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1.
Anal Chim Acta ; 1124: 176-183, 2020 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-32534670

RESUMO

This study targets the synthesis of high external-porosity poly(styrene-co-divinylbenzene) monolithic support structures with macropore and globule sizes in the sub-micron range, aiming at the realization of high-speed and high-resolution gradient separations of intact proteins and peptides. The thermodynamic and kinetic aspects of the free-radical polymerization synthesis were adjusted by tuning the porogen to monomer ratio, the porogen ratio, the initiator content, and polymerization temperature. Next, column morphology was linked to eddy-dispersion and mobile-phase mass-transfer contributions and the chromatographic performance limits were benchmarked against conventional packed columns and silica monoliths. Polymer monolithic structures yielding a separation impedance as low as 976 were created allowing to generate N > 1,000,000 (for an unretained marker), albeit the expense of very long analysis times. Decreasing the macropore and globule sizes below a certain threshold led to significant increase in eddy dispersion, as globular entities agglomerate, and a small number of large flow-through pores permeate the overall fine interconnected polymer network with small diameter flow-through pores. The potential of monolith chromatography for proteomics application is demonstrated with a ballistic 6 s gradient separation of intact proteins and a high-resolution nanoLC-Orbitrap mass spectrometric analysis of a tryptic E. coli digest applying a coupled-column system.


Assuntos
Nanoestruturas/química , Peptídeos/isolamento & purificação , Polímeros/química , Proteínas/isolamento & purificação , Proteômica , Cinética , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Peptídeos/química , Polímeros/síntese química , Porosidade , Proteínas/química , Propriedades de Superfície
2.
Anticancer Agents Med Chem ; 20(16): 1918-1926, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32400336

RESUMO

OBJECTIVE: Polydopamine coated iron oxide nanoparticles (Fe3O4@PDA NPs) were synthesized, characterized, and their MR imaging contrast agents and photothermal potency were evaluated on melanoma (B16-F10 and A-375) cells and normal skin cells. To this end, MTT assay, Fe concentration, and MR imaging of both coated and uncoated NPs were assessed in C57BL/6 mice. METHODS: Fe3O4 nanoparticles were synthesized using co-precipitation, and coated with polydopamine. The cytotoxicity of Fe3O4 and Fe3O4@PDA NPs on melanoma cells, with different concentrations, were obtained using MTT assay. MR images and Fe concentrations of nanoprobe and nanoparticles were evaluated under in vivo conditions. RESULTS: Findings indicated that uncoated Fe3O4 showed the highest toxicity in animal (B16-F10) cells at 450µg/ml after 72h, while the highest toxicity in human (A-375) cells were observed at 350µg/ml. These nanoparticles did not reveal any cytotoxicity to normal skin cells, despite having some toxicity features in A-375 cells. MR image signals in the tumor were low compared with other tissues. The iron concentration in the tumor was higher than that of other organs. CONCLUSION: It is concluded that the cytotoxicity of Fe3O4@PDA was found to be significantly lower than uncoated nanoparticles (p <0.001), which allows some positive effects on reducing toxicity. The prepared nanoprobe may be used as a contrast agent in MR imaging.


Assuntos
Meios de Contraste/química , Indóis/química , Nanopartículas Magnéticas de Óxido de Ferro/química , Imageamento por Ressonância Magnética , Melanoma/diagnóstico por imagem , Polímeros/química , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Meios de Contraste/síntese química , Meios de Contraste/farmacologia , Humanos , Indóis/síntese química , Indóis/farmacologia , Camundongos Endogâmicos C57BL , Estrutura Molecular , Polímeros/síntese química , Polímeros/farmacologia
3.
Food Chem ; 309: 125618, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31767479

RESUMO

In this study, a porous organic polymer (denoted as Car-DMB) was fabricated by a simple one-step crosslinking polymerization of carbazole and p-dimethoxybenzene for the first time. Then the Car-DMB was served as adsorbent of solid phase extraction to enrich triazine herbicides from white gourd, tomato and soybean milk samples prior to their determination by high performance liquid chromatography. Under the optimal conditions, the response linearity was in the range of 0.3-100.0 ng g-1 for white gourds and tomato samples, and 0.5-100.0 ng mL-1 for soybean milk, with the coefficient of determination higher than 0.996. The detection limits were 0.1-0.2 ng g-1 for white gourd and tomato samples, and 0.15-0.3 ng mL-1 for soybean milk. The adsorption mechanism of the Car-DMB for the triazines was attributed to the strong H-bonding and weak π-π interactions. The efficient extraction for several other compounds demonstrated that Car-DMB holds great potential for diverse analysis applications.


