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1.
Int J Mol Sci ; 22(15)2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34360943

RESUMO

Good sorption properties and simple synthesis route make schwertmannite an increasingly popular adsorbent. In this work, the adsorption properties of synthetic schwertmannite towards Cr(VI) were investigated. This study aimed to compare the properties and sorption performance of adsorbents obtained by two methods: Fe3+ hydrolysis (SCHA) and Fe2+ oxidation (SCHB). To characterise the sorbents before and after Cr(VI) adsorption, specific surface area, particle size distribution, density, and zeta potential were determined. Additionally, optical micrographs, SEM, and FTIR analyses were performed. Adsorption experiments were performed in varying process conditions: pH, adsorbent dosage, contact time, and initial concentration. Adsorption isotherms were fitted by Freundlich, Langmuir, and Temkin models. Pseudo-first-order, pseudo-second-order, intraparticle diffusion, and liquid film diffusion models were used to fit the kinetics data. Linear regression was used to estimate the parameters of isotherm and kinetic models. The maximum adsorption capacity resulting from the fitted Langmuir isotherm is 42.97 and 17.54 mg·g-1 for SCHA and SCHB. Results show that the adsorption kinetics follows the pseudo-second-order kinetic model. Both iron-based adsorbents are suitable for removing Cr(VI) ions from aqueous solutions. Characterisation of the adsorbents after adsorption suggests that Cr(VI) adsorption can be mainly attributed to ion exchange with SO42- groups.


Assuntos
Compostos Férricos/química , Compostos de Ferro/química , Dicromato de Potássio/química , Adsorção , Hidrólise , Oxirredução
2.
J Microbiol ; 59(9): 819-826, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34382148

RESUMO

Phosphate solubilizing fungi (PSF) have been widely applied to dissolve insoluble phosphates (IPs). However, the PSF usually demonstrates a different phosphate solubilizing capacity for various IPs. This study explored the mechanisms of Aspergillus niger for the dissolution of ferric phosphate (FePO4, Fe-P), and tricalcium phosphate (Ca3[PO4]2, Ca-P) regarding the tricarboxylic acid (TCA) cycle. Aspergillus niger has higher phosphorus (P) content released from Ca-P, reached the maximum value of 861 mg/L after seven days of incubation, compared with the 169 mg/L from Fe-P. Oxalic acid promoted the release of P from Ca-P through the formation of calcium oxalate. The presence of Fe-P can stimulate A. niger to secrete large amounts of citric acid, confirmed by the enhancement of citrate synthase (CS) activity. However, citric acid only promotes 0.5% of P released from Fe-P. Meanwhile, although oxalic acid still dominates the release of P from Fe-P, its abundance was significantly declined. In contrast, oxalic acid also shows a higher P release ratio in Ca-P than citric acid, i.e., 36% vs. 22%. This study points to the future usage of A. niger to dissolve IPs in soil required to enhance oxalic acid secretion.


Assuntos
Aspergillus niger/metabolismo , Fosfatos de Cálcio/metabolismo , Compostos Férricos/metabolismo , Aspergillus niger/genética , Fosfatos de Cálcio/química , Citrato (si)-Sintase/genética , Citrato (si)-Sintase/metabolismo , Ácido Cítrico/metabolismo , Compostos Férricos/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Ácido Oxálico/metabolismo , Solo/química
3.
Int J Mol Sci ; 22(13)2021 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-34206928

RESUMO

Brush-like α-Fe2O3-ZnO heterostructures were synthesized through a sputtering ZnO seed-assisted hydrothermal growth method. The resulting heterostructures consisted of α-Fe2O3 rod templates and ZnO branched crystals with an average diameter of approximately 12 nm and length of 25 nm. The gas-sensing results demonstrated that the α-Fe2O3-ZnO heterostructure-based sensor exhibited excellent sensitivity, selectivity, and stability toward low-concentration NO2 gas at an optimal temperature of 300 °C. The α-Fe2O3-ZnO sensor, in particular, demonstrated substantially higher sensitivity compared with pristine α-Fe2O3, along with faster response and recovery speeds under similar test conditions. An appropriate material synergic effect accounts for the considerable enhancement in the NO2 gas-sensing performance of the α-Fe2O3-ZnO heterostructures.


