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1.
Food Chem ; 337: 127763, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32791431

RESUMO

In this work, water-resistant poly (vinyl alcohol) (PVA)/poly (acrylic acid) (PAA) electrospun fibers encapsulating tangeretin (Tan) were fabricated by emulsion-electrospinning. To optimize the electrospinning condition, the size and morphology of electrospun fibers were characterized by dynamic light scattering (DLS), optical light microscope, fluorescence microscopy, and scanning electron microscopy (SEM), respectively. The optimized initial concentration of PVA/PAA was 10% (w/w) with a mass ratio of 3:7. The time and temperature of optimized thermal crosslinking treatment were 2 h and 145 °C, respectively. The results of XRD and SEM showed that the Tan was successfully incorporated into smooth PVA/PAA electrospun fibers and those fibers possessed nano-diameter size and high porosity. The encapsulation of Tan had no significant impact on the antioxidant activity of PVA/PAA/Tan crosslinking electrospun fibers. The in vitro release test showed the PVA/PAA/Tan crosslinking electrospun fibers achieved durable release profiles and lower burst release rates than that from the pure Tan emulsion. Based on these results, it is concluded that PVA/PAA/Tan crosslinking electrospun fibers prepared by emulsion-electrospinning serve as a promising technique in the fields of water-insoluble drug delivery and slow-release.


Assuntos
Resinas Acrílicas/química , Antioxidantes/química , Portadores de Fármacos/química , Eletricidade , Flavonas/química , Álcool de Polivinil/química , Liberação Controlada de Fármacos , Emulsões
2.
Int J Nanomedicine ; 15: 6945-6960, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33061361

RESUMO

Background: Natural clay nanomaterials are an emerging class of biomaterial with great potential for tissue engineering and regenerative medicine applications, most notably for osteogenesis. Materials and Methods: Herein, for the first time, novel tissue engineering scaffolds were prepared by 3D bioprinter using nontoxic and bioactive natural attapulgite (ATP) nanorods as starting materials, with polyvinyl alcohol as binder, and then sintered to obtain final scaffolds. The microscopic morphology and structure of ATP particles and scaffolds were observed by transmission electron microscope and scanning electron microscope. In vitro biocompatibility and osteogenesis with osteogenic precursor cell (hBMSCs) were assayed using MTT method, Live/Dead cell staining, alizarin red staining and RT-PCR. In vivo bone regeneration was evaluated with micro-CT and histology analysis in rat cranium defect model. Results: We successfully printed a novel porous nano-ATP scaffold designed with inner channels with a dimension of 500 µm and wall structures with a thickness of 330 µm. The porosity of current 3D-printed scaffolds ranges from 75% to 82% and the longitudinal compressive strength was up to 4.32±0.52 MPa. We found firstly that nano-ATP scaffolds with excellent biocompatibility for hBMSCscould upregulate the expression of osteogenesis-related genes bmp2 and runx2 and calcium deposits in vitro. Interestingly, micro-CT and histology analysis revealed abundant newly formed bone was observed along the defect margin, even above and within the 3D bioprinted porous ATP scaffolds in a rat cranial defect model. Furthermore, histology analysis demonstrated that bone was formed directly following a process similar to membranous ossification without any intermediate cartilage formation and that many newly formed blood vessels are within the pores of 3D-printed scaffolds at four and eight weeks. Conclusion: These results suggest that the 3D-printed porous nano-ATP scaffolds are promising candidates for bone tissue engineering by osteogenesis and angiogenesis.


