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1.
Chem Commun (Camb) ; 56(15): 2300-2303, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-31989132

RESUMO

A novel signal self-enhancement photoelectrochemical immuno-sensor has been developed based on the curing of sacrificial agent SO32- coated-Au NPs sensitizing Ag2S/CuS/α-Fe2O3 n-p-n hetero-structure films for the first time. This strategy has acquired high sensitivity and low background without addition of a sacrificial agent in solution in the detection of prostate antigen.


Assuntos
Técnicas Biossensoriais , Cobre/química , Técnicas Eletroquímicas , Compostos Férricos/química , Imunoensaio , Antígeno Prostático Específico/análise , Compostos de Prata/química , Humanos , Tamanho da Partícula , Processos Fotoquímicos , Soluções , Propriedades de Superfície
2.
J Agric Food Chem ; 68(7): 2124-2131, 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-31985223

RESUMO

Lignin acylated with acetate and/or p-coumarate is common in many herbaceous plants. Herein, the biomimetic oxidation of γ-acylated monolignols with Ag2O was studied to understand the effect of γ-acyl groups on monolignol polymerization. The oxidation of sinapyl acetate gave γ-acylated and α-acylated ß-O-4 dimers in 71 and 9.5% yields, respectively. The oxidation of sinapyl p-coumarate produced γ-acylated ß-O-4 and γ-acylated tetralin ß-ß dimers in 53 and 16% yields, respectively. Only the sinapyl alcohol moiety in sinapyl p-coumarate reacted, and the p-coumarate moiety remained unchanged, suggesting that p-coumaric acid is not incorporated into the lignin backbone in the acylated lignins. All of the γ-acylated monolignols used in this study produced the γ-acylated ß-O-4 dimers, which suggests that the γ-acylated monolignols act as lignin monomers. The relatively high yields of the ß-O-4 dimers indicate that Ag2O oxidation of the monolignols can be used as an easy method for synthesizing the ß-O-4 dimer model compounds.


Assuntos
Ácidos Cumáricos/química , Dioxanos/química , Lignina/química , Óxidos/química , Compostos de Prata/química , Acetatos/química , Biomimética , Oxirredução
3.
Chemistry ; 26(5): 1042-1051, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31614042

RESUMO

Following the recent discovery that traditional silver(I) oxide-promoted glycosidations of glycosyl bromides (Koenigs-Knorr reaction) can be greatly accelerated in the presence of catalytic TMSOTf, reported herein is a dedicated study of all major aspects of this reaction. A thorough investigation of numerous silver salts and careful refinement of the reaction conditions led to an improved mechanistic understanding. This, in turn, led to a significant reduction in the amount of silver salt required for these glycosylations. The progress of this reaction can be monitored by naked eye, and the completion of the reaction can be judged by the disappearance of characteristic dark color of Ag2 O. Further evidence on higher reactivity of benzoylated α-bromides in comparison to that of their benzylated counterparts has been acquired.


Assuntos
Ácidos/química , Glicosídeos/química , Brometos/química , Catálise , Glicosilação , Óxidos/química , Compostos de Prata/química
4.
Chemosphere ; 239: 124721, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31493752

RESUMO

In this work, Metal-organic Frameworks (MOFs) were applied to inactivate algae under visible light with low doses. Five MOFs with different compositions (Zn and Fe; carboxylates or imidazolates) were successfully synthesized and characterized by XRD, SEM and UV-vis. The effects of MOFs on Microcystis aeruginosa were evaluated with regard to morphology characteristics, physiological activity, cell integrity and pigment degradation. The results indicated that Ag/AgCl@ZIF-8 outperformed MOF-235, ZIF-8, Bi2WO6/MIL-100(Fe) and BiOBr/MOF-5 in the degradation of chlorophyll a at the dose of 10 mg L-1. After 6 h of irradiation, 93.1% of Microcystis aeruginosa died and was unable to regrow and reproduce, which was demonstrated by changes in cell morphology, damage of cell membrane integrity and antioxidant enzyme system. Besides, the intracellular organic matter (IOM) and extracellular organic matter (EOM) were proven to be efficiently removed by MOF-assisted photocatalytic inactivation. Superoxide radical (O2·-) was demonstrated to be the major reactive oxygen species. A probable mechanism was proposed that the electrons in the valence band of Ag/AgCl@ZIF-8 transfer into the conduction band under irradiation to produce O2·- which inactivated the algae cells. Furthermore, Ag/AgCl@ZIF-8 can effectively remove Microcystis aeruginosa under sunlight and is of great application prospects for algae removal in real water bodies.


