title: Poly-lactide-co-glycolide microparticle sizes: a rational factorial design and surface response analysis.
abstract: Microsphere size is a primary determinant of solute release velocity. We present here a rational way for producing PLGA microspheres with different and controlled sizes. The following process variables were studied: Stirring velocity during the second emulsion step, dispersed and continuous phases volume ratio, and poly(vinyl alcohol) concentration in the continuous phase. A full factorial experimental design 2(3) with triplicate at the central point was used to determine the influence of variables on PLGA microsphere mean size. The stirring velocity and poly(vinyl alcohol) concentration were the main variables at 0.95 significance level. An influence of PVA and stirring velocity on microspheres size is observed, there is no correlation for DP/CP volume ratio on size of microspheres. By combining the two variables--the stirring velocity and poly(vinyl alcohol) concentration, the surface response was analyzed. The increase of poly(vinyl alcohol) concentration with concomitant increase on stirring velocity produced microspheres with the lower sized. In contrast the lower poly(vinyl alcohol) concentration and the lower stirring velocity used produced the higher microspheres sized. Uniformly spherical and smooth microspheres (4-15 microm of diameter) were obtained. No significant difference was observed on Ponca S loading within the experimental region. Our results open the possibility of formulating PLGA microspheres with custom sizes performing a minimum of experiments as required for specific applications.
authors.affiliation: Lab. De Microesferas e Lipossomas - C. de Biotecnologia-I Butantan, Av. Vital Brasil, 1500, 05503-900 Butantan, São Paulo, SP, Brasil.
authors.forename: Jocimara Ambrósio de Moraes
authors.initials: JA
authors.lastname: Namur
authors.forename: Elaine Christine de Magalhães
authors.initials: EC
authors.lastname: Cabral-Albuquerque
authors.forename: Wagner
authors.initials: W
authors.lastname: Quintilio
authors.forename: Maria Helena Andrade
authors.initials: MH
authors.lastname: Santana
authors.forename: Mario José
authors.initials: MJ
authors.lastname: Politi
authors.forename: Pedro Soares
authors.initials: PS
authors.lastname: de Araujo
authors.forename: Antônio Carlos
authors.initials: AC
authors.lastname: Lopes
authors.forename: Maria Helena Bueno
authors.initials: MH
authors.lastname: da Costa
mesh_terms: D000941:Antigens / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry; D004337:Drug Carriers; D016503:Drug Delivery Systems; D008863:Microspheres; D053758:Nanoparticles / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D011098:Polyglactin 910 / Q000737:chemistry*; D011142:Polyvinyl Alcohol / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000941:Antigens; D001672:Biocompatible Materials; D004337:Drug Carriers; D011098:Polyglactin 910; D011142:Polyvinyl Alcohol