Calcium Carbonate Microparticles Growth Templated by an Oxadiazole-Functionalized Maleic Anhydride-co-N-vinyl-pyrrolidone Copolymer, with Enhanced pH Stability and Variable Loading Capabilities

Abstract

The crystallization characteristics of CaCO3 microparticles from supersaturate aqueous solutions in the presence of a conjugate drug-copolymer has been investigated, comparative with particles prepared in similar conditions but without polymer. The polymer conjugate, P(NVP-MA-Ox), is based on poly(N-vinylpyrrolidone-co-maleic anhydride) as support and 2-amino-5-(4-methoxy-phenyl)-1,3,4-oxadiazole. The influence of the polymer/CaCO3 ratio on the microparticles' characteristics and the particles' pH stability was deeply investigated by scanning electron microscopy, X-ray diffraction, flow particle image analysis, particles charge density, and electrophoresis. The presence of P(NVP-MA-Ox) as a template in the CaCO3 crystallization process induced the particles stability increase up to the polymer isoelectric point located at pH = 3.4, irrespective of carbonate content in composite particles. The adsorption capacity of the microparticles as a function of their characteristics was tested using methylene blue. The sorption capacity of composite materials increased with the increase of polymer content in the composites, suggesting that the sorption process takes place mainly by electrostatic interactions.

Highly Efficient Copper(II) Ion Sorbents Obtained by Calcium Carbonate Mineralization on Functionalized Cross‐Linked Copolymers

“…The initial concentration of the inorganic components used in this study (0.1–0.4 M ) ensures solutions supersaturation with respect to calcite and vaterite. It is therefore expected that by mixing the reactant solutions at ambient temperatures will induce the growth of vaterite and calcite polymorphs 24. Usually, calcite crystallizes as mono‐crystalline well‐faceted particles, whereas vaterite particles are polycrystalline, exhibit a spherical shape, and are built up by 25–35 nm crystallites 33.…”

Complex calcium carbonate/polymer microparticles as carriers for aminoglycoside antibiotics

“…The CaCO 3 crystallization in the presence of pectin induce the increase of the particles stability vs. pH up to the polymer pzc. 8 As the NPECs are formed with pH-sensitive polymers, their stability is also inuenced by pH. A previous study 20 showed for the NPECs with n + /n À ¼ 0.5 a slightly decrease of zeta-potential values with the increase of pH.…”

“…6,7 Our previous studies focused on the synthesis of composite particles by co-precipitation with macromolecules (natural or synthetic) following the effect on the morphology of the formed CaCO 3 materials. [8][9][10][11] Also, the sorption properties of the composites for dyes, heavy metal ions and drugs has been followed as a function of the composites properties. 8,9,11 Nonstoichiometric polyelectrolyte complexes (NPEC), which are obtained by mixing aqueous solutions of oppositely charged polymers, 12 were also used in the composite preparation.…”

“…[8][9][10][11] Also, the sorption properties of the composites for dyes, heavy metal ions and drugs has been followed as a function of the composites properties. 8,9,11 Nonstoichiometric polyelectrolyte complexes (NPEC), which are obtained by mixing aqueous solutions of oppositely charged polymers, 12 were also used in the composite preparation. 13,14 Most important stimuli-dependent systems from the biomedical point of view are the pH-sensitive polymers.…”

“…12 The use of weak polymers in CaCO 3 composites preparation allows the control of materials stability on the environmental pH variation, from pH 5.5 (of CaCO 3 itself) up to strong acidic pH (2)(3). 8,9 Streptomycin (STR) and kanamycin (KAN) sulfate are broad spectrum aminoglycoside antibiotics. 19 STR is not absorbed from the gastrointestinal tract but, aer intramuscular administration, it diffuses readily into the extracellular component of most body tissues and it attains bactericidal concentrations, particularly in tuberculous cavities.…”