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1.
Int J Nanomedicine ; 14: 7609-7624, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571866

RESUMO

Background: Iron oxide nanoparticles (IONs) have been increasingly utilized in a wide spectrum of biomedical applications. Surface coatings of IONs can bestow a number of exceptional properties, including enhanced stability of IONs, increased loading of drugs or their controlled release. Methods: Using two-step sonochemical protocol, IONs were surface-coated with polyoxyethylene stearate, polyvinylpyrrolidone or chitosan for a loading of two distinct topo II poisons (doxorubicin and ellipticine). The cytotoxic behavior was tested in vitro against breast cancer (MDA-MB-231) and healthy epithelial cells (HEK-293 and HBL-100). In addition, biocompatibility studies (hemotoxicity, protein corona formation, binding of third complement component) were performed. Results: Notably, despite surface-coated IONs exhibited only negligible cytotoxicity, upon tethering with topo II poisons, synergistic or additional enhancement of cytotoxicity was found in MDA-MB-231 cells. Pronounced anti-migratory activity, DNA fragmentation, decrease in expression of procaspase-3 and enhancement of p53 expression were further identified upon exposure to surface-coated IONs with tethered doxorubicin and ellipticine. Moreover, surface-coated IONs nanoformulations of topo II poisons exhibited exceptional stability in human plasma with no protein corona and complement 3 binding, and only a mild induction of hemolysis in human red blood cells. Conclusion: The results imply a high potential of an efficient ultrasound-mediated surface functionalization of IONs as delivery vehicles to improve therapeutic efficiency of topo II poisons.


Assuntos
Materiais Revestidos Biocompatíveis/química , DNA Topoisomerases Tipo II/metabolismo , Liberação Controlada de Fármacos , Compostos Férricos/química , Nanopartículas/química , Sonicação/métodos , Inibidores da Topoisomerase II/farmacologia , Morte Celular/efeitos dos fármacos , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Doxorrubicina/farmacologia , Humanos , Cinética , Masculino , Eletricidade Estática , Propriedades de Superfície , Cicatrização/efeitos dos fármacos
2.
Int J Nanomedicine ; 14: 7017-7038, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31564863

RESUMO

Background: Fabrication of a smart drug delivery system that could dramatically increase the efficiency of chemotherapeutic drugs and reduce the side effects is still a challenge for pharmaceutical researchers. By the emergence of nanotechnology, a huge window was opened towards this goal, and a wide type of nanocarriers were introduced for delivering the chemotherapeutic to the cancer cells, among them are cyclodextrins with the ability to host different types of hydrophobic bioactive molecules through inclusion complexation process. Aim: The aim of this study is to design and fabricate a pH-responsive theranostic nanocapsule based on cyclodextrin supramolecular nano-structure. Materials and methods: This nanostructure contains iron oxide nanoparticles in the core surrounded with three polymeric layers including polymeric ß-cyclodextrin, polyacrylic acid conjugated to sulfadiazine, and polyethylenimine functionalized with ß-cyclodextrin. Sulfadiazine is a pH-responsive hydrophobic component capable of making inclusion complex with ß-cyclodextrin available in the first and third layers. Doxorubicin, as an anti-cancer drug model, was chosen and the drug loading and release pattern were determined at normal and acidic pH. Moreover, the biocompatibility of the nanocapsule (with/without drug component) was examined using different techniques such as MTT assay, complement activation, coagulation assay, and hemolysis. Results: The results revealed the successful preparation of a spherical nanocapsule with mean size 43±1.5 nm and negatively charge of -43 mV that show 160% loading efficacy. Moreover, the nanocapsule has an on/off switching release pattern in response to pH that leads to drug released in low acidic pH. The results of the biocompatibility tests indicated that this nano drug delivery system had no effect on blood and immune components while it could affect cancer cells even at very low concentrations (0.3 µg mL-1). Conclusion: The obtained results suggest that this is a "switchable" theranostic nanocapsule with potential application as an ideal delivery system for simultaneous cancer diagnosis and therapy.


