title: Localization of bovine serum albumin in double-walled microspheres.
abstract: Phase separation of binary blends of various combinations of poly (L-lactide) (PLA), and poly (D,L-lactide-co-glycolide) (PLGA), was investigated using differential scanning calorimetry (DSC). Based on this phase separation phenomenon, double-walled microspheres were fabricated. A model agent, bovine serum albumin (BSA) labeled with fluorescein isothiocyanate (FITC-BSA) was localized in each layer. Scanning electron microscopy (SEM) and fluorescence microscopy (FM) were used to assess the formation of double-walled microspheres and the localization of the drug, respectively. When a 1:1 polymer ratio was used, the FITC-BSA was localized in the outer layer. When the relative ratio of PLGA to PLA was increased to 3:1 using the same overall polymer concentration, the FITC-BSA was localized in the inner core. Release studies were carried out to evaluate the advantage of double-walled microspheres compared to single walled microspheres. Microspheres made with FITC-BSA localized in the inner core exhibited a significantly lower initial release rate compared to microspheres where the drug was located in the outer layer, or compared to microspheres made from PLA only. Hence microspheres with a double-walled morphology have the potential for therapeutic use where a high burst might be detrimental.
authors.affiliation: Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Box G, Providence, RI 02912, USA.
authors.forename: N A
authors.initials: NA
authors.lastname: Rahman
authors.forename: E
authors.initials: E
authors.lastname: Mathiowitz
mesh_terms: D000818:Animals; D002417:Cattle; D008863:Microspheres; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D012710:Serum Albumin, Bovine