Studies on the particle size control of gelatin microspheres

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, the mean diameters of GMs decreased 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.

Keywords

gelatin microspheres (GMs) / emulsification-coacervation method / preparation parameters / particle size / surface morphology

References

[1] Tanaka N, Takino S, Utsumi I. A new oral gelatinized sustained-release dosage form. J Pharm Sci, 1963, 52(7): 664-667

[2] Maria A V, Marcello R, Alessandra M, Manuela G, Paolo G, Francesco R, Flavio F. Microwave-treated gelatin microspheres as drug delivery system. J Control Release, 2004, 96: 67-84

[3] Kawaguchi H. Functional polymer microspheres. Prog Polym Sci, 2000, 25: 1171-1210

[4] Wang J, Tabata Y, Morimoto K. Aminated gelatin microspheres as a nasal delivery system for peptide drugs: Evaluation of in vitro release and in vivo insulin absorption in rats. J Control Release, 2006, 113: 31-37

[5] Wu H, Zhang Z X, Wu D C, Zhao H P, Yu K T, Hou Z Q. J Biomed Mater Res B, 2006, 78B: 56-62

[6] Mi F-L. Synthesis and characterization of a novel chitosan-gelatin bioconjugate with fluorescence emission. Biomacromolecules, 2005, 6: 975-987

[7] Narayani R, Panduranga R K. Gelatin microsphere cocktails of different sizes for the controlled release of anti cancer drugs. Int J Pharm, 1996, 143: 255-258

[8] He P, Cui L L, Qiang W L, Xu H, Gu H C. Acta Polymerica Sinica, 2007, 8: 731-736 (in Chinese)

[9] Xue P ,Liu H F. Acta Polymerica Sinica, 2007, 1: 64-69 (in Chinese)

[10] Vandelli M A, Rivasi F, Guerra P, Forni F, Arletti R. Gelatin microspheres crosslinked with D, L-glyceraldehyde as a potential drug delivery system: preparation, characterisation, in vitro and in vivo studies. Int J Pharm, 2001, 215: 175-184

[11] Kim H-W, Yoon B-H, Kim H-E. J Mater Sci-Mater M, 2005, 16: 1105-1109

[12] Zhan G P, Huang K L, Xie E W. Chin Hosp Pharm J, 2005, 25(7): 625-628 (in Chinese)

[13] Li W X, Gao G D, Liang Q C. J Fourth Mil Med Univ, 2001, 22(19): 1812-1814 (in Chinese)

[14] Esposito E, Cortesi R, Nastruzzi C. Gelatin microspheres: influence of preparation parameters and thermal treatment on chemico-physical and biopharmaceutical properties. Biomaterials, 1996, 17: 2009-2020

[15] Eric D. Food Hydrocolloid, 2003, 17: 25-39

[16] Freiberg S, Zhu X X. Polymer microspheres for controlled drug release. Int J Pharm, 2004, 282: 1-18

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg