title: Non-aqueous encapsulation of excipient-stabilized spray-freeze dried BSA into poly(lactide-co-glycolide) microspheres results in release of native protein.
abstract: Encapsulation of the model protein bovine serum albumin (BSA) into poly(D,L lactide-co-glycolide) (PLG) microspheres was performed by a non-aqueous oil-in-oil (o/o) methodology. Powder formulations of BSA obtained by spray-freeze drying were first suspended in methylene chloride containing PLG followed by coacervation by adding silicon oil and microsphere hardening in heptane. The secondary structure of BSA was determined at relevant steps of the encapsulation procedure by employing Fourier-transform infrared (FTIR) spectroscopy. This fast and non-invasive method demonstrated the potential to rapidly screen pharmaceutically relevant protein delivery systems for their suitability. Structural perturbations in BSA were reduced during the spray-freeze drying step by employing the excipient trehalose. The protein was then encapsulated into PLG microspheres under various conditions without inducing significant structural perturbations. BSA released from these microspheres had a similar monomer content as unencapsulated BSA and also the same secondary structure. Upon blending of a poloxamer (Pluronic F-68) with the polymer phase, in vitro release was characterized by a small initial release and a prolonged and continuous sustained phase. In conclusion, the developed o/o methodology coupled with FTIR spectroscopic monitoring of protein structure is a powerful approach for the development of sustained release microspheres.
authors.affiliation: University of Puerto Rico, Department of Chemistry, Río Piedras Campus, P.O. Box 23346, San Juan, Puerto Rico 00931-3346, USA.
authors.forename: K G
authors.initials: KG
authors.lastname: Carrasquillo
authors.forename: A M
authors.initials: AM
authors.lastname: Stanley
authors.forename: J C
authors.initials: JC
authors.lastname: Aponte-Carro
authors.forename: P
authors.initials: P
authors.lastname: De Jésus
authors.forename: H R
authors.initials: HR
authors.lastname: Costantino
authors.forename: C J
authors.initials: CJ
authors.lastname: Bosques
authors.forename: K
authors.initials: K
authors.lastname: Griebenow
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004337:Drug Carriers; D004339:Drug Compounding; D016503:Drug Delivery Systems; D005612:Freeze Drying; D019344:Lactic Acid; D008863:Microspheres; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D012710:Serum Albumin, Bovine / Q000008:administration & dosage*; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D004337:Drug Carriers; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D012710:Serum Albumin, Bovine; D019344:Lactic Acid