Assuntos
Herbicidas/isolamento & purificação , Polímeros/química , Extração em Fase Sólida/métodos , Triazinas/isolamento & purificação , Verduras/química , Adsorção , Anisóis/química , Carbazóis/química , Cromatografia Líquida de Alta Pressão , Reagentes de Ligações Cruzadas/química , Teoria da Densidade Funcional , Análise de Alimentos/métodos , Herbicidas/análise , Limite de Detecção , Nanotubos de Carbono/química , Polímeros/síntese química , Poliestirenos/química , Porosidade , Extração em Fase Sólida/instrumentação , Triazinas/análise
4.
J Sep Sci ; 42(24): 3662-3678, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31591808

RESUMO

In this study, we have developed a method to assess adenosine 5'-triphosphate by adsorptive extraction using surface adenosine 5'-triphosphate-imprinted polymer over polystyrene nanoparticles (412 ± 16 nm) for selective recognition/separation from urine. Molecularly imprinted polymer was synthesized by emulsion copolymerization reaction using adenosine 5'-triphosphate as a template, functional monomers (methacrylic acid, N-isopropyl acrylamide, and dimethylamino ethylmethacrylate) and a crosslinker, methylenebisacrylamide. The binding capacities of imprinted and non-imprinted polymers were measured using high-performance liquid chromatography with UV detection with a detection limit of 1.6 ± 0.02 µM of adenosine 5'-triphosphate in the urine. High binding affinity (QMIP , 42.65 µmol/g), and high selectivity and specificity to adenosine 5'-triphosphate compared to other competitive nucleotides including adenosine 5'-diphosphate, adenosine 5'-monophosphate, and analogs such as adenosine, adenine, uridine, uric acid, and creatinine were observed. The imprinting efficiency of imprinted polymer is 2.11 for urine (QMIP , 100.3 µmol/g) and 2.51 for synthetic urine (QMIP , 48.5 µmol/g). The extraction protocol was successfully applied to the direct extraction of adenosine 5'-triphosphate from spiked human urine indicating that this synthesized molecularly imprinted polymer allowed adenosine 5'-triphosphate to be preconcentrated while simultaneously interfering compounds were removed from the matrix. These submicron imprinted polymers over nano polystyrene spheres have a potential in the pharmaceutical industries and clinical analysis applications.


Assuntos
Trifosfato de Adenosina/química , Trifosfato de Adenosina/isolamento & purificação , Impressão Molecular , Nanosferas/química , Polímeros/química , Poliestirenos/química , Adsorção , Biomarcadores/urina , Indústria Farmacêutica , Estrutura Molecular , Polímeros/síntese química , Propriedades de Superfície
5.
Int J Biol Macromol ; 139: 40-48, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31369780

RESUMO

The purpose work is devoted to design of a simple, one-pot and green approach for the synthesis of molecularly imprinted polymer to construct a selective sorbent for pipette-tip solid phase extraction of Rhodamine B from chili powder samples and its subsequence separation and quantification by high performance liquid chromatography-ultraviolet/visible detection. The prepared molecularly imprinted polymer was synthesized using chitosan as versatile natural multi-functional bio-monomer and Rhodamine B as template in aqueous media. The effects of influential parameters (sorbent dosage, flow rate and eluent solvent volume) and their influences on Rhodamine B extraction recovery were examined and optimized by central composite design based response surface methodology as a powerful multivariate optimization tool. Under the optimized conditions, the linear range and limit of detection and quantification of proposed method were achieved to be 0.005-15 mg kg-1, 0.0015 mg kg-1 and 0.00488 mg kg-1, respectively, with satisfactory recoveries (>85.0%) and excellent repeatability (relative standard deviation < 6.1%). The easy synthesis conditions as well as satisfactory figures of merit are good indication of applicability of suggested method for extraction and determination of Rhodamine B from chili powder samples in terms of simplicity, cost effectiveness, selectivity and accurate analysis.