Assuntos
Compostos Férricos/química , Nanoestruturas/química , Dióxido de Nitrogênio/análise , Óxido de Zinco/química , Técnicas de Química Analítica/métodos , Dióxido de Nitrogênio/química , Sensibilidade e Especificidade
4.
Int J Mol Sci ; 22(13)2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34210014

RESUMO

Human serum transferrin (HST) is a glycoprotein involved in iron transport that may be a candidate for functionalized nanoparticles to bind and target cancer cells. In this study, the effects of the simple and doped with cobalt (Co) and copper (Cu) ferrihydrite nanoparticles (Fh-NPs, Cu-Fh-NPs, and Co-Fh-NPs) were studied by spectroscopic and molecular approaches. Fluorescence spectroscopy revealed a static quenching mechanism for all three types of Fh-NPs. All Fh-NPs interacted with HST with low affinity, and the binding was driven by hydrogen bonding and van der Waals forces for simple Fh-NPs and by hydrophobic interactions for Cu-Fh-NPs and Co-Fh-NPs binding, respectively. Of all samples, simple Fh-NPs bound the most to the HST binding site. Fluorescence resonance energy transfer (FRET) allowed the efficient determination of the energy transfer between HST and NPs and the distance at which the transfer takes place and confirmed the mechanism of quenching. The denaturation of the HST is an endothermic process, both in the case of apo HST and HST in the presence of the three types of Fh-NPs. Molecular docking studies revealed that Fh binds with a low affinity to HST (Ka = 9.17 × 103 M-1) in accord with the fluorescence results, where the interaction between simple Fh-NPs and HST was described by a binding constant of 9.54 × 103 M-1.


Assuntos
Cobalto/química , Compostos Férricos/síntese química , Transferrina/química , Transferrina/metabolismo , Cobre/química , Compostos Férricos/química , Transferência Ressonante de Energia de Fluorescência , Humanos , Ligação de Hidrogênio , Modelos Moleculares , Simulação de Acoplamento Molecular , Nanopartículas , Ligação Proteica , Conformação Proteica , Espectrometria de Fluorescência , Termodinâmica
5.
Int J Mol Sci ; 22(13)2021 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-34202550

RESUMO

In this study, we determined the potential of polyethylene glycol-encapsulated iron oxide nanoparticles (IONPCO) for the intracellular delivery of the chemotherapeutic doxorubicin (IONPDOX) to enhance the cytotoxic effects of ionizing radiation. The biological effects of IONP and X-ray irradiation (50 kV and 6 MV) were determined in HeLa cells using the colony formation assay (CFA) and detection of γH2AX foci. Data are presented as mean ± SEM. IONP were efficiently internalized by HeLa cells. IONPCO radiomodulating effect was dependent on nanoparticle concentration and photon energy. IONPCO did not radiosensitize HeLa cells with 6 MV X-rays, yet moderately enhanced cellular radiosensitivity to 50 kV X-rays (DMFSF0.1 = 1.13 ± 0.05 (p = 0.01)). IONPDOX did enhance the cytotoxicity of 6 MV X-rays (DMFSF0.1 = 1.3 ± 0.1; p = 0.0005). IONP treatment significantly increased γH2AX foci induction without irradiation. Treatment of HeLa cells with IONPCO resulted in a radiosensitizing effect for low-energy X-rays, while exposure to IONPDOX induced radiosensitization compared to IONPCO in cells irradiated with 6 MV X-rays. The effect did not correlate with the induction of γH2AX foci. Given these results, IONP are promising candidates for the controlled delivery of DOX to enhance the cytotoxic effects of ionizing radiation.


