title: Influence of excipients on characteristics and release profiles of poly(ε-caprolactone) microspheres containing immunoglobulin G.
abstract: Protein instability during microencapsulation has been one of the major drawbacks of protein delivery systems. In this study, the effects of various excipients (poly vinyl alcohol, glucose, starch, heparin) on the stability of encapsulated human immunoglobulin G (IgG) in poly(ε-caprolactone) (PCL) microspheres and on microsphere characteristics were investigated before and after γ-sterilization. Microspheres formulated without any excipients and with glucose had a mean particle size around 3-4μm whereas the mean particle sizes of other microspheres were around 5-6μm. Use of PVA significantly increased the IgG-loading and encapsulation efficiency of microspheres. After γ-irradiation, IgG stability was mostly maintained in the microspheres with excipients compared to microspheres without any excipients. According to the μBCA results, microspheres without any excipient showed a high initial burst release as well as a fast release profile among all groups. Presence of PVA decreased the loss in the activity of IgG released before (completely retained after 6h and 15.69% loss after 7days) and after γ-irradiation (26.04% loss and 52.39% loss after 6h and 7days, respectively). The stabilization effect of PVA on the retention of the activity of released IgG was found more efficient compared to other groups formulated with carbohydrates.
authors.affiliation: Department of Engineering Sciences, Middle East Technical University, Ankara, Turkey.
authors.forename: Özge
authors.initials: Ö
authors.lastname: Erdemli
authors.affiliation: Department of Engineering Sciences, Middle East Technical University, Ankara, Turkey; Biomaterials and Tissue Engineering Center of Excellence, Middle East Technical University, Ankara, Turkey.
authors.forename: Dilek
authors.initials: D
authors.lastname: Keskin
authors.affiliation: Department of Engineering Sciences, Middle East Technical University, Ankara, Turkey; Biomaterials and Tissue Engineering Center of Excellence, Middle East Technical University, Ankara, Turkey. Electronic address: tezcaner@metu.edu.tr.
authors.forename: Ayşen
authors.initials: A
authors.lastname: Tezcaner
mesh_terms: D003692:Delayed-Action Preparations; D005079:Excipients / Q000737:chemistry*; D005720:Gamma Rays; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry*; D008863:Microspheres; D011091:Polyesters / Q000737:chemistry*; D055550:Protein Stability / Q000528:radiation effects; D013242:Sterilization
chemical_list: D003692:Delayed-Action Preparations; D005079:Excipients; D007074:Immunoglobulin G; D011091:Polyesters; C016240:polycaprolactone
keywords: Excipients; In vitro release; Microspheres; Polymeric drug delivery; Protein delivery; γ-Sterilization