Assuntos
Capsicum/química , Impressão Molecular , Polímeros/síntese química , Rodaminas/isolamento & purificação , Extração em Fase Sólida/métodos , Técnicas de Química Sintética , Custos e Análise de Custo , Química Verde , Polímeros/química , Pós , Extração em Fase Sólida/economia
6.
Biomacromolecules ; 20(9): 3513-3523, 2019 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-31355634

RESUMO

Mycelium, the vegetative growth of filamentous fungi, has attracted increasing commercial and academic interest in recent years because of its ability to upcycle agricultural and industrial wastes into low-cost, sustainable composite materials. However, mycelium composites typically exhibit foam-like mechanical properties, primarily originating from their weak organic filler constituents. Fungal growth can be alternatively utilized as a low-cost method for on-demand generation of natural nanofibrils, such as chitin and chitosan, which can be grown and isolated from liquid wastes and byproducts in the form of fungal microfilaments. This study characterized polymer extracts and nanopapers produced from a common mushroom reference and various species of fungal mycelium grown on sugarcane byproduct molasses. Polymer yields of ∼10-26% were achieved, which are comparable to those of crustacean-derived chitin, and the nanopapers produced exhibited much higher tensile strengths than the existing mycelium materials, with values of up to ∼25 MPa (mycelium) and ∼98 MPa (mushroom), in addition to useful hydrophobic surface properties resulting from the presence of organic lipid residues in the nanopapers. HCl or H2O2 treatments were used to remove these impurities facilitating tuning of mechanical, thermal, and surface properties of the nanopapers produced. This potentially enables their use in a wide range of applications including coatings, membranes, packaging, and paper.


Assuntos
Fungos/metabolismo , Resíduos Industriais , Micélio/química , Polímeros/química , Quitina/biossíntese , Quitina/química , Quitosana/química , Fungos/química , Peróxido de Hidrogênio/química , Micélio/metabolismo , Polímeros/síntese química , Propriedades de Superfície , Resistência à Tração
7.
Mater Sci Eng C Mater Biol Appl ; 94: 597-607, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30423745

RESUMO

Composite coating of hydroxyapatite-polypyrrole is synthesized with the help of pulsed reverse electrochemical deposition method from aqueous bath through in-situ formation and co-deposition of both phases simultaneously over metallic stainless steel surface. The inter phase bonding along with surface energy variation and morphology is tuned with the help of deposition current density, deposition time and reverse duty cycle. Hydroxyapatite (HA) lattice exhibits unidirectional growth along the highest atomic plane of 〈111〉 parallel to the coating surface. Different kind of deposited hydroxyapatite structures, namely lamellar and spherical particle scaffold, are observed at moderate and high current densities respectively together with the incorporation of polypyrrole (PPy) phase in between. Pyrrole ring stretching and bond strengthening represent the bonding with hydroxyapatite lattice, which in turn helps to increase the overall corrosion resistance of composite coating by ten-fold as compared to bare PPY coating. The coating deposited with moderate current density (10 mA/cm2) seems to be the optimum one regarding the faster-interconnected growth of MG63 cells over the coating surface along with highest corrosion resistance and anodic passivation capability. Presence of sub-micron level ceramic hydroxyapatite scaffold along with polymer filler material makes this composite biocompatible coating as a potential candidate to use over the load bearing metallic implant surfaces due to its sufficient elasticity along with superior toughness.