Assuntos
Antibióticos Antineoplásicos/administração & dosagem , Doxorrubicina/administração & dosagem , Portadores de Fármacos , Compostos Férricos , Nanopartículas Metálicas , Tolerância a Radiação/efeitos dos fármacos , Relação Dose-Resposta à Radiação , Portadores de Fármacos/química , Compostos Férricos/química , Células HeLa/efeitos dos fármacos , Células HeLa/patologia , Células HeLa/efeitos da radiação , Células HeLa/ultraestrutura , Humanos , Nanopartículas Metálicas/química , Radiação Ionizante
6.
Molecules ; 26(13)2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34202245

RESUMO

Cancer-based magnetic theranostics has gained significant interest in recent years and can contribute as an influential archetype in the effective treatment of cancer. Owing to their excellent biocompatibility, minute sizes and reactive functional surface groups, magnetic nanoparticles (MNPs) are being explored as potential drug delivery systems. In this study, MgFe2O4 ferrite MNPs were evaluated for their potential to augment the delivery of the anticancer drug doxorubicin (DOX). These MNPs were successfully synthesized by the glycol-thermal method and functionalized with the polymers; chitosan (CHI), polyvinyl alcohol (PVA) and polyethylene glycol (PEG), respectively, as confirmed by Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) confirmed the formation of the single-phase cubic spinel structures while vibrating sample magnetometer (VSM) analysis confirmed the superparamagnetic properties of all MNPs. Transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) revealed small, compact structures with good colloidal stability. CHI-MNPs had the highest DOX encapsulation (84.28%), with the PVA-MNPs recording the lowest encapsulation efficiency (59.49%). The 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) cytotoxicity assays conducted in the human embryonic kidney (HEK293), colorectal adenocarcinoma (Caco-2), and breast adenocarcinoma (SKBR-3) cell lines showed that all the drug-free polymerized MNPs promoted cell survival, while the DOX loaded MNPs significantly reduced cell viability in a dose-dependent manner. The DOX-CHI-MNPs possessed superior anticancer activity (<40% cell viability), with approximately 85.86% of the drug released after 72 h in a pH-responsive manner. These MNPs have shown good potential in enhancing drug delivery, thus warranting further optimizations and investigations.


Assuntos
Antibióticos Antineoplásicos , Doxorrubicina , Portadores de Fármacos , Nanopartículas de Magnetita , Neoplasias/tratamento farmacológico , Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/farmacocinética , Antibióticos Antineoplásicos/farmacologia , Células CACO-2 , Quitosana/química , Doxorrubicina/química , Doxorrubicina/farmacocinética , Doxorrubicina/farmacologia , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Portadores de Fármacos/farmacologia , Compostos Férricos/química , Células HEK293 , Humanos , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/uso terapêutico , Neoplasias/metabolismo , Neoplasias/patologia , Polietilenoglicóis/química , Álcool de Polivinil/química
7.
Nat Nanotechnol ; 16(8): 918-925, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34083772

RESUMO

Minimizing the spread of viruses in the environment is the first defence line when fighting outbreaks and pandemics, but the current COVID-19 pandemic demonstrates how difficult this is on a global scale, particularly in a sustainable and environmentally friendly way. Here we introduce and develop a sustainable and biodegradable antiviral filtration membrane composed of amyloid nanofibrils made from food-grade milk proteins and iron oxyhydroxide nanoparticles synthesized in situ from iron salts by simple pH tuning. Thus, all the membrane components are made of environmentally friendly, non-toxic and widely available materials. The membrane has outstanding efficacy against a broad range of viruses, which include enveloped, non-enveloped, airborne and waterborne viruses, such as SARS-CoV-2, H1N1 (the influenza A virus strain responsible for the swine flu pandemic in 2009) and enterovirus 71 (a non-enveloped virus resistant to harsh conditions, such as highly acidic pH), which highlights a possible role in fighting the current and future viral outbreaks and pandemics.