Assuntos
Nanocápsulas/química , Polietilenoimina/química , Nanomedicina Teranóstica , beta-Ciclodextrinas/química , Animais , Doxorrubicina/química , Doxorrubicina/farmacologia , Sistemas de Liberação de Medicamentos , Liberação Controlada de Fármacos , Compostos Férricos/química , Hemólise/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Células MCF-7 , Camundongos , Nanocápsulas/ultraestrutura , Tempo de Tromboplastina Parcial , Tempo de Protrombina , Eletricidade Estática , Compostos de Sulfidrila/síntese química , Compostos de Sulfidrila/química , Difração de Raios X , beta-Ciclodextrinas/síntese química
3.
Int J Nanomedicine ; 14: 7879-7889, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31576129

RESUMO

Introduction and objective: Precisely and sensitively diagnosing diseases especially early and accurate tumor diagnosis in clinical magnetic resonance (MR) scanner is a highly demanding but challenging task. Gadolinium (Gd) chelate is the most common T 1 magnetic resonance imaging (MRI) contrast agent at present. However, traditional Gd-chelates are suffering from low relaxivity, which hampers its application in clinical diagnosis. Currently, the development of nano-sized Gd based T 1 contrast agent, such as incorporating gadolinium chelate into nanocarriers, is an attractive and feasible strategy to enhance the T 1 contrast capacity of Gd chelate. The objective of this study is to improve the T 1 contrast ability of Gd-chelate by synthesizing nanoparticles (NPs) for accurate and early diagnosis in clinical diseases. Methods: Reverse microemulsion method was used to coat iron oxide (IO) with tunable silica shell and form cores of NPs IO@SiO2 at step one, then Gd-chelate was loaded on the surface of silica-coated iron oxide NPs. Finally, Gd-based silica coating magnetite NPs IO@SiO2-DTPA-Gd was developed and tested the ability to detect tumor cells on the cellular and in vivo level. Results: The r 1 value of IO@SiO2-DTPA-Gd NPs with the silica shell thickness of 12 nm was about 33.6 mM-1s-1, which was approximately 6 times higher than Gd-DTPA, and based on its high T 1 contrast ability, IO@SiO2-DTPA-Gd NPs could effectively detect tumor cells on the cellular and in vivo level. Conclusion: Our findings revealed the improvement of T 1 relaxation was not only because of the increase of molecular tumbling time caused by the IO@SiO2 nanocarrier but also the generated magnetic field caused by the IO core. This nanostructure with high T 1 contrast ability may open a new approach to construct high-performance T 1 contrast agent.


Assuntos
Quelantes/química , Materiais Revestidos Biocompatíveis/química , Gadolínio/química , Imagem por Ressonância Magnética , Nanopartículas de Magnetita/química , Dióxido de Silício/química , Animais , Morte Celular , Meios de Contraste/química , Feminino , Compostos Férricos/química , Gadolínio DTPA/química , Células HeLa , Humanos , Nanopartículas de Magnetita/ultraestrutura , Camundongos Endogâmicos BALB C , Camundongos Nus , Imagem Molecular
4.
Environ Pollut ; 254(Pt B): 113112, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31479811

RESUMO

Antimony, as the Sb(V) species, often occurs in oxic soils and sediments as coprecipitates with poorly-crystalline Fe(III)-bearing minerals. It is common for these Sb(V)-Fe(III) coprecipitates to also contain varying quantities of co-occurring humic acid (HA). When exposed to reducing conditions, the production of Fe(II) may cause the initial metastable HA-Sb(V)-Fe(III) phases to undergo rapid transformations to more stable phases, thereby potentially influencing the geochemical behavior of coprecipitated Sb(V). However, little is known about the impacts of this transformation on the mobility and speciation of Sb. In this study, we reacted synthetic HA-Sb(V)-Fe(III) coprecipitates (Fe:Sb ratio = 4, and C:Fe molar ratios = 0, 0.3, 0.8 and 1.3) with 0, 1 or 10 mM Fe(II) under O2-free conditions at pH 7.0 for 15 days. Fe K-edge EXAFS spectroscopy revealed that solid-phase Fe(III) in the initial coprecipitates contained a mixture of ∼4/5 ferrihydrite (Fe10O14(OH)2) and ∼1/5 tripuhyite (FeSbO4), regardless of the corresponding amount of coprecipitated HA. Tripuhyite persisted throughout the full experiment duration, while ferrihydrite was partially replaced by goethite (FeOOH) when either 1 or 10 mM Fe(II)aq was added to the coprecipitates. The greatest level of goethite formation (∼55% of solid-phase Fe) was observed in the HA-free/10 mM Fe(II)aq treatment, with ferrihydrite transformation being partially attenuated at higher levels of HA. Mobilisation of aqueous Sb was the greatest for 1 mM Fe(II) treatments at high HA:Fe ratios. Sb K-edge XANES spectroscopy showed that the largest reduction of Sb(V) to Sb(III) (∼37%) and the greatest repartitioning of Sb to the mineral surface (∼7.9-9.8%) occurred in the coprecipitates with the highest HA contents in the presence of 10 mM Fe(II). The results indicate that the amount of HA in HA-Sb(V)-Fe(III) coprecipitates can greatly influence mobility and speciation of Sb in Fe(II)-rich conditions. The results of this study provide new insights into alterations in Sb mobility and retention in response to Fe cycling under organic matter-rich reducing conditions.