Assuntos
Materiais Revestidos Biocompatíveis/síntese química , Durapatita/síntese química , Eletroquímica/métodos , Polímeros/síntese química , Pirróis/síntese química , Morte Celular , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Forma Celular , Materiais Revestidos Biocompatíveis/química , Corrosão , Espectroscopia Dielétrica , Durapatita/química , Módulo de Elasticidade , Dureza , Humanos , Polímeros/química , Pirróis/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Difração de Raios X
8.
Int J Mol Sci ; 19(10)2018 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-30301253

RESUMO

A new form-stable composite phase change material (PEG/ASB) composed of almond shell biochar (ASB) and polyethylene glycol (PEG) was produced via a simple and easy vacuum impregnation method. The supporting material ASB, which was cost effective, environmentally friendly, renewable and rich in appropriate pore structures, was produced from agricultural residues of almond shells by a simple pyrolysis method, and it was firstly used as the matrix of PEG. Different analysis techniques were applied to investigate the characteristics of PEG/ASB, including structural and thermal properties, and the interaction mechanism between ASB and PEG was studied. The thermogravimetric analysis (TGA) and thermal cycle tests demonstrated that PEG/ASB possessed favorable thermal stability. The differential scanning calorimetry (DSC) curves demonstrated that the capacities for latent heat storage of PEG/ASB were enhanced with increasing PEG weight percentage. Additionally, PEG/ASB had an excellent thermal conductivity of 0.402 W/mK, which was approximately 1.6 times higher than that of the pure PEG due to the addition of ASB. All the study results indicated that PEG/ASB had favorable phase change properties, which could be used for thermal energy storage.


Assuntos
Carvão Vegetal/química , Transição de Fase , Polímeros/síntese química , Prunus dulcis/química , Custos e Análise de Custo , Polietilenoglicóis/química , Polímeros/economia , Eliminação de Resíduos/economia , Eliminação de Resíduos/métodos , Condutividade Térmica
9.
Biomaterials ; 178: 570-582, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29680158

RESUMO

Size and shape have progressively appeared as some of the key factors influencing the properties of nanosized drug delivery systems. In particular, elongated materials are thought to interact differently with cells and therefore may allow alterations of in vivo fate without changes in chemical composition. A challenge, however, remains the creation of stable self-assembled materials with anisotropic shape for delivery applications that still feature the ability to disassemble, avoiding organ accumulation and facilitating clearance from the system. In this context, we report on cyclic peptide-polymer conjugates that self-assemble into supramolecular nanotubes, as confirmed by SANS and SLS. Their behaviour ex and in vivo was studied: the nanostructures are non-toxic up to a concentration of 0.5 g L-1 and cell uptake studies revealed that the pathway of entry was energy-dependent. Pharmacokinetic studies following intravenous injection of the peptide-polymer conjugates and a control polymer to rats showed that the larger size of the nanotubes formed by the conjugates reduced renal clearance and elongated systemic circulation. Importantly, the ability to slowly disassemble into small units allowed effective clearance of the conjugates and reduced organ accumulation, making these materials interesting candidates in the search for effective drug carriers.


Assuntos
Sistemas de Liberação de Medicamentos , Metacrilatos/química , Nanotubos/química , Peptídeos Cíclicos/química , Animais , Linhagem Celular Tumoral , Humanos , Masculino , Metacrilatos/farmacocinética , Difração de Nêutrons , Peptídeos Cíclicos/sangue , Peptídeos Cíclicos/farmacocinética , Polímeros/síntese química , Polímeros/química , Ratos Sprague-Dawley , Espalhamento de Radiação , Distribuição Tecidual
10.
Artigo em Inglês | MEDLINE | ID: mdl-29537947

RESUMO

Polyphenylsulfone (PPSU) is a new material for the production of baby bottles. PPSU is a polyether plastic formally composed of bisphenol S (BPS) and 4,4'-dihydroxybiphenyl (DHBP), which both have slight endocrine activities in in vitro tests. So far, little is known about the presence and the release of potentially hazardous substances from PPSU baby bottles. In this study, we present a three-step approach for the analysis of PPSU starting with polymer characterisation in terms of chemical structure, total oligomer content and hydrolytic stability. Second is the determination of extractables focussing on monomers, monomer derivatives, linear and cyclic oligomers below 1000 Da and residual solvent. Third is a risk assessment on migration-related substances in accordance to European Union plastics regulation no. 10/2011 based on triplicate consecutive migration experiments using official milk simulant 50% ethanol. We analysed five types of PPSU baby bottles from different brands as well as corresponding raw materials from different manufacturers by various analytical techniques (high-performance liquid chromatography (HPLC)-diode array detector /fluorescence detector/Corona/electrospray ionisation-MS, HPLC-size exclusion chromatography, gas chromatography-mass spectrometry (GC-MS), 1H-NMR). We found significant variations of PPSU materials from different producers with regard to polymer and oligomer chain end groups (methoxylation, chlorination), while total oligomer content below 1000 Da was similar (mean about 0.48%). BPS was not detected above 0.3 mg/kg polymer in any PPSU sample. Residual DHBP content ranged between 1.7 and 15.5 mg/kg polymer. The most common oligomer in all PPSU samples was the cyclic tetramer (about 1200 mg/kg polymer), which is the only cyclic compound below 1000 Da. Residual solvent, sulfolane, was determined to a maximum of 1300 mg/kg polymer. In migration tests, we detected exceedances of neither specific migration limits for listed substances nor of thresholds of toxicological concern for non-listed substances (monomer derivatives, oligomers). Based on our analytical results, no concerns exist regarding migration of polymer-related substances from PPSU baby bottles.