Assuntos
Amiloide/química , Antivirais/farmacologia , Compostos Férricos/química , Filtros Microporos , Nanopartículas/química , Amiloide/farmacologia , Antivirais/química , Compostos Férricos/farmacologia , Humanos , Lactoglobulinas/química , Filtros Microporos/virologia , Inativação de Vírus/efeitos dos fármacos , Vírus/classificação , Vírus/efeitos dos fármacos , Vírus/isolamento & purificação , Purificação da Água
8.
Inorg Chem ; 60(12): 8651-8664, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34110140

RESUMO

Four high-spin Fe(III) macrocyclic complexes, including three dinuclear and one mononuclear complex, were prepared toward the development of more effective iron-based magnetic resonance imaging (MRI) contrast agents. All four complexes contain a 1,4,7-triazacyclononane macrocyclic backbone with two hydroxypropyl pendant groups, an ancillary aryl or biphenyl group, and a coordination site for a water ligand. The pH potentiometric titrations support one or two deprotonations of the complexes, most likely deprotonation of hydroxypropyl groups at near-neutral pH. Variable-temperature 17O NMR studies suggest that the inner-sphere water ligand is slow to exchange with bulk water on the NMR time scale. Water proton T1 relaxation times measured for solutions of the Fe(III) complexes at pH 7.2 showed that the dinuclear complexes have a 2- to 3-fold increase in r1 relaxivity in comparison to the mononuclear complex per molecule at field strengths ranging from 1.4 T to 9.4 T. The most effective agent, a dinuclear complex with macrocycles linked through para-substitution of an aryl group (Fe2(PARA)), has an r1 of 6.7 mM-1 s-1 at 37 °C and 4.7 T or 3.3 mM-1 s-1 per iron center in the presence of serum albumin and shows enhanced blood pool and kidney contrast in mice MRI studies.


Assuntos
Meios de Contraste/química , Complexos de Coordenação/química , Compostos Férricos/química , Compostos Macrocíclicos/química , Imageamento por Ressonância Magnética , Animais , Meios de Contraste/síntese química , Meios de Contraste/farmacocinética , Complexos de Coordenação/síntese química , Complexos de Coordenação/farmacocinética , Compostos Férricos/farmacocinética , Humanos , Compostos Macrocíclicos/síntese química , Compostos Macrocíclicos/farmacocinética , Camundongos , Camundongos Endogâmicos BALB C , Estrutura Molecular , Albumina Sérica Humana/química
9.
Inorg Chem ; 60(12): 8710-8721, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34110143

RESUMO

A handful of oxygen-activating enzymes has recently been found to contain Fe/Mn active sites, like Class 1c ribonucleotide reductases and R2-like ligand-binding oxidase, which are closely related to their better characterized diiron cousins. These enzymes are proposed to form high-valent intermediates with Fe-O-Mn cores. Herein, we report the first examples of synthetic Fe/Mn complexes that mimic doubly bridged intermediates proposed for enzymatic oxygen activation. Fe K-edge extended X-ray absorption fine structure (EXAFS) analysis has been used to characterize the structures of each of these compounds. Linear compounds accurately model the Fe···Mn distances found in Fe/Mn proteins in their resting states, and doubly bridged diamond core compounds accurately model the distances found in high-valent biological intermediates. Unlike their diiron analogues, the paramagnetic nature of Fe/Mn compounds can be analyzed by EPR, revealing S = 1/2 signals that reflect antiferromagnetic coupling between the high-spin Fe(III) and Mn(III) units of heterobimetallic centers. These compounds undergo electron transfer with various ferrocenes, linear compounds being capable of oxidizing diacetyl ferrocene, a weak reductant, and diamond core compounds being capable of oxidizing acetyl ferrocene. Diamond core compounds can also perform HAT reactions from substrates with X-H bonds with bond dissociation free energies (BDFEs) up to 75 kcal/mol and are capable of oxidizing TEMPO-H at rates of 0.32-0.37 M-1 s-1, which are comparable to those reported for some mononuclear FeIII-OH and MnIII-OH compounds. However, such reactivity is not observed for the corresponding diiron compounds, a difference that Nature may have taken advantage of in evolving enzymes with heterobimetallic active sites.


