Development of Ca-alginate-chitosan microcapsules for encapsulation and controlled release of imidacloprid to control dengue outbreaks

Ca-alginate-chitosan based microcapsules were prepared and used for the controlled release of imidacloprid larvacide against Aedes aegypti larvae. Imidacloprid encapsulation was evidenced through HPLC and FTIR analysis. Imidacloprid loading varied from 2.79% to 6.85% with encapsulation efficiency of up to 39.16%. TGA and DSC studies revealed good thermal stability and compatibility between the polymers and imidacloprid. X-ray diffractometry (XRD) results indicated a molecular level dispersion of imidacloprid in the polymer matrix. The in vitro release profiles of imidacloprid could be controlled by modifying the formulation, pH, or temperature. The imidacloprid release kinetics fit the Korsmeyer-Peppas model and follows the anomalous transport profile. The mechanism of imidacloprid release was proposed. In vivo release studies demonstrated that a dose of 6.11 mg/L is sufficient to destroy Aedes aegypti larvae. It was predicted that 50% and 100% larvae mortality are achieved for 369 and 141 days respectively. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.