Assuntos
Antimônio/química , Compostos Férricos/química , Compostos Ferrosos/química , Substâncias Húmicas , Poluentes do Solo/química , Compostos de Ferro/química , Minerais/química , Oxirredução , Espectroscopia por Absorção de Raios X
5.
Chemosphere ; 235: 1015-1021, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561290

RESUMO

Phosphate is one of the main contaminations in water, so an effective method of decreasing or removing phosphate is needed. The main purpose of this paper is to synthesize CaFe-LDHs and MgFe-LDHs from the mixture of calcined dolomite and ferric chloride to remove orthophosphate and pyrophosphate. The study showed that removal of orthophosphate was attributed to the precipitation by Ca2+ and adsorption by MgFe-LDHs, where the former played a main role. As for pyrophosphate, it was mainly removed by precipitation at the initial pyrophosphate concentration ranging from 3.228 to 17.04 mmol/L. When the initial concentrations became relatively higher, the removal efficiency of pyrophosphate decreased because the complexation effects by Fe3+, Ca2+ and Mg2+ took place.


Assuntos
Carbonato de Cálcio/química , Cloretos/química , Difosfatos/análise , Compostos Férricos/química , Hidróxidos/química , Magnésio/química , Fosfatos/análise , Poluentes Químicos da Água/análise , Difosfatos/isolamento & purificação , Fosfatos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
6.
Chemosphere ; 234: 917-924, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31519100

RESUMO

Nickel, massively used in plating industry but detrimental to ecosystem, tends to form stable complexes with organic additives in industrial effluents. Currently, most of the available processes aim at water decontamination from free toxic metal ions and thus, could not effectively remove nickel-carboxyl complexes from water. Herein, we employed a proprietary combined process Fe(III)/UV/NaOH, namely Fe(III) displacement and UV irradiation followed by alkaline precipitation, to validate its feasibility on the efficient removal of nickel-carboxyl complexes from synthetic and authentic effluents. Fe(III)/UV/NaOH outperformed other commonly used processes including NaOH precipitation, UV/NaOH, Fe(III) coagulation, and Fenton/NaOH. Each unit of the combined process was optimized, and the underlying mechanism was elucidated. Fe(III) displacement favored the stoichiometric release of free nickel ions and formation of Fe(III)-carboxyl complexes, which could be decarboxylated via ligand-metal charge transfer under UV irradiation. The precipitation unit aims at simultaneously removing the released Ni along with Fe species. Attractively, the presence of other organic species (ethylene glycol, ethyl acetate and humic acid) and anions (chloride and sulfate) exerted very slight effect on the final Ni removal, whereas greatly adverse effect occurred on the Fenton process under similar conditions. The feasibility of the combined process was validated by testing on an authentic electroplating effluent, resulting in the residual Ni below 0.1 mg/L, the most stringent discharge standard for Ni in electroplating effluent in China.


Assuntos
Compostos Férricos/química , Níquel/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , China , Ecossistema , Galvanoplastia , Hidróxido de Sódio , Sulfatos , Raios Ultravioleta , Água , Poluentes Químicos da Água/análise
7.
J Agric Food Chem ; 67(41): 11489-11497, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31560530

