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1.
Ecotoxicol Environ Saf ; 195: 110517, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32220793

RESUMO

Phthalate esters (PAEs), a class of toxic anthropogenic compounds, have been predominantly used as additives or plasticizers, and great concern and interests have been raised regarding its environmental behavior and degradation mechanism. In the present study, a bacterial consortium consisting of Microbacterium sp. PAE-1 and Pandoraea sp. PAE-2 was isolated by the enrichment method, which could degrade dibutyl phthalate (DBP) completely by biochemical cooperation. DBP was converted to phthalic acid (PA) via monobutyl phthalate (MBP) by two sequential hydrolysis steps in strain PAE-1, and then PA was further degraded by strain PAE-2. Strain PAE-1 could hydrolyze many dialkyl Phthalate esters (PAEs) including dimethyl, diethyl, dibutyl, dipentyl, benzyl butyl, dihexyl, di-(2-ethyhexyl) and their corresponding monoalkyl PAEs. Two esterase genes named dpeH and mpeH, located in the same transcription unit, were cloned from strain PAE-1 by the shotgun method and heterologously expressed in Escherichia. coli (DE3). The Km and kcat values of DpeH for DBP were 9.60 ± 0.97 µM and (2.72 ± 0.06) × 106 s-1, while those of MpeH for MBP were 18.61 ± 2.00 µM and (5.83 ± 1.00) × 105 s-1, respectively. DpeH could only hydrolyze dialkyl PAEs to the corresponding monoalkyl PAEs, which were then hydrolyzed to PA by MpeH. DpeH shares the highest similarity (53%) with an alpha/beta hydrolase from Microbacterium sp. MED-G48 and MpeH shows only 25% identity with a secreted lipase from Trichophyton benhamiae CBS 112371, indicating that DpeH and MpeH are two novel hydrolases against PAEs.


Assuntos
Dibutilftalato/análise , Poluentes Ambientais/análise , Esterases/genética , Consórcios Microbianos/efeitos dos fármacos , Plastificantes/análise , Actinobacteria/efeitos dos fármacos , Actinobacteria/enzimologia , Burkholderiaceae/efeitos dos fármacos , Burkholderiaceae/enzimologia , Dibutilftalato/química , Poluentes Ambientais/química , Genes Bacterianos , Hidrólise , Lipase/genética , Consórcios Microbianos/genética , Ácidos Ftálicos/análise , Plastificantes/química
2.
Food Chem ; 317: 126465, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32114276

RESUMO

Based on the experimental data of gas chromatography-mass spectrometry, an improved artificial neural network was first established to predict the migration of 2-ethylhexyl phthalate (DEHP) plasticizer from poly(vinylidene chloride) (PVDC) into food simulants (ie., heptane, ethanol and water). The sensitivity analysis indicated that temperature acted as a crucial factor influencing the migration values of DEHP. Then, a combined experimental and molecular dynamic (MD) simulation was performed to understand the migration kinetics and the mechanism of DEHP. Hansen solubility parameters of three component (δd, δp, δh) were simplified into two-component solubility parameters (δvdW, δe), and the tuple was successfully applied to describe the interactions between PVDC and food simulants. The MD results showed that high interaction energy and fractional free volume in PVDC/DEHP/food simulant systems accelerated the migration of DEHP. These fundamental studies would provide significant insights into the migration of environmental contaminants.


Assuntos
Dietilexilftalato/análise , Embalagem de Alimentos , Redes Neurais de Computação , Plastificantes/análise , Dietilexilftalato/química , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas , Simulação de Dinâmica Molecular , Plastificantes/química , Cloreto de Polivinila/análogos & derivados , Cloreto de Polivinila/química , Solubilidade , Temperatura
3.
PLoS One ; 15(2): e0228814, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32053641