Assuntos
Regeneração Óssea/fisiologia , Células-Tronco Mesenquimais/citologia , Engenharia Tecidual/métodos , Tecidos Suporte/química , Animais , Osso e Ossos/fisiologia , Cálcio/metabolismo , Chlorocebus aethiops , Condrogênese , Força Compressiva , Regulação da Expressão Gênica , Humanos , Compostos de Magnésio/química , Masculino , Teste de Materiais , Nanotubos/química , Osteogênese/fisiologia , Álcool de Polivinil/química , Porosidade , Impressão Tridimensional , Ratos Sprague-Dawley , Compostos de Silício/química , Células Vero , Microtomografia por Raio-X
3.
Int J Nanomedicine ; 15: 5113-5129, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764940

RESUMO

Background: Low bioavailability and poor permeability of the blood-brain barrier are problematic when delivering therapeutic agents and particularly anti-human immunodeficiency virus therapy to the central nervous system. The intranasal route offers an alternative for central nervous system delivery. Cubosomes have been reported as helpful vehicles for intranasal delivery of therapeutics to enable brain targeting. Objective: In this study, we aimed to develop the intranasal cubosomal thermogelling dispersion of saquinavir mesylate for central nervous system delivery. Methods: The Box-Behnken design was applied to study the effect of monoolein, Poloxamer 407, and polyvinyl alcohol as independent factors and the particle size, entrapment efficiency, gelation temperature, and stability index as responses. The optimized cubosomes were evaluated using transmission electron microscopy, ex vivo permeation, and in vivo pharmacokinetics. Results: The optimized formula consisting of monoolein (8.96%), Poloxamer 407 (17.45%), and polyvinyl alcohol (7.5%) was prepared and evaluated. Higher values for the steady-state flux, permeability coefficient, and enhancement factor were observed for the cubosomal thermogelling dispersion of saquinavir during ex vivo permeation in comparison with an aqueous suspension of saquinavir. From the pharmacokinetic profile, the relative bioavailability for the intranasal optimized formula was approximately 12-fold higher when compared with oral aqueous suspension and 2.5-fold greater when compared to the intranasal aqueous suspension of saquinavir. Conclusion: Overall, the saquinavir-loaded cubosomal thermogelling formulation is promising for central nervous system delivery by intranasal administration.


Assuntos
Portadores de Fármacos/química , Cristais Líquidos/química , Nanoestruturas/química , Saquinavir/farmacologia , Temperatura , Administração Intranasal , Animais , Disponibilidade Biológica , Barreira Hematoencefálica/metabolismo , Géis , Glicerídeos/química , Masculino , Tamanho da Partícula , Permeabilidade , Poloxâmero/química , Álcool de Polivinil/química , Saquinavir/administração & dosagem , Saquinavir/metabolismo
4.
Ecotoxicol Environ Saf ; 202: 110935, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800218

RESUMO

This study investigated the ability of dual crosslinked interpenetrating polymer network (IPN) blend beads (DIN:SA/PVA-beads), composed of sodium alginate (SA) and poly (vinyl alcohol) (PVA), as a base-triggered carrier for the controlled release of dinotefuran (DIN) in Spodoptera litera midgut. The blend beads were characterized for morphology, encapsulation efficiency, swelling degree, and in vitro release of the blend beads were characterized. The results revealed that the double-crosslinked gel beads had a tightly interpenetrating network structure and exhibited a satisfactory embedding effect for DIN. The maximum of the DIN loading capacity was approximately 1.01%, with a high encapsulation efficiency of 83.19%. The triggered release of DIN from the blend beads was studied in deionized water (pH 3.0-11.0) via high-performance liquid chromatography (HPLC); it was found that the release rate was higher in alkaline pH conditions than in acidic and neutral conditions. An in vivo dynamics and degradation study also demonstrated that the excellent release characteristics of DIN:SA/PVA-beads in the midgut of S. litera. This study provides a promising controlled-release form of dinotefuran that is more effective and can be used for the targeted control of pests with alkaline midgut.


Assuntos
Guanidinas/metabolismo , Neonicotinoides/metabolismo , Nitrocompostos/metabolismo , Spodoptera/metabolismo , Alginatos/química , Animais , Preparações de Ação Retardada/química , Etanol , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Hidrogéis/química , Concentração de Íons de Hidrogênio , Polímeros , Álcool de Polivinil/química
5.
AAPS PharmSciTech ; 21(5): 199, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32676796