Assuntos
Contaminação de Alimentos/análise , Embalagem de Alimentos , Plásticos/análise , Polímeros/análise , Sulfonas/análise , Cromatografia em Gel , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Lactente , Polímeros/síntese química , Espectrometria de Fluorescência
11.
Food Chem ; 250: 188-196, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29412910

RESUMO

Innovative host-tailored polymers were prepared, characterized and used as recognition elements in potentiometric transducers for the selective quantification of 2,4-dichlorophenol (DCP).The polymer beads were synthesized using DCP as a template molecule, acrylamide (AM),methacrylic acid (MAA) and ethyl methacrylate (EMA) as functional monomers and divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA) as cross-linkers. The sensors were fabricated by the inclusion of MIPs in plasticized polyvinyl chloride (PVC) matrix. Response characteristics of the proposed sensors revealed anionic slopes of -59.2, -49.7 and -80.6 mV/decade with detection limits of 5.6 × 10-5,5.9 × 10-5 and 13.2 × 10-5 mol/L for MIP/AM/DVB, MIP/MAA/DVB and MIP/EMA/EGDMA membrane based sensors, respectively. Good selectivity was observed over common inorganic/organic anions. Validation of the assay method according to IUPAC recommendations was justified ensuring the synthesis of good reliable novel sensors for DCP determination. The method was successfully applied for routine analysis of food taint in fish and fish farms water samples.


Assuntos
Clorofenóis/análise , Polímeros/química , Potenciometria/métodos , Acrilamida/química , Animais , Contaminação de Alimentos/análise , Limite de Detecção , Metacrilatos/química , Impressão Molecular , Polímeros/síntese química , Cloreto de Polivinila/química , Potenciometria/instrumentação , Alimentos Marinhos/análise , Poluentes Químicos da Água/análise
12.
J Mol Recognit ; 31(3)2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-28791744

RESUMO

The efficiency of the stoichiometric non-covalent imprinting of the imide 2,3,5-tri-O-acetyluridine (TAU) with 2,6-bis(acrylamido)pyridine (BAAPy) as functional monomer due to their strong donor-acceptor-donor/acceptor-donor-acceptor (DAD/ADA) hydrogen bond array interaction has been evaluated by bulk imprinting. This study is the first to investigate the imprinting and template rebinding efficiencies of the TAU/BAAPy molecularly imprinted polymeric (MIP) system prepared by precipitation polymerisation. We found that the stoichiometric 1:1 T:FM ratio has not been maintained in precipitation polymerisation and an optimal TAU:BAAPy ratio of 1:2.5 was obtained in acetonitrile without agitation affording an affinity constant (1.7 × 104 M-1 ) and a binding capacity (3.69 µmol/g) higher than its bulk counterpart. Molecular modelling, NMR studies, and selectivity assays against analogues uridine and 2,3,5-tri-O-acetyl cytidine (TAC) indicate that, aside from the DAD/ADA hydrogen bond interaction, BAAPy also interacts with the acetyl groups of TAU. Template incorporation and rebinding in precipitation MIPs are favoured by a moderate initiator concentration, ie, initiator:total monomer (I:TM) ratio of 1:131, while low I:TM ratio (ie, 1:200) drastically reduced template incorporation and binding capacity. Vigorous agitation by stirring showed higher template incorporation but significantly lower template rebinding compared to that prepared without agitation. While the imprinting efficiencies for the best performing bulk and precipitation TAU MIPs generated in this study were moderate, 41% and 60%, respectively, their rebinding capacities were only between 3 and 4% of the incorporated template. We also present quantitative nuclear magnetic resonance spectroscopy as an efficient method for MIP characterisation.