RESUMO

The design of gelatin-based hydrogels with high mechanical strength, high gelation temperature, and a rapid self-healing property still presents a challenge to researchers. In the present study, single cross-linked gelatin-oxidized tannic acid (SC-GT/OTA) hydrogels were fabricated through covalent cross-linking between gelatin and tannic acid (TA) oxidized by using sodium periodate (NaIO4). Double cross-linked gelatin-OTA-FeCl3·6H2O (DC-GT/OTA/FeIII) hydrogels were also created using metal coordination bonds formed between the catechol groups present in OTA and FeIII in ferric chloride. As a result, the maximum gelling temperature of the SC-GT/OTA hydrogel (37 °C) was considerably higher than that of the pure gelatin hydrogel (15.4 °C). Moreover, the maximum values of compressive stress of SC-GT/OTA hydrogels increased significantly by almost seven times the original value as the molar ratio of NaIO4 to TA increased from 3:1 to 5:1. When the molar ratio of NaIO4 to TA was maintained at the constant of 4:1, the storage modulus values of DC-GT/OTA/FeIII hydrogels with the FeIII-to-TA molar ratio of 1.5:1 were three to 4 orders of magnitude higher than those of SC-GT/OTA hydrogels in the whole angular frequency range. The double cross-linked gelatin hydrogels developed in this research can be used widely in agriculture and material science fields.


Assuntos
Cloretos/química , Compostos Férricos/química , Gelatina/química , Hidrogéis/química , Taninos/química , Fenômenos Biomecânicos , Reagentes para Ligações Cruzadas/química , Oxirredução , Temperatura Ambiente
8.
Ecotoxicol Environ Saf ; 182: 109456, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31398779

RESUMO

The seasonal flooding and drainage process affect the paddy soils, the existence of the iron state either Fe(III) or Fe(II) is the main redox system of paddy soil. Its morphological transformation affects the redox nature of paddy soils, which also affects the distribution of bacterial community diversity. This study based on molecular biological methods (qPCR, Illumina MiSeq sequencing technique) to investigate the effect of Fe(II) and environmental factors on cbbM genes containing carbon fixing microbes. Both Eh5 and pH were reduced with Fe(II) concentrations. The Fe(II) addition significantly affects the cbbM gene copy number in both texture soils. In loamy soil, cbbM gene copy number increased with high addition of Fe(II), while both low and high concentrations significantly reduced the cbbM gene copy number in sandy soil. Chemotrophic bacterial abundance significantly increased by 79.7% and 54.8% with high and low Fe(II) addition in loamy soil while in sandy soil its abundance decreased by 53% and 54% with the low and high Fe(II) accumulation. The phototrophic microbial community increased by 37.8% with low Fe(II) concentration and decreased by 16.2% with a high concentration in loamy soil, while in sandy soil increased by 21% and 14.3% in sandy soil with low and high Fe(II) addition. Chemoheterotrophic carbon fixing bacterial abundance decreased with the Fe(II) accumulation in both soil textures in loamy soil its abundance decreased by 5.8% and 24.8%, while in sand soil 15.7% and 12.8% with low and high Fe(II) concentrations. The Fe(II) concentration and soil textures maybe two of the major factors to shape the bacterial community structure in paddy soils. These results provide a scientific basis for management of paddy soil fertility and it can be beneficial to take measures to ease the greenhouse gases effect.


Assuntos
Ferro/química , Microbiologia do Solo , Bactérias , Carbono , Compostos Férricos/química , Compostos Ferrosos , Inundações , Microbiota , Oryza/química , Oxirredução , Solo/química , Poluentes do Solo/análise
9.
Life Sci ; 234: 116756, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31419444

RESUMO

AIMS: Conventional radiotherapy is mainly restricted by the low radiation absorption efficiency of tumors tissues and the hypoxic tumor cells radio-resistance. In this paper, novel nano-radiosensitizers, magnetic nanoparticles core coated with silica, were successfully prepared to overcome these limitations. MAIN METHODS: The prepared nanoparticles have been characterized by transmission electron microscope (TEM), Dynamic light scattering (DLS), atomic force microscope (AFM) and vibration sample magnetometer (VSM). MTT cytotoxicity and DNA double-strand breaks (Comet) assays have been used to assess the radio-enhancing effect of iron oxide magnetic nanoparticles (IO-MNPs) and silica-coated iron oxide magnetic nanoparticles (SIO-MNPs) against MCF7 breast cancer cells. MCF7 cells were treated with different concentrations of the prepared nanoformulations and exposed to an electron beam at doses 0, 0.5, 1, 2, 4 Gy. KEY FINDINGS: DLS measurements revealed that the main hydrodynamic diameter of the prepared IO-MNPs and SIO-MNPs was 18.17 ±â€¯4.5 nm and 164.18 ±â€¯16.1 nm, respectively, which was confirmed by TEM micrographs. MTT and comet assays results showed that the radiosensitizing effect of the prepared nanoformulations was dose and concentration dependent. Interestingly, the dose enhancement factor (DEF) for SIO-MNPs was, on average, 1.3-fold greater than that of IO-MNPs. SIGNIFICANCE: Coating of IO-MNPs with silica led to enhance their electron radiosensitization and consequently their therapeutic efficacy. Therefore, SIO-MNPs represent a promising engineered nano-formulation for enhancing breast cancer radiosensitivity.