RESUMO

The harmful cyanobacteria blooms which usually form in spring and summer, cause global eutrophication of freshwater and coastal marine ecosystems. This study tried to utilize cyanobacteria as a raw material to produce biological poly(vinyl)alcohol-based films. Cyanobacteria was firstly modified with poly(ethylene glycol), guanidine hydrochloride, carboxymethyl cellulose and 3-glycidoxypropyltrimethoxysilane as plasticizer, modifier, toughening agent and coupling agent, respectively. And then the modified cyanobacteria was introduced to poly(vinyl)alcohol and cellulose nanofibers/poly(vinyl)alcohol matrix to improve the barrier properties of poly(vinyl)alcohol to light and water. Compared with poly(vinyl)alcohol and cellulose nanofibers/poly(vinyl)alcohol films, the obtained cyanobacteria/poly(vinyl)alcohol and the cyanobacteria/cellulose nanofibers/poly(vinyl)alcohol composites exhibit better resistance to light and water. More interestingly, we found that after adding cyanobacteria, the poly(vinyl)alcohol-based films present better barrier properties to blue-violet light and red light. In adddition, introducing cyanobacteria into poly(vinyl)alcohol or cellulose nanofibers/poly(vinyl)alcohol matrix increases the surface roughness and contact angle to water of the composites.


Assuntos
Materiais Biomiméticos/química , Cianobactérias/química , Luz , Álcool de Polivinil/química , Água/química , Materiais Biomiméticos/efeitos da radiação , Celulose/química , Guanidina/química , Teste de Materiais , Nanofibras/química , Oxigênio/química , Plastificantes/química , Propriedades de Superfície , Raios Ultravioleta
4.
Food Chem ; 311: 125899, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31784071

RESUMO

The novel hyperbranched poly(trimellitic glyceride) (PTG) starch plasticizer synthesized in our previous study was neutralized with different alkaline metal hydroxides. Mixed with starch, the effects of different alkaline metal cations, M+, on gelatinization of starch suspensions and thermal behaviors of the films were analyzed using RVA and DMA, respectively. The structures of the starch suspensions, films and freeze-dried samples (S/PTG-M) were investigated using DSC, XRD and FTIR spectroscopy, respectively. M+ increased the gelatinization temperature of starch suspensions in the order of S/PTG-Li > S/PTG-Na > S/PTG-K. The formation of a complex between M+ and starch in the films observed using FTIR spectroscopy improved the stability of the starch paste and gel, and increased the gel temperature of starch dispersions. The corresponding starch gel was relatively thermostable, but not shear-resistant. PTG decreased the Tg of starch films with different paired M+. PTG-Li and PTG-K, but not PTG-Na, strengthened the mechanical properties of starch films.


Assuntos
Metais/química , Plastificantes/química , Amido/química , Liofilização , Géis/química , Concentração de Íons de Hidrogênio , Íons/química , Plastificantes/síntese química , Reologia , Temperatura , Viscosidade , Água/química
5.
Carbohydr Polym ; 229: 115427, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31826501

RESUMO

In this paper, lemon and fennel wastes were recovered and used as secondary-raw polysaccharide sources. These polysaccharides were exploited as natural plasticizers of sodium alginate (A) based films, in order to improve sodium alginate performances, limited by its fragility, extending its potential application in a cost effective and eco-friendly way. Different green processes, such as maceration (MAC), ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), were carried out for obtaining high yield of lemon and fennel polysaccharides (LP and FP). Actually, HPAE-PAD and TLC analyses evidenced the presence of xyslose, galactose, glucose and rhamnose monomers and galacturonic acid, typical of polysaccharides like pectin and xyloglucan chains. These findings were confirmed by NMR and FTIR spectroscopic analyses. Moreovers, gel filtration chromatography assessed the high molecular weight of recovered polysaccharides, particularly of FP waste fraction. The extracted polysaccharides were used as eco-friendly and cost-effective plasticizers of sodium alginate films (AFP and ALP). DSC analysis evidenced a significant decreasing of glass transition temperature of the polymer, tensile tests showed an enlightened rising of elongation at break and TGA analysis showed a faster degradation kinetics of AFP and ALP films, as expected in a plasticized system.


Assuntos
Citrus , Foeniculum , Plastificantes/química , Polissacarídeos/química , Verduras , Resíduos
6.
Molecules ; 24(24)2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31817642

RESUMO

Glycidyl azide polymer (GAP), an energetic binder, is the focus of this review. We briefly introduce the key properties of this well-known polymer, the difference between energetic and non-energetic binders in propellant and explosive formulations, the fundamentals for producing GAP and its copolymers, as well as for curing GAP using different types of curing agents. We use recent works as examples to illustrate the general approaches to curing GAP and its derivatives, while indicating a number of recently investigated curing agents. Next, we demonstrate that the properties of GAP can be modified either through internal (structural) alterations or through the introduction of external (plasticizers) additives and provide a summary of recent progress in this area, tying it in with studies on the properties of such modifications of GAP. Further on, we discuss relevant works dedicated to the applications of GAP as a binder for propellants and plastic-bonded explosives. Lastly, we indicate other, emerging applications of GAP and provide a summary of its mechanical and energetic properties.