Assuntos
Substâncias Macromoleculares/química , Impressão Molecular , Polímeros/química , Acetatos/química , Ligação de Hidrogênio , Imidas/síntese química , Imidas/química , Substâncias Macromoleculares/síntese química , Polimerização , Polímeros/síntese química , Piridinas/síntese química , Piridinas/química , Uridina/análogos & derivados , Uridina/química
13.
Mater Sci Eng C Mater Biol Appl ; 82: 330-335, 2018 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-29025666

RESUMO

Biodegradable polyesters, namely polycaprolactone (PCL) and copolymer of polylactide and polycaprolactone (PLCL) were electrospun into various fibrous structures and their hemocompatibility was evaluated in vitro. Firstly, hemolytic effect was evaluated upon incubation with diluted whole blood. The results showed that the degree of hemolysis depended on chemical composition and fibrous morphology. Electrospun polycaprolactone induced slight degree of hemolysis depending on its molecular weight and fibrous morphology; copolymer PLCL did not cause detectable hemolysis. The influence of coagulation pathways was examined by measurement of coagulation times. It was showed that intrinsic coagulation pathway assessed by activated partial thromboplastin time (APTT) was moderately accelerated after incubation with PCL and prolonged after incubation with copolymer PLCL. Extrinsic activation of coagulation tested by prothrombin time (PT) was slightly accelerated after incubation with all tested electrospun samples. Thrombogenicity assessment of fibrous samples revealed high thrombogenic properties of fibrous materials that was comparable to high degree of collagen thrombogenicity. The level of platelet activation was dependent on chemical composition and surface morphology of tested materials.


Assuntos
Materiais Biocompatíveis/química , Polímeros/química , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/farmacologia , Células Sanguíneas/citologia , Células Sanguíneas/efeitos dos fármacos , Células Sanguíneas/metabolismo , Colágeno/química , Hemólise/efeitos dos fármacos , Humanos , Microscopia Eletrônica de Varredura , Tempo de Tromboplastina Parcial , Poliésteres/química , Polímeros/síntese química , Tempo de Protrombina
14.
Macromol Rapid Commun ; 38(22)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29028137

RESUMO

Continuous flow methods are utilized in conjunction with direct arylation polymerization (DArP) for the scaled synthesis of the roll-to-roll compatible polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(4,7-di(thiophen-2-yl)-benzo[c][1,2,5]thiadiazole)] (PPDTBT). PPDTBT is based on simple, inexpensive, and scalable monomers using thienyl-flanked benzothiadiazole as the acceptor, which is the first ß-unprotected substrate to be used in continuous flow via DArP, enabling critical evaluation of the suitability of this emerging synthetic method for minimizing defects and for the scaled synthesis of high-performance materials. To demonstrate the usefulness of the method, DArP-prepared PPDTBT via continuous flow synthesis is employed for the preparation of indium tin oxide (ITO)-free and flexible roll-coated solar cells to achieve a power conversion efficiency of 3.5% for 1 cm2 devices, which is comparable to the performance of PPDTBT polymerized through Stille cross coupling. These efforts demonstrate the distinct advantages of the continuous flow protocol with DArP avoiding use of toxic tin chemicals, reducing the associated costs of polymer upscaling, and minimizing batch-to-batch variations for high-quality material.