RESUMO

A new transdermal drug delivery system of nanofiber membrane with good biocompatibility and high drug loading was developed by electrospinning technology in this study. Using vinyl alcohol-co-ethylene (PVA-co-PE) polymer as a spinning matrix and non-steroidal anti-inflammatory drug (NSAID) sulindac (SUL) as a model drug, the SUL@PVA-co-PE nanofiber membrane was prepared and characterized systematically. The morphology, molecular vibrational transitions, thermogravimetric attributes, and in vitro drug release and transdermal characteristics of drug-loaded nanofiber membranes were analyzed. The results indicated that the surface of PVA-co-PE nanofibers was uniform and smooth with the diameter ranged from 461 to 696 nm. Notably in vitro simulation experiments demonstrated that SUL@PVA-co-PE nanofiber membrane could provide a continuous drug release to reach the effective concentration of the drug, and exhibited significantly higher cumulative drug permeability compared to commercially available patches, Taken together, PVA-co-PE nanofiber membranes exhibited the characteristics of high drug loading and stability, and represented the potential to be utilized as a new transdermal drug delivery carrier with pronounced development prospect.


Assuntos
Membranas Artificiais , Nanofibras , Polietileno/química , Álcool de Polivinil/química , Administração Cutânea , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Portadores de Fármacos , Masculino , Camundongos , Camundongos Endogâmicos ICR , Permeabilidade , Sulindaco/administração & dosagem
6.
J Cancer Res Ther ; 16(2): 276-279, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32474513

RESUMO

Purpose: To study the arterial distribution of embosphere microsphere (EM) and polyvinyl alcohol (PVA) particles in rabbit mesenteric artery using in vivo microscopy.To study the arterial distribution of embosphere microsphere (EM) and polyvinyl alcohol (PVA) particles in rabbit mesenteric artery using in vivo microscopy. Methods: Sixteen New Zealand rabbits were divided into four groups, namely large PVA (560-710 µm), small PVA (150-350 µm), large EM (500-700 µm), and small EM (100-300 µm). The mesenteric arteries of the experimental animals were embolized under fluoroscopic guidance and visualized using in vivo microscopy. The embolized vessel diameter and arterial distribution of embolic agents were compared. Results: The diameters of occluded vessels in large PVA, small PVA, large EM, and small EM groups were 430.60 ± 67.30, 200.95 ± 70.54, 387.79 ± 92.51, and 143.81 ± 39.65 µm, respectively. PVA occluded significantly larger vessels than EM when the particle size was similar (P < 0.001). The proportion of EM at the bifurcation of the artery was significantly higher than that of PVA particles (large PVA < large EM, χ2 = 4.325, P < 0.038; small PVA < small EM, χ2 = 6.68, P < 0.01). Conclusion: Both PVA and EM could occlude vessels smaller than the particle size, and EM resulted in deeper penetration. The location of embolic particles in the artery is mainly related to the shape of particles.


Assuntos
Angiografia/métodos , Embolização Terapêutica/métodos , Microscopia Intravital/métodos , Artérias Mesentéricas/metabolismo , Microesferas , Álcool de Polivinil/farmacocinética , Animais , Sistemas de Liberação de Medicamentos/métodos , Artérias Mesentéricas/diagnóstico por imagem , Modelos Animais , Tamanho da Partícula , Álcool de Polivinil/química , Coelhos
7.
J Chromatogr A ; 1624: 461260, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540085

RESUMO

Complexation between poly(vinyl alcohol) (PVA) and borax in aqueous solution yields a dynamic polyelectrolyte. Study of chain conformation of such a polyelectrolyte is challenging due to the difficulty in separating different macromolecular species. In this study, we investigated conformation of dilute PVA chains complexed with borax in a wide concentration range between 0.02 and 78.6 mM using asymmetrical flow field-flow fractionation (AF4). We find that elution of the complexes is strongly influenced by the borax concentration owing to (1) the charged complex is repelled electrostatically by the charged bottom membrane of the AF4 channel, and (2) the Debye screening length reduces with increasing a charge density. The chain conformation of PVA-borax complexes depends on both polymer molar mass and borax concentration. At low borax concentrations of 0.02~0.5 mM, a transition from random coil to rod-like conformation is observed with increasing the chain size. At borax concentrations of 1 mM and higher, all chains become random coil owing to a reduced screening length of the electrostatic repulsion.


