Prevention of structural perturbations and aggregation upon encapsulation of bovine serum albumin into poly(lactide-co-glycolide) microspheres using the solid-in-oil-in-water technique

Abstract

Bovine serum albumin (BSA) was encapsulated into poly(lactide-co-glycolide) (PLG) microspheres by a solid-in-oil-in-water (s/o/w) technique. We tested whether perturbations in BSA secondary structure could be minimized during encapsulation by using trehalose and how this would influence BSA aggregation and release. BSA secondary structure was monitored noninvasively by Fourier-transform infrared spectroscopy. When BSA was co-lyophilized with trehalose, lyophilization-induced structural perturbations were significantly reduced. The formulation obtained (BSA-Tre) was encapsulated into PLG microspheres and, by optimizing critical encapsulation parameters, a loading efficiency of 85% was achieved. However, due to the loss of the excipient in the o/w emulsion step, the structure of BSA-Tre was more perturbed than before encapsulation. Excipient-loss and encapsulation-induced structural perturbations could be prevented by saturating the aqueous phase in the o/w step with trehalose and by using the organic solvent chloroform. This in turn reduced the formation of soluble BSA aggregates. BSA was released from PLG microspheres using the improved formulations with an initial release in 24 h of not more than 22%, followed by a sustained release over at least 2 weeks. In summary, optimization of the encapsulation conditions in the s/o/w procedure resulted in the encapsulation of BSA without procedure-induced structural perturbations and minimized the release of aggregated protein. This demonstrates that the s/o/w technique is an excellent alternative to the most common encapsulation procedure, namely the water-in-oil-in-water technique.

Preparation of bioactive interferon alpha– loaded polysaccharide nanoparticles using a new approach of temperature-induced water phase/water-phase emulsion

“…A polyethylene glycol (PEG)ylated long-efficacy IFN has been developed, but PEGylated IFNα-2b induces side effects more easily than native IFNα-2b. A sustained or controlled drug-delivery system has also been used for IFNα-2b delivery, [3][4][5][6][7][8][9][10] but it often results in activity lost and incomplete release Spray-drying, antisolvent precipitation, spray-freezedrying, and supercritical fluid technology have been investigated for preparing protein nanoparticles. [18][19][20] However, due to pressure, interfaces, heating, and organic solvents involved in different manufacturing steps, these methods are potentially detrimental to the structures and functions of proteins.…”

Sustained prolonged topical delivery of bioactive human insulin for potential treatment of cutaneous wounds

“…Likewise, polypeptides such as insulin can be exposed to highly acidic microenvironments within PLGA microspheres, causing peptide denaturation during the bulk erosion process (Shao and Bailey, 1999;Ding et al, 2006;Rosa et al, 2000;Yeh, 2000). As a result, crystalline forms of enzymes and peptides have been used to overcome formulation stresses and maintain bioactivity during release in vitro (Wang et al, 2004;Castellanos et al, 2001). As a consequence of these findings, better methods of release need to be developed using FDA approved materials.…”

Stabilization and encapsulation of human immunoglobulin G into biodegradable microspheres

“…Solid protein particles are obtained after the frozen droplets are freeze-dried under vacuum. Then the protein particles can be incorporated into a polymer matrix such as polylactide-co-glycolide (PLGA) microspheres by an S/O/W method [17][18][19].…”