title: Determination of the internal morphology of poly (D,L-lactide) microspheres using stereological methods.
abstract: The morphological characteristics of the internal structure of poly (D,L-lactide) microspheres have been determined by stereological methods in two different formulations of microspheres, with different internal structures, prepared by using a double emulsion method. In one formulation the internal emulsion was produced by homogenisation at 3000 rpm, whilst the other was prepared at 11000 rpm. As expected the formulation prepared at the lower speed contained larger and more broadly distributed pores than that prepared at the higher speed. The porosity, pore size distribution and total internal surface area of the microspheres were obtained by stereological methods from electron microscopic measurements of the sectioned microspheres. It was found that whilst the porosity of the microspheres was 0.6 in both formulations, the preparation method gave rise to large differences in their pore size distribution characteristics. The pore size distribution was simulated by computer modelling to validate and compare alternative stereological algorithms. It was found that the Saltykov unfolding method predicts the measured pore size distribution more accurately than the Cruz-Orive unfolding method (at significance level alpha=0.1). This finding was attributed to the violation of one of the basic assumptions of the Cruz-Orive unfolding method.
authors.affiliation: Department of Pharmaceutical Sciences, University Park, Nottingham NG7 2RD, UK.
authors.forename: T
authors.initials: T
authors.lastname: Ehtezazi
authors.forename: C
authors.initials: C
authors.lastname: Washington
authors.forename: C D
authors.initials: CD
authors.lastname: Melia
mesh_terms: D000465:Algorithms; D001672:Biocompatible Materials / Q000737:chemistry*; D003198:Computer Simulation; D004655:Emulsions; D020342:Finite Element Analysis; D019344:Lactic Acid / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D004655:Emulsions; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid