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1.
J Adhes Dent ; 22(4): 365-372, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32666062

RESUMO

PURPOSE: To investigate the reparability of aged and fresh resin composite after different mechanical surface pretreatments. MATERIALS AND METHODS: Sixty composite specimens (Filtek Supreme XTE, 3M Oral Care) were either aged by thermal cycling (5000 cycles, 5-55°C) and six months of water storage, or immediately processed within 5 min after polymerization. Both aged and fresh specimens were either ground with fine (46-µm) or coarse (100-µm) diamond burs and then silanized or sandblasted with aluminum oxide (Al2O3) and silanized. In the negative control group, no mechanical surface pretreatment or silanization was performed. Specimens (n = 6 per group) were repaired with an adhesive (OptiBond FL, Kerr) and a resin composite (Filtek Supreme XTE). Directly adhered composite-to-composite increments served as the positive control group. After thermoycling, microtensile repair bond strength was assessed and statistically analyzed (α = 0.05). RESULTS: Aged composite surfaces revealed significantly lower repair bond strength than immediately repaired composite. The negative control group demonstrated the significantly lowest microtensile bond strength of all groups. No significant differences in repair bond strength were observed between the different mechanical pretreatments for both aged and fresh specimens. The repair bond strength of fresh composite pretreated with a fine diamond bur + Al2O3 + silane or a coarse diamond bur with/without Al2O3 + silane did not differ significantly from the positive control group. CONCLUSION: The age of the repaired composite has a greater influence on repair bond strength than does the type of composite surface pretreatment.


Assuntos
Colagem Dentária , Resinas Compostas , Teste de Materiais , Silanos , Estresse Mecânico , Propriedades de Superfície , Resistência à Tração
2.
J Prosthodont Res ; 64(3): 319-325, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32423658

RESUMO

PURPOSE: The purpose of this study was to evaluate the effectiveness of both a resin primer containing methyl methacrylate (MMA) and a silanizing agent on bonding to indirect resin composite blocks, using two types of build-up hybrid resin composites. METHODS: SHOFU BLOCK HC (Shofu) specimens were blasted with alumina, after which one of two surface treatments was applied: CERA RESIN BOND (Shofu, the Silane group) or HC primer (Shofu, the MMA group). Resin composites made using either Solidex Hardura (SDH, Shofu) or Ceramage Duo (CMD, Shofu) were built up and micro-tensile bond strength (µTBS) values were measured after storage in water for either 24h or 6 months (n=24 per group). The fracture surfaces after µTBS measurements and the resin block/build-up resin interfaces were observed by scanning electron microscopy (SEM). RESULTS: The bond strength of the Silane/SDH group significantly decreased after 6 months (p<0.001), whereas in the MMA group there was no significant loss after 24h or 6 months (p=0.99). In the CMD group, the bond strength after 6 months was significantly lowered in both the Silane group (p<0.001) and the MMA group (p<0.001), but the latter still showed greater adhesion. SEM images demonstrated that the matrix resin was partially destroyed at the fracture surfaces of the MMA group and fracture surface unevenness was observed. CONCLUSIONS: A primer containing MMA produced stronger bonding to CAD/CAM resin even after long-term aging compared to a silane treatment.


Assuntos
Colagem Dentária , Cimentos de Resina , Resinas Compostas , Desenho Assistido por Computador , Teste de Materiais , Microscopia Eletrônica de Varredura , Silanos , Propriedades de Superfície , Resistência à Tração
3.
Pestic Biochem Physiol ; 165: 104475, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32359550

RESUMO

The development of plant protection product (PPPs)-resistant populations of plant pathogens, pests, and weeds, represents a major challenge that the crop protection sector is facing. Focusing on plant pathogenic fungi, the increased efflux of the active ingredients (a.i.) from the cytoplasm is highly correlated to elevated resistance levels to the applied fungicides. Such mechanism is regulated by ATP-binding cassette transporters (ABC transporters), and although it has been investigated for the past two decades, the latest developments in "omics" technologies could provide new insights with potential applications in crop protection. Within this context, and based on results from preliminary experiments, we have undertaken the task of mining the involvement of the ABC transporter YCF1, which is located in the vacuole membrane, in the fungicide resistance development, applying a functional genomics approach and using yeast (Saccharomyces cerevisiae) as the model organism. Among the fungicides being assessed, flusilazole, which belongs to the azole group of dimethylation inhibitors (DMIs), was discovered as a possible substrate of the YCF1. GC/EI/MS metabolomics analysis revealed the effect of the fungicide's toxicity and that of genotype on yeast's metabolism, confirming the role of this transporter. Fluctuations in the activity of various yeast biosynthetic pathways associated with stress responses were recorded, and corresponding metabolites-biomarkers of flusilazole toxicity were discovered. The metabolites α,α-trehalose, glycerol, myo-inositol-1-phosphate, GABA, l-glutamine, l-tryptophan, l-phenylalanine, l-tyrosine, and phosphate, were the major identified biomarkers of toxicity. Among these, are metabolites that play important roles in fungal metabolism (e.g., cell responses to osmotic stress) or serve as signaling molecules. To the best of our knowledge, this is the first report on the implication of YCF1 in fungal resistance to PPPs. Additionally, the results of GC/EI/MS yeast metabolomics confirmed the robustness of the method and its applicability in the high-throughput study of fungal resistance to fungicides.