Assuntos
Substâncias Explosivas/química , Plastificantes/química , Polímeros/química , Triazinas/química
7.
Sheng Wu Gong Cheng Xue Bao ; 35(11): 2104-2120, 2019 Nov 25.
Artigo em Chinês | MEDLINE | ID: mdl-31814358

RESUMO

Phthalates esters (PAEs) are important organic compounds used as plasticizers to enhance their plasticity and versatility. At the same time, PAEs are also typical environmental endocrine disruptors. Long-term production and use of plastic products have caused harm to the environment and organisms, as well as human health. Previous studies found that biodegradation has become a main pathway to reduce PAEs in the environment. This article reviews PAEs' structural characteristics and classifications, toxicology, pollution in the environment, summarizes the diversity of PAEs-degrading bacterial species, and explores the possible mechanisms of bacterial PAEs degradation. The article may provide some reference in solving the problem of PAEs pollution.


Assuntos
Biodegradação Ambiental , Ésteres , China , Poluição Ambiental , Ésteres/química , Ésteres/metabolismo , Ácidos Ftálicos/química , Ácidos Ftálicos/metabolismo , Plastificantes/química , Plastificantes/metabolismo
8.
Int J Pharm ; 572: 118833, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31715363

RESUMO

Different types of in-situ forming implants based on poly(lactic-co-glycolic acid) (PLGA) for the controlled dual release of an antiseptic drug (chlorhexidine) and an anti-inflammatory drug (ibuprofen) were prepared and thoroughly characterized in vitro. N-methyl-pyrrolidone (NMP) was used as water-miscible solvent, acetyltributyl citrate (ATBC) as plasticizer and hydroxypropyl methylcellulose (HPMC) was added to enhance the implants' stickiness/bioadhesion upon formation within the periodontal pocket. Different drug forms exhibiting substantially different solubilities were used: chlorhexidine dihydrochloride and digluconate as well as ibuprofen free acid and lysinate. The initial drug loadings were varied from 1.5 to 16.1%. In vitro drug release, dynamic changes in the pH of the surrounding bulk fluid and in the systems' wet mass as well as polymer degradation were monitored. Importantly, the release of both drugs, chlorhexidine and ibuprofen, could effectively be controlled simultaneously during several weeks. Interestingly, the tremendous differences in the drug forms' solubilities (e.g., factor >5000) did not translate into major differences in the resulting release kinetics. In the case of ibuprofen, this can likely (at least in part) be attributed to significant drug-polymer interactions (ibuprofen acts as a plasticizer for PLGA). In the case of chlorhexidine, the release of the much less soluble dihydrochloride was even faster compared to the more soluble digluconate (when combined with ibuprofen free acid). In the case of ibuprofen, at higher initial drug loadings also limited solubility effects within the implants seem to play a role, in contrast to chlorhexidine. In the latter case, instead, increased system porosity effects likely dominate at higher drug loadings.


Assuntos
Anti-Infecciosos Locais/administração & dosagem , Anti-Inflamatórios não Esteroides/administração & dosagem , Clorexidina/administração & dosagem , Ibuprofeno/administração & dosagem , Adesividade , Anti-Infecciosos Locais/química , Anti-Inflamatórios não Esteroides/química , Química Farmacêutica , Clorexidina/química , Preparações de Ação Retardada , Combinação de Medicamentos , Implantes de Medicamento , Liberação Controlada de Fármacos , Excipientes/química , Ibuprofeno/química , Doenças Periodontais/tratamento farmacológico , Plastificantes/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Porosidade , Solubilidade , Solventes/química
9.
Carbohydr Polym ; 225: 115123, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31521280

RESUMO

Different amounts of cellulose nanocrystals (CNCs) were added to glycerol-plasticized thermoplastic starch (TPS) to obtain bio-based nanocomposites. First, nanocomposites are prepared by extrusion and their structure is studied at different scales using WAXS (Wide Angle X-ray Scattering) and solid-state NMR (Nuclear Magnetic Resonance) for local/crystalline organization, AF4 (Asymmetrical Flow Field-Flow Fractionation) for molecular weight and chain length, and SEM (Scanning Electron Microscopy) for the morphology at a larger scale. Then, relevant mechanical properties and behavior in physiological conditions (swelling, enzymatic degradation) are characterized. The results show that the incorporation of cellulose nanocrystals up to 2.5 wt% causes a mechanical reinforcement as determined by DMTA (Dynamic Mechanical Thermal Analysis) and reduces the swelling and the enzymatic degradation of the materials compared to reference TPS. This could be linked to the formation of starch-cellulose hydrogen and hydroxyl bonds. Conversely, above 5 wt% CNC content nanocrystals seem to aggregate which in turn worsens the behavior in physiological conditions.