Assuntos
Estruturas Metalorgânicas/química , Microcystis/química , Purificação da Água/métodos , Clorofila A/química , Luz , Microcystis/metabolismo , Microscopia Eletrônica de Varredura , Processos Fotoquímicos , Compostos de Prata/química , Espectrofotometria Ultravioleta , Luz Solar , Difração de Raios X
5.
Biofouling ; 35(7): 719-731, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31505979

RESUMO

A novel Z-scheme AgBr/Ag2MoO4@ZnO photocatalyst was fabricated via a hydrothermal process and in situ growth method. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were used to determine the structure of the photocatalyst. The results showed that the composites were tightly connected by the (101) lattice plane of ZnO, the (222) plane of Ag2MoO4 and the (200) lattice plane of AgBr. Because of the strong redox activity and good separability of photoelectrons and holes induced by the Z-scheme structure, the photodegradation rate for ciprofloxacin (CIP) solution was 80.5% by the photocatalysis of 0.5 AgBr/Ag2MoO4@ZnO. In addition, more than 99.999% of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa cells were killed within 60 min. These results demonstrate that AgBr/Ag2MoO4@ZnO is a promising photocatalyst, which can be used in organic pollutant degradation and the photocatalytic antibacterial area.


Assuntos
Antibacterianos/química , Ciprofloxacino/química , Compostos de Prata/química , Óxido de Zinco/química , Antibacterianos/farmacologia , Catálise , Ciprofloxacino/farmacologia , Escherichia coli/efeitos dos fármacos , Luz , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Fotólise , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Difração de Raios X
6.
J Photochem Photobiol B ; 199: 111593, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31505420

RESUMO

Greener way of synthesizing nanoparticles has emerged as a substitute method, as it is ecological and cost effectual. Numerous efforts have been completed for green synthesis of silver oxide nanoparticles (Ag2O NPs) by various plant extracts. Current work disclosed the green combustion synthesis of Ag2O NPs by using Lippia citriodora plant powder. Furthermore, photocatalytic properties of Ag2O NPs were studied on acid orange 8(AO8) dye was assessed under UV light irradiation. The catalyst shows good photocatalytic activity (PCA) for the degradation of AO8 dye, NPs synthesized by Lippia citriodora powder shows high percentage of degradation. The Ag2O NPs act as excellent antibacterial against S. Aureus and antifungal activity against A. Aureus. Further wound healing studies in excision skin wound model in albino wistar rats showed the effective wound healing activity of Ag2O NPs incorporated hydrogels compared to untreated and plant extract treatments. The majority upshot of this research will be recommended that biologically synthesized Ag2O from Lippia citriodora plant powder has more valuable against various disease-causing pathogens and hence could be useful for developing wound dressing agents for nursing care.


Assuntos
Anti-Infecciosos/química , Lippia/química , Nanopartículas Metálicas/química , Óxidos/química , Extratos Vegetais/química , Compostos de Prata/química , Cicatrização/efeitos dos fármacos , Animais , Anti-Infecciosos/farmacologia , Compostos Azo/química , Bandagens , Benzenossulfonatos/química , Catálise , Estabilidade de Medicamentos , Química Verde , Hidrogéis/química , Masculino , Metilcelulose/química , Testes de Sensibilidade Microbiana , Oxirredução , Óxidos/farmacologia , Processos Fotoquímicos , Ratos Wistar , Compostos de Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície , Resultado do Tratamento
7.
ACS Appl Mater Interfaces ; 11(37): 34364-34375, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31442020

RESUMO

In this study, a multifunctional hybrid coating composed of AgBr nanoparticles (AgBrNPs) and two-dimensional molybdenum sulfide (MoS2) nanosheets (AgBr@MoS2) was constructed on Ti implant materials using an in situ growth method for the first time. With 660 nm light and visible light irradiation, the electrons were rapidly excited from the valence band of MoS2 to its conduction band, at the same time, AgBrNPs was used as a photoelectric receiver, which exhibited an enhanced photocatalytic activity due to the rapid transfer of photoelectrons from MoS2 nanosheets to AgBrNPs and the suppression of the recombination of electron-hole pairs. This contributed to the rapid production of reactive oxygen species under 660 nm light irradiation, thus the AgBr@MoS2 system killed bacteria and degraded organic matter quickly and efficiently in a short time. Meanwhile, the AgBr@MoS2 system showed excellent stability due to the strong covalent binding between S and Ag in the system, thus preventing AgBrNPs from being reduced to metal Ag.