Assuntos
Polímeros/química , Polimerização , Polímeros/síntese química , Teoria Quântica , Energia Solar , Espectrofotometria
15.
Anal Chem ; 89(21): 11484-11490, 2017 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-28952718

RESUMO

There is an increasing demand for rapid, sensitive, and low cost analytical methods to routinely screen antibiotic residues in food products. Conventional detection of antibiotics involves sample preparation by liquid-liquid or solid-phase extraction, followed by analysis using liquid chromatography-mass spectrometry (LC-MS), capillary electrophoresis (CE), or gas chromatography (GC). The process is labor-intensive, time-consuming, and expensive. In this study, we developed a new analytical method that combines magnetic molecularly imprinted polymer (MMIP)-based sample preparation with surface-enhanced Raman spectroscopy (SERS)-based detection for quantitative analysis of cloxacillin in pig serum. MMIP microspheres were synthesized using a core-shell technique. The large loading capacity and high selectivity of the MMIP microspheres enabled efficient extraction of cloxacillin, while the magnetically susceptible characteristics greatly simplified sample handling procedures. Low cost and robust SERS substrates consisting of vertical gold capped silicon nanopillars were fabricated and employed for the detection of cloxacillin. Quantitative SERS was achieved by normalizing signal intensities using an internal standard. By coherently combining MMIP extraction and silicon nanopillar-based SERS biosensor, good sensitivity toward cloxacillin was achieved. The detection limit was 7.8 pmol. Cloxacillin recoveries from spiked pig plasma samples were found to be more than 80%.


Assuntos
Cloxacilina/análise , Cloxacilina/isolamento & purificação , Análise de Alimentos/métodos , Limite de Detecção , Imãs/química , Polímeros/síntese química , Análise Espectral Raman , Animais , Custos e Análise de Custo , Resíduos de Drogas/análise , Análise de Alimentos/economia , Contaminação de Alimentos/análise , Microesferas , Impressão Molecular , Polímeros/química , Suínos , Fatores de Tempo
16.
J Ind Microbiol Biotechnol ; 44(10): 1491-1502, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28756564

RESUMO

Dodecanedioic acid (DDA) is highly useful to the chemical industry as a versatile precursor for producing the polyamide nylon-6,12, which is used for many technical applications, such as heat and chemical-resistant sheaths. However, DDA synthesis has several drawbacks, such as high energy input and cost-intensive removal of by-products. Therefore, alternative bio-based production routes are required due to increasing industrial demand for green chemicals and renewable products. Candida tropicalis converts petrochemical-based n-dodecanes to the corresponding dicarboxylic acids by targeted functionalization. To increase sustainability of the DDA production process, we tested dodecanoic acid methyl ester, which can be easily obtained from transesterification of coconut oil, in whole-cell biotransformation by C. tropicalis. By modifying selected process parameters, a final DDA concentration of 66 g/L was achieved using a highly reliable, small-scale bioreactor system. Crucial process development included a gradual pH shift, an optimized substrate feeding strategy, and monitoring the transcriptional profile.


Assuntos
Reatores Biológicos , Candida tropicalis/metabolismo , Ácidos Dicarboxílicos/metabolismo , Óleos de Plantas/química , Óleos de Plantas/metabolismo , Alcanos/metabolismo , Biotransformação , Caprolactama/análogos & derivados , Caprolactama/síntese química , Óleo de Coco/química , Óleo de Coco/metabolismo , Química Verde , Polímeros/síntese química
17.
Angew Chem Int Ed Engl ; 56(1): 188-192, 2017 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-27918135

RESUMO

We report star polymer metal-organic cage (polyMOC) materials whose structures, mechanical properties, functionalities, and dynamics can all be precisely tailored through a simple three-component assembly strategy. The star polyMOC network is composed of tetra-arm star polymers functionalized with ligands on the chain ends, small molecule ligands, and palladium ions; polyMOCs are formed via metal-ligand coordination and thermal annealing. The ratio of small molecule ligands to polymer-bound ligands determines the connectivity of the MOC junctions and the network structure. The use of large M12 L24 MOCs enables great flexibility in tuning this ratio, which provides access to a rich spectrum of material properties including tunable moduli and relaxation dynamics.