Assuntos
Plásticos Biodegradáveis/química , Celulose/química , Nanocompostos/química , Nanopartículas/química , Plastificantes/química , Amido/química , Solanum tuberosum/metabolismo , Resistência à Tração , Molhabilidade
10.
Int J Biol Macromol ; 141: 325-332, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31491516

RESUMO

The in-situ reactive interfacial compatibilization and properties of polylactic acid-g-bamboo fiber (PLA-g-BF)/polylactic acid (PLA) composites, produced by blending with a three-component plasticizer, glycerol/formamide/tributyl citrate, were investigated. The PLA-g-BF/PLA composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA) and rotational rheometer, and the bending, tensile, and water resistance properties were also tested. The bending strength and elongation at break of PLA-g-BF/PLA composite reached 35.6 MPa and 5.59%, which increased by 19.3% and 30.1% relative to the ungrafted composites. The initial contact angle of the PLA-g-BF/PLA composite was 74.3°, which was larger than that of the ungrafted composite (41.2°), and the water absorption ratio reached 4.3% after 24 h, which was less than the unmodified material (6.1%). SEM results showed that PLA matrix showed smooth surfaces and the interfacial adhesion between modified BF and matrix PLA was greatly improved after grafting modification. The crystal structure results proved that the grafting treatment of BF strengthened the interfacial interactions between the filler BF and matrix PLA, and reduced the mobility of PLA molecular chain. The rotational rheometer illustrated that the initial storage modulus of PLA-g-BF/PLA composites was the largest and decreased slowly, which improved the processing properties of composites.


Assuntos
Poliésteres/química , Polímeros/química , Sasa/química , Fenômenos Químicos , Interações Hidrofóbicas e Hidrofílicas , Fenômenos Mecânicos , Plastificantes/química , Polimerização , Reologia , Análise Espectral , Termogravimetria
11.
Int J Pharm ; 569: 118581, 2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31369828

RESUMO

The purpose of this work was to investigate the feasibility to manufacture enteric capsules, which could be used in compounding pharmacies, by fused-deposition modeling. It is well-known that conventional enteric dip coating of capsules in community pharmacies or hospitals is a time-consuming process which is characterized by an erratic efficacy. Fused-deposition modeling was selected as a potential 3D printing method due its ease and low-cost implementation. Before starting to print the capsules, an effective sealing system was designed via a computer-aided design program. Hot melt extrusion was used to make printable enteric filaments. They were made of the enteric polymer, a plasticizer and a thermoplastic polymer, namely Eudragit® L100-55, polyethylene glycol 400 and polylactic acid, respectively. Riboflavine-5'-phosphate was selected as a coloured drug model to compare the efficacy of the 3D printed capsules to that of enteric dip coated capsules as they are currently produced in community pharmacies and hospitals. Different parameters of fabrication which could influence the dissolution profile of the model drug, such as the layer thickness or post-processing step, were studied. It was demonstrated that our 3D printed enteric capsules did not release the drug for 2 h in acid medium (pH 1.2). However, they completely dissolved within 45 min at pH 6.8 which allowed the release of a minimal amount of 85% w/w of drug as it was recommended by the European Pharmacopoeia 9th Edition for enteric products.


Assuntos
Composição de Medicamentos/métodos , Impressão Tridimensional , Cápsulas , Excipientes/química , Estudos de Viabilidade , Farmácias , Plastificantes/química , Poliésteres/química , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química
12.
Int J Biol Macromol ; 140: 775-781, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31446109

RESUMO

Thermoplastic starch (TPS) and polyvinyl alcohol (PVA) blends were prepared by extrusion method in the presence of water/glycerol and citric acid, and their phase behavior was investigated. Results of scanning electron microscopy (SEM) and X-ray diffractometry (XRD) tests demonstrated the complete plasticization of starch during the melt mixing. PVA crystal phase was not formed in blends with less than 50 wt% PVA. Fourier-transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA) analysis revealed high compatibility between two phases, starch and PVA. Addition of PVA to TPS resulted in the reduction of the glass transition temperature and dynamic moduli and improvement of sample flexibility. However, at 10 wt% PVA, an anti-plasticization effect caused to increase the Tg and storage modulus of the blend.


