RESUMEN
The present work reports a nanotechnology strategy to prepare a low-viscosity poly(acrylic acid) (PAAc)-based tear substitute with enhanced efficacy and compliance. Specifically, nanogels composed of PAAc and polyvinylpyrrolidone (PVP) were prepared by adapting an ionizing radiation method. For this purpose, different aqueous systems: PVP/PAAc nanoparticulate complexes, PVP/acrylic acid (AAc), N-vinylpyrrolidone (N-VP)/PAAc, and N-VP/AAc were exposed to gamma rays. The dynamic light scattering technique showed that stable nanogels are only produced in a relatively high yield from the PVP/AAc system. Nanogel formation was driven by the hydrogen-bonding complexation between PVP and PAAc (formed in situ) as well as the radiation-induced cross-linking. Transparency, viscosity and mucoadhesiveness of emerged nanogels were optimized by controlling the feed composition and irradiation dose. Furthermore, neutralized nanogels were topically applied in a dry eye model and compared with a PAAc-based commercial tear substitute, namely Vidisic® Gel. The results of Schirmer's test and tear break-up time demonstrated that nanogels prepared from AAc-rich feed solutions at 20 kGy enhanced markedly the dry eye conditions. The histopathological analysis also ensured the competence of PAAc-rich nanogels to completely return the corneal epithelium to its normal state.
Asunto(s)
Resinas Acrílicas , Materiales Biomiméticos , Síndromes de Ojo Seco/tratamiento farmacológico , Hidrogeles , Gotas Lubricantes para Ojos , Resinas Acrílicas/química , Resinas Acrílicas/farmacología , Animales , Materiales Biomiméticos/química , Materiales Biomiméticos/farmacología , Modelos Animales de Enfermedad , Síndromes de Ojo Seco/metabolismo , Hidrogeles/química , Hidrogeles/farmacología , Gotas Lubricantes para Ojos/química , Gotas Lubricantes para Ojos/farmacología , Conejos , ViscosidadRESUMEN
Superabsorbent hydrogels based on polyacrylamide (PAAm) and Na-alginate (Alg) or chitosan (CS) were synthesized by γ-rays. The effect of dose and copolymer composition on gel content and water absorbency of PAAm/Alg, PAAm/CS and PAAm/Alg/CS hydrogels were studied. The gel content and water absorbency follows the order PAAm/Alg>PAAm/Alg/CS>PAAm/CS. The effect of different cations, fertilizers, buffers on water absorbency of the hydrogels was investigated. Water retention capability of swollen hydrogels as a function of time was studied. PAAm/Alg hydrogel has a high water retention capability. An application of the prepared hydrogels in agricultural fields was performed using maize plants. The results showed that the presence of hydrogels had growth promotion effect on quality and quantity of maize plants. The plants treated by PAAm/Alg hydrogels showed 50% increase in the grain yield suggesting their possible use as a soil conditioner and a water reservoir for plant-soil system.
Asunto(s)
Resinas Acrílicas/efectos de la radiación , Agroquímicos/química , Alginatos/química , Quitosano/química , Hidrogeles/química , Resinas Acrílicas/química , Peso Molecular , Zea mays/crecimiento & desarrolloRESUMEN
Poly(lactic acid) (PLA) has shown much success in the preparation of tissue engineering scaffolds as it can be fabricated with a tailored architecture. However, the PLA surface has drawbacks including the lack of biofunctional motifs which are essential for high affinity to biological cells. Therefore, this study describes a multistep physicochemical approach for the immobilization of d-glucosamine (GlcN), a naturally occurring monosaccharide having many biological functions, on the PLA surface aiming at enhancing the cell proliferation activity. In this approach, poly(acrylic acid) (PAAc) spacer arms are first introduced into the PLA surface via plasma post-irradiation grafting technique. Then, covalent coupling or physical adsorption of GlcN with/on the PAAc spacer is carried out. Factors affecting the grafting yield are controlled to produce a suitable spacer for bioimmobilization. X-ray photon spectroscopic (XPS) analyses confirm the immobilization of GlcN on the PLA surface. The XPS results reveal also that increasing the yield of grafted PAAc spacer on the PLA surface increases the amount of covalently immobilized GlcN, but actually inhibits the immobilization process using the physical adsorption method. Contact angle measurements and atomic force microscopy (AFM) show a substantial increase of surface energy and roughness of PLA surface, respectively, upon the multistep modification procedure. The cytocompatibility of the modified surfaces is assessed using a mouse embryonic fibroblast (MEF) cell line. Observation from the cell culture basically demonstrates the potential of GlcN immobilization in improving the cytocompatibility of the PLA surface. Moreover, the covalent immobilization of GlcN seems to produce more cytocompatible surfaces if compared with the physical adsorption method. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3176-3188, 2017.
