Characterization of FITC-albumin encapsulated poly(DL-lactide-co-glycolide) microspheres and its release characteristics.

In this study, the fluorescein isothiocyanate (FITC)-albumin distribution, the amount of FITC-albumin release and the degradation of poly (DL-lactic-co-glycolic acid) (PLGA) microspheres were evaluated. The higher the FITC-albumin concentration in the W1 phase, the higher the protein concentration and loading efficiency in the microspheres, the larger the particle size of microspheres. Confocal laser scanning microscopy (CLSM) showed that the FITC-albumin was distributed uniformly in the microspheres with a low concentration while it was aggregated at higher concentrations. The high protein concentration in the microspheres showed significantly large initial release (above 70% w/w) during the 10 days. A higher PVA concentration in the W2 phase resulted in a smaller particle size, higher protein contents and loading efficiency and decreased release rate. After a 10 day incubation period, the microspheres with a low FITC-albumin concentration had an almost spherical morphology, while microspheres with a high FITC-albumin concentration had a more distorted morphology, suggesting that rapid morphological changes and microspheres ruptures can be induced by an initial burst release.