Assuntos
Plastificantes/química , Álcool de Polivinil/química , Amido/química , Materiais Biocompatíveis/química , Fenômenos Mecânicos , Microscopia Eletrônica de Varredura , Plastificantes/farmacologia , Álcool de Polivinil/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termogravimetria
13.
Int J Mol Sci ; 20(17)2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31438576

RESUMO

The existing mold concept of fabricating magnetorheological elastomer (MRE) tends to encounter several flux issues due to magnetic flux losses inside the chamber. Therefore, this paper presents a new approach for enhancing particle alignment through MRE fabrication as a means to provide better rheological properties. A closed-loop mold, which is essentially a fully guided magnetic field inside the chamber, was designed in order to strengthen the magnetic flux during the curing process with the help of silicone oil (SO) plasticizers. The oil serves the purpose of softening the matrix. Scanning electron microscopy (SEM) was used to observe the surface morphology of the fabricated MRE samples. The field-dependent dynamic properties of the MREs were measured several ways using a rheometer, namely, strain sweep, frequency sweep, and magnetic field sweep. The analysis implied that the effectiveness of the MRE was associated with the use of the SO, and the closed-loop mold helped enhance the absolute modulus up to 0.8 MPa. The relative magnetorheological (MR) effects exhibited high values up to 646%. The high modulus properties offered by the MRE with SO are believed to be potentially useful in industry applications, particularly as vibration absorbers, which require a high range of stiffness.


Assuntos
Elastômeros/química , Plastificantes/química , Óleos de Silicone/química , Microscopia Eletrônica de Varredura
14.
Sci Total Environ ; 687: 732-740, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31412476

RESUMO

Organophosphate flame retardants (OPFRs) were frequently detected in biotic and abiotic matrix owing to their persistence and recalcitrant degradation. Some specific OPFRs, such as tris-(2-chloroisopropyl) phosphate (TCPP), pose a significant potential risk to human health due to their high water solubility. Therefore, an environmentally sound and high efficient technique is in urgent need of controlling TCPP. This research is focused on degrading TCPP using ultraviolet-persulfate (UV/PS) technique. The degradation reaction of TCPP followed a pseudo-first order kinetics with an apparent rate constant (kobs) at 0.1653 min-1. As the photocatalytic reaction proceeded, TCPP was transformed to twelve degradation intermediates via the selective electron-transfer reactions induced by activated sulfate radical. Anions existence and pH value significantly inhibited the degradation efficiency, implying that it was hard for TCPP to reach up to complete mineralization in actual water treatment process. Additionally, toxicological assessment of degradation intermediate mixture was conducted using Flow cytometry (FCM) analyses, and the result showed that the intracellular reactive oxygen species (ROS) and cell apoptotic rates significantly declined, and membrane potential (MP) increased in comparison with original TCPP. On the other hand, the negative impacts of these degradation products on DNA biosynthesis in Escherichia coli were weakened based on cell cycle analysis, all of which indicated that toxicity of these degradation intermediates was obviously reduced via UV/PS treatment. To summarize, an appropriate mineralization is effective for TCPP detoxification, suggesting the feasibility of TCPP control using UV/PS treatment in water matrix.


Assuntos
Retardadores de Chama/análise , Organofosfatos/química , Plastificantes/química , Cinética , Modelos Químicos , Organofosfatos/análise , Oxirredução , Fosfatos , Plastificantes/análise , Sulfatos , Raios Ultravioleta , Poluentes Químicos da Água/química
15.
Biopolymers ; 110(10): e23321, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31260091

