Abamectin B2-loaded alginate-chitosan embedding granules: preparation and characteristics

In order to improve the pesticide utilization rate of the abamectin B2, the abamectin B2-loaded alginate-chitosan embedding granules was prepared by complex coacervation method. Sodium alginate and chitosan were used as composite carriers. The physicochemical properties and release characteristics of embedding granules were studied. Optimization formula was obtained through orthogonal test design. The most important factors of orthogonal test that influence the entrapment efficiency of embedding granules were carried out by single factor tests. The chemical structure of the abamectin B2-loaded embedding granules was characterized by infrared (IR) spectroscopy. The morphology of the embedding granules was examined using scanning electron microscopy (SEM). The soil embedment release assay was employed to explore the release characteristics of the prepared abamectin B2-loaded alginate-chitosan embedding granules. The optimum formula was as follows: 1.5%(m/m) of sodium alginate, 1%(m/m) of chitosan, 0.75% (m/m) of Tween-20, the dosage of m (abamectin B2) : m (alginate) = 1 : 2, and oil to water ratio =1 : 20. The embedding granules prepared under optimum conditions had a drug loading of 22.38% ± 0.25%. And the entrapment efficiency was 95.26% ± 0.61%. Scanning electron microscope images showed that the prepared abamectin B2-loaded embedding granules exhibited Irregular appearance. Infrared spectroscopy data revealed that abamectin B2 was successfully embedded in the carrier. Release property testing of three kinds of embedding granules in soil indicated that serious burst release was observed. The release amount of the abamectin B2 in the first 30 d was higher than 60% of the total release volume in 80 d. And smaller particles had faster release rate. The cumulative release of abamectin B2-loaded alginate-chitosan embedding granules followed a first-order kinetics equation (150-300 μm and > 300 μm) and the Higuchi equation (150-300 μm and < 150 μm).