Assuntos
Neoplasias da Mama/radioterapia , Compostos Férricos/uso terapêutico , Nanopartículas/uso terapêutico , Radiossensibilizantes/uso terapêutico , Dióxido de Silício/uso terapêutico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Sobrevivência Celular/efeitos da radiação , Dano ao DNA/efeitos da radiação , Elétrons , Feminino , Compostos Férricos/química , Humanos , Células MCF-7 , Nanopartículas/química , Radiossensibilizantes/química , Dióxido de Silício/química
10.
Einstein (Sao Paulo) ; 17(4): eAO4786, 2019 Aug 01.
Artigo em Inglês, Português | MEDLINE | ID: mdl-31390427

RESUMO

OBJECTIVE: To evaluate the potential of magnetic hyperthermia using aminosilane-coated superparamagnetic iron oxide nanoparticles in glioblastoma tumor model. METHODS: The aminosilane-coated superparamagnetic iron oxide nanoparticles were analyzed as to their stability in aqueous medium and their heating potential through specific absorption rate, when submitted to magnetic hyperthermia with different frequencies and intensities of alternating magnetic field. In magnetic hyperthermia in vitro assays, the C6 cells cultured and transduced with luciferase were analyzed by bioluminescence in the absence/presence of alternating magnetic field, and also with and without aminosilane-coated superparamagnetic iron oxide nanoparticles. In the in vivo study, the measurement of bioluminescence was performed 21 days after glioblastoma induction with C6 cells in rats. After 24 hours, the aminosilane-coated superparamagnetic iron oxide nanoparticles were implanted in animals, and magnetic hyperthermia was performed for 40 minutes, using the best conditions of frequency and intensity of alternating magnetic field tested in the in vitro study (the highest specific absorption rate value) and verified the difference of bioluminescence before and after magnetic hyperthermia. RESULTS: The aminosilane-coated superparamagnetic iron oxide nanoparticles were stable, and their heating capacity increased along with higher frequency and intensity of alternating magnetic field. The magnetic hyperthermia application with 874kHz and 200 Gauss of alternating magnetic field determined the best value of specific absorption rate (194.917W/g). When these magnetic hyperthermia parameters were used in in vitro and in vivo analysis, resulted in cell death of 52.0% and 32.8%, respectively, detected by bioluminescence. CONCLUSION: The magnetic hyperthermia was promissing for the therapeutical process of glioblastoma tumors in animal model, using aminosilane-coated superparamagnetic iron oxide nanoparticles, which presented high specific absorption rate.


Assuntos
Neoplasias Encefálicas/terapia , Compostos Férricos/uso terapêutico , Glioblastoma/terapia , Hipertermia Induzida/métodos , Terapia de Campo Magnético/métodos , Nanopartículas de Magnetita/uso terapêutico , Análise de Variância , Animais , Temperatura Corporal , Linhagem Celular Tumoral , Modelos Animais de Doenças , Compostos Férricos/química , Medições Luminescentes , Nanopartículas de Magnetita/química , Masculino , Ratos Wistar , Valores de Referência , Reprodutibilidade dos Testes , Fatores de Tempo , Resultado do Tratamento
11.
Bioresour Technol ; 291: 121866, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31374417

RESUMO

The study was to explore the feasibility of polyurethane (PU), Fe3O4@PU, powdered activated carbon (PAC), Fe(OH)3@PAC, biochar, and Fe(OH)3@biochar as biological carriers in strengthening anaerobic degradation of quinoline, pyridine, and indole. When the concentrations of pollutants were 25 mg/L and 50 mg/L, reactors based on PAC and Fe(OH)3@PAC had higher degradation ratios than the other reactors. However, when the concentrations of pollutants were 75 mg/L and 100 mg/L, with the addition of PU and Fe3O4@PU, reactors began to show their superiority in the degradation of the selected NHCs. Among these, the reactor based on Fe3O4@PU had the optimal degradation ratio on quinoline, pyridine, and indole. PU, PAC, Fe(OH)3@PAC, biochar, and Fe(OH)3@biochar benefited the enrichment of Acinetobacter, Comamonas, Levilinea, Longilinea, and Desulfomicrobium. The reactor with the carrier of Fe3O4@PU had some specificity, which benefited the enrichment of Zoogloea, Thiobacillus, Anaeromyxobacter, Sphingobium, Terrimonas, Parcubacteria genera incertae sedis, Bdellovibrio, Rhizobium, and Acidovorax.