Assuntos
Saccharomyces cerevisiae , Vacúolos , Proteínas Fúngicas , Metabolômica , Silanos , Triazóis
4.
Braz Oral Res ; 34: e045, 2020 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-32401935

RESUMO

This in vitro study aimed to evaluate the effect of a silane-containing universal adhesive used with or without a silane agent on the repair bond strength between aged and new composites. Forty nanohybrid composite resin blocks were stored in distilled water for 14 d and thermo-cycled. Sandpaper ground, etched, and rinsed speciments were randomly assigned into four experimental groups: silane + two-step etch-and-rinse adhesive system, two-step etch-and-rinse adhesive system, silane + silane-containing universal adhesive system, and silane-containing universal adhesive system. Blocks were repaired using the same composite. After 24 h of water storage, the blocks were sectioned and bonded sticks were submitted to microtensile testing. Ten unaged, non-repaired composite blocks were used as a reference group to evaluate the cohesive strength of the composite. Two-way ANOVA and Tukey's tests were used to analyze average µTBS. One-way ANOVA and Dunnet post-hoc tests were used to compare the cohesive strength values and bond strength obtained in the repaired groups (α = 0.05). The µTBS values were higher for the silane-containing universal adhesive compared to the two-step etch-and-rinse adhesive system (p = 0.002). Silane application improved the repair bond strength (p = 0.03). The repair bond strength ranged from 39.3 to 65.8% of the cohesive strength of the reference group. Using universal silane-containing adhesive improved the repair bond strength of composite resin compared to two-step etch-and-rinse adhesive. However, it still required prior application of a silane agent for best direct composite resin repair outcomes.


Assuntos
Resinas Compostas/química , Cimentos Dentários/química , Cimentos de Resina/química , Silanos/química , Análise de Variância , Colagem Dentária/métodos , Teste de Materiais , Valores de Referência , Reprodutibilidade dos Testes , Propriedades de Superfície , Resistência à Tração , Fatores de Tempo
5.
Int J Nanomedicine ; 15: 2583-2603, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32368042

RESUMO

Introduction: Over the past several years, nano-based therapeutics were an effective cancer drug candidate in order to overcome the persistence of deadliest diseases and prevalence of multiple drug resistance (MDR). Methods: The main objective of our program was to design organosilane-modified Fe3O4/SiO2/APTS(~NH2) core magnetic nanocomposites with functionalized copper-Schiff base complex through the use of (3-aminopropyl)triethoxysilane linker as chemotherapeutics to cancer cells. The nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), TEM, and vibrating sample magnetometer (VSM) techniques. All analyses corroborated the successful synthesis of the nanoparticles. In the second step, all compounds of magnetic nanoparticles were validated as antitumor drugs through the conventional MTT assay against K562 (myelogenous leukemia cancer) and apoptosis study by Annexin V/PI and AO/EB. The molecular dynamic simulations of nanoparticles were further carried out; afterwards, the optimization was performed using MM+, semi-empirical (AM1) and Ab Initio (STO-3G), ForciteGemo Opt, Forcite Dynamics, Forcite Energy and CASTEP in Materials studio 2017. Results: The results showed that the anti-cancer activity was barely reduced after modifying the surface of the Fe3O4/SiO2/APTS nanoparticles with 2-hydroxy-3-methoxybenzaldehyde as Schiff base and then Cu(II) complex. The apoptosis study by Annexin V/PI and AO/EB stained cell nuclei was performed that apoptosis percentage of the nanoparticles increased upon increasing the thickness of Fe3O4 shell on the magnetite core. The docking studies of the synthesized compounds were conducted towards the DNA and Topoisomerase II via AutoDock 1.5.6 (The Scripps Research Institute, La Jolla, CA, USA). Conclusion: Results of biology activities and computational modeling demonstrate that nanoparticles were targeted drug delivery system in cancer treatment.


