl-OPEs in reaction systems. Our results showed that TDCPP and TCPP were adsorbed onto the nZVI or S-nZVI surface and subsequently degraded. In contrast, TCEP was just adsorbed onto the particle surface without further degradation. The addition of CTAB significantly enhanced the hydrophobic adsorption between Cl-OPEs and nZVI or S-nZVI, leading to increased degradation of Cl-OPEs (especially TCEP). CTAB adsorption isotherms indicated that S-nZVI had a higher adsorption capacity for CTAB than nZVI. The S-nZVI/CTAB composite exhibited a better performance than nZVI/CTAB composite. When S-nZVI was combined with 100.0 mg L-1 CTAB, 100% of TDCPP, TCPP and TCEP was degraded within 3 hours, 5 and 14 days, respectively. As the concentration of CTAB was increased up to 335.0 mg L-1, TCEP could be completely degraded within 3 days by S-nZVI. Five degradation products of TCEP were identified, of which O,O-di-(2-chloroethyl) O-ethyl phosphate (DCEEP) and ethane were reported for the first time. We propose that TCEP is dechlorinated by nZVI or S-nZVI through the electron attack at the ethyl-chlorine group to form bis(2-chloroethyl) phosphate, DCEEP, chloride, ethene and ethane, representing previously unknown degradation pathways.

Enhanced tetrabromobisphenol A debromination by nanoscale zero valent iron particles sulfidated with S0 dissolved in ethanol.

Modification of nanoscale zero-valent iron (nZVI) with reducing sulfur compounds has proven to improve the reactivity of nZVI towards recalcitrant halogenated organic contaminants. In this study, we develop a novel method for the preparation of sulfidated nZVI (S-nZVI) with S0 (a low cost and available reducing sulfur agent) dissolved in ethanol under mild conditions and apply it for the transformation of tetrabromobisphenol A (TBBPA), a potential persistent organic pollutant. Surface analysis shows that S0 dissolved in ethanol has been successfully doped into nZVI via a reaction with Fe0 to form a relatively homogeneous layer of FeS/FeS2 on the nZVI surface. The H2 production test and the electrochemical analysis show that the FeS/FeS2 layer not only slows the H2 evolution reaction but also enhances the electron transfer. Debromination kinetics indicate that the resulting S-nZVI with a S/Fe ratio of 0.015-0.05 possesses higher debromination activity for TBBPA and its debromination products (i.e., tri-BBPA, di-BBPA, mono-BBPA and BPA) in comparison with nZVI. Among them, S-nZVI at a S/Fe of 0.025 (S-nZVIS-0.025) has the greatest debromination rate constant (kobs) of 1.19 ± 0.071 h-1 for TBBPA. It debrominates TBBPA at a faster rate than other conventional S-nZVI made from Na2S and Na2S2O4 and has been successfully applied in the treatment of TBBPA-spiked environmental water samples (including river water, groundwater, and tap water). The results suggest that the modification of nZVI with S0 dissolved in ethanol is a simple, safe, inexpensive, and effective sulfidation technique, which can be applied for the large-scale production of S-nZVI for treating contaminated water.

The reaction of amorphous iron sulfide with Mo(VI) under different pH conditions.

Iron sulfide (FeS) is an important scavenger for hexavalent molybdate (Mo(VI)) in an anoxic environment; it plays a crucial role in the mobilization and transformation of Mo(VI), although the underlying reaction mechanisms between Mo(VI) and FeS remain unclear. This study investigates the Mo(VI) reaction kinetics with the amorphous FeS over a pH range 5.0-9.0 and Mo's chemical form on the FeS surface. It is found that the Mo(VI) reaction kinetics with FeS follow a pseudo first-order model, and the reaction rate constant (kobs) increases with a decrease in the pH value. The kobs at pH 5.0 is 0.027 min-1, which is about 38 times higher than that at pH 9.0. The rapid Mo(VI) removal under acidic conditions is due to quick Mo(VI) transformation into stable MoS2 and thiomolybdate (MoVOxSy). The amount of MoS2 formed on the surface of FeS increases with a decrease in the pH value. Under neutral and alkaline conditions, Mo(VI) is not transformed into MoS2 by FeS because the precipitation of iron oxy-hydroxide passivates the active sites of FeS. The study also investigates the effect of the initial dosage of FeS (20-200 mg L-1) and Mo(VI) (10-50 mg L-1) on the reaction kinetics of Mo(VI) with FeS. The results provides important information on the environmental fate of Mo(VI) in the anoxic environment containing amorphous FeS.

Remarkable promotion in particle dispersion and electron transfer capacity of sulfidated nano zerovalent iron by coating alginate polymer.

Alginate has been widely employed to increase the performance of nanoscale zerovalent iron (nZVI)-based materials for site remediation. Yet, the effects of alginate on reactivity of sulfidated nZVI (an efficient reductant material) towards contaminants have been understood poorly. In this study, we have developed a one-step synthesis of alginate-coated sulfidated nZVI (S-nZVI@alginate) under air atmosphere and evaluated the reactivity of S-nZVI@alginate towards tetrabromobisphenol A (TBBPA) debromination. Surface analysis shows that S-nZVI has been successfully coated by alginate through the interaction of OH and COO- groups of alginate with Fe species. The coating of alginate increases particle stability and dispersion under various conditions and facilitates FeS precipitation on the particle surface. Reactivity experiments show that the coating of alginate significantly enhances TBBPA debromination by S-nZVI. The optimized alginate to Fe weight ratio of S-nZVI@alginate is 0.06, with ~3-fold greater TBBPA debromination rate than S-nZVI. S-nZVI@alginate can completely debrominate TBBPA into bisphenol A via a four-sequential step debromination pathway while S-nZVI not. Its superior reactivity may be attributed to that the formation of alginate-Fe complex can lower the redox potential of Fe species to accelerate electron transfer on the particle surface. The TBBPA debromination rate by S-nZVI@alginate is initially enhanced followed by a decrease with an increase in TBBPA concentration, while it can increase 3.3-, 8.9- and 5.6-fold by increasing S-nZVI@alginate dosage, decreasing pH and adding co-contaminant Cd2+, respectively. S-nZVI@alginate has greater performance in aging and reusability tests than S-nZVI, and achieves rapid TBBPA removal from wastewater, which may be due to the role of alginate on inhibiting surface oxidation of Fe and S species. Taken together, these results suggest that S-nZVI@alginate provides better reactivity, longevity and reusability than S-nZVI, having the great potential for application into site remediation.