Assuntos
Boratos/química , Fracionamento por Campo e Fluxo/métodos , Conformação Molecular , Álcool de Polivinil/química , Difusão Dinâmica da Luz , Etanol/química , Peso Molecular , Eletricidade Estática , Água
8.
Chemosphere ; 258: 127227, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554003

RESUMO

Eight different types of complexing agents were employed for the development of new biodegradable decontamination solutions that are able to form strippable coatings after they are dispersed and allowed to dry on a variety of surfaces contaminated with 60Co, 133Ba, 137Cs and 241Am radioactive isotopes. The new generation of eco-friendly chelators with superior biodegradability, utilized for the first time in such applications, can easily replace the non-biodegradable and carcinogenic complexing agents that are still in use today, due to their decontamination performances. Furthermore, besides the complexing action over the radionuclides, the solutions contain two types of clays, Bentonite (BT) and Saponite (SP), which have the capacity to adsorb specific ions, improving the decontamination efficiency of the solutions. Our research revealed that it is preferable to replace BT with SP, due to its better dispersibility, thermal stability, next to superior ability to gel and better thermal stability (Miles, 2011). The solutions showed a decontamination factor superior to 95% for 137Cs (on all surfaces), over 90% for 60Co and 133Ba, and more than 72% 241Am (on all surfaces), except for galvanized metal plates, where lower decontamination factors were obtained: over 70% for 133Ba, maximum 41.87% for 241Am and 43.19% for 60Co.


Assuntos
Quelantes/química , Descontaminação/métodos , Substâncias Perigosas/análise , Nanoestruturas/química , Radioisótopos/análise , Adsorção , Silicatos de Alumínio/química , Bentonita/química , Biodegradação Ambiental , Álcool de Polivinil/química , Radioatividade , Soluções , Propriedades de Superfície
9.
Pharm Res ; 37(6): 92, 2020 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-32394200

RESUMO

PURPOSE: The aim of the study was to evaluate organogel nanoparticles as a lipophilic vehicle to increase the oral bioavailability of poorly soluble compounds. Efavirenz (EFV), a Biopharmaceutical Classification System (BCS) Class II, was used as drug model. METHODS: Organogel nanoparticles loaded with EFV were formulated with sunflower oil, 12-hydroxystearic acid (HSA) and polyvinyl alcohol (PVA). Various parameters have been investigated in the current study such as (i) the release profile of organogel assessed by USP 4 cell flow dialysis, (ii) the impact of organogel on intestinal absorption, using Caco-2 cells as in vitro model and jejunum segments as ex vivo assay and (iii) the bioavailability of organogel following oral pharmacokinetic study. RESULTS: 250-300 nm spherical particles with a final concentration of 4.75 mg/mL drug loading were obtained, corresponding to a thousand fold increase in EFV solubility, combined to a very high encapsulation efficiency (>99.8%). Due to rapid diffusion, drug was immediately released from the nanoparticles. The biopharmaceutical evaluation on ex vivo jejunum segments demonstrated an increased absorption of EFV from organogel nanoparticles compare to a native EFV suspension. In vitro assays combining Caco-2 cell cultures with TEM and confocal microscopy demonstrated passive diffusion, while paracellular integrity and endocytosis activity remain expelled. Oral pharmacokinetics of EFV organogel nanoparticles improve oral bioavailability (Fr: 249%) and quick absorption compared to EFV suspension. CONCLUSION: Organogel nanoparticles increase the bioavailability of BCS Class II drugs. The main phenomena is simply oil transfer from the gelled particles through the cell membrane.