Assuntos
Cobre/química , Compostos Férricos/síntese química , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Propilaminas/síntese química , Bases de Schiff/síntese química , Silanos/síntese química , Dióxido de Silício/síntese química , Apoptose , Núcleo Celular/metabolismo , DNA/química , DNA Topoisomerases Tipo II/química , Compostos Férricos/química , Humanos , Células K562 , Magnetismo , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/ultraestrutura , Propilaminas/química , Bases de Schiff/química , Silanos/química , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
6.
Food Chem ; 320: 126683, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32229401

RESUMO

Here, we demonstrate use of acetylcholinesterase (AChE)-responsive polyoxometalate (POM)/surfactant supramolecular spheres to build a liquid crystal (LC)-based sensing platform for detection of organophosphorus pesticides. The self-assembled spheres are composed of hybrid materials of a POM, sodium dodecatungstophosphate (PW12), and a surfactant, myristoylcholine (Myr). It displays dark appearance when the aqueous solution is in contact with LCs supported on the octadecyltrichlorosilane-treated glass deposited with the supramolecular spheres, suggesting perpendicular orientation of LCs at the aqueous/LC interface. In contrast, LCs show bright appearance when the surface-deposited supramolecular spheres are enzymatically hydrolyzed by AChE, corresponding to planar orientation of LCs at the aqueous/LC interface. Detection of organophosphates are successfully achieved as they are potent inhibitors of AChE. The detection limit of the sensing platform reached 0.9 ng/mL for dimethoate. This method can avoid disturbance of external interference with excellent specificity and sensitivity, which makes it very promise in detection of organophosphorus pesticides.


Assuntos
Acetilcolinesterase/metabolismo , Análise de Alimentos/métodos , Cristais Líquidos/química , Praguicidas/análise , Análise de Alimentos/instrumentação , Hidrólise , Lagos/análise , Limite de Detecção , Compostos Organofosforados/análise , Silanos/química , Tensoativos/química , Compostos de Tungstênio/química , Água/química , Poluentes Químicos da Água/análise
7.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 38(2): 155-159, 2020 Apr 01.
Artigo em Chinês | MEDLINE | ID: mdl-32314888

RESUMO

OBJECTIVE: This work aimed to evaluate the effect of different surface treatments on the shear bond strength of resin nano ceramic to resin cement, thereby providing a theoretical basis for the improvement of clinical application. METHODS: A total of 150 specimens (10 mm×10 mm×3 mm) were milled from resin nano ceramic blocks (Lava Ultimate) using computer-aided design/computer aided manufacturing(CAD/CAM) technology. The specimens were randomly divided into five groups according to the surface treatment performed, as follows: control, sandblasted, sandblasted+silane, hydrofluoric acid, and hydrofluoric acid+silane groups. After the corresponding surface treatment, the specimens were cemented using Single Bond Universal Adhesive and RelyXTM Ultimate ClickerTM adhesive resin cement. All cemented specimens were placed in distilled water for 24 h and 30 days and subjected to a shear bond strength test in a universal testing machine. RESULTS: The surface treatment and water storage periods showed significant effects on bond strength. Surface treatment with sandblasted+silane showed the highest shear strength values among all tested groups, and the difference was statistically significant (P<0.05). A difference was observed between the control and hydrofluoric acid groups, and both had significantly difference compared with other groups (P<0.05). Sandblasted and hydrofluoric acid+silane groups were not statistically different, and both had significantly difference compared with other groups (P<0.05). CONCLUSIONS: The surface of resin nanoceramic treated by sand-blasted, sandblasted+silane, and hydrofluoric acid+silane can improve the bond strength. The sandblasted+silane group had the best the shear bond strength among the groups.


