title: Calcium carbonate microparticle growth controlled by a conjugate drug-copolymer and crystallization time.
abstract: The influence of crystallization reaction time on CaCO3 microparticle growth from supersaturate aqueous solutions, in the presence of a conjugate drug-copolymer, has been investigated. The polymer conjugate, P(NVP-MA-Ox), is based on poly(N-vinylpyrrolidone-co-maleic anhydride) as the support and 2-amino-5-(4-methoxyphenyl)-1,3,4-oxadiazole as the drug. The microparticles are characterized by optical, scanning and transmission electron microscopy, dynamic light scattering, X-ray diffraction, flow particle image analysis and particle charge density. X-ray diffraction (XRD) investigations showed that calcite polymorph content increased with an increase in crystallization time, even if the electrostatic interactions between Ca(2+) and polyanionic sites of P(NVP-MA-Ox) structure conduct to an increased vaterite phase stability. The strong particle size increase after 6 h of ageing can be ascribed to partially vaterite recrystallization and adsorption of nano-scaled calcite crystallite nuclei at microparticles surfaces. The pH stability of the particles was shown by zeta potential changes and their adsorption capacity as a function of their composition, and characteristics were tested using methylene blue. The sorption capacity of composite materials was strongly influenced by the ratio between polymorphs in the composites, and increased with the increase of calcite content and ageing time.
authors.affiliation: `Petru Poni' Institute of Macromolecular Chemistry of Romanian Academy, 41 A Grigore Ghica Voda Alley, 700487 Iasi, Romania.
authors.forename: Florica
authors.initials: F
authors.lastname: Doroftei
authors.affiliation: `Petru Poni' Institute of Macromolecular Chemistry of Romanian Academy, 41 A Grigore Ghica Voda Alley, 700487 Iasi, Romania.
authors.forename: Mariana Dana
authors.initials: MD
authors.lastname: Damaceanu
authors.affiliation: `Petru Poni' Institute of Macromolecular Chemistry of Romanian Academy, 41 A Grigore Ghica Voda Alley, 700487 Iasi, Romania.
authors.forename: Bogdan C
authors.initials: BC
authors.lastname: Simionescu
authors.affiliation: `Petru Poni' Institute of Macromolecular Chemistry of Romanian Academy, 41 A Grigore Ghica Voda Alley, 700487 Iasi, Romania.
authors.forename: Marcela
authors.initials: M
authors.lastname: Mihai
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D002119:Calcium Carbonate / Q000737:chemistry*; D003460:Crystallization / Q000379:methods; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D008298:Maleates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D010069:Oxadiazoles / Q000737:chemistry; D010316:Particle Size; D000071228:Polyelectrolytes; D011108:Polymers / Q000737:chemistry; D011205:Povidone / Q000737:chemistry; D055672:Static Electricity; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D002119:Calcium Carbonate; D008298:Maleates; D010069:Oxadiazoles; D000071228:Polyelectrolytes; D011108:Polymers; D011205:Povidone; C102419:(1-vinyl-2-pyrrolidone)-(maleic anhydride) copolymer
keywords: pH stability; polymers; sorption capacity; spherical microparticles