Study On Preparation And Drug Loading Ability Of Crosslinked Starch Microsphere

Starch, which presented in speed, tuber, root, fruit, and leaf of the plants’cell tissuein the form of starch grain, had a wide distribution in the nature. It was a kind ofnon-toxic, no antigenicity, biodegradable natural polymer materials. Starchmicrospheres, which had well mechanical strength and three dimensional netted textures,were one artificial derivative of starch. The starch microspheres as drug carriers hadwide prospect of application in drug targeting, arterial embolization, ntranasaladministration, and so on.In this thesis, the starch microspheres were synthesized from corn starch in thecondition of strong base and weak base by inverse suspension with epoxychloropropane as the cross-linking agent,Span60and Tween80as the emulsifying agentand chloroform as the organic phase. The structure and morphology of starchmicrosphere were characterized by environment scanning electron microscope（ESEM）,Fourier Transform infrared spectroscopy (FT-IR), and X-ray diffraction(XRD). In strong base condition, the single factor experiments results showed that：thedifferent amount of crosslinking agent,mixing speed were important effects in averageparticle,and there was a negative correlation between them. Furthermore, starch solutionconcentration and the quality of emulsifying agent were weak effects in average particle.The optimum conditions of synthesis were as follows:15%amylum concentration(mass fraction),6mL cross-linking agent,1.8g emulsifying agent was,9000r/minemulsification speed,6h reaction time, the ratio of aqueous phase and oil phase was5:1.The testing of morphology results show that starch microspheres were round, graindiameter distribution was homogeneous, and their surface was smooth. In weak basecondition, the optimum conditions of synthesis were as follows:15%amylumconcentration,2.7g emulsifying agent,9000r/min emulsification speed,10mLcross-linking agent,6h reaction time, and the ratio of aqueous phase and oil phase was5:1.The starch microspheres were prepared from corn starch by inverse suspensionwith epoxy chloropropane as the cross-linking agent,Span60as the emulsifying agentand cyclohexane and chloroform as the organic phase. The structure and morphology ofstarch microsphere were characterized by ESEM, FT-IR, and XRD. The alteration ruleof sphere’s diameter with the change of reaction condition was studied. The optimal preparation conditions of starch microspheres were as: amylum concentration was15%(the ratio of quality), aqueous phase was turned to pH=12.0using NaOH aqueoussolution whose concentration was2mol/L, emulsification speed was3000r/min, theratio of aqueous phase and oil phase was5:1, the quality of emulsifying agent was1.2g,volume of cross-linking agent was10mL and reaction time was4h. The microsphereswhich were prepared at this condition are round, their surface with some hole was roughand grain diameter distribution was homogeneous.Corn starch microspheres embed oxacillin sodium in weak base condition wereprepared. The results were as follows: when the ratio of sphere and drug was5:1, drugloading and envelop rate come to the relative high degree. At this moment, embeddingdrug was31%and drug loading is15.5mg/g.10h later, the drug released in vitroreaches basic balance, which means that the starch microspheres had a goodsustained-release effect.Nimodipine was adsorbed by soluble starch microsphere. The relation betweendrug loading and envelop rate was studied by ultraviolet spectro-photometer. The singlefactor experimental results were as follows: when the ratio of sphere and drug is15:1,the adsorption time was4h, and the adsorption temperature is37℃, drug loading andenvelop rate reach the relative high degree. At this moment, drug loading was33%anddrug loading was22mg/g.