Assuntos
Complexos de Coordenação/metabolismo , Compostos Férricos/metabolismo , Manganês/metabolismo , Ribonucleotídeo Redutases/metabolismo , Sítios de Ligação , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Compostos Férricos/química , Manganês/química , Modelos Moleculares , Estrutura Molecular , Oxigênio/química , Oxigênio/metabolismo , Ribonucleotídeo Redutases/química
10.
Ecotoxicol Environ Saf ; 221: 112451, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34174737

RESUMO

Manganese oxides and iron oxides have been widely introduced in constructed wetlands (CWs) for sewage treatment due to their extensiveness in nature and their ability to participate in various reactions, but their effects on greenhouse gas (GHG) emissions remain unclear. Here, a set of vertical subsurface-flow CWs (Control, Fe-VSSCWs, and Mn-VSSCWs) was established to comprehensively evaluate which are the better metal substrate materials for CWs, iron oxides or manganese oxides, through water quality and the global warming potential (GWP) of nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2). The results revealed that the removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in Mn-VSSCWs were all higher than that in Fe-VSSCWs, and manganese oxides could almost completely suppress the CH4 production and reduce GWP (from 8.15 CO2-eq/m2/h to 7.17 mg CO2-eq/m2/h), however, iron oxides promoted GWP (from 8.15 CO2-eq/m2/h to 10.84 mg CO2-eq/m2/h), so manganese oxides are the better CW substrate materials to achieve effective sewage treatment while reducing the greenhouse gas effect.


Assuntos
Poluentes Atmosféricos/química , Compostos Férricos/química , Efeito Estufa/prevenção & controle , Compostos de Manganês/química , Óxidos/química , Purificação da Água/métodos , Áreas Alagadas , Análise da Demanda Biológica de Oxigênio , Dióxido de Carbono/química , Metano/química , Nitrogênio/química , Óxido Nitroso/química , Fósforo/química , Poluentes da Água/química , Qualidade da Água
11.
Int J Mol Sci ; 22(11)2021 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-34074010

RESUMO

The trimaltol iron complex (International Non-proprietary Name: ferric maltol) was originally designed, synthesised, and screened in vitro and in vivo in 1980-1981 by Kontoghiorghes G.J. following his discovery of the novel alpha-ketohydroxyheteroaromatic (KHP) class of iron chelators (1978-1981), which were intended for clinical use, including the treatment of iron deficiency anaemia (IDA). Iron deficiency anaemia is a global health problem affecting about one-third of the world's population. Many (and different) ferrous and ferric iron complex formulations are widely available and sold worldwide over the counter for the treatment of IDA. Almost all such complexes suffer from instability in the acidic environment of the stomach and competition from other dietary molecules or drugs. Natural and synthetic lipophilic KHP chelators, including maltol, have been shown in in vitro and in vivo studies to form stable iron complexes, to transfer iron across cell membranes, and to increase iron absorption in animals. Trimaltol iron, sold as Feraccru or Accrufer, was recently approved for clinical use in IDA patients in many countries, including the USA and in EU countries, and was shown to be effective and safe, with a better therapeutic index in comparison to other iron formulations. Similar properties of increased iron absorption were also shown by lipophilic iron complexes of 8-hydroxyquinoline, tropolone, 2-hydroxy-4-methoxypyridine-1-oxide, and related analogues. The interactions of the KHP iron complexes with natural chelators, drugs, metal ions, proteins, and other molecules appear to affect the pharmacological and metabolic effects of both iron and the KHP chelators. A new era in the treatment of IDA and other possible clinical applications, such as theranostic and anticancer formulations and metal radiotracers in diagnostic medicine, are envisaged from the introduction of maltol, KHP, and similar lipophilic chelators.


Assuntos
Anemia Ferropriva/tratamento farmacológico , Quelantes de Ferro/farmacologia , Quelantes de Ferro/uso terapêutico , Ferro/uso terapêutico , Pironas/farmacologia , Animais , Disponibilidade Biológica , Compostos Férricos/química , Compostos Férricos/farmacologia , Compostos Férricos/uso terapêutico , Humanos , Técnicas In Vitro , Quelantes de Ferro/química , Pironas/química , Pironas/uso terapêutico
12.
Chem Commun (Camb) ; 57(52): 6416-6419, 2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34095911

RESUMO

Herein, based on iron oxyhydroxide (FeOOH) as the photoactive material and exonuclease III (exo III)-aided dual recycling signal amplification, a new photoelectrochemical (PEC) biosensor was successfully developed for human papillomavirus-16 (HPV-16) detection with a wide linear range from 0.5 fM to 1 nM and a low detection limit of 0.17 fM.