Assuntos
Colagem Dentária , Cimentos de Resina , Cerâmica , Porcelana Dentária , Análise do Estresse Dentário , Teste de Materiais , Resistência ao Cisalhamento , Silanos , Propriedades de Superfície
8.
J Chromatogr A ; 1621: 461035, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32188564

RESUMO

The present work described two triacontyl-bonded silica adsorbents containing different polar embedded groups (i.e. amide- and carbamate-type) for high performance liquid chromatography, which were prepared by covalent surface modification of silica gel with respective pre-synthesized polar-embedded triacontyl (C30) silane. The acylimidazole-mediated method was used for the first time for the synthesis of amide-type alkyl silane, while the carbamate-type silane was obtained via an improved solvent-free procedure. A conventional C30 stationary phase was also developed on the same silica substrate in the similar manner, which was used as a reference column for comparison of the unique mechanisms facilitated and/or furnished by the polar groups. The successful immobilization of the designed C30 species was confirmed by infrared spectroscopy and elemental analysis. In further comparison with an amide-embedded octadecyl (C18) two other conventional C18 stationary phases of different surface chemistry, detailed chromatographic characterization of the C30 series stationary phases was performed in terms of surface density, hydrophobicity, aromatic selectivity, shape selectivity and water tolerance using a diversified range of analytes, including homologous alkylbenzenes, isomeric polycyclic aromatic hydrocarbons, carotenes, congeners of polychlorobiphenyls, aromatic amines, phenolic compounds, estrogens and nucleosides. A high resemblance between the chromatographic behaviors of the two polar-modified C30 stationary phases was observed, meanwhile they demonstrated noticeable differences from non-polar C30 stationary phase. The polar-embedded C30 phases showed satisfactory performance towards the solutes of interest in the studied conditions. The beneficial synergy of the polar groups and the triacontyl chains enabled these polar-enhanced C30 stationary phases to address challenging separation tasks with high selectivity.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Dióxido de Silício/química , Amidas/química , Aminas/análise , Derivados de Benzeno/análise , Carbamatos/química , Carotenoides/análise , Estrogênios/análise , Interações Hidrofóbicas e Hidrofílicas , Nucleosídeos/análise , Fenóis/análise , Bifenilos Policlorados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Silanos/química , Sílica Gel/química
9.
Artigo em Inglês | MEDLINE | ID: mdl-32222675

RESUMO

C60-based magnetic nanospheres were synthesized by coating Fe3O4 nanospheres with silica, then modifying with 3-aminopropyltriethoxysilane as a linker and a C60 fullerene stationary phase. The morphologies, magnetic properties, infrared absorption and carbon content of magnetic nanospheres were studied by TEM, VSM, FTIR and carbon and sulfur analyzer. The magnetic nanospheres were employed for the magnetic solid-phase extraction (MSPE) of 16 polycyclic aromatic hydrocarbons (PAHs) in nine Chinese herbal medicines. The analyses were conducted by isotope dilution gas chromatography-mass spectrometry. The main parameters influencing the extraction, including extraction solvent, adsorbent amount, and extraction time were optimized. Method validation showed that the limit of detection (LOD) was 0.02-0.11 µg/kg, and the limit of quantification (LOQ) was 0.07-0.36 µg/kg. The spiked recoveries rates for 16 PAHs in white peony root were 84.7-107.2%. The relative standard deviation (RSD) was 1.7-8.4%. The established method was further used for the determination 16 PAHs in nine Chinese herbal medicines. Total content of 16 PAHs varied from 73.6 µg/kg (fructus lycii) to 2172.6 µg/kg (astragalus root). The results indicate that the pollution of PAHs in Chinese herbal medicines is serious. The established method can effective detect PAHs contamination in Chinese herbal medicines.


Assuntos
Medicamentos de Ervas Chinesas/análise , Fulerenos/química , Isótopos/química , Nanopartículas de Magnetita/química , Nanosferas/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Adsorção , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Fenômenos Magnéticos , Propilaminas/química , Silanos/química , Dióxido de Silício/química , Extração em Fase Sólida/métodos , Propriedades de Superfície
10.
Nature ; 579(7799): 421-426, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32188939

RESUMO

Bioorthogonal chemistry capable of operating in live animals is needed to investigate biological processes such as cell death and immunity. Recent studies have identified a gasdermin family of pore-forming proteins that executes inflammasome-dependent and -independent pyroptosis1-5. Pyroptosis is proinflammatory, but its effect on antitumour immunity is unknown. Here we establish a bioorthogonal chemical system, in which a cancer-imaging probe phenylalanine trifluoroborate (Phe-BF3) that can enter cells desilylates and 'cleaves' a designed linker that contains a silyl ether. This system enabled the controlled release of a drug from an antibody-drug conjugate in mice. When combined with nanoparticle-mediated delivery, desilylation catalysed by Phe-BF3 could release a client protein-including an active gasdermin-from a nanoparticle conjugate, selectively into tumour cells in mice. We applied this bioorthogonal system to gasdermin, which revealed that pyroptosis of less than 15% of tumour cells was sufficient to clear the entire 4T1 mammary tumour graft. The tumour regression was absent in immune-deficient mice or upon T cell depletion, and was correlated with augmented antitumour immune responses. The injection of a reduced, ineffective dose of nanoparticle-conjugated gasdermin along with Phe-BF3 sensitized 4T1 tumours to anti-PD1 therapy. Our bioorthogonal system based on Phe-BF3 desilylation is therefore a powerful tool for chemical biology; our application of this system suggests that pyroptosis-induced inflammation triggers robust antitumour immunity and can synergize with checkpoint blockade.