Assuntos
Antibacterianos , Bactérias/crescimento & desenvolvimento , Brometos , Desinfecção , Dissulfetos , Luz , Molibdênio , Nanopartículas/química , Compostos de Prata , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Brometos/química , Brometos/farmacologia , Linhagem Celular , Dissulfetos/química , Dissulfetos/farmacologia , Humanos , Camundongos , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Molibdênio/química , Molibdênio/farmacologia , Ratos , Ratos Sprague-Dawley , Compostos de Prata/química , Compostos de Prata/farmacologia
8.
J Colloid Interface Sci ; 555: 759-769, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31419626

RESUMO

As photocatalyst the low recombination efficiency and efficient utilization of photoelectron-holes are crucial for high photodegradation efficiencies, rapid disinfection in water catalytic purification. Herein, a sandwich-structured Z-scheme Silver sulfide/ferroferric oxide/silver metavanadate graphene microtube composite photocatalyst (Ag2S/Fe3O4/AgVO3@GM) was successfully prepared by a novel strategy using capillary effect combined with hydrothermal method. In this sandwich-structured composite, Ag2S, Fe3O4 and AgVO3 are anchored in the inner, middle and outer layers of graphene microtube, respectively, which construct a Z-scheme system with spatially separated microtopography. The Fe3O4 nanoparticles (NPs) in the middle of graphene microtube layer not only help the composite photocatalyst recycle due to their superparamagnetism but also serve as the redox mediator in the Z-scheme system to collect and consume the electrons and holes from AgVO3 and Ag2S on inner/outer layer graphene microtube, which can effectively facilitate the separation rate of photo-generated charge carriers, and generate more activity radicals. Moreover, the spatially separated graphene microtube micromorphology can significantly promote the mass transport efficiency in photocatalytic reaction. The obtained Ag2S/Fe3O4/AgVO3@GM shows remarkable performance for photocatalytic degradation (towards methyl orange (MO) about 98% within 30 min) and disinfection (100% Escherichia coli (E. coli) inactivation) and high cyclic stability.


Assuntos
Compostos Férricos/química , Grafite/química , Microtúbulos/química , Compostos de Prata/química , Prata/química , Temperatura Ambiente , Catálise , Tamanho da Partícula , Processos Fotoquímicos , Propriedades de Superfície
9.
J Colloid Interface Sci ; 555: 770-782, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31419627

RESUMO

As a sustainable and cost-efficient technique, photocatalytic technology provides an ideal method for energy utilization and environmental pollution control. The current photocatalyst is commonly based on single charge transfer approach, which cannot meet the demand of rapidly charge transfer to improve the photocatalytic performance. Herein, a novel Ag3PO4/MWCNT/Bi2WO6 Z-scheme heterojunction photocatalyst with multiple charge-carrier transfer channels was successfully prepared by a simple hydrothermal and deposition procedure, which possessed remarkable charge carriers separation efficiency and broad photoabsorption: (i) Z-scheme charge transfer channel was formed by Ag3PO4, Bi2WO6 and Ag; (ii) Ag showed the "electron sink" property and surface plasmon resonance (SPR) effect; (iii) multi-walled carbon nanotube (MWCNT) can act as electron accepter to improve the transfer efficiency of photoinduced electron. Ag3PO4/MWCNT/Bi2WO6 composite shows excellent visible light drive photocatalytic performance for organic pollution degradation. And the degradation pathways of tetracycline (TC) were investigated at length. In addition, the cyclic experiments confirmed that the photocatalytic stability of Ag3PO4/MWCNT/Bi2WO6. The hole (h+) and superoxide radical (O2-) radicals were confirmed that played a key role in the photodegradation system. This work provides inspiration for rational fabrication of excellent photocatalyst with multi-charge carrier transfer channels to meet increasing environmental requirements.