Assuntos
Técnicas Biossensoriais/métodos , Exodesoxirribonucleases/metabolismo , Compostos Férricos/química , Papillomavirus Humano 16/isolamento & purificação , DNA de Cadeia Simples/química , DNA de Cadeia Simples/metabolismo , Técnicas Eletroquímicas , Eletrodos , Papillomavirus Humano 16/genética , Humanos , Luz , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico , Reprodutibilidade dos Testes
13.
Int J Biol Macromol ; 183: 2088-2099, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34097963

RESUMO

Efficient photocatalysis methods with a production of less number of toxic intermediates are extremely advantageous for water decontamination. The degradation efficiency, specific surface area, stability and porosity will be improving by wrapping of Fe2O3 using appropriate biopolymers. In this work, Fe2O3 reinforced chitosan (Fe2O3@CS) nanocomposite was fabricated using co-precipitation method. The chitosan makes available its surface for the useful generation of the nanocomposite. These wrapping of Fe2O3 on chitosan provides synergistically improved properties that could be attributed to the elevated partition efficiency and faster transfer of the photo-generated charge carriers, which was substantiated by the experimental outcomes from photoluminescence and ESR spectroscopy. The results obtained from DRS analysis entail the reduction in band gap of Fe2O3@CS (2.52 eV) as compared with 3.52 eV of Fe2O3. The results indicated that 89.2% and 94.6% were the maximum degradations correspondingly for MO and OG. The trapping investigation emphasized the involvement of OH radicals in the degradation of dyes over Fe2O3@CS composites. The five cycles of regeneration experiment recommended the superior photostability of the fabricated Fe2O3@CS composite. This work proposed a practical arrangement and subsequent influence of an advanced photocatalyst for the useful remediation dyes from contaminated water without causing any secondary pollution.


Assuntos
Compostos Azo/química , Quitosana/química , Compostos Férricos/química , Nanopartículas Magnéticas de Óxido de Ferro/química , Fotólise , Poluentes Químicos da Água/química , Poluição Química da Água , Purificação da Água , Catálise , Quitosana/análogos & derivados , Recuperação e Remediação Ambiental , Modelos Químicos , Nanocompostos , Nanofibras , Oxirredução , Fatores de Tempo
14.
ACS Appl Mater Interfaces ; 13(21): 24865-24876, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34009929

RESUMO

As the use of pesticides in agriculture is increasing at an alarming rate, food contamination by pesticide residues is becoming a huge global problem. It is essential to develop a sensitive and user-friendly sensor device to quantify trace levels of pesticide and herbicide residues in food samples. Herein, we report an electrocatalyst made up of yttrium iron garnet (Y3Fe5O12; YIG) and graphitic carbon nitride (GCN) to attain picomolar-level detection sensitivity for mesotrione (MTO), which is a widely used herbicide in agriculture. First, YIG was prepared by a hydrothermal route; then, it was loaded on GCN sheets via a calcination method. The surface structures, composition, crystallinity, and interfacial and electrocatalytic properties of the YIG and YIG/GCN were analyzed. As the YIG/GCN displayed better surface and catalytic properties than YIG, YIG/GCN was modified on a screen-printed carbon electrode to fabricate a sensor for MTO. The YIG/GCN-modified electrode displayed a detection limit of 950 pM for MTO. The method was demonstrated in (spiked) fruits and vegetables. Then, the modified electrode was integrated with a miniaturized potentiostat called KAUSTat, which can be operated wirelessly by a smartphone. A first smartphone-based portable sensor was demonstrated for MTO that is suitable for use in nonlaboratory settings.