Assuntos
Compostos Organometálicos/química , Paládio/química , Polímeros/química , Bibliotecas de Moléculas Pequenas/química , Técnicas de Química Sintética/economia , Técnicas de Química Sintética/métodos , Módulo de Elasticidade , Géis/síntese química , Géis/química , Ligantes , Compostos Organometálicos/síntese química , Polímeros/síntese química , Bibliotecas de Moléculas Pequenas/síntese química , Estresse Mecânico
18.
Biomed Res Int ; 2016: 4158376, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27840825

RESUMO

Introduction. Polymerization of light-cured dental materials used for restoration of hard tooth tissue may lead to an increase in temperature that may have negative consequence for pulp vitality. Aim. The aim of this study was to determine maximum temperatures reached during the polymerization of selected dental materials, as well as the time that is needed for samples of sizes similar to those used in clinical practice to reach these temperatures. Materials and Methods. The study involved four composite restorative materials, one lining material and a dentine bonding agent. The polymerization was conducted with the use of a diode light-curing unit. The measurements of the external surface temperature of the samples were carried out using the Thermovision®550 thermal camera. Results. The examined materials significantly differed in terms of the maximum temperatures values they reached, as well as the time required for reaching the temperatures. A statistically significant positive correlation of the maximum temperature and the sample weight was observed. Conclusions. In clinical practice, it is crucial to bear in mind the risk of thermal damage involved in the application of light-cured materials. It can be reduced by using thin increments of composite materials.


Assuntos
Cimentos Dentários/síntese química , Cimentos Dentários/efeitos da radiação , Temperatura Alta , Cura Luminosa de Adesivos Dentários/métodos , Polímeros/síntese química , Polímeros/efeitos da radiação , Dureza/efeitos da radiação , Luz , Teste de Materiais
19.
Biofabrication ; 8(2): 025005, 2016 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-27150345

RESUMO

Square microchannels are easy to fabricate by means of micromachining or lithographic techniques. However, in vitro vascular microcapillaries--as well as plug production and microparticle alignment--require mainly circular microchannels that can be used also in applications based on open microchannels. Nowadays, a simple, low cost, and versatile method to fabricate circular microchannels is still missing. Here, we report on a fast, inexpensive, flexible and reproducible method to fabricate circular microchannels by coupling spin coating with micromilled square microchannels. The proposed method is based on the balance between the displacement of liquid PDMS induced by centrifugal forces and the surface tension that tends to keep the liquid accumulated especially in the corners, which become therefore rounded. To show the versatility of the described experimental study we prepared a variety of rounded microchannels, including branched and PMMA-PDMS hybrid configuration microchannels. Finally, an endothelial cell layer was formed by culturing brain endothelial bEnd.3 cells inside the proposed circular microchannels. Results demonstrated a more successful adhesion, growth, and homogeneous distribution of the cells along the circular microchannel than those observed in the square microchannel used as a control.


Assuntos
Técnicas de Cultura de Células/instrumentação , Técnicas Eletroquímicas/métodos , Células Endoteliais/citologia , Microfluídica/instrumentação , Polímeros/síntese química , Animais , Adesão Celular , Técnicas de Cultura de Células/economia , Proliferação de Células , Técnicas Eletroquímicas/economia , Camundongos , Microfluídica/métodos , Polímeros/química , Polímeros/economia
20.
Ecotoxicol Environ Saf ; 130: 1-3, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27060197

RESUMO

Filler is one of the major additives in rubber compounds to enhance the physical properties. Even though numerous benefits obtained from agricultural by products like coconut shell, rice husk etc., still they constitute a large source of environmental pollution. In this investigation, one of the agricultural bye product coconut shell powder (CSP) is used as filler in the compounding KNB rubber. It shows the positive and satisfied result was achieved only by the use of filler Fast Extrusion Furnace (FEF) and coconut shell powder (CSP) which was used 50% in each. The effect of these fillers on the mechanical properties of a rubber material at various loading raging from 0 to 60PHP was studied. Mercaptodibanzothiazole disulphide (MBTS) was used as an accelerator. The result shows that presence of 25% and 50% of the composites has better mechanical properties like Hardness, Tensile strength, Elongation at break and Specific gravity when compared with other two combinations. Even though both 25% and 50% of composites shows good mechanical properties, 50% of CSP have more efficient than 25% of CSP.


Assuntos
Acrilonitrila/síntese química , Cocos , Borracha/síntese química , Butadienos , Dureza , Polímeros/síntese química , Pós , Resistência à Tração
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