Assuntos
Bismuto/química , Fosfatos/química , Compostos de Prata/química , Prata/química , Tetraciclina/química , Compostos de Tungstênio/química , Catálise , Tamanho da Partícula , Processos Fotoquímicos , Fotólise , Propriedades de Superfície
10.
J Environ Sci (China) ; 84: 1-12, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31284901

RESUMO

A series of functional organic-metal AgCl-decorated graphitic carbon nitride (AgCl-CNx) composites were synthesized and applied for the degradation of oxalic acid (OA) under visible light. The highest photocatalytic activity was achieved with AgCl decoration ratio of 1.0 (denoted as AgCl-CN1.0). The pseudo-first-order constant for OA degradation was 0.0722 min-1 with the mineralization efficiency of 90.80% after 60 min reaction in the photocatalytic process with AgCl-CN1.0. A variety of characterization techniques including Brunauer-Emmett-Teller, X-ray diffraction, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, ultraviolet-visible diffuse reflectance spectra, photoluminescence, and Mott-Schottky were utilized to elucidate the physicochemical, microstructure, and optical properties contributing to the improvement of the photocatalytic performance. The results showed that AgCl-CN1.0 had an oblate flaky erythrocyte-like structure with a moderate band gap energy of ~3.00 eV. In addition, the effects of the key parameters (i.e., AgCl-CN1.0 dosage, initial OA concentration, solution pH, and presence of natural organic matter) on OA degradation were systematically investigated. Radical scavenger experiments indicated that photogenerated holes, electrons, superoxide anion radicals, and hydroxyl radicals were the dominant reactive species. Moreover, AgCl-CN1.0 exhibited excellent stability and reusability for OA degradation without detectable Ag+ release in the solution over multiple reaction cycles. The efficient OA mineralization could be mainly ascribed to the moderate specific surface area, increased numbers of active sites, and effective interfacial charge transfer of AgCl-CN1.0. Overall, the AgCl-CN1.0 composite was demonstrated to be a highly efficient, stable, and recoverable photocatalyst.


Assuntos
Grafite/química , Compostos de Nitrogênio/química , Ácido Oxálico/química , Fotólise , Compostos de Prata/química , Poluentes Químicos da Água/química
11.
Molecules ; 24(15)2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31357478

RESUMO

Pt-decorated Ag@Cu2O heterostructures were successfully synthesized using a simple and convenient method. The Pt nanoparticle density on the Ag@Cu2O can be controlled by changing the concentration of the Pt precursor. The synthesized Ag@Cu2O-Pt nanoparticles exhibited excellent catalytic performance, which was greatly affected by changes in the Ag@Cu2O-Pt structure. To optimize the material's properties, the synthesized Ag@Cu2O-Pt nanoparticles were used to catalyze toxic pollutants and methyl orange (MO), and nontoxic products were obtained by catalytic reduction. The Pt-decorated Ag@Cu2O nanoparticles showed excellent catalytic activity, which significantly decreased the pollutant concentration when the nanoparticles were used for catalytic reduction. The redistribution of charge transfer is the nanoparticles' main contribution to the catalytic degradation of an organic pollutant. This Pt-decorated Ag@Cu2O material has unique optical and structural characteristics that make it suitable for photocatalysis, local surface plasmon resonance, and peroxide catalysis.


Assuntos
Cobre/química , Poluentes Ambientais/química , Nanopartículas Metálicas/química , Compostos Orgânicos/química , Óxidos/química , Compostos de Prata/química , Catálise , Nanopartículas Metálicas/ultraestrutura , Nanocompostos/química , Nanocompostos/ultraestrutura , Análise Espectral
12.
Environ Sci Pollut Res Int ; 26(26): 26883-26892, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31302891

RESUMO

A highly uniform 3D flower-like hierarchical AgCl microsphere was prepared by sonochemical method with the existence of ß-dextrin. The 3D flower-like hierarchical structure can be ascribed to the existence of ß-dextrin, which provides nucleation sites for the growth of nanosheets because of the strong interaction between ß-dextrin and Ag+. The 3D flower-like hierarchical AgCl microspheres were assembled by numerous interleaving nanosheet petals with small thickness. Benefiting from the unique structural features, the as-prepared 3D flower-like hierarchical AgCl microsphere exhibited higher degradation efficiency with degrading 98.17% of methylene blue (MB) and 88.50% of tetracycline (TC) within 40 min, which were both remarkably higher than those of irregular AgCl under visible light irradiation. Besides, the photocatalytic degradation rate constant of 3D flower-like hierarchical AgCl microsphere (0.063 min-1) for MB was 3.94 times higher than that of irregular AgCl (0.016 min-1). Moreover, a possible mechanism for the formation and excellent photocatalytic performance of 3D flower-like hierarchical AgCl microsphere was also proposed.