Assuntos
Benzoxazinas/química , Portadores de Fármacos/química , Géis/química , Nanocápsulas/química , Álcool de Polivinil/química , Ácidos Esteáricos/química , Óleo de Girassol/química , Animais , Benzoxazinas/administração & dosagem , Benzoxazinas/farmacocinética , Disponibilidade Biológica , Células CACO-2 , Permeabilidade da Membrana Celular , Sobrevivência Celular/efeitos dos fármacos , Difusão , Composição de Medicamentos/métodos , Liberação Controlada de Fármacos , Excipientes/química , Humanos , Absorção Intestinal , Masculino , Solubilidade , Suspensões/química , Distribuição Tecidual
10.
Chemosphere ; 257: 127144, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32473409

RESUMO

Polyvinylidene fluoride (PVDF) membrane was coated with polyvinyl alcohol (PVA)/titanium dioxide (TiO2) solution using dip-coating method. The effect of PVA loading (0-12 wt%) at a fixed TiO2 concentration (1 wt%) was investigated through physical and morphological characterization of the membranes. The experimental results showed that increasing the PVA content from 0 to 12 wt% in the coating solution increased the hydrophilicity and tensile strength as well as the young's modulus of the coated membranes. It also increased the thickness of the thin film coating which enhanced the removal of dyes but affected the permeate flux adversely. Larger the molecular weight of the dye, higher the rejection and lower the permeate flux obtained. The antifouling performance of the membrane was studied using Bovine Serum Albumin (BSA) solution and the fouling was measured using the irreversible fouling factor. The results indicated that the PVA/TiO2 coated PVDF membrane had lower irreversible fouling factors compared to plain PVDF membrane. The PVDF membrane with a thin film coating containing 3 wt% of PVA and 1 wt% of TiO2 showed high photocatalytic degradation for the three dyes studied under UV irradiation due to uniform dispersion of TiO2 nanoparticles over the membrane surface. Further, smaller the molecular weight of the dye, larger the photodegradation that was observed.


Assuntos
Corantes/química , Álcool de Polivinil/química , Polivinil/química , Eliminação de Resíduos Líquidos/métodos , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Nanopartículas , Fotólise , Soroalbumina Bovina , Têxteis , Titânio , Raios Ultravioleta
11.
PLoS One ; 15(5): e0233021, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32396571

RESUMO

The time-dependent properties of rubber-like synthesized and biological materials are crucial for their applications. Currently, this behavior is mainly measured using axial tensile test, compression test, or indentation. Limited studies performed on using multi-axial loading measurements of time-dependent material behavior exist in the literature. Therefore, the aim of this study is to investigate the viscoelastic response of rubber-like materials under multi-axial loading using cavity expansion and relaxation tests. The tests were performed on PVA hydrogel specimens. Three hyperelasitc models and one term Prony series were used to characterize the viscoelastic response of the hydrogels. Finite element (FE) simulations were performed to verify the validity of the calibrated material coefficients by reproducing the experimental results. The excellent agreement between the experimental, analytical and numerical data proves the capability of the cavity expansion technique to measure the time-dependent behavior of viscoelastic materials.


Assuntos
Álcool de Polivinil/química , Bioengenharia , Fenômenos Biomecânicos , Elasticidade , Elastômeros/química , Análise de Elementos Finitos , Hidrogéis/química , Teste de Materiais , Estresse Mecânico , Viscosidade
12.
Artigo em Inglês | MEDLINE | ID: mdl-32371329

RESUMO

High-performance liquid chromatography (HPLC) and solid phase micro membrane tip extraction (SPMMTE) methods are developed for the simultaneous analysis of eleven cardiovascular drugs in human plasma. Iron nanoparticles were obtained by the green method, characterized by XRD, FT-IR, TEM, and EDS and utilized in SPMMTE for sample preparation. The mobile phase used was ammonium acetate buffer-methanol-acetonitrile (65:18:17) with a 1.0 mL/min flow rate at 260 nm detection. Column used was Sunshell C18 150 × 4.6 mm, 2.6 µm. The values of k, α, and Rs were ranged from 040 to109.22, 1.20 to 2.67 and 1.0 to 26.18. SPMMTE and HPLC methods were fast, reproducible, precise, robust, economic and rugged for analysis of methyldopa, hydrochlorothiazide, prazosin hydrochloride, furosemide, labetalol, propranolol, valsartan, losartan potassium, diltiazem, irbesartan and spironolactone in human plasma. The recoveries (%) of methyldopa, hydrochlorothiazide, prazosin hydrochloride, furosemide, labetalol, propranolol, valsartan, losartan potassium, diltiazem, irbesartan, and spironolactone were 91.0, 85.2, 92.3, 90.4, 90.1, 85.6, 86.6, 86.2, 85.1, 86.6, and 85.7, respectively. These results showed that SPMMTE and HPLC methods can be applied to test the described drugs in several matrices.


