Effect of polymer compositions on the fabrication of poly(ortho-ester) microspheres for controlled release of protein

• Published in: Journal of applied polymer science Vol. 80; no. 10; pp. 1630 - 1642
• Main Authors: Bai, Xin-Lai, Yang, Yi-Yan, Chung, Tai-Shung, Ng, Steve, Heller, Jorge
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 16.06.2001; Wiley
• Subjects: Applied sciences; Biological and medical sciences; bovine serum albumin; Exact sciences and technology; General pharmacology; Medical sciences; microspheres; Organic polymers; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Physicochemistry of polymers; poly(ortho-ester)s; Properties and characterization; release profile; Special properties (catalyst, reagent or carrier); surface erosion; Glycolic acid copolymer; Microsphere; Property composition relationship; Controlled release form; Control release polymer; Lactic acid copolymer; Drug carrier; Serum albumin; Experimental study; In vitro; Structure composition relationship; Spiran copolymer; Ester copolymer; Morphology; Kinetics; Dioxane copolymer; Manufacturing; Release
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.1257

Eight kinds of self‐catalyzed poly(ortho‐esters) (POEs) are used to fabricate bovine serum albumin (BSA)‐containing microspheres using a W/O/W double‐emulsion solvent extraction/evaporation method. All eight kinds of POE polymers used in this study are shown able to form microspheres under proposed fabrication conditions. The surface morphology and inner structure of the microspheres are analyzed using scanning electron microscopy (SEM). The microspheres have a size range from 64.7 to 120.2 μm. POE with a higher viscosity leads to bigger microspheres. It was found that the POE composition has a significant effect on BSA release profiles. POEs, which are more hydrophilic and contain a greater amount of glycolide or lactate (latent acid), yield higher BSA release rates. Specifically, POE containing 1,6‐hexanediol diglycolide (HD‐diGL) microspheres have the highest BSA release rate after a 20‐day test through a combination of surface erosion and diffusion mechanisms. POE containing a high percentage of the trans‐cyclohexanedimethanol (CDM) segment tends to yield microspheres with a lower release rate because of its hydrophobic nature. It was also found that the BSA release rate is more rapid at 37°C than at 22°C because of faster polymer degradation and water penetration at 37°C. Experimental results suggest that various protein release rates can be achieved by using different compositions of POEs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1630–1642, 2001