Preparation and characterization of double-shelled avermectin microcapsules based on copolymer matrix of silica-glutaraldehyde-chitosan.

Controlled release formulation (CRF) of pesticides is highly desirable for attaining the most effective utilization of the pesticide as well as reducing environmental pollution. Due to the selective permeation and protection properties of the semi-permeable membrane, pesticide microcapsules have been widely used. In this work, we developed a novel two-step method for synthesizing highly stable silica-glutaraldehyde-chitosan composite avermectin microcapsules. The silica shell was formed through the hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) at the oil droplet-water interface by using TEOS as the silica precursor and hexadecyl trimethyl ammonium chloride as a surfactant. Then the silica shell was modified with 3-aminopropyltriethoxysilane. Chitosan nanospheres were prepared by adjusting the pH value of the solution and then cross-linking with modified silica at the surface of the silica shell in the presence of glutaraldehyde to form double-shelled avermectin microcapsules. The results showed that the resulting microcapsules had a remarkable loading ability for avermectin (about 40% w/w) and can protect avermectin against photo- and thermal degradation effectively. Compared to single-shelled microcapsules, the double-shelled ones had better controlled release properties under all conditions. The present study provides a novel CRF comprising a pesticide which is light-sensitive or high temperature-sensitive, and a method for preparing the improved pesticide formulation so that the pesticide release rate and release period could be adjusted.

[1]  Stella M. Marinakos,et al.  Gold particles as templates for the synthesis of hollow polymer capsules. Control of capsule dimensions and guest encapsulation , 1999 .

[2]  Nicholas A. Peppas,et al.  A simple equation for description of solute release II. Fickian and anomalous release from swellable devices , 1987 .

[3]  C. Ha,et al.  Microfluidic Synthesis of Reversibly Swelling Porous Polymeric Microcapsules with Controlled Morphology , 2008 .

[4]  J. Ji.  Mathematical model for encapsulation by interfacial polymerization , 2001 .

[5]  J. Kumar,et al.  Release kinetics of β-Cyfluthrin from its encapsulated formulations in water , 2011, Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes.

[6]  A. Bajpai,et al.  SWELLING DYNAMICS OF A TERNARY INTERPENETRATING POLYMER NETWORK (IPN) AND CONTROLLED RELEASE OF POTASSIUM NITRATE AS A MODEL AGROCHEMICAL , 2002 .

[7]  M. Blackford,et al.  Sol–gel matrices for controlled release: from macro to nano using emulsion polymerisation , 2008 .

[8]  Ying Liu,et al.  Stabilized polymeric nanoparticles for controlled and efficient release of bifenthrin. , 2008, Pest management science.

[9]  M. Paoletti,et al.  Current views on fungal chitin/chitosan, human chitinases, food preservation, glucans, pectins and inulin: A tribute to Henri Braconnot, precursor of the carbohydrate polymers science, on the chitin bicentennial , 2012 .

[10]  Jianfeng Chen,et al.  Controlled release of avermectin from porous hollow silica nanoparticles: influence of shell thickness on loading efficiency, UV-shielding property and release. , 2006, Journal of controlled release : official journal of the Controlled Release Society.

[11]  B. Vincent,et al.  Aqueous dispersions of silica shell/water-core microcapsules. , 2010, Journal of colloid and interface science.

[12]  M. Sambrook,et al.  Preparation of aqueous core/silica shell microcapsules. , 2012, Journal of colloid and interface science.

[13]  Jian Li,et al.  Polyurea microcapsules: Surface modification and capsule size control , 2011 .

[14]  A. Lefebvre,et al.  SiOH-Functionalized Polystyrene Latexes. A Step toward the Synthesis of Hollow Silica Nanoparticles , 2002 .

[15]  R. Parsad,et al.  Development of controlled release formulations of carbofuran and evaluation of their efficacy against Meloidogyne incognita. , 2006, Journal of agricultural and food chemistry.

[16]  Nikolaos A. Peppas,et al.  Controlled release of fragrances from polymers: I. Thermodynamic analysis , 1996 .

[17]  Yi Yan Yang,et al.  Effect of preparation temperature on the characteristics and release profiles of PLGA microspheres containing protein fabricated by double-emulsion solvent extraction/evaporation method. , 2000, Journal of controlled release : official journal of the Controlled Release Society.

[18]  I. Capek.  Microemulsion polymerization of styrene in the presence of a cationic emulsifier. , 1999, Advances in colloid and interface science.

[19]  R. Arshady,et al.  Microspheres and microcapsules: A survey of manufacturing techniques. Part 1: Suspension cross-linking , 1989 .

[20]  Peter In Pyo Park,et al.  The design of flexible ciprofloxacin-loaded PLGA implants using a reversed phase separation/coacervation method. , 2011, European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V.

[21]  J. Lai,et al.  PTFE/polyamide thin-film composite membranes using PTFE films modified with ethylene diamine polymer and interfacial polymerization: preparation and pervaporation application. , 2009, Journal of colloid and interface science.

[22]  Gwo‐Jaw Wang,et al.  Controlled release carrier of BSA made by W/O/W emulsion method containing PLGA and hydroxyapatite. , 2008, Journal of controlled release : official journal of the Controlled Release Society.

[23]  K. Leong,et al.  Poly(D,L-lactide-co-ethyl ethylene phosphate)s as new drug carriers. , 2003, Journal of controlled release : official journal of the Controlled Release Society.

[24]  A. Rodrigues,et al.  Release of Thyme Oil from Polylactide Microcapsules , 2011 .

[25]  Yadong Yin,et al.  Self-templated synthesis of hollow nanostructures , 2009 .

[26]  L. Gan,et al.  Recent advances in the synthesis of nanoparticles of polymer latexes with high polymer-to-surfactant ratios by microemulsion polymerization , 2005 .

[27]  D. Hunkeler,et al.  Polyvinylamine hydrochloride-based microcapsules: polymer synthesis, permeability and mechanical properties , 2002, Journal of microencapsulation.

[28]  Alfons van Blaaderen,et al.  Metallodielectric Colloidal Core−Shell Particles for Photonic Applications , 2002 .

[29]  K. Anderson,et al.  Kinetic and thermodynamic modeling of the formation of polymeric microspheres using solvent extraction/evaporation method , 1995 .

[30]  A. R. Gonçalves,et al.  Controlled release of 2,4-D from granule matrix formulations based on six lignins , 1997 .

[31]  Eugene Khor,et al.  Implantable applications of chitin and chitosan. , 2003, Biomaterials.