Preparation And Properties Of Sodium Alginate/Feather Keratin Sustained-release Microsphere

Pesticide sustained-release technology has attracted much attention because of it’sfunction on the contradiction between efficient utilization and environmental protection. Bythe advantages of non-toxic, low cost, wide source, biological degradation and good gelperformance sodium alginate（SA）becomes one of widly applied sustained-release material.But the drug loading capacity of SA microsphere is poor, and burst release phenomenon canbe observed during the process of drug release. So, it is limited in drug sustained-release. Inorder to solve the above problem，feather keratin（FK） is choosed as a blending modifier ofSA which iss extracted from wasted feathers in this paper. This work looks forwardto develope a cheap, environment friendly, intelligent sustained-release microsphere. Theresearch contains several major topics：(1) SA/FK microspheres was prepared by dripping method. The results indicate that,electrostatic interaction is the main interaction force, which is followed by hydrogen bondingbetween FK and SA. The FTIR shows that,2,4-D has been coated in composite microspheresuccessfully. SEM, DSC and XRD shows that, components have good compatibilities andamorphous2,4-D is dispersed in microspheres evenly. Drug loading capacity andencapsulation rate reach a maximum value when m(FK)/m(SA)=60%, which are decreasedwith the further increasing of mass ratio.(2) The swelling properties of composite microspheres were investigated. The resultsindicate that，over time, swelling rate becomes slow, and it meets equilibrium swelling at last.SA/FK microspheres have compact network structures when m(FK)/m(SA)=60%, w(CaCl2)=7%and crosslinking time is60min. SA/FK microspheres possess the ionic strength/pH/temperature sensitivity. Diffusion type of water molecule changes from Non-Fickian toFickianⅠwhen pH rises from1to13and temperature rises from30℃to45℃. However, itchanges from Non-Fickian to FickianⅡ when ionic strength increases from0to0.6mol/L.(3) Chlorpyrifos/SA/FK microspheres were prepared, and the sustained-releaseperformance was also investigated. The results indicate that, thermal stability of chlorpyrifosimproves obviously, whose decomposition temperature increases from180℃to210℃afterloading. Controlled realse property of microsphere can be improved with the increase of FKand cross-linking agent. The crosslinking time of0.5hour or more have little effect onsustained-release performance. Effect of ionic strength on sustained-release performance,1mol/L>0.5mol/L>0mol/L. Effect of pH on sustained-release performance, pH=9> pH=11> pH=3> pH=5> pH=7. Effect of temperature on sustained-release performance,30℃>45℃.Sustained-release possess the ionic strength/pH/temperature sensitivity. The drug release inaccordance with the Fick diffusion mechanism when ionic strength is less than0.5mol/L,pH>9and temperature is45℃. However, it in accordance with the non-Fick diffusionmechanism when ionic strength is more than0.5mol/L, pH<7and temperature is30℃.(4) SA/FK microsphere was prepared by emulsification-internal gelation method whichcan be used for pesticide sustained-release system. The optimal conditions contain that, amountof emulsifier is0.1%, emulsifying time is30min, emulsifying rate is300rpm, V(oil)∶V(water)=3∶1and amount of nano calcium carbonate is0.6%.