Assuntos
Preparações de Ação Retardada/administração & dosagem , Neoplasias Mamárias Experimentais/imunologia , Piroptose/imunologia , Animais , Cumarínicos/administração & dosagem , Cumarínicos/química , Cumarínicos/metabolismo , Cumarínicos/farmacocinética , Preparações de Ação Retardada/química , Preparações de Ação Retardada/metabolismo , Preparações de Ação Retardada/farmacocinética , Feminino , Proteínas de Fluorescência Verde/administração & dosagem , Proteínas de Fluorescência Verde/química , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Fluorescência Verde/farmacocinética , Células HeLa , Humanos , Imunoconjugados/administração & dosagem , Imunoconjugados/química , Imunoconjugados/metabolismo , Imunoconjugados/farmacocinética , Inflamassomos/imunologia , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Neoplasias Mamárias Experimentais/metabolismo , Neoplasias Mamárias Experimentais/patologia , Camundongos , Camundongos Endogâmicos BALB C , Oligopeptídeos/administração & dosagem , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Oligopeptídeos/farmacocinética , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Proteínas/administração & dosagem , Proteínas/química , Proteínas/metabolismo , Proteínas/farmacocinética , Silanos/administração & dosagem , Silanos/química , Silanos/metabolismo , Silanos/farmacocinética , Linfócitos T/imunologia , Trastuzumab/administração & dosagem , Trastuzumab/química , Trastuzumab/metabolismo , Trastuzumab/farmacocinética , Ensaios Antitumorais Modelo de Xenoenxerto
11.
Food Chem ; 319: 126575, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32172051

RESUMO

A core-shell molecular imprinting fluorescence nanosensor was developed for the ratiometric fluorescence and visual detection of folic acid (FA). The nanosensor was prepared by anchoring imprinting shell on the silica nanoparticles, and embedding the CdTe quantum dots in imprinted shell to provide FA-dependent fluorescence signals. Under the optimum conditions, a favorable linearity relationship between the fluorescence intensities ratio (I449/I619) and the FA concentration over 0.23-113 µM was offered with a detection limit (LOD) of 48 nM. The visual detection for FA was realized by evaluating profuse fluorescence color change from red to pink to purple to final blue. The proposed sensor possessed excellent sensing performances of rapid response, high precision, super sensitivity and selective recognition. Furthermore, endogenous FA was detected in real samples ranging from 37.4 to 265.8 µg/100 g; satisfactory spiked recoveries were obtained within 94.8-104.2%, which conformed to the measurement results by HPLC-UV.


Assuntos
Ácido Fólico/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Impressão Molecular/métodos , Compostos de Cádmio/química , Cor , Ácido Fólico/química , Limite de Detecção , Nanopartículas/química , Propilaminas/química , Pontos Quânticos/química , Sensibilidade e Especificidade , Silanos/química , Dióxido de Silício/química , Espectrometria de Fluorescência/instrumentação , Espectrometria de Fluorescência/métodos , Telúrio/química
12.
Chemosphere ; 251: 126384, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32143082

RESUMO

Aminosilane materials, with their low cost and ease of modification, have exhibited great potential for the adsorption of perfluorinated compounds (PFCs) from water. However, this kind of material may be facing two drawbacks during its application: low resistance to hydrolysis and difficulties in separation from the water matrix. This work proposed a strategy of grafting N-(2-aminoethyl) aminopropyltrimethoxysilane (AE-APTMS) on the surface of magnetic γ-Fe2O3 nanoparticles by full utilization of the sorption sites provided by the aminosilane and the magnetism by γ-Fe2O3. The FTIR and XRD results verified the formation of the magnetic AE-APTMS nanocomposite. The core-shell nanocomposite showed a superparamagnetic property and an isoelectric point at pH = 8.2. Particularly, compared to the aminopropyltriethoxysilane (APTES) nanocomposite, the AE-APTMS nanocomposite exhibited improved hydrolytic stability with 60% less loss of the amine groups during the 48 h adsorption process, as the longer alkyl chain hindered the aminosilane detachment. The AE-APTMS nanocomposite exhibited a rapid adsorption with the removal efficiency of 78% for perfluorooctane sulfonate (PFOS) and 65% for perfluorooctanoate (PFOA) due to the electrostatic interaction and hydrophobic interaction. The regeneration and reuse of the magnetic AE-APTMS nanocomposite were conveniently realized with the removal efficiency higher than 70% for both PFOS and PFOA even after 15 adsorption-desorption cycles. The stable magnetic aminosilane nanocomposite with the ease of separation may provide a new strategy to achieve the economical and effective removal of typical PFCs from water.


