Studies on the particle size control of gelatin microspheres |
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Authors: | Ruixue Sun Jingjing Shi Yanchuan Guo Lijuan Chen |
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Institution: | (1) Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China;(2) Graduate University of Chinese Academy of Sciences, Beijing, 100049, China |
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Abstract: | 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 dispersion of GMs was examined. The studied
preparation parameters include concentration of gelatin solutions, concentration of the emulsifier, w/o ratio, emulsifying
time, stirring speed, and so on. The surface morphology, dispersion, 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 increased from 0.050 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, themean diameters ofGMsdecreased from 17.32 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 of 0.050 g/mL of emulsifier concentration, 0.100 g/mL of gelatin solution concentration, 1/5 of w/o 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 spherical shape, and fluidity. The w/o ratio has the same influence on particle size of GMs as
that of gelatin solution concentration. With the increase of w/o ratio, the average particle sizes increased linearly, and
the surface of microspheres become smoother as well. It is supposed that w/o ratio can be used to change the diameters and
surface morphologies of GMs. The emulsifying time has little influence on the mean diameters of GMs, but it affects the dispersion
of GMs apparently. When the emulsifying time was shorter than 5 min, the GMs had bad dispersion. After increasing the emulsifying
time to 13 min, the dispersion of GMs changed greatly, whereas the dispersion 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 has the similar influence on GMs’ morphologies as that of emulsifying time. Slow stirring rate made large
size distribution and bad spherical shape of GMs; excessive stirring speed results in aggregation among GMs likewise. The
smaller size distribution and better spherical shape of GMs were observed under the stirring rate between 500 and 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 at proper emulsifying time, and stirring
speed would get the best spherical shape of GMs. These are the basic laws governing the design and manufacture of the GMs.
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Translated from Acta Polymerica Sinica, 2008, 8 (in Chinese) |
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Keywords: | gelatin microspheres (GMs) emulsification-coacervation method preparation parameters particle size surface morphology |
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