明胶微球粒径控制的研究

采用乳化-凝聚法,在油包水(w/o)的体系中对明胶微球(GMs)粒径、微球的形态和分散性等进行了研究.扫描电子显微镜(SEM)和粒径分布曲线的结果表明在乳化体系中,提高明胶溶液的浓度或水油比例,明胶微球的粒径增大;增加乳化剂的用量,微球的粒径减小;选择合适的乳化时间和搅拌速率,可以改善微球的分散性和表面光滑程度.同时,通过调控实验条件,在明胶溶液浓度0.100 g/mL,水油比1/5,乳化剂浓度0.05g/mL时研制出了平均粒径为3.58μm的表面光滑、分散性好的明胶微球.

STUDIES ON PARTICLE SIZE CONTROL OF GELATION MICROSPHERES

A series of gelatin microspheres(GMs) were prepared through emulsification-coacervation method in water-in-oil(w/o) emulsions.The influence of preparation parameters on particle size,surface morphology and dispersity of GMs was examined.The studied preparation parameters include concentration of gelatin solutions,concentration of the emulsifier,water/oil ratio,emulsifying time,stirring speed and so on.The surface morphology,dispersity and particle sizes of GMs were determined by the scanning electron microscopy(SEM),SemAfore 4 Demo software and particle size distribution graphic charts.The experimental results indicated that increasing the concentration of gelatin solution would increase the particle size of GMs.When the solution concentration increasing from 0.050 g/mL to 0.200 g/mL gradually,the particle size increased correspondingly.The relationship between the two quantities was linear.On the contrary,increasing the concentration of the emulsifier would decrease the particle size of GMs.Furthermore,the particle size reduced quickly at initial time and slowed down latterly.With the increase of emulsifier concentration from 0 to 0.020 g/mL,the mean diameters of GMs decreased from 17.32 μm to 5.38 μm.However,the particle size dwindled slowly when emulsifier concentration was higher than 0.020 g/mL.The excellent result was obtained with the condition:0.050 g/mL of emulsifier concentration,0.100 g/mL of gelatin solution concentration,1/5 of water/oil ratio,10 min of emulsifying time and 900 r/min of the stirring speed.The GMs prepared at this condition had the smallest sizes,the narrowest size distribution,the best sphericity and fluidity.The water/oil ratio has the same influence on particle size of GMs as that of gelatin solution concentration.With the increase of water/oil ratio the average particle size increased linearly,and the surface of microspheres became smoother as well.It is supposed that water/oil ratio can be used to change the diameters and surface morphologies of GMs.The emulsifying time had little influence on the mean diameters of GMs,but it affected the dispersity of GMs apparently.When the emulsifying time was shorter than 5 min,the GMs had bad dispersity;after increasing the emulsifying time to 13 min,the dispersity of GMs changed greatly;whereas the dispersity of GMs became bad again when the emulsifying time was longer than 13 min.According to the experimental results,13 min was considered to be the best emulsifying time.The stirring speed had the similar influence on GMs' morphologies as that of emulsifying time.Slow stirring rate made large size distribution and bad sphericity of GMs;excessive stirring speed resulted in aggregation among GMs likewise.The smaller size distribution and better sphericity of GMs were observed under the stirring rate between 500 r/min to 1500 r/min by SEM.In conclusion,increasing the concentration of gelatin solution or w/o ratio would increase the particle sizes of GMs,increasing the concentration of the emulsifier would decrease the sizes of GMs,proper emulsifying time and stirring speed would resultin in the best sphericity of GMs.