Preparation And Application Of Chitosan Microcapsules

The use of plastic film and the abuse of chemical pesticides have caused serious environmental pollution.The development of green and environmentally friendly packaging substitutes for traditional packaging by natural macromolecule materials has attracted worldwide attention.Chitosan is the only alkaline polysaccharide in nature which is the product of partial removal of acetyl group from natural polysaccharide chitin.And China has abundant chitin resources for the production of chitosan raw materials.Because chitosan has good adsorption,biocompatibility,film-forming and antibacterial properties,and non-toxic,harmless,easy to biodegrade.In recent years,researchers have found that chitosan as a wall material of microcapsules has broad application prospects and can be used in medicine,food,textile and functional materials and other fields.In our study,two kinds of chitosan microcapsules were prepared by compounding chitosan with other polymer materials.The coating of chitosan microcapsules on two kinds of core materials was studied.1.Chitosan/silver nanoparticles composite microcapsules were prepared by cross-linking method with silver nanoparticles as core material and chitosan as wall material.The effects of temperature,silver nanoparticles content and the amount of cross-linking agent on the composite microcapsules were investigated.The reaction conditions of the microcapsules were determined as follows:the concentration of chitosan in 3%acetic acid solution was 1%,the reaction temperature was 60?,and the ratio of chitosan to silver nanoparticles was 3:1.Under the optimized conditions,the microcapsules with different sizes were characterized by particle size distribution,scanning electron microscopy,Fourier transform infrared spectroscopy,differential scanning calorimetry and UV-visible spectroscopy.The results showed that the surface of microcapsules was smooth and round,and the particle size dispersion was good.The average particle size was about 300 ?m.The microcapsules with smaller size had better antibacterial properties and prolonged the shelf life of fruits.2.Anti-UV inactivated insect viruses were prepared by emulsion cross-linking method with American white moth virus as core material and chitosan as wall material.The optimum reaction conditions were as follows:the concentration of chitosan in 4.8 pH acetic acid solution was 2%,the ratio of chitosan to virus was 4:1,the ratio of oil to water was 15:1,the ratio of stearic acid to span-80 was 1:1,and the ratio of glutaraldehyde to chitosan was 15:1.The anti-UV deactivation properties of the microcapsules were investigated by means of particle size distribution,scanning electron microscopy,microscopy and fluorescence microscopy.The results showed that the microcapsules were granular and had good particle size dispersion.The average particle size was about 15 ?m.Chitosan wall played a protect role on the core material,improved the anti-UV inactivation ability of insect viruses,and prolonged the duration of efficacy.