Controlled release system for ametryn using polymer microspheres: preparation, characterization and release kinetics in water.
ABSTRACT The purpose of this work was to develop a modified release system for the herbicide ametryn by encapsulating the active substance in biodegradable polymer microparticles produced using the polymers poly(hydroxybutyrate) (PHB) or poly(hydroxybutyrate-valerate) (PHBV), in order to both improve the herbicidal action and reduce environmental toxicity. PHB or PHBV microparticles containing ametryn were prepared and the efficiencies of herbicide association and loading were evaluated, presenting similar values of approximately 40%. The microparticles were characterized by scanning electron microscopy (SEM), which showed that the average sizes of the PHB and PHBV microparticles were 5.92±0.74 μm and 5.63±0.68 μm, respectively. The ametryn release profile was modified when it was encapsulated in the microparticles, with slower and more sustained release compared to the release profile of pure ametryn. When ametryn was associated with the PHB and PHBV microparticles, the amount of herbicide released in the same period of time was significantly reduced, declining to 75% and 87%, respectively. For both types of microparticle (PHB and PHBV) the release of ametryn was by diffusion processes due to anomalous transport (governed by diffusion and relaxation of the polymer chains), which did not follow Fick's laws of diffusion. The results presented in this paper are promising, in view of the successful encapsulation of ametryn in PHB or PHBV polymer microparticles, and indications that this system may help reduce the impacts caused by the herbicide, making it an environmentally safer alternative.
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ABSTRACT: This paper briefly introduced the preparation and application of flavor and essential oils microcapsules based on complex coacervation technology. The conventional encapsulating agents of oppositely charged proteins and polysaccharides that were used for microencapsulation of flavor and essential oils were reviewed along with the recent advances in the complex coacervation methods. Proteins extracted from animal derived products (gelatin, whey proteins, silk fibroin) and from vegetables (soy proteins, pea proteins), and polysaccharides such as gum Arabic, pectin, chitosan, agar, alginate, carrageenan and sodium carboxymethyl cellulose were described deeply. In the recent decades, flavor and essential oils microcapsules have numerous potential practical applications in food, textiles, agriculturals and pharmaceuticals. In this paper, the different coating materials and their application were discussed in detail. Consequently, the information obtained allows establishing criteria for selecting a method for preparation of microcapsules according to its advantages, limitations and behaviors as a flavor and essential oils carrier.Journal of the Science of Food and Agriculture 11/2013; · 1.76 Impact Factor
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ABSTRACT: Ca-alginate hydrogel beads of Lagenaria siceraria (LS) fruit extract using co-precipitates of LS seed starch and colloidal silicon dioxide (SSD) as filler was studied. Effect of different concentrations of SSD on the encapsulation efficiency, size of microspheres, moisture content and antioxidant potential of the microspheres comprising extract was determined. The chemical composition of ethanolic extract was analysed by LC-MS. The prepared microspheres were characterized by SEM, FTIR and XRD. The incorporation of filler in hydrogel beads modified the micromeritic properties and release profile of LS fruit extract. It is observed that fillers have improved the stability of antioxidant potential of the extract. The application of this technology would improve the stability of LS fruit extract in pharmaceutical and food products.International journal of biological macromolecules 02/2014; · 2.37 Impact Factor