Asunto(s)
Materiales Biocompatibles/química , Glucosamina/química , Poliésteres/química , Adsorción , Animales , Línea Celular , Proliferación Celular , Fibroblastos/citología , Cinética , Ratones , Microscopía de Fuerza Atómica , Propiedades de Superficie , Andamios del Tejido/químicaRESUMEN
Ionizing radiation and oxidizing agent like H2O2 were used to degrade chitosan (CS) and its derivatives; N-maleoylchitosan (NMCS), and N-phthaloylchitosan (NPhCS). The structure changes were detected using gel permeation chromatography (GPC). The results revealed that ionizing radiation degraded CS, MNCS, NPhCS and altered their molecular weights and antioxidant activity. The higher the irradiation dose, the lower the molecular weight and the higher antioxidant activity. The addition of irradiated CS and NMCS to minced chicken resulted in highly significant reduction in malondialdehyde (MDA) content (50 and 70%, respectively) if compared with the control. The irradiated NMCS toxicity study did not show strong proliferative effect at small concentrations or cytotoxic effects at higher concentrations. The obtained results suggested that CS and NMCS could be used as natural antioxidant for improving the oxidative deterioration of minced chicken during refrigerated storage.
Asunto(s)
Antioxidantes/química , Antioxidantes/farmacología , Pollos , Quitosano/química , Quitosano/farmacología , Manipulación de Alimentos , Rayos gamma , Animales , Células CACO-2 , Quitosano/análogos & derivados , Almacenamiento de Alimentos , Humanos , Oxidación-Reducción , Solubilidad , Agua/químicaRESUMEN
The aim of this study was to improve the stability and bioavailability of pilocarpine in order to maintain an adequate concentration of the pilocarpine at the site of action for prolonged period of time. Thus, pH-sensitive polyvinylpyrrolidone-poly(acrylic acid) (PVP/PAAc) nanogels prepared by γ radiation-induced polymerization of acrylic acid (AAc) in an aqueous solution of polyvinylpyrrolidone (PVP) as a template polymer were used to encapsulate pilocarpine. Factors affecting size and encapsulation efficiency were optimized to obtain nanogel suitable for entrapping drug efficiently. The PVP/PAAc nanogel particles were characterized by dynamic light scattering (DLS), zeta potential, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), and their size can be controlled by the feed composition and concentration as well as the irradiation dose. Pilocarpine was loaded into the nanogel particles through electrostatic interactions where the AAc-rich nanogels exhibited the highest loading efficiency. The transmittance, mucoadhesion, and rheological characteristics of the nanogel particles were studied to evaluate their ocular applicability. The in vitro release study conducted in simulated tear fluid showed a relatively long sustained release of pilocarpine from the prepared PVP/PAAc nanogel particles if compared with pilocarpine in solution.
