Resarch Of Tebuconazole Nanocapsules

Compared with conventional pesticide formulations,microcapsule can increase lasting time of pesticide, raise the effective utilization rate,decrease the decomposition and loss of pesticide,reduce the toxicity and hazard of pesticide and minify the environment pollution,etc. Tebuconazole is very efficient triazole fungicide and widely used in the prevention and control of diseases and insect pests in agriculture.The main formulation of tebuconazole is emulsifiable concentrate,its lating time is short, and the extensive use of organic solvent easily cause environmental pollution and waste of resources.To a great extent, the problems above can be solved by microencapsulation.In order to find a suitable wall material for encapsulating tebuconazole and research preliminarily nanocapsule preparation technology and test methods of tebuconazole microcapsule, in this paper, through using research production of loaded micelle in medical polymer field about directional conveying slow-release and controlled release,we prepare loaded micelle with the amphiphilic polymers as wall materials and tebuconazole as core material, and study the drug loading efficiency and encapsulation rate, the diameter of particles, suspension stability, antibacterial properties, slow-release function and the stability of light and heat. The major results as follow:l.The poly(ethylene glycol)-polycaprolactone block copolymer (PEG-b-PCL) was synthetized by ring-opening polymerization method, undecyl-chitosan (CS-CT11) and hexadecyl-chitosan (CS-CT16) were prepared by alkyl substitution reaction, deoxycholic acid-chitosan(CS-DC) was synthetized by amidation reaction.2. The self-assembled PEG-b-PCL micelles was applied as carrier to load tebuconazole by dialysis method.. The diameter of the tebuconazole-loaded micelles was characterised with dynamic light scattering (DLS) and transmission electron microscope(TEM). The drug loading efficiency, encapsulation rate and release characteristics in vitro were measured with the application of ultraviolet specrophotometer and high performance liquid chromatography (HPLC). The mould inhibition properties of drug-loaded micelles to Trichoderma viride were evaluated with filter paper methods. Results showed that tebuconazole-loaded PEG-b-PCL micelles were spherical and uniform, with a mean particle diameter of250nm, The drug loading efficiency and encapsulation rate were26.4%and18%respectively, in the UV lamp(20W) for4h, the light decomposition rate was8.7%and at54℃for14d, the thermal decomposition rate was3.0%, its stability was better then tebuconazole ethyl alcohol solution(the light decomposition rate16.8%and the thermal decomposition rate6.9%). Tebuconazole-loaded PEG-b-PCL micelles had good slow-release characteristics. After192h, the drug release percentage of tebuconazole-loaded PEG-b-PCL micelles was83.35%. Tebuconazole-loaded PEG-b-PCL micelles also exhibited more efficient mould inhibitions to Trichoderma viride than the naked tebuconazole. The diameters of the inhibition zone of the former was20mm and the latter was10mm.3. Using CS-CT11-TBA,CS-CT16and CS-DC as wall material, the tebuconazole-loaded micelles were prepared by solvent inducement method. The diameter of the tebuconazole-loaded micelles of amphiphilic chitosan copolymers were characterised with dynamic light scattering (DLS) and transmission electron microscope(TEM).The drug loading efficiency, encapsulation rate, release characteristics, slow release performance and the stability in vitro were measured with the application of ultraviolet specrophotometer and high performance liquid chromatography (HPLC).Results showed that the mean particle diameter of the tebuconazole-loaded micelles of CS-CT11was410nm. The drug loading efficiency, encapsulation rate and suspension rate were13.0%,14.9%and73.7%respectively. In the UV lamp(20W) for4h, the light decomposition rate was9.8%and at54℃for14d, the thermal decomposition rate was3.5%; the mean particle diameter of the tebuconazole-loaded micelles of CS-CT16was650nm. The drug loading efficiency, encapsulation rate and suspension rate were15.5%,18.3%and80.9%respectively.In the UV lamp(20W) for4h,the light decomposition rate was10.9%and at54℃for14d,the thermal decomposition rate was3.9%;the mean particle diameter of the tebuconazole-loaded micelles of CS-DC was260nm. The drug loading efficiency, encapsulation rate and suspension rate were11.3%,12.8%and78.5%respectively.In the UV lamp(20W) for4h, the light decomposition rate was11.6%and at54℃for14d,the thermal decomposition rate was3.7%.The stability of tebuconazole-loaded micelle of all three amphiphilic chitosan copolymers were better then tebuconazole ethyl alcohol solution(the light decomposition rate16.8%and the thermal decomposition rate6.9%). After192h,the drug release percentage of all three tebuconazole-loaded micelles were87.8%、90%、86.3%,While the drug release percentage of tebuconazole ethyl alcohol solution was100%. With the concentration of6.4mg/mL, the bacteriostatic rate of all three tebuconazole-loaded micelles to Trichoderma viride are higher than the tebuconazole ethyl alcohol solution with same concentration.According to the mensuration, after120h, the bacteriostatic rate of three loaded micelles to Trichoderma viride is100%, while the bacteriostatic rate of the tebuconazole ethyl alcohol solution with same concentration was89.6%.In conclusion, with PEG-b-PCL and modified chitosan as wall materials,the tebuconazole-loaded micelle with high drug loading efficiency and encapsulation rate were spherical and uniform, improved the stability of tebuconazole to light and heat and has good slow-release characteristics,favourable antibacterial properties and suspension stability.