Assuntos
Ácidos Alcanossulfônicos/química , Caprilatos/química , Fluorcarbonetos/química , Nanocompostos/química , Poluentes Químicos da Água/química , Adsorção , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Magnetismo , Propilaminas , Silanos , Água , Poluentes Químicos da Água/análise , Purificação da Água/métodos
13.
Chemosphere ; 251: 126387, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32151812

RESUMO

Adsorption is a simple and effective method for the removal of hexavalent chromium (Cr(VI)) from contaminated water. Several amino silane-graphene oxide (GO) composites with different species of amino groups (pN-GO, psN-GO, and pssN-GO; p: primary, s: secondary, N: amine) were evaluated to investigate their adsorption capacity and the effects of primary and secondary amines on Cr(VI) adsorption. We conducted a quantitative analysis to reveal the difference between primary and secondary amines in terms of Cr(VI) removal efficiency. A synergic effect was observed between the neighboring secondary amines in pssN-GO. From the Langmuir model prediction, we found that the composite with pssN-GO exhibited the highest maximum adsorption capacity (260.74 mg/g), followed by those with psN-GO (208.22 mg/g) and pN-GO (189.47 mg/g). Monolayer adsorption was more dominant when using pssN-GO, with the pseudo-second-order model best fitting the kinetic experiment results, whereas multilayer adsorption was dominant when using psN-GO and pN-GO.


Assuntos
Cromo/química , Grafite/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Silanos/química
14.
Chemosphere ; 251: 126376, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32169694

RESUMO

Highly selective surface molecularly imprinted polymer (SMIP) was prepared on glucose-derived microporous carbon nanospheres (GMCNs) by surface molecular imprinting technology for the removal of phenol from wastewater. GMCNs with rich pore structure and surface oxygenic functional groups were adopted as support materials, on which the active layers were constructed by grafting silane coupling agent 3-(methacryloyloxy) propyltrimethoxysilane. Then with phenol as template molecule, different types and amounts of functional monomer (including methacrylic acid and 4-vinylpyridine (4-VP)) were screened for optimizing imprinting conditions suitable for phenol adsorption, and a series of SMIP was obtained through crosslinking polymerization. The adsorption behaviors of SMIP were evaluated by UV spectrophotometry. The results show that, when 4-VP is used as functional monomer, the resultant 4-VP/SMIP exhibites an excellent adsorption capacity of 85.72 mg g-1. The relative selectivity factor for phenol against hydroquinone, p-nitrophenol and p-tert-butylphenol is 8.38, 7.96 and 6.67, respectively, indicating outstanding adsorption capacity and selectivity of 4-VP/SMIP. The pseudo-second-order model and Langmuir‒Freundlich model fit better than other models for the adsorption of phenol. 4-VP/SMIP is promising for selective removal and enrichment recovery towards phenol in wastewater.


Assuntos
Nanosferas/química , Polímeros/química , Eliminação de Resíduos Líquidos/métodos , Adsorção , Carbono , Metacrilatos , Impressão Molecular , Nitrofenóis , Fenol , Polimerização , Silanos , Águas Residuárias
15.
Braz Oral Res ; 34: e018, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187304

RESUMO

The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.