Asunto(s)
Resinas Acrílicas/química , Rayos gamma , Pilocarpina/farmacocinética , Polietilenglicoles/química , Polietileneimina/química , Povidona/química , Materiales Biocompatibles/farmacocinética , Disponibilidad Biológica , Glaucoma/tratamiento farmacológico , Concentración de Iones de Hidrógeno , Microscopía Electrónica de Transmisión , Mucinas/metabolismo , Nanogeles , Tamaño de la Partícula , Pilocarpina/química , Polímeros/química , Reología , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
Modification of chitosan (CS) to N-maleoylchitosan (NMCS), N-phthaloylchitosan (NPhCS) and sulfonated-chitosan (SCS) was done using maleic anhydride, phthalic anhydride and chlorosulfonic acid, respectively followed by exposing them to γ-rays at different doses. The molecular weights and structural changes of irradiated chitosan derivatives were determined by GPC, FT-IR and UV-vis spectrophotometer. The molecular weights decreased with increasing irradiation dose. Results revealed that the main polysaccharide structure remained after irradiation. To investigate the enhancement of antioxidant activity of chitosan and its derivatives of different molecular weights, radical mediated lipid peroxidation inhibition, scavenging effect of DPPH radicals, reducing power and ferrous ion chelating activity assays were used. Chitosan derivatives with different molecular weights exhibit antioxidant activity. The lower the molecular weights of chitosan and its derivatives, the higher the antioxidant activity. NMCS possessed high scavenging effect on DPPH radicals compared with NPhCS, SCS and ascorbic acid. The irradiated chitosan and its derivatives could be used as natural antioxidants.
Asunto(s)
Quitosano/química , Quitosano/farmacología , Depuradores de Radicales Libres/química , Depuradores de Radicales Libres/farmacología , Radiación Ionizante , Conformación de Carbohidratos/efectos de la radiación , Quitosano/síntesis química , Depuradores de Radicales Libres/síntesis química , Radicales Libres/antagonistas & inhibidores , Quelantes del Hierro/química , Quelantes del Hierro/farmacología , Peso Molecular , Oxidación-Reducción/efectos de la radiaciónRESUMEN
Study has been made on the preparation of functionalized copolymer by grafting N,N-(dimethylaminoethyl) methacrylate (DMAEMA) onto polypropylene (PP) films using gamma-irradiation technique. The effect of monomer concentration and irradiation dose on the grafting yield was studied. It was found that grafting yield increases with increasing the monomer concentration and irradiation dose. Subsequent quaternization of the amine group of PDMAEMA graft chain using different reagents, 1-bromo octadecane, methyl iodide and benzyl chloride, to improve their ionic character was carried out. The grafted PP films were characterized by IR spectroscopy, and mechanical and thermal properties. During the adsorption of phosphate (PO(4)(3-)) and nitrate (NO(3)(-)) ions, the rate of adsorption, pH effect, desorbability and initial feed concentration effect were investigated. It was found that the adsorption of PO(4)(3-) and NO(3)(-) ions increases with increasing the adsorption time up to 10h and decreases with increasing the pH of medium. The desorbability is ranging from 18 to 30%, and it is relatively difficult to desorb PO(4)(3-) and NO(3)(-) ions from the functionalized grafted copolymers. Results showed good possibility for the use of such functionalized grafted film in the field of removal of some anions such as PO(4)(3-) and NO(3)(-) from their media.
Asunto(s)
Metacrilatos/química , Nitratos/química , Fosfatos/química , Adsorción , Concentración de Iones de Hidrógeno , Nitratos/aislamiento & purificación , Fosfatos/aislamiento & purificación , Espectroscopía Infrarroja por Transformada de Fourier , Resistencia a la Tracción , TermogravimetríaRESUMEN
pH-sensitive hydrogels were prepared from poly(ethylene glycol) (PEG) and acrylic acid (AAc) in aqueous solution employing gamma-radiation-induced copolymerization and crosslinking. The swelling behavior of the prepared hydrogels was determined by investigating the time and pH-dependent swelling of the (PEG/AAc) hydrogels of different PEG content. The effect of environmental parameters such as pH and ionic strength on the swelling kinetics was studied. The results not only show the dependence of the swelling indices on the pH value of the swelling medium but also show a clear dependence of the diffusion coefficient on the ionic strength of the medium. To estimate the ability of the prepared copolymer to be used as a colon-specific drug carrier, the release of ketoprofen was studied as a function of time at pH 1 and pH 7.