title: Self-healing of pores in PLGAs.
abstract: Self-healing of pores in Poly(lactic-co-glycolic acid)s (PLGA) plays an important role in the encapsulation and controlled release of drugs from PLGA microparticles. Despite the importance of this phenomenon, neither the mechanics of the deformation nor the material properties that control it have been fully studied. In this study, the material properties of PLGA have been characterized using mechanical tests, and a finite-element model has been developed to predict how pores heal. This model assumes that the healing process occurs by viscous flow resulting from the deviatoric stress field induced by the interaction between the surface curvature and the surface tension of the PLGA. The simulations, which incorporate measured material properties, show good agreement with experimental observations. However, annealing processes that occur over prolonged times increase the viscosity and slow the healing times of PLGA films at intermediate temperatures above the glass-transition temperature. These findings may be reasonably applied towards the prediction of healing processes in PLGA and in related biomaterials for important biomedical applications such as drug delivery.
authors.affiliation: Department of Mechanical Engineering and Department of Materials Science & Engineering, University of Michigan, 2350 Hayward St., Ann Arbor, MI 48109, USA.
authors.forename: J
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of MI, NCRC, 2800 Plymouth Road, Ann Arbor, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Mazzara
authors.affiliation: Department of Pharmaceutical Sciences and the Biointerfaces Institute, University of MI, NCRC, 2800 Plymouth Road, Ann Arbor, USA; Department of Biomedical Engineering, University of Michigan, 2200 Bonisteel Blvd., Ann Arbor, MI 48109, USA. Electronic address: schwende@umich.edu.
authors.forename: S P
authors.initials: SP
authors.lastname: Schwendeman
authors.affiliation: Department of Mechanical Engineering and Department of Materials Science & Engineering, University of Michigan, 2350 Hayward St., Ann Arbor, MI 48109, USA. Electronic address: thouless@umich.edu.
authors.forename: M D
authors.initials: MD
authors.lastname: Thouless
mesh_terms: D003198:Computer Simulation; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004548:Elasticity; D020342:Finite Element Analysis; D019344:Lactic Acid / Q000737:chemistry*; D008956:Models, Chemical; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D016062:Porosity; D013500:Surface Tension; D013696:Temperature; D014783:Viscosity
chemical_list: D003692:Delayed-Action Preparations; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid
keywords: Finite element; PLGA; Self-healing; Simulations; Surface pores; Viscoelasticity