Assuntos
Carvão Vegetal/metabolismo , Compostos Férricos/química , Indóis/metabolismo , Poliuretanos/química , Piridinas/metabolismo , Quinolinas/metabolismo , Anaerobiose
12.
J Agric Food Chem ; 67(44): 12155-12163, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31415171

RESUMO

Photoresponsive hydrogels from polysaccharides and Fe(III) were used as a new system to capture and release PO43- from waste solutions. Uptake of 0.6-1.5 mg of phosphate per gram of hydrogels was determined from 800 ppm phosphate solutions (pH 4.8-9.0). These beads also captured 1.2 mg g-1 of phosphate from animal waste (raw manure, 727 ppm phosphate, pH 7.6), which accounted for above 80% phosphate uptake. Irradiation of phosphate-loaded hydrogels degraded the gels due to the photochemistry of the Fe(III)-carboxylates, giving controlled phosphate release (∼81% after 7 days). No release (<2% after 7 days) was seen in the dark. Kale plant trials showed complete degradation of the hydrogels in ∼2 weeks under greenhouse conditions. Biomass analysis of kale treated with phosphate-loaded beads compared to controls indicated no signs of toxicity. These results show that Fe(III)-polysaccharide hydrogels were able to reclaim phosphates from waste solutions and can be used as a controlled-release fertilizer.


Assuntos
Preparações de Ação Retardada/química , Compostos Férricos/química , Fertilizantes/análise , Hidrogéis/química , Fosfatos/química , Polissacarídeos/química , Águas Residuárias/química , Adsorção , Animais , Brassica/crescimento & desenvolvimento , Brassica/metabolismo , Preparações de Ação Retardada/metabolismo , Esterco/análise , Fosfatos/metabolismo , Fotoquímica
13.
Ecotoxicol Environ Saf ; 183: 109496, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31376808

RESUMO

Iron nanoparticles (NPs) are widely used for the removal of arsenic from water. In this study, we evaluated the interaction between arsenate (AsO43-) and Fe2O3-NPs on early seedling growth of Vigna radiata. Seedlings were raised in AsO43- and Fe2O3-NPs, alone and in combination. While Fe2O3-NPs slightly promoted seedling growth, AsO43- reduced seedling growth drastically. AsO43--induced decline in the seedling growth was recovered by Fe2O3-NPs. In contrast, equivalent concentrations of FeCl3, alone and together with AsO43-, inhibited seed germination completely. Lower arsenic content in seedlings raised in the presence of Fe2O3-NPs indicated that Fe2O3-NPs restricted arsenic uptake. Ability of Fe2O3-NPs to restrict the arsenic uptake of the seedlings was due to adsorption of AsO43-, as revealed by transmission and scanning electron microscopy. Non-toxic levels of iron in seedlings were due to restriction of Fe2O3-NPs to root-surface. AsO43- enhanced the ferric chelate reductase activity of root which was recovered by Fe2O3-NPs. The AsO43--induced oxidative stress, evident from high levels of proline, H2O2 and malondialdehyde, and lowered root oxidisability was ameliorated by Fe2O3-NPs. AsO43-induced enhancement in total antioxidant capacity, superoxide dismutase and catalase activity, and decline in guaiacol peroxidase activity were antagonized by Fe2O3-NPs. Our findings reveal that Fe2O3-NPs provide effective resistance/amelioration to arsenic toxicity by reducing arsenic availability to plants.


Assuntos
Arsênico/toxicidade , Compostos Férricos/farmacologia , Nanopartículas Metálicas , Estresse Oxidativo/efeitos dos fármacos , Vigna/crescimento & desenvolvimento , Adsorção , Antioxidantes/metabolismo , Arsênico/metabolismo , Compostos Férricos/química , Compostos Férricos/metabolismo , Nanopartículas Metálicas/química , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo , Vigna/efeitos dos fármacos , Vigna/metabolismo
14.
Chemistry ; 25(63): 14290-14294, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31448834

RESUMO

The reactivity of the previously reported peroxo adduct [FeIII 2 (µ-O2 )(MeBzim-Py)4 (CH3 CN)2 ]4+ (1) (MeBzim-Py=2-(2'-pyridyl)-N-methylbenzimidazole) towards aldehyde substrates including phenylacetaldehyde (PAA), hydrocinnamaldehyde (HCA), propionaldehyde (PA), 2-phenylpropionaldehyde (PPA), cyclohexanecarboxaldehyde (CCA), and para-substituted benzaldehydes (benzoyl chlorides) has been investigated. Complex 1 proved to be a nucleophilic oxidant in aldehyde deformylation reaction. These models, including detailed kinetic and mechanistic studies, may serve as the first biomimics of aldehyde deformylating oxygenase (ADO) enzymes.


