Fx. Lacasse et al., SURFACE AND MORPHOLOGY OF SPRAY-DRIED PEGYLATED PLA MICROSPHERES, International journal of pharmaceutics, 174(1-2), 1998, pp. 101-109
The morphology, the surface structure, and the mean diameter of spray-
dried biodegradable pegylated microspheres were studied by X-ray photo
electron spectroscopy (XPS) technique, scanning electron microscopy (S
EM) and photo correlation spectroscopy. PEG 400-distearate (PEG-400(C-
18)(2)) was incorporated into poly(D,L-lactic acid) (PLA) by spray-dry
ing using different concentrations of PLA and polyethylene glycol-dist
earate (PEG-distearate). The use of these different concentrations res
ulted in systems with different sizes, morphologies and surfaces. Micr
osphere characteristics such as size distribution, morphology, and PEG
distribution were investigated and proven to be highly dependent on t
he concentrations of PLA and PEG in the solutions to be spray-dried. S
canning electron microscopy showed that the PLA concentration in the p
olymeric solution rise to microparticles rather than microspheres. Red
blood cell-like structures were observed for a high PLA concentration
. Photocorrelation spectroscopy proved that the size distribution depe
nded on the initial viscosity of the polymeric solution. The more visc
ous was the solution, the bigger the microspheres (and vice versa). X-
ray photoelectron spectroscopy confirmed the assumption that greater i
s the amount of PEG-distearate in the formulation, the more it is foun
d on the surface. These results have allowed us to predict pegylated b
iodegradable microspheres to be the best microencapsulation process. (
C) 1998 Elsevier Science B.V. All rights reserved.