Assuntos
Anti-Hipertensivos/sangue , Nanopartículas Metálicas/química , Nanocompostos/química , Adsorção , Cromatografia Líquida de Alta Pressão , Diltiazem/sangue , Furosemida/sangue , Humanos , Hidroclorotiazida/sangue , Irbesartana/sangue , Ferro/química , Labetalol/sangue , Limite de Detecção , Losartan/sangue , Metildopa/sangue , Álcool de Polivinil/química , Prazosina/sangue , Propranolol/sangue , Reprodutibilidade dos Testes , Microextração em Fase Sólida , Espironolactona/sangue , Valsartana/sangue
13.
Chemosphere ; 256: 127107, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32445992

RESUMO

The massive use of petroleum-based polymers and their improper waste treatment has brought on significant global environmental problems due to their non-biodegradable nature. Starch/poly(vinyl alcohol) (PVA) bioplastics are suitable substitutes for conventional polymers, such as polyethylene, due to their full biodegradability and excellent mechanical properties. Knowledge of the pollutant emissions during pyrolysis and combustion of starch/PVA films is important because they can arrive at landfills mixed with conventional polymers and be thermally degraded in uncontrolled fires. On the other hand, controlled thermal treatments could result in thermal valorization of the waste. Pyrolysis and combustion experiments were carried out at 650, 750, 850 and 950 °C in a laboratory furnace. The analysis of carbon oxides, light hydrocarbons, and semivolatile compounds, including polycyclic aromatic hydrocarbons (PAHs), is shown. Experiments showed lower pollutant emissions than those found with conventional polymers, such as polyethylene and polyester, in the same equipment. Nevertheless, the pyrolysis run at 950 °C showed the highest light hydrocarbon yield (123013 mg kg-1), but this is considerably lower than the values found for polyethylene. The main semivolatile compounds (not PAHs) emitted, with maximum yields ranging from 1351 to 4694 mg kg-1, were benzaldehyde, phenol, indene, and acetophenone. Specifically, the total semivolatile compounds emitted after pyrolysis and combustion of starch/PVA samples represent only 38 and 50%, respectively, of those emitted with polyethylene. Further, the main PAHs were naphthalene, acenaphthylene, and phenanthrene with maximum values of 4694, 2704 and 1496 mg kg-1, respectively. The PAH yield was considerably higher in experiments with low oxygen content.


Assuntos
Poluentes Atmosféricos/química , Incineração , Álcool de Polivinil/química , Poluentes Atmosféricos/análise , Carbono/análise , Etanol/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Cloreto de Polivinila/análise , Pirólise , Amido/análise
14.
Sci Rep ; 10(1): 6929, 2020 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-32332779

RESUMO

Tube-shaped blood vessel models that mimic their geometries and mechanical properties can deliver reliable and realistic behavioral information such as deformation and rupture during procedures such as insertion of medical devices. Thickness of vessel walls is an important parameter for fabricating the blood vessel models owing to their strong influence on the model behavior, especially during deformation. The dip-coating method is used to fabricate blood vessel models; however, non-uniform wall thicknesses are observed using this method. This study aimed at finding the characteristics of stereo "angular control dip-coating" (ACDC) system to develop a dip-coating system that can produce tubular models with uniformed wall thickness. The system developed here enables an observation of the substrate behavior from two different views. The conditions of dip-coating used in this study produce 1.36-1.82 mm in the maximum and 0.188-0.435 mm in minimum wall thickness and the fabricated walls cover the realistic range of carotid arterial dimensions. The characteristics of the ACDC system indicate that ACDC is effective for fabricating the uniform wall thickness particularly in the strong curved parts.