Assuntos
Aldeídos/química , Materiais Biomiméticos/química , Complexos de Coordenação/química , Compostos Férricos/química , Materiais Biomiméticos/metabolismo , Complexos de Coordenação/metabolismo , Cinética , Oxigenases/química , Oxigenases/metabolismo
15.
Sci Total Environ ; 686: 1194-1201, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31412515

RESUMO

Extracellular enzymes are mainly responsible for depolymerizing soil organic matter (SOM) in terrestrial ecosystems, and soil minerals are known to affect enzyme activity. However, the mechanisms and the effects of mineral-enzyme interactions on enzymatic degradation of organic matter remain poorly understood. In this study, we examined the adsorption of fungal ß-glucosidase enzyme on minerals and time-dependent changes of enzymatic reactivity, measured by the degradation of two organic substrates (i.e., cellobiose and indican) under both cold (4 °C) and warm (20 and 30 °C) conditions. Hematite, kaolinite, and montmorillonite were used, to represent three common soil minerals with distinctly different surface charges and characteristics. ß-glucosidase was found to sorb more strongly onto hematite and kaolinite than montmorillonite. All three minerals inhibited enzyme degradation of cellobiose and indican, likely due to the inactivation or hindrance of enzyme active sites. The mineral-bound ß-glucosidase retained its specificity for organic substrate degradation, and increasing temperature from 4 to 30 °C enhanced the degradation rates by 2-4 fold for indican and 5-9 fold for cellobiose. These results indicate that enzyme adsorption, mineral type, temperature, and organic substrate specificity are important factors influencing enzymatic reactivity and thus have important implications in further understanding and modeling complex enzyme-facilitated SOM transformations in terrestrial ecosystems.


Assuntos
Bentonita/química , Celobiose/química , Compostos Férricos/química , Glicosídeos/química , Caulim/química , beta-Glucosidase/química , Adsorção , Hidrólise , Solo/química , Temperatura Ambiente
16.
Chemosphere ; 233: 946-953, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340422

RESUMO

Scorodite is an important mineral not only for arsenic (As) removal from industrial wastewaters but also in the mobility and final fate of As in waste rocks, contaminated soils and sediments, and mine tailings. Because of the mineral's high As-loading capacity and stability, numerous studies have been done to understand its formation. Unfortunately, most of these studies were limited to elevated temperatures (>70 °C), so the processes involved in scorodite formation under ambient conditions remain unclear. This study provides evidence of the catalytic effects of hematite on the formation of scorodite at 25 °C in a pyrite-rich natural geologic material. Scorodite peaks were detected in the XRD patterns of the leaching residues with and without hematite, but those in the former were stronger and more pronounced than the latter. These results suggest that the formation of scorodite was catalysed by hematite, a generalisation that is further supported by strong characteristic IR absorption bands of scorodite at 819 cm-1 (As-O bending vibration), 785 and 725 cm-1 (As-O stretching vibrations), and 2990 cm-1 (OH-vibration) as well as the distinct XPS binding energies of Fe(III)-As (709.7 eV), As(V)-O (44.8, 44.31 and 43.7 eV), O2- (530.5 eV) and coordinated water (531.3 eV) in scorodite. This phenomenon could be attributed to three possible mechanisms: (1) more rapid precipitation promoted by the "seeding" effect of hematite particles, (2) additional supply of Fe3+ from hematite dissolution under acidic conditions, and (3) enhanced oxidations of Fe2+ to Fe3+ and As(III) to As(V) on the surface of hematite.


