Preparation And Characteristics Analysis Of Microcapsule Controlled-releasing Agent Of Pesticide-chitosan Copolymer

Low effective availability of modern pesticides places heavy burden to both environmentand cost to farmers. Pesticide-microcapsule has widely been attention using amphiphilicmacromoleculed copolymer as a drug carrier. Nano-augmented delivery systems seem to bemore promising and potential to address the present challenge modern pesticides are facing, It iseasy to complete many of the polymerization reaction for many amino and hydroxyl of naturalchitosan. In this paper, chitosan-lactide copolymer (CPLA) was prepared and characterized ashydrophobic pesticide-microcapsule carrier because it has good biological compatibility andbiodegradable properties as a good carrier.The chemical structures and thermogravimetri of CS and the copolymers CPLA werecharacterized and analysis by FT-IR,1H NMR and (TG/DTA), it showed that CPLA polymercan be degraded at low temperature is better than CS. Emulsion/solvent evaporation method andnano-precipitation method were used to fabricate spinosad-loaded microcapsules andpyraclostrobin-loaded microcapsules respectively. The size and size distribution of the resultingmicrocapsules were investigated by dynamic light scattering (DLS) and Transmission electronmicroscopy (TEM). Active ingredient contained within microspheres was protected from lightcompared with technical material. It showed that microcapsules have very small size anduniform distribution.The fluorescence and surface tension experiments showed that CPLA havea strong stability and surface activity in water medium with very low critical micelleconcentrations (CMC).The size of pyraclostrobin-loaded microcapsules and spinosad-loaded microcapsules canbe adjusted between50to200nm by varying the feed mass ratio of copolymer to pesticide from50/1to5/1, then loading content (LC)17.61%of nano-precipitation method is betterthanemulsion/solvent evaporation5.61%investigated by HPLC. These microcapsulses showedan initial burst, subsequent sustained and pH-controlled release profile. The pesticides-loadedmicrocapsules showed bactericidal or insecticidal effect rapidly and the sustained releaseprocess at the same time.Fungicidal activity experiment was designed in order to further study for microcapsule biochemical activity. For25%pyraclostrobin EC, the percentages of inhibition were37.0%–81.5%,48.1%–86.5%and40.3%–83.6%on the3rd,5th and7th days. Forpyraclostrobin-loaded nanoparticles, the percentages of inhibition were11.1%–81.5%,42.3%–84.6%and52.2%–85.1%on the3rd,5th and7th days. Compared to25%pyraclostrobinemulsifiable concentrate (EC), the microcapsules demonstrated better fungicidal activity againstColletotrichum gossypii Southw The experiment showd that of strong of fungicidal activitypesticides-loaded microcapsules and long persistent effect under long incubation time, whichfurther exhibited sustained release characteristic.