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2832350 
Journal Article 
Non-aqueous encapsulation of excipient-stabilized spray-freeze dried BSA into poly(lactide-co-glycolide) microspheres results in release of native protein 
Carrasquillo, KG; Stanley, AM; Aponte-Carro, JC; De Jesus, P; Costantino, HR; Bosques, CJ; Griebenow, K 
2001 
Yes 
Journal of Controlled Release
ISSN: 0168-3659
EISSN: 1873-4995 
76 
3 
199-208 
English 
11578736 
WOS:000171515700001 
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. (C) 2001 Elsevier Science B.V. All rights reserved. 
microspheres; non-aqueous encapsulation; poly(lactide-co-glycolide); protein aggregation; spray-freeze drying