RESUMO

Films derived from natural sources such as proteins provide an advantage over synthetic films due to their noncytotoxicity, biodegradability, and vast functionality. A new protein source gained from the cataractous eye protein isolate (CEPI) obtained after surgery has been investigated for this purpose. Glycerol has been employed as the plasticizer and glutaraldehyde (GD) as a cross-linker. Fourier transform infrared spectroscopy was employed to characterize the films. Nanoindentation and thermogravimetric analyses reveal improved mechanical and thermal properties of the cross-linked films. The films with 20% (w/w) GD exhibited properties such as the highest modulus and low water solubility. It is possible to tune the properties based on the extent of cross-linking. All the films were completely degraded by the enzyme trypsin. The similarity of these films was checked by using the prepared films as a delivery vehicle for a model compound, ampicillin sodium. The encapsulation efficiency was found to be 74%, and in vitro release studies showed significant amounts of drug release at physiological pH. This study will help us understand how the properties of protein films can be tuned to obtain the desired physicochemical properties. These biodegradable protein films could find use in pharmaceutical industries as delivery carriers.


Assuntos
Ampicilina , Sistemas de Liberação de Medicamentos , Proteínas do Olho/química , Membranas Artificiais , Ampicilina/química , Ampicilina/farmacocinética , Ampicilina/farmacologia , Reagentes para Ligações Cruzadas/química , Feminino , Glutaral/química , Glicerol/química , Humanos , Masculino , Pessoa de Meia-Idade , Plastificantes/química
16.
Ther Deliv ; 10(7): 443-464, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31264527

RESUMO

Pediatric and geriatric patients experience swallowing difficulties for traditional oral dosage forms, such as tablets. Further, microbial contamination, chemical stability, unpleasant taste and swallowing large volumes of fluids have led to low therapeutic efficacy and patient noncompliance. The emergence of oral thin films has resulted in dramatic improvements in compliance and drug therapy outcomes in pediatric and geriatric patients. Oral thin films do not require water for administration, are readily hydrated upon contact with saliva, adhere to the mucosa and disintegrate ideally under 1 min. This article provides an overview of oral thin films, modern trends in their formulation and characterization, available commercial products, information to fill knowledge gaps and future potential and economic prospects of oral thin film technology, with emphasis on their use in the pediatric and geriatric patient groups.


Assuntos
Composição de Medicamentos/métodos , Preparações Farmacêuticas/química , Administração Oral , Idoso , Criança , Humanos , Cooperação do Paciente , Preparações Farmacêuticas/metabolismo , Plastificantes/química , Polímeros/química , Solubilidade
17.
Drug Dev Ind Pharm ; 45(10): 1599-1609, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31271320

RESUMO

We recently reported lowly hydrolyzed polyvinyl alcohol (L-PVA, 70-74% hydrolyzed, about 580 polymerized, JR-05) as a promising matrix for hot-melt extrusion (HME) due to its unique micelle formation ability compared to the most commonly used PVA (87-89% hydrolyzed, about 580 polymerized). In the present study, we focused on the effect of composition [indomethacin (IND), L-PVA, sorbitol] and process parameters (temperature and screw speed) on each response, i.e. processing torque, and physicochemical properties such as residual crystallinity, residual ratio, and area under the dissolution curve (AUDC) in supersaturated solution using a HME by applying the design of experiment (DoE) approach. To overcome the poor processability of L-PVA, given its semicrystalline nature, we applied sorbitol as a plasticizer and systematically and simultaneously evaluated its influence on the outputs based on the mixture design combined with process factors. Few studies have focused on comprehensive evaluation of the composition and HME process conditions because obtaining a design space requires numerous experiments. We found that incorporating sorbitol into the L-PVA greatly improved the processing torque. However, sorbitol negatively influenced the degree of residual crystallinity and the AUDC of IND. Lastly, we established a laboratory-scale design space that could achieve high supersaturation and ensure adequate miscibility between each component, using an acceptable processing torque for HME, by applying the minimum amount of sorbitol. These fundamental results suggest that sorbitol maximizes the potency of L-PVA as a carrier in HME.


Assuntos
Indometacina/química , Álcool de Polivinil/química , Química Farmacêutica/métodos , Cristalização/métodos , Composição de Medicamentos/métodos , Hidrólise , Micelas , Plastificantes/química , Solubilidade/efeitos dos fármacos , Sorbitol/química , Temperatura
18.
Carbohydr Polym ; 222: 114973, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31320052

RESUMO

The viscoelastic behaviour of cellulose acetate with a degree of substitution (DS) of 245 plasticized by triacetin was studied at short times by dynamic oscillatory measurements. Two distinct regimes and unexpected scaling behaviour according to plasticizer content were highlighted. The dynamics of chains and their structural organization are not modified up to 35 wt% of triacetin. The rheological behaviour is led by a constant correlation length corresponding to the distance between strong intermolecular interactions subsisting in the melt state at high temperature even in the presence of plasticizer. This particular structure involves the apparition of strain hardening effects during uniaxial extensional flow tests and an important elasticity corresponding to the apparition of a Weissenberg effect at really low shear rates during shear sweeps. Intramolecular hydrogen bonds are responsible of the high rigidity of cellulose acetate chains. Plasticized cellulose acetate in the melt state belongs to the class of associating polymers and its rheological behaviour is mainly led by stickers.