Assuntos
Silicatos de Alumínio/química , Colagem Dentária/métodos , Ácido Fluorídrico/química , Ácidos Fosfóricos/química , Compostos de Potássio/química , Análise de Variância , Porcelana Dentária/química , Teste de Materiais , Metacrilatos/química , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Cimentos de Resina/química , Resistência ao Cisalhamento/efeitos dos fármacos , Silanos/química , Propriedades de Superfície , Fatores de Tempo
16.
Food Chem ; 315: 126276, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32014669

RESUMO

Cellulose nanofibers (CNF) coated with inorganic nanoparticles are novel hybrid nanocomposites that have great potential in various areas including agriculture and food science. The objectives of this study were to synthesize nanocomposites consisted of CNF coated with silver nanoparticles (AgNPs), which can be used as a surface-enhanced Raman spectroscopy (SERS) platform for measuring pesticides in Oolong tea. CNF were coated with AgNPs to form uniform CNF-AgNP nanocomposites that were investigated by transmission electron microscopy. Three-dimensional and porous CNF structures were loaded with AgNPs with an average size of 41 nm. CNF-AgNP substrates were applied in characterization and measurement of flusilazole in Oolong tea samples by SERS. A detection limit of 0.5 mg/kg for flusilazole was obtained based on partial least squares (PLS) regression analysis. These results indicate that CNF-AgNP nanocomposites combined with SERS is an accurate, sensitive, and efficient technique for identification and quantification of pesticide residues in Oolong tea.


Assuntos
Celulose/química , Nanopartículas Metálicas/química , Nanocompostos/química , Nanofibras/química , Silanos/química , Prata/química , Chá/química , Triazóis/química , Limite de Detecção , Análise Espectral Raman , Propriedades de Superfície
17.
J Chromatogr A ; 1617: 460807, 2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-31889519

RESUMO

Click chemistry has attracted increasing attention for the synthesis of novel stationary phases. Considering the advantage of click chemistry, a strategy based on thiol-Michael addition was developed for the preparation of a new stationary phase herein, and a phenyl vinyl sulfone stationary phase (M-PVS) was prepared. The resulting M-PVS bonded silica was characterized by elemental analysis, solid-state 13C cross-polarization/magic-angle spinning NMR and infrared spectroscopy, confirming the successful immobilization of phenyl vinyl sulfone on the silica support. The retention properties of M-PVS were investigated and exhibited unambiguous reversed phase retention characteristics. Moreover, shape selectivity and silanol activity were studied to reveal the diverse interactions of M-PVS, including hydrophobic, π-π, hydrogen bonding, and ion-exchange interactions. In addition, de-wetting tolerance and hydrophilic properties were evaluated and a pronounced "U" retention curves were obtained, indicating enhanced retention for polar analytes and transitions of different interaction modes. Selectivity differences between M-PVS column, phenyl column and conventional C18 column were examined using series natural standards. The diverse interactions of M-PVS demonstrated its improved selectivity for the compounds with similar hydrophobic skeleton but different polar substituents.


Assuntos
Cromatografia Líquida , Química Click , Interações Hidrofóbicas e Hidrofílicas , Espectroscopia de Ressonância Magnética , Silanos/química , Dióxido de Silício/química , Espectrofotometria Infravermelho , Compostos de Sulfidrila/química , Sulfonas/química
18.
J Chromatogr A ; 1617: 460819, 2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-31898947

RESUMO

Polymers obtained from tetraethyl orthosilicate (TEOS) and triethoxymethylsilane (MTEOS) have been functionalized with different metal and metal oxide nanoparticles (NPs), and used as coatings of extractive capillaries for the extraction of polar compounds by in-tube solid-phase microextraction (IT-SPME) coupled on-line to nano-liquid chromatography (nano-LC). The extraction capabilities of the new phases have been studied using several triazinic herbicides with log of octanol/water partition coefficients (Kow) ranging from -0.7 to 3.21 under reversed phase chromatographic conditions. Best extraction efficiencies for the most polar compounds (log Kow ≤ 2.3) were typically obtained with the CuO NPs doped phase. The TEOS-MTEOS polymer can be modified with two types of NPs in order to obtain extractive phases capable of interacting with compounds of a wide range of polarities; alternatively, two capillaries each with a different type of NPs can be combined in series with the same goal. Under the later approach the limits of detection (LODs) found for the tested herbicides were 0.02-1.5 µg/L, and the precision expressed as relative standard deviation (RSD) varied from 2 to 10% (n = 3). The recoveries found in sea water samples ranged from 80 to 107%. In addition, the developed CuO NPs doped phase can be used in hydrophilic interaction chromatography (HILIC), which is the separation mode recommended for highly polar compounds. This has been illustrated using the amino acids tyrosine (log Kow = -2.26) and tryptophan (log Kow = -1.06) as model compounds, being their respective LOD 0.1 and 0.3 µg/mL. Examples of application of the developed bimodal extractive phase to different environmental and waste waters are given in order to show its utility and versatility.