Assuntos
Cicloexanonas/análise , Compostos Férricos/química , Contaminação de Alimentos/análise , Grafite/química , Compostos de Nitrogênio/química , Praguicidas/análise , Sistemas Automatizados de Assistência Junto ao Leito , Smartphone , Ítrio/química , Técnicas Eletroquímicas , Microscopia Eletrônica de Transmissão , Reprodutibilidade dos Testes , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
16.
Int J Biol Macromol ; 182: 1495-1506, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34019924

RESUMO

Semiconductor materials have shown a good photocatalytic behaviour for the photodegradation of organic pollutants. In this work, maleated liquid natural rubber (MLNR) based hydrogel supported bismuth ferrite (BiFeO3) as photocatalyst was successfully synthesized by crosslinking with acrylic acid (AAc) assisted by the ultrasonication method to study the efficiency for the removal of methylene blue (MB) dye in wastewater. Response surface methodology (RSM) was used to optimize the parameters for adsorption of the methylene blue (MB) dye compound, whereby the effects of the initial concentration of MB and the adsorption time were examined to obtain a quadratic model for the respective hydrogel composite. The prepared composite sample was characterized by Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX) and X-ray Diffraction (XRD) analysis. Remarkable improvement for removal of methylene blue (99% removal) was found within 3 h adsorption time with a MLNR/AAc-BiFeO3 hydrogel composite as compared to the pristine hydrogel. A synergistic mode of dye removal by adsorption and photodegradation is proposed. Based on the isotherm and kinetic study conducted, it was found that Freundlich isotherm model and a pseudo second-order kinetic model was best fitted for adsorption of MB dye. The MLNR/AAc-BiFeO3 composite maintains its removal efficiency after 5 cycles without the necessity of post-treatment separation. Therefore, it is crucial to note that the resultant low-cost MLNR/AAc-BiFeO3 hydrogel composite in this study offers excellent potential for water and wastewater treatment applications with improved recyclability and recovery.


Assuntos
Compostos Férricos/química , Catálise , Hidrogéis/química , Luz , Azul de Metileno/química , Nanocompostos/química , Fotoquímica/métodos
17.
Chem Commun (Camb) ; 57(36): 4460-4463, 2021 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-33949502

RESUMO

We report a facile and reversible method to immobilize a broad range of His6-tagged proteins on the E. coli cell surface through Fe(iii)-metal complexes. A His6-tagged eGFP and four His6-tagged enzymes were successfully immobilized on the cell surface. Additionally, a hydrogel sheath around E. coli cells was generated by immobilized His6-tagged HRP.


Assuntos
Oxirredutases do Álcool/metabolismo , Escherichia coli/metabolismo , Compostos Férricos/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Lacase/metabolismo , Lipase/metabolismo , Oxirredutases do Álcool/química , Bacillus licheniformis/enzimologia , Bacillus subtilis/enzimologia , Candida tropicalis/enzimologia , Membrana Celular/química , Membrana Celular/metabolismo , Escherichia coli/química , Escherichia coli/citologia , Compostos Férricos/química , Proteínas de Fluorescência Verde/química , Histidina/química , Histidina/metabolismo , Lacase/química , Lipase/química , Oligopeptídeos/química , Oligopeptídeos/metabolismo
18.
Int J Biol Macromol ; 183: 1784-1793, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34051253

RESUMO

Naturally occurring peroxidases are important for living organisms and have manifold utility in industries. However, lack of stability in harsh reaction conditions hinders wide applicability of such enzymes. Thus, suitable alternative is vital which can endure severe reaction conditions. As a substitute of natural peroxidase, herein, biopolymer-based polyelectrolyte complexes (PECs) coordinated with Fen+ is proposed as macromolecular peroxidase mimicking systems. Three PECs were engineered via complexation of protonated chitosan and alginate with Fe2+ (Fe2+-PEC), Fe3+ (Fe3+-PEC), and Fe3O4 (Fe3O4-PEC), respectively. Computational study showed the Fe3+-PEC was highly stable with abundant electrostatic and intramolecular hydrogen bonding interactions. The versatility of the Fe-PECs as artificial peroxidase biocatalysts was probed by two types of peroxidase assays - ABTS oxidation in buffer systems (pH 4.0 and 7.0) and pyrogallol oxidation in organic solvents (acetonitrile, ethyl acetate and toluene). Overall, Fe3+-PEC showed remarkably high peroxidase activity both in aqueous buffers and in organic solvents, whereas, Fe3O4-PEC showed least catalytic activity. Finally, as a proof of concept, the ability of the biocatalyst to carry out deep oxidative desulphurization was demonstrated envisaging removal of dibenzothiophene from model fossil fuel in a sustainable way.