Assuntos
Microesferas , Nanoestruturas/química , Compostos de Prata/química , Catálise , Dextrinas/química , Poluentes Ambientais/química , Luz , Azul de Metileno/química , Processos Fotoquímicos , Tetraciclina/química , Difração de Raios X
13.
Molecules ; 24(12)2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31248162

RESUMO

Surgical site infections (SSIs) represent the most common nosocomial infections, and surgical sutures are optimal surfaces for bacterial adhesion and biofilm formation. Staphylococcus spp., Enterococcus spp., and Escherichia coli are the most commonly isolated microorganisms. The aim of this research was to evaluate the antibiofilm activity of a medical device (MD) containing TIAB, which is a silver-nanotech patented product. The antibacterial effect was evaluated against Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, and E. coli ATCC 25922 by assessing the minimum inhibitory concentration (MIC) by the Alamar Blue® (AB) assay. The antibiofilm effect was determined by evaluation of the minimum biofilm inhibitory concentration (MBIC) and colony-forming unit (CFU) count. Subsequently, the MD was applied on sutures exposed to the bacterial species. The antimicrobial and antibiofilm effects were evaluated by the agar diffusion test method, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). The MIC was determined for S. aureus and E. faecalis at 2 mg/mL, while the MBIC was 1.5 mg/mL for S. aureus and 1 mg/mL for E. faecalis. The formation of an inhibition zone around three different treated sutures confirmed the antimicrobial activity, while the SEM and CLSM analysis performed on the MD-treated sutures underlined the presence of a few adhesive cells, which were for the most part dead. The MD showed antimicrobial and antibiofilm activities versus S. aureus and E. faecalis, but a lower efficacy against E. coli. Surgical sutures coated with the MD have the potential to reduce SSIs as well as the risk of biofilm formation post-surgery.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Materiais Revestidos Biocompatíveis , Equipamentos e Provisões/efeitos adversos , Equipamentos e Provisões/microbiologia , Compostos de Prata/química , Infecção da Ferida Cirúrgica/etiologia , Bactérias/efeitos dos fármacos , Bactérias/ultraestrutura , Humanos , Testes de Sensibilidade Microbiana
14.
Talanta ; 203: 161-167, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31202322

RESUMO

A simple and rapid impedimetric sensor applicable for industrial lipase activity quantification was developed and characterized. It is based on the lipase catalyzed degradation by hydrolysis of a thin nanocomposite substrate sensitive layer deposited on a PCB stick electrode usable as disposable or regenerable. The sensitive layer degradation rate was evaluated by the impedance changes registration along time resulting from its thickness diminution applying a small amplitude AC voltage with a constant frequency. The AC current phase shift variations along the time caused by the impedance changes were registered as s sensor response. The sensor was characterized in terms of linear quantification range, LOD, precision and quantification time. The response time was found to be from 80 to 6 s for the linear concentration range from 0.99x10-2 to 1.68 U.S.P. U mL-1 with relative errors from 3.75% to 1.24% respectively and a LOD of 8x10-3 U.S.P. U mL-1. Finally, lipase spiked whey samples taken from milk industry were quantified and the results were validated by a titrimetric method revealing a good agreement (relative error less than 4.5%).