Assuntos
Cromatografia Líquida/métodos , Cobre/química , Nanopartículas Metálicas/química , Microextração em Fase Sólida/métodos , Cromatografia de Fase Reversa , Herbicidas/análise , Herbicidas/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Polímeros/química , Água do Mar/química , Silanos/química , Triazinas/análise , Triazinas/isolamento & purificação , Triptofano/análise , Tirosina/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
19.
J Chromatogr A ; 1618: 460866, 2020 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-31964513

RESUMO

An energy-efficient and environment-friendly approach to prepare porous monodispersed micro-sized silica particles with methyltrimethoxysilane (MTMS) as the precursor is described. The particles were synthesized by a two-step hydrolysis/condensation procedure, with post-synthetic aging and calcination for methyl group removal. They show uniform spherical morphology, narrow particle size distribution (D90/10, 1.2-1.6), tailored particle size (3, 5, 7 µm) and mesopore structure (10, 13 nm), which can be directly used as packing materials for HPLC without size classification. C18, sulfonate, and C18/sulfonate mixed-mode stationary phases were produced by a green vapor deposition method based on the synthesized silica particles. The newly synthesized C18 phase exhibits mechanical stability, kinetic behavior and separation performance expected from the commercial C18 column. The C18/sulfonate phase exhibits prominent mixed-mode retention behavior which can be applied to the simultaneous separation of multiple substances in the compound drugs.


Assuntos
Cromatografia Líquida de Alta Pressão , Preparações Farmacêuticas/análise , Dióxido de Silício/química , Hidrólise , Tamanho da Partícula , Preparações Farmacêuticas/isolamento & purificação , Porosidade , Silanos/química , Dióxido de Silício/síntese química
20.
J Nanobiotechnology ; 18(1): 14, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31941495

RESUMO

BACKGROUND: In orthopedics, the treatment of implant-associated infections represents a high challenge. Especially, potent antibacterial effects at implant surfaces can only be achieved by the use of high doses of antibiotics, and still often fail. Drug-loaded magnetic nanoparticles are very promising for local selective therapy, enabling lower systemic antibiotic doses and reducing adverse side effects. The idea of the following study was the local accumulation of such nanoparticles by an externally applied magnetic field combined with a magnetizable implant. The examination of the biodistribution of the nanoparticles, their effective accumulation at the implant and possible adverse side effects were the focus. In a BALB/c mouse model (n = 50) ferritic steel 1.4521 and Ti90Al6V4 (control) implants were inserted subcutaneously at the hindlimbs. Afterwards, magnetic nanoporous silica nanoparticles (MNPSNPs), modified with rhodamine B isothiocyanate and polyethylene glycol-silane (PEG), were administered intravenously. Directly/1/7/21/42 day(s) after subsequent application of a magnetic field gradient produced by an electromagnet, the nanoparticle biodistribution was evaluated by smear samples, histology and multiphoton microscopy of organs. Additionally, a pathohistological examination was performed. Accumulation on and around implants was evaluated by droplet samples and histology. RESULTS: Clinical and histological examinations showed no MNPSNP-associated changes in mice at all investigated time points. Although PEGylated, MNPSNPs were mainly trapped in lung, liver, and spleen. Over time, they showed two distributional patterns: early significant drops in blood, lung, and kidney and slow decreases in liver and spleen. The accumulation of MNPSNPs on the magnetizable implant and in its area was very low with no significant differences towards the control. CONCLUSION: Despite massive nanoparticle capture by the mononuclear phagocyte system, no significant pathomorphological alterations were found in affected organs. This shows good biocompatibility of MNPSNPs after intravenous administration. The organ uptake led to insufficient availability of MNPSNPs in the implant region. For that reason, among others, the nanoparticles did not achieve targeted accumulation in the desired way, manifesting future research need. However, with different conditions and dimensions in humans and further modifications of the nanoparticles, this principle should enable reaching magnetizable implant surfaces at any time in any body region for a therapeutic reason.


Assuntos
Portadores de Fármacos/química , Compostos Férricos/química , Nanopartículas de Magnetita/química , Próteses e Implantes , Dióxido de Silício/química , Animais , Portadores de Fármacos/administração & dosagem , Portadores de Fármacos/farmacocinética , Portadores de Fármacos/toxicidade , Feminino , Corantes Fluorescentes/química , Membro Posterior , Nanopartículas de Magnetita/toxicidade , Camundongos Endogâmicos BALB C , Ortopedia , Polietilenoglicóis/química , Porosidade , Rodaminas/química , Silanos/química , Distribuição Tecidual
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