Assuntos
Biopolímeros/química , Compostos Férricos/síntese química , Peroxidase/síntese química , Tiofenos/análise , Alginatos/química , Biocatálise , Catálise , Quitosana/química , Compostos Férricos/química , Gasolina , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Peroxidase/química
19.
J Photochem Photobiol B ; 219: 112201, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33962112

RESUMO

In this project, we studied the thermal and chemical method for the synthesis of carbon dots (CDs)/Hematite (α-Fe2O3) quantum dots and the preparation of hydroxypropyl cellulose cross-linked chitosan (HPCCS) and ulvan (UN) was performed by chemical method. Carbon dots/α-Fe2O3 quantum dots with size distribution of 3-5 nm were completely encapsulated in the HPCCS/UN NPs to obtain composites, which indicated unique characteristics with respect to antimicrobial, pH-responsive and optical properties. The CDs-HQDs/HPCCS/UN nanocomposites exhibited a single-excitation (440 nm), dual-emission fluorescence property (505 nm and 628 nm for green and red light from CDs-HQDs and HPCCS/UN NPs). The nanocomposites played as a pH-responsive drug delivery process to release ulvan at a fast rate in pH 7.4 buffer solution but at a slow rate in low pH solutions. The CDs-HQDs/HPCCS/UN nanocomposites gained the highest photocatalytic activity for degrading 4-chlorophenol (4-CPh) as a pollutant (>98% during 70 min under sunlight irradiation). Moreover, the nanocomposites indicated great inhibitory influences towards bacterial and fungal.


Assuntos
Anti-Infecciosos/química , Celulose/análogos & derivados , Quitosana/química , Nanocompostos/química , Pontos Quânticos/química , Luz Solar , Anti-Infecciosos/farmacologia , Carbono/química , Catálise , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Celulose/química , Clorofenóis/química , Portadores de Fármacos/química , Liberação Controlada de Fármacos/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Compostos Férricos/química , Humanos , Concentração de Íons de Hidrogênio , Nanocompostos/toxicidade , Staphylococcus aureus/efeitos dos fármacos , Poluentes Químicos da Água/química
20.
Int J Biol Macromol ; 183: 1047-1057, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-33984379

RESUMO

In this study, an optimized method was developed for the synthesis of biological macromolecule blend supported iron oxide nanoparticles (IO NPs). The nanostructure was composed of binary polymer blends of konjac gum (KG) and xanthan gum (XG). The synthesized KG/XG@IO NPs were characterized by SEM, EDX, HRTEM, FTIR, XRD, XPS, zeta potential, DLS, TGA, and DSC. According to results, the KG/XG@IO NPs had a spherical shape with an average diameter range of ~40 nm using Scherrer's equation and Williamson-Hall equation. The results of TGA and DSC analysis confirmed that the KG/XG@IO NPs maintained good thermal stability. Our motivation was to determine the effect of the biopolymer blend matrix on the morphology, size, stability, and thermal properties of the green KG/XG@IO NPs. Furthermore, the effects of sonication process time (10-30 min), mass ratio of biological macromolecule blend (KG/XG) (1:1, 1:2, and 1:4), and amplitude frequency (5%-40%) on the rheological parameters of NPs were investigated to optimize the sonochemical process. From optimization analysis, we concluded that the sonication had a role in the size distribution and the formation of nanoparticles with the optimum mixture ratio of binary biopolymer matrix as it provided long-term stability.


Assuntos
Compostos Férricos/química , Nanopartículas Metálicas/química , Gomas Vegetais/química , Polissacarídeos Bacterianos/química , Biopolímeros/química
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