Assuntos
Lipase/análise , Impedância Elétrica , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Desenho de Equipamento , Limite de Detecção , Nanopartículas Metálicas/química , Nanocompostos/química , Azeite de Oliva/química , Óxidos/química , Dióxido de Silício/química , Compostos de Prata/química
15.
IET Nanobiotechnol ; 13(4): 435-440, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31171749

RESUMO

The silver oxide nanoparticles (AgO2-NPs) were synthesised using silver foil as a new precursor in wet chemical method. X-ray diffraction analysis shows crystallographic structures of AgO2-NPs with crystallite size of 35.54 nm well-matched with standard cubic structure. Scanning electron microscopy analysis clearly shows the random distribution of spherical-shaped nanoparticles. Energy dispersive X-ray analysis confirmed the purity of the samples as it shows no impurity element. Fourier transforms infra-red analysis confirmed the formation of AgO2-NPs with the presence of Ag-O-Ag stretching bond. All the techniques also confirmed the loading of ceftriaxone drug on the surface of AgO2-NPs. This study also described the effect of AgO2-NPs having synergistic activity with ß lactam antibiotic i.e. ceftriaxone against ESBL generating Escherichia coli (E. coli). Among isolated strains of E. coli, 60.0% were found to be ESBL producer. The synergistic activities of AgO2-NPs with ceftriaxone suggest that these combinations are effective against MDR-ESBL E. coli strains as evident by increase in zone sizes. The present study observed rise in MDR-ESBL E. coli with polymorphism of blaCTXM and blaSHV causing UTI infections in Pakistani population. The antibiotic and AgO2-NPs synergistic effect can be used as an efficient approach to combat uro-pathogenic infections.


Assuntos
Antibacterianos/farmacologia , Ceftriaxona/farmacologia , Escherichia coli/efeitos dos fármacos , Nanopartículas Metálicas/química , Óxidos/farmacologia , Compostos de Prata/farmacologia , Antibacterianos/química , Ceftriaxona/química , Sinergismo Farmacológico , Testes de Sensibilidade Microbiana , Óxidos/química , Compostos de Prata/química
16.
Biomed Res Int ; 2019: 4676354, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31211137

RESUMO

The incorporation of nanoparticles into endodontic sealers aims at increasing antimicrobial activity of the original material. Aim. The aim of this study is to incorporate the nanostructured silver vanadate decorated with silver nanoparticles (AgVO3, at 2.5%, 5%, and 10%) into three endodontic sealers and evaluate the antibacterial activity of freshly sealers, surface topography and chemical composition, and setting time. Material and Methods. The AgVO3 was incorporated into AH Plus, Sealer 26, and Endomethasone N at concentrations 0%, 2.5%, 5%, and 10% (in mass). The antibacterial activity of freshly sealers was assessed by direct contact with Enterococcus faecalis and CFU/mL count (n=10), surface topography, and chemical composition were measured by SEM/EDS, and the setting time was measured by Gillmore needle (n=10). The Kruskal-Wallis and Dunn statistical tests were applied (α=0.05). Results. All groups of sealers evaluated inhibited E. faecalis (p>0.05). The incorporation of AgVO3 altered the atomic proportions between components of the endodontic sealers, and the percentage of silver (Ag) and vanadium (V) increased proportionally to the concentrations of AgVO3. Topography analysis showed differences in components distribution on the surface of the specimens. The sealers incorporated with AgVO3 of AH Plus presented a lower setting time than the control group (p<0.05). For Sealer 26 and Endomethasone N, the incorporation of AgVO3 increased the setting time in relation to control group (p<0.05). Conclusions. The modification of endodontic sealers by AgVO3 increased the atomic percentage of Ag and V proportionally to the concentration of the nanomaterial and changed the atomic percentage of the sealer components and setting times. It cannot be affirmed that the AgVO3 promote differences in the antimicrobial activity of freshly sealers, and further investigations of the antimicrobial activity of the set sealers should be carried out.


Assuntos
Antibacterianos , Bismuto , Hidróxido de Cálcio , Enterococcus faecalis/crescimento & desenvolvimento , Nanoestruturas/química , Materiais Restauradores do Canal Radicular , Compostos de Prata , Vanadatos , Antibacterianos/farmacologia , Bismuto/química , Bismuto/farmacologia , Hidróxido de Cálcio/química , Hidróxido de Cálcio/farmacologia , Dexametasona/química , Dexametasona/farmacologia , Combinação de Medicamentos , Formaldeído/química , Formaldeído/farmacologia , Humanos , Hidrocortisona/química , Hidrocortisona/farmacologia , Materiais Restauradores do Canal Radicular/química , Materiais Restauradores do Canal Radicular/farmacologia , Compostos de Prata/química , Compostos de Prata/farmacologia , Timol/análogos & derivados , Timol/química , Timol/farmacologia , Vanadatos/química , Vanadatos/farmacologia
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 222: 117216, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31176158