Assuntos
Arsênico/química , Arsenicais/síntese química , Compostos Férricos/química , Águas Residuárias/química , Purificação da Água/métodos , Catálise , Ferro/química , Oxirredução , Poluentes do Solo/análise , Sulfetos/química , Poluentes Químicos da Água/análise
17.
J Agric Food Chem ; 67(32): 9032-9038, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31334646

RESUMO

It is estimated that approximately 200 million people are exposed to arsenic levels above the World Health Organization provisional guideline value, and various agencies have indicated the need to reduce this exposure. In view of the difficulty of removing arsenic from water and food, one alternative is to reduce its bioavailability (the amount that reaches the systemic circulation after ingestion). In this study, dietary components [glutathione, tannic acid, and Fe(III)] were used to achieve this goal. As(III) or As(V) (1 mg/kg body weight) was administered daily to BALB/c mice, along with the dietary components, for 15 days. The results confirm the efficacy of Fe(III) and glutathione as reducers of arsenic bioavailability and tissue accumulation. Also, these treatments did not result in reductions of Ca, K, P, and Fe contents in the liver. These data suggest that use of these two compounds could be part of valid strategies for reducing inorganic arsenic exposure in chronically exposed populations.


Assuntos
Arsenicais/metabolismo , Compostos Férricos/química , Glutationa/química , Animais , Arsenicais/química , Disponibilidade Biológica , Exposição Dietética/análise , Exposição Dietética/prevenção & controle , Compostos Férricos/metabolismo , Contaminação de Alimentos/análise , Glutationa/metabolismo , Fígado/metabolismo , Pulmão/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Oryza/química , Oryza/metabolismo
18.
Environ Pollut ; 253: 111-119, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31302397

RESUMO

Mesoporous nanocomposite of MgFe2O4 nanoparticles (NPs) and graphene oxide (GO) was synthesized using facile sonication method. Its potential was tested for the removal of Ni (II) and Pb (II) ions from water. The 2:1 w/w ratio of MgFe2O4:GO was optimum for the maximum removal of metal ions. Nanocomposite was characterized employing XRD, FT-IR, VSM, SEM-EDX, XPS, TEM and BET analyses. It possessed higher surface area (63.0 m2 g-1) than pristine NPs. Batch experiments were performed to study the effect of process parameters viz. pH, dose, contact time, initial metal ion concentration, co-existing ions and temperature. Statistical parameters were also determined. Langmuir, Temkin and Freundlich models were followed in perfect way. Langmuir model showed the monolayer adsorption of metal ions onto the homogeneous surface of nanocomposite with maximum adsorption capacity of 100.0 mg g-1 and 143.0 mg g-1 for Ni (II) and Pb (II) ions respectively, which was higher than the same for MgFe2O4 NPs and GO. Kinetic studies demonstrated that the pseudo-second order model well described the adsorption process. The ΔS° and ΔG° values revealed spontaneous nature of adsorption process. Positive ΔH° values using MgFe2O4 NPs and nanocomposite indicated endothermic removal; whereas using GO the removal was exothermic. The observed trend for coexisting ions correlated with hydrated ion radii. Efficiency of the adsorbents was also tested for realistic nickel electroplating industrial effluent. Apart from the higher adsorption potential of nanofabricated composite, its magnetic properties are advantageous in utilizing metal loaded nanocomposite for adsorption-desorption cycles for reuse.


Assuntos
Grafite/química , Chumbo/química , Poluentes Químicos da Água/química , Adsorção , Compostos Férricos/química , Íons , Cinética , Compostos de Magnésio/química , Modelos Químicos , Nanocompostos/química , Níquel/análise , Óxidos , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Termodinâmica , Água , Poluentes Químicos da Água/análise , Purificação da Água/métodos
19.
Inorg Chem ; 58(15): 9557-9561, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31313577

RESUMO

An iron(III) methoxide complex reacts with para-substituted triarylmethyl radicals to give iron(II) and methoxyether products. Second-order rate constants for the radical derivatives were obtained. Hammett and Marcus plots suggest the radical transfer reactions proceed via a concerted process. Calculations support the concerted nature of these reactions involving a single transition state with no initial charge transfer. These findings have implications for the radical "rebound" step invoked in nonheme iron oxygenases, halogenases, and related synthetic catalysts.


Assuntos
Compostos Férricos/metabolismo , Compostos Ferrosos/metabolismo , Oxirredutases/metabolismo , Oxigênio/metabolismo , Oxigenases/metabolismo , Biocatálise , Compostos Férricos/química , Compostos Ferrosos/química , Estrutura Molecular , Oxirredutases/química , Oxigênio/química , Oxigenases/química
20.
Chem Commun (Camb) ; 55(61): 9015-9018, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31290867
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