Assuntos
Vasos Sanguíneos/fisiologia , Modelos Biológicos , Engenharia Tecidual/métodos , Álcool de Polivinil/química , Microtomografia por Raio-X
15.
Molecules ; 25(6)2020 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-32204526

RESUMO

Swellable polymers that respond to pH (including a portion of the physiological pH range) have been prepared from N-isopropylacrylamide (NIPA) copolymerized with acrylic acid, methacrylic acid, ethacrylic acid or propacrylic acid by dispersion polymerization. When the swellable polymer particles are dispersed in a polyvinyl alcohol (PVA) hydrogel membrane, large changes occur in the turbidity of the membrane (which is measured using an absorbance spectrometer) as the pH of the buffer solution in contact with the hydrogel membrane is varied. The swelling of the NIPA copolymer is nonionic, as the ionic strength of the buffer solution in contact with the PVA membrane was increased from 0.1 to 1.0 M without a decrease in the swelling. For many of these NIPA copolymers, swelling was also reversible in both low- and high ionic strength pH-buffered media and at ambient and physiological temperatures. The composition of the formulation used to prepare these copolymers of NIPA can be correlated to the enthalpy and entropy of the pH-induced swelling.


Assuntos
Acrilamidas/química , Acrilatos/química , Polímeros/química , Entropia , Concentração de Íons de Hidrogênio , Metacrilatos/química , Álcool de Polivinil/química
16.
Carbohydr Polym ; 235: 115979, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32122510

RESUMO

In this study, Response Surface Methodology was used to optimize the electrospinning process parameters including voltage, distance, and flow rate in order to obtain catechin-loaded electrospun nanofibers from Azivash (Corchorus olitorius. L) gum-polyvinyl alcohol with the minimum diameter of nanofibers. The optimum electrospinning conditions were applied for catechin encapsulation at different loading concentrations (500, 1000, 2000 and 3000 mg L-1). According to the results, increase in catechin concentration led to increment in polymer solution viscosity. However, electrical conductivity decreased and mean diameter of nanofibers increased from 89 nm to 371 nm. There was a robust interaction between the catechin and polymer matrix; also addition of catechin improved thermal stability of nanofibers. In general, at higher catechin levels, despite increasing loading capacity, encapsulation efficiency was significantly reduced (p < 0.05). Optimum nanofibers loaded with 500 and 1000 mg L-1 catechin can be considered to apply in active food packaging and pharmaceutical applications.


Assuntos
Materiais Biocompatíveis/química , Catequina/química , Corchorus/química , Nanofibras/química , Gomas Vegetais/química , Álcool de Polivinil/química , Catequina/síntese química , Condutividade Elétrica , Tamanho da Partícula , Propriedades de Superfície
17.
Carbohydr Polym ; 235: 116018, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32122516

RESUMO

The stretchable hydrogels provide potential alternatives to bionic skins. However, skin simulation remains seriously challenging due to its complex nature, including mechanical property, protective effect, and sensory capability. Herein, conductive gels toughened by sodium alginate fibers in oil-water system were developed for preparation of skin-like ionic sensors. The dynamic network was constructed by polyvinyl alcohol and sodium alginate fibers, providing a wide scope of mechanical properties, such as high toughness, anti-fatigue fracture and remodelability. Moreover, salts imparted good conductivity to gels. As a result, gels exhibited sensory capability toward stress and strain, so they were considered sensors to monitor various movements of human body. In particular, gels demonstrated temperture tolerance ranging from -20 °C to 40 °C and non-drying for 6 days at 25 °C. In this study, gels showed complex intelligence similar to natural skin, and might find applications in artificial intelligence, human-mechanial interactions, and smart wearable devices.


