Abstract： The objective was to obtain solid dispersion to improve the dissolution rate, solubility and oral absorption of MB （mebendazole）, poor water-soluble drugs. The new formulation was characterized by DSC （d...Abstract： The objective was to obtain solid dispersion to improve the dissolution rate, solubility and oral absorption of MB （mebendazole）, poor water-soluble drugs. The new formulation was characterized by DSC （differential scanning calorimetry）, PXRD （powder X-ray diffraction）, FT-1R （fourier transform infrared spectroscopy） and STEM （scanning transmission electron microscopy） methods. Solid dispersions of MB with polyvinylpyrrolidone K-30 （PVP K30） were prepared by solvent evaporation method. The solubility of MB （original powder） and that of the solid dispersions was measured at 25℃ in ethanol-water. The aqueous solubility of MB was favoured by the presence of the polymer in solvent mixtures. Combination of solid dispersions with co-solvents increased the water solubility of MB in a larger extent that each method separately. Solubility parameter （o） was used to relate to solubility profiles. MB and the solid dispersions show a solubility curve with a single peak at 51 = 30.78 MPav2. Solid state characterizations indicated that the solid dispersion exist an amorphous material entrapped in polymer matrix getting highest improvement in wettability and solubility.展开更多
Lactic acid(LA)is an important building block for high added value polymers with technological and biomedical applications,such as 3d printing filaments,surgical sutures or food packaging.The traditional manufacture o...Lactic acid(LA)is an important building block for high added value polymers with technological and biomedical applications,such as 3d printing filaments,surgical sutures or food packaging.The traditional manufacture of these materials uses harmful organic solvents,metallic catalysts and high temperatures.The current trend in green chemistry demands a cleaner and more sustainable process.In this research,the esterification reaction of low-cost racemic LA was explored in a reusable biphasic water/heptane system at low temperature(30℃).The chosen catalyst was Candida antarctica lipase B(CALB),in the free and immobilized form.The functional groups of the recovered solid products were identified by DRIFTS spectroscopy.The commercial immobilized CALB(Novozym435^(■))did not return any solid product under the explored conditions and significant leaching of the enzyme was observed by UV-Vis spectroscopy.On the other hand,the commercial CALB broth produced variable amounts of solid product in the water/heptane interphase with conversions(X)in the range of 2-47%,measured by HPLC.The highest product recovery was reached at 24 h when conversion of LA achieved 37%.After that time the reaction went backwards.The LA polycondensation products were mostly water-soluble oligomers.The results suggest that CALB can start a new chain with either R or S-LA,but is stereoselective towards the R-LA for the chain growth.Additional experimental difficulties arose from the lipase broth’s excipients like sorbitol and glycerol which interfere in the esterification reaction.The outcomes presented herein provide a new starting point for LA polycondensation.展开更多
Nanosized magnetite has emerged as an adsorbent of pollutants in water remediation. Nanoadsor- bents include magnetic iron oxide and its modifiers/ stabilizers, such as carbon, silica, clay, organic moieties （polymer...Nanosized magnetite has emerged as an adsorbent of pollutants in water remediation. Nanoadsor- bents include magnetic iron oxide and its modifiers/ stabilizers, such as carbon, silica, clay, organic moieties （polymers, aminoaeids, and fatty acids） and other inorganic oxides. This review is focused on the recent developments on the synthesis and use of magnetic nanoparticles and nanocomposites in the treatment of contaminated water. The emphasis is on the influence of the iron oxide modifiers on some properties of interest such as size, BET area, and magnetization. The characteristics of these nanomaterials are related to their ability to eliminate heavy metal ions and dyes from wastewater. Comparative analysis of the actual literature was performed aiming to present the magnetic material, its preparation methodology and performance in the elimination of the selected pollutants. Vast information has been properly summarized according to the materials, their properties and preferential affinity for selected contaminants. The mechanisms governing nanomaterial＇s formation as well as the interactions with heavy metals and dyes have been carefully analyzed and associated to their efficiency.展开更多
文摘Abstract： The objective was to obtain solid dispersion to improve the dissolution rate, solubility and oral absorption of MB （mebendazole）, poor water-soluble drugs. The new formulation was characterized by DSC （differential scanning calorimetry）, PXRD （powder X-ray diffraction）, FT-1R （fourier transform infrared spectroscopy） and STEM （scanning transmission electron microscopy） methods. Solid dispersions of MB with polyvinylpyrrolidone K-30 （PVP K30） were prepared by solvent evaporation method. The solubility of MB （original powder） and that of the solid dispersions was measured at 25℃ in ethanol-water. The aqueous solubility of MB was favoured by the presence of the polymer in solvent mixtures. Combination of solid dispersions with co-solvents increased the water solubility of MB in a larger extent that each method separately. Solubility parameter （o） was used to relate to solubility profiles. MB and the solid dispersions show a solubility curve with a single peak at 51 = 30.78 MPav2. Solid state characterizations indicated that the solid dispersion exist an amorphous material entrapped in polymer matrix getting highest improvement in wettability and solubility.
基金Agencia Nacional de Promoción Científica y Tecnológica,Grant/Award Numbers:PICT 2018–03425,PICT 2018–3476Consejo Nacional de Investigaciones Científicas y TécnicasUniversidad Nacional del Sur,Grant/Award Number:24/Q125.
文摘Lactic acid(LA)is an important building block for high added value polymers with technological and biomedical applications,such as 3d printing filaments,surgical sutures or food packaging.The traditional manufacture of these materials uses harmful organic solvents,metallic catalysts and high temperatures.The current trend in green chemistry demands a cleaner and more sustainable process.In this research,the esterification reaction of low-cost racemic LA was explored in a reusable biphasic water/heptane system at low temperature(30℃).The chosen catalyst was Candida antarctica lipase B(CALB),in the free and immobilized form.The functional groups of the recovered solid products were identified by DRIFTS spectroscopy.The commercial immobilized CALB(Novozym435^(■))did not return any solid product under the explored conditions and significant leaching of the enzyme was observed by UV-Vis spectroscopy.On the other hand,the commercial CALB broth produced variable amounts of solid product in the water/heptane interphase with conversions(X)in the range of 2-47%,measured by HPLC.The highest product recovery was reached at 24 h when conversion of LA achieved 37%.After that time the reaction went backwards.The LA polycondensation products were mostly water-soluble oligomers.The results suggest that CALB can start a new chain with either R or S-LA,but is stereoselective towards the R-LA for the chain growth.Additional experimental difficulties arose from the lipase broth’s excipients like sorbitol and glycerol which interfere in the esterification reaction.The outcomes presented herein provide a new starting point for LA polycondensation.
文摘Nanosized magnetite has emerged as an adsorbent of pollutants in water remediation. Nanoadsor- bents include magnetic iron oxide and its modifiers/ stabilizers, such as carbon, silica, clay, organic moieties （polymers, aminoaeids, and fatty acids） and other inorganic oxides. This review is focused on the recent developments on the synthesis and use of magnetic nanoparticles and nanocomposites in the treatment of contaminated water. The emphasis is on the influence of the iron oxide modifiers on some properties of interest such as size, BET area, and magnetization. The characteristics of these nanomaterials are related to their ability to eliminate heavy metal ions and dyes from wastewater. Comparative analysis of the actual literature was performed aiming to present the magnetic material, its preparation methodology and performance in the elimination of the selected pollutants. Vast information has been properly summarized according to the materials, their properties and preferential affinity for selected contaminants. The mechanisms governing nanomaterial＇s formation as well as the interactions with heavy metals and dyes have been carefully analyzed and associated to their efficiency.