RESUMO

Advanced exploitation in the green synthesis of nanomaterials has received considerable attention in the recent years. So that, an eco-friendly approach is proposed for the synthesis of silver­silver chloride nanoparticles (Ag@AgCl-NPs) which does not require any external reducing & capping agents, organic solvent and external halide sources using an aqueous extract green marine alga (Chaetomorpha sp).In order to characterize the formation of Ag@AgCl-NPs, several instruments including UV-vis, FTIR, HR-TEM, EDS mapping, XRD, XPS, SAED and DLS were used. On the other hands, although numerous methods have been reported for the analysis of toxic Hg2+ in drinking water, development of simple, rapid, inexpensive, selective and sensitive sensors still remains a great challenge. Herein, the colorimetric sensor studies of this green synthesized Ag@AgCl-NPs showed an interesting feature for sensing of hazardous Hg2+ in water. The colorimetric assay is based on the concentration - dependent degradation of as-prepared Ag@AgCl-NPs in the presence of Hg2+. The detection limit of this affordable assay is 4.19 nM which is below the defined value by china agency and more importantly is below the defined by the U.S. Environmental Protection Agency for drinkable water.


Assuntos
Clorófitas/química , Mercúrio/análise , Nanopartículas Metálicas/química , Compostos de Prata/química , Prata/química , Poluentes Químicos da Água/análise , Colorimetria/métodos , Água Potável/análise , Química Verde/métodos , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Oxirredução , Compostos de Prata/síntese química
18.
Environ Monit Assess ; 191(6): 374, 2019 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-31104171

RESUMO

In the present study, the synthesizing of silver@reduced graphene oxide nanocomposite, through a facile precipitation method, is reported. In this method, in the synthesizing step, reduced graphene oxide was applied as a support, silver acetate as a precursor of Ag0, and sodium hydroxide as a medium for reducing procedure. Then synthesized particles were characterized by using transmission electron microscopy analysis, Fourier-transform infrared spectroscopy, field emission scanning microscopy/energy dispersive X-ray, and X-ray diffraction. Adsorbent potentials of the prepared nanocomposite were evaluated for sulfamethoxazole removal from polluted aqueous solutions via two different experimental methods, namely, "one-at-a-time" and "central composite design". The given results from the one-at-a-time method confirms that 0.007 g of silver@reduced graphene oxide nanocomposite can remove 88% (188.57 mg/g) of sulfamethoxazole from a 0.05 dm3 solution (initial concentration 30 mg/dm3) at pH = 5 after 3600 s' contact time. However, in the central composite design method, the optimum condition was 95% (79.17 mg/g) uptake of this drug from 0.05 dm3 of polluted solution with initial concentration of 30 mg/dm3 and pH = 7.5, using 0.018 g of the adsorbent in 3600 s. The main mechanism for sulfamethoxazole removal can be suggested as a suitable interaction between S atoms in functional groups in the drug and Ag atoms on the surface of nanoparticles. The pseudo-second-order patterns and Freundlich model described the empirical data isotherm and kinetics for the adsorption processes, respectively. The maximum adsorption capacity by experimental and theoretical isotherm methods (Langmuir) obtained 250 and 357 mg/g, respectively. Efficiency of the adsorbent in treatment of SMX from real samples displayed less hardness and electrical conductance samples have the maximum uptake percent while existence of nitrate ions in the solutions did not induce any negative effect on the removal of the SMX. All obtained results indicated loading of Ag nanoparticles on rGO nanosheets is an effective strategy for SMX uptake with high proficiency and shows great promise as pollutant adsorbent for environmental applications.


Assuntos
Acetatos/química , Antibacterianos/química , Grafite/química , Compostos de Prata/química , Sulfametoxazol/química , Adsorção , Monitoramento Ambiental/métodos , Cinética , Nanopartículas Metálicas , Microscopia Eletrônica de Transmissão , Nanocompostos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Água/análise , Poluentes Químicos da Água/química , Difração de Raios X
19.
J Nanobiotechnology ; 17(1): 58, 2019 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-31036008