Assuntos
Alginatos/química , Inteligência Artificial , Fibras na Dieta , Pele/química , Dispositivos Eletrônicos Vestíveis , Configuração de Carboidratos , Condutividade Elétrica , Géis/química , Humanos , Tamanho da Partícula , Álcool de Polivinil/química , Propriedades de Superfície
18.
World J Microbiol Biotechnol ; 36(3): 45, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32130535

RESUMO

Entrapment of halloysite nanotubes (HNTs) loaded with enzyme, into a polymer matrix (PVA/Alg), is a way to produce an environment surrounding the adsorbed enzyme molecules which improves the enzyme properties such as storage and operational stability. Hence, in this study, we optimised the factors affecting lipase adsorption onto halloysite nanotubes including halloysite amounts (5, 42.5 and 80 mg), lipase concentrations (30, 90 and 150 µg/ml), temperatures (5, 20 and 35 °C) and adsorption times (30, 165 and 300 min). The optimal conditions were determined as an halloysite amount of 50 to 80 mg, a lipase concentration of 30 to 57 µg/ml, an adsorption temperature of 20 °C and an adsorption time of 165 min, which resulted in a specific activity and adsorption efficiency of 15,000 (U/g protein) and 70%, respectively. Then, lipase adsorbed under optimal conditions was entrapped in a PVA/Alg hydrogel. The formation mechanism of immobilized lipase was investigated by FESEM and FTIR. Subsequent entrapment of adsorbed lipase improved the lipase storage and operational stability. Km, Vmax, Kcat and Kcat/Km values showed an increase in the entrapped HNT-lipase performance in comparison with the free and adsorbed lipase.


Assuntos
Argila/química , Lipase/química , Álcool de Polivinil/química , Adsorção , Candida/enzimologia , Estabilidade Enzimática , Enzimas Imobilizadas/química , Nanotubos
19.
Soft Matter ; 16(13): 3319-3324, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32187247

RESUMO

Self-healing hydrogels as renewable materials have attracted significant attention recently. However, traditional self-healing hydrogels require a long time for self-healing and cannot be used at low temperatures. Besides, their poor biocompatibility limits the application of hydrogels. Herein, we have prepared a hydrogel composed of polyvinyl alcohol (PVA) and modified sodium alginate. Due to the dynamic recombination of borate bonds, these hydrogels show a strong self-healing ability, with the shortest self-healing time up to 15 seconds. Also, glycerin (GI) was added into the hydrogel to increase the cold resistance of the hydrogel. At -25 °C, the hydrogel still displayed good frost resistance and elasticity. NaCl and other inorganic salts were added to endow the hydrogel with good electrical conductivity. The hydrogel also had good skin-like properties and could activate the capacitive screen of an electronic device.


Assuntos
Alginatos/química , Hidrogéis/química , Álcool de Polivinil/química , Cicatrização/efeitos dos fármacos , Alginatos/farmacologia , Temperatura Baixa , Elasticidade , Condutividade Elétrica , Humanos , Hidrogéis/farmacologia , Álcool de Polivinil/farmacologia , Pele/efeitos dos fármacos , Resistência à Tração/efeitos dos fármacos
20.
Carbohydr Polym ; 233: 115859, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32059910

RESUMO

Naked-eye detection pH sensor is becoming a powerful tool in food safety monitoring. In this work, a pH sensor was developed by incorporating cellulose modified with acidochromic dye into polyvinyl alcohol (PVA). The results indicated that the dye (up to 170.4 µmol/g) was successfully anchored to cellulose. It was demonstrated that the addition of acidochromic regenerated cellulose (ARC) resulted in enhancement of tensile strength, elongation at break and maximum decomposition temperature by 44 %, 43.6 % and 11 °C, respectively. The pH sensor demonstrated that a visible color change from yellow to brick-red and to purple when placed in solutions of pH = 7, 10 and 12. The pH sensor showed excellent resistance to leaching under strong acidic and alkaline conditions. When applied to spoiled shrimp, an evident color change from yellow to brown was observed, suggesting it could serve as an easy-to-use, non-destructive visual indicator system for real-time food monitoring.


Assuntos
Celulose/química , Corantes/química , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Naftalenossulfonatos/química , Álcool de Polivinil/química , Animais , Cor , Concentração de Íons de Hidrogênio , Penaeidae , Temperatura , Resistência à Tração
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