Assuntos
Celulose/análogos & derivados , Plastificantes/química , Triacetina/química , Celulose/química , Elasticidade , Ligação de Hidrogênio , Reologia , Temperatura , Viscosidade
19.
J Agric Food Chem ; 67(46): 12652-12662, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31246019

RESUMO

Organophosphate esters (OPEs) are chemicals extensively used as plasticizers and flame retardants in commercial and consumer products. In this study, we developed and validated a method for the analysis of 13 common OPEs in meat (chicken, pork, and beef) and fish (catfish and salmon) to study their occurrence in those foods in the United States. The method was based on QuEChERS extraction with acetonitrile and automated robotic cleanup of the extracts, followed by low pressure gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis for 8 of the OPEs and ultrahigh-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis for 13 OPEs, including 8 overlapping OPEs. The developed method was validated in the muscle tissues at four spiking levels (5, 10, 20, and 40 ng/g). The background levels in the laboratory environment and materials presented a challenge for accurate quantification at low ng/g levels. UHPLC-Q-Orbitrap MS analysis was utilized to pinpoint the source of their contamination. OPEs were found in the water used in the liquid chromatography (LC) mobile phase, and flow injection analysis with organic mobile phase was suggested as an alternative to avoid OPEs contamination in LC-MS/MS analysis. The validated method was applied to the analysis of 68 real-world meat and fish samples from the U.S. markets by three instrumental methods. Tris(2-chloro-isopropyl) phosphate (TCPP), tri-n-butyl phosphate (TnBP), and triphenyl phosphate (TPP) were found in meat, and TCPP and TPP were measured in fish samples. The sum of median OPE concentrations (averaged for the three instrumental methods) measured in the meat and fish samples were 6.2 and 8.7 ng/g wet weight, respectively. No regulations on the maximum residue levels of OPEs permitted in food were found for the U.S. or other countries.


Assuntos
Ésteres/química , Retardadores de Chama/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Carne/análise , Organofosfatos/química , Plastificantes/química , Espectrometria de Massas em Tandem/métodos , Animais , Peixes-Gato , Bovinos , Galinhas , Contaminação de Alimentos/análise , Contaminação de Alimentos/estatística & dados numéricos , Salmão , Estados Unidos
20.
Int J Biol Macromol ; 135: 647-658, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31150672

RESUMO

Active films were produced with sulphated polysaccharides "ulvan", extracted from the green seaweed Ulva lactuca with different extraction procedures, by varying the glycerol or sorbitol plasticizer concentration at 1% and 2% (w/v). The surface charge and glass transition temperature (Tg) of ulvans were carried out by zeta (ζ)-potential and DSC analysis, respectively. The investigation revealed that ulvans were anionic stable polymers and they had great Tg values. Regardless of the extraction procedure, ulvans can give successful films formulations. However, the optical, thermal, structural and antioxidant characteristics of ulvan films were strongly affected by extraction conditions and by the variation of the type and concentration of plasticizer. In general, as plasticizer concentration increased, ferrous chelating activity and compact structure increased as well, while, Tg, lightness and DPPH radical-scavenging activity decreased. Interestingly, the films plasticized with glycerol exhibited better compact structure, more negative temperature of transition, and greater free radical scavenging ability than with sorbitol. However, the films prepared with sorbitol had the highest L* values and chelating ability. The current study revealed a high correlation between zeta (ζ)-potential of ulvans and their Tg (R2 = 0.98), as well as with scavenging activity of ulvan films (R2 = 0.8-0.99).


Assuntos
Antioxidantes/química , Antioxidantes/isolamento & purificação , Fenômenos Ópticos , Plastificantes/química , Polissacarídeos/química , Polissacarídeos/isolamento & purificação , Temperatura , Cor
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