RESUMO

BACKGROUND: Iron oxide nanocomposites have received a great attention for their application in various fields like physics, medicine, biology, and material science etc., due to their unique properties, such as magnetism, electrical properties, small size, biocompatibility and low toxicity. METHODS: Fe3O4/Ag3PO4@WO3 nanocomposites with different weight percent of Ag3PO4 were successfully prepared through fabricated Ag3PO4/Fe3O4 with WO3 via in situ fabrication method, electrospinning involved precursor solution preparation and spinning to enhance photocatalyst performance under simulated sunlight for the degradation of methylene blue (MB) and antibacterial activity against Staphylococcus aureus (S. aureus). RESULTS: The photocatalytic degradation of methylene blue (MB) under simulated light irradiation indicated that the nanocomposite with 0.25 mg of Ag3PO4 has the best activity. An additional advantage of these photocatalysts is magnetic recoverability, using external magnetic field and photocatalytic stability of the nanocomposites was evaluated for three cycles. In addition, using different scavengers, holes (h+) and superoxide radical (O 2 ·-) radicals and hydroxide radical (·OH) were identified the main oxidative species in the degradation reaction of methylene blue. CONCLUSIONS: The results reveal that Fe3O4/Ag3PO4@WO3-0.25 nanocomposites have photocatalytic and antibacterial activity against S. aureus. The photocatalyst and mechanism based on the enhancement of electron transfer processes between Ag3PO4 and WO3 nanoparticles.


Assuntos
Antibacterianos/química , Óxido Ferroso-Férrico/química , Nanopartículas Metálicas/química , Nanocompostos/química , Oxidantes Fotoquímicos/química , Óxidos/química , Compostos de Prata/química , Tungstênio/química , Catálise , Transporte de Elétrons , Hidróxidos/química , Luz , Magnetismo/métodos , Azul de Metileno/química , Oxirredução , Tamanho da Partícula , Staphylococcus aureus , Superóxidos/química , Poluentes Químicos da Água/química
20.
J Mater Sci Mater Med ; 30(6): 59, 2019 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-31127361

RESUMO

Recently, chronic osteomyelitis is still a challenging surgical problem. Unfortunately, the traditional clinical method using bone cement loaded antibiotics is restricted due to its non-biodegradability and limited release of antibiotics. Hydroxyapatite is a good adsorbent with good biocompatibility, an ideal bone repair material, and can avert the requirement for the secondary surgical procedure of removal. In this study, nano-hydroxyapatite combined with a polyurethane containing 3% silver (Ag/n-HA/PU) was synthesized, and investigated for its efficacy of treating chronic bone infection with bone defects. To clarify its silver ions release characteristics, the concentration of the Ag+ in the elution was analyzed every day after in vitro deionized water immersion. A chronic osteomyelitis of tibia in rabbit model was established, and 70 New Zealand rabbits were divided into 4 groups, including the blank control group, nano-hydroxyapatite combined with polyurethane (n-HA/PU) implant group, 3% Ag/n-HA/PU group and 10% Ag/n-HA/PU group after debridement. Routine blood tests, radiography, Micro-CT, and histological staining were conducted at 4 days, 3, 6 and 12 weeks post-treatment. The results showed that the released silver from the 3% Ag/n-HA/PU and 10% Ag/n-HA/PU exhibited an initial burst release and followed by a slow controlled release up to 39 days and 42 days respectively. A good repair of bone defects, an appropriate rate of degradation of scaffolds and no significant toxicity were observed in the 3% Ag/n-HA/PU group, indicating the advantages of this novel synthetic scaffold to be a potential option for the treatment of chronic osteomyelitis. A novel nano-composite, nano-hydroxyapatite combined with a polyurethane containing 3% silver (Ag/n-HA/PU) provide controlled release of Ag+, illustrated by its abilities of biodegradation, antimicrobial activity, and favorable repair of bone defects in the treatment of chronic osteomyelitis.


Assuntos
Substitutos Ósseos , Durapatita/química , Osteomielite/terapia , Fosfatos/química , Compostos de Prata/química , Adsorção , Animais , Antibacterianos/administração & dosagem , Materiais Biocompatíveis/química , Regeneração Óssea/efeitos dos fármacos , Doença Crônica , Modelos Animais de Doenças , Masculino , Nanopartículas/química , Poliuretanos/química , Coelhos , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/prevenção & controle , Staphylococcus aureus/efeitos dos fármacos , Tíbia/patologia , Tecidos Suporte , Cloreto de Tolônio , Microtomografia por Raio-X
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