title: Precipitation of calcium phosphate and calcium carbonate induced over chitosan membranes: a quick method to evaluate the influence of polymeric matrices in heterogeneous calcification.
abstract: Precipitation of calcium compounds (phosphate and carbonate) was performed on chitosan porous and dense membranes. In order to observe the influence of acetyl groups on the nature of formed precipitates, some chitosan membranes were acetylated in methanol solution before undergoing calcification. Calcification experiments were performed more quickly than using SBF. In this method, a faster precipitation is induced by soaking the membranes in calcium chloride solutions and, in sequence, immersing the same membranes into sodium phosphate or carbonate solutions. This procedure induced the formation of calcium compound precipitates on membrane surfaces, which were analysed through optical microscopy, X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy with attenuated total reflection apparatus (FTIR-ATR) and small angle X-ray scattering (SAXS). The results indicated the biomimetic influence of the organic matrix on morphology, organization and composition of precipitates. The acetyl group induced the formation of organized calcium carbonate better than phosphate, which may correlate with the fact that these two compounds are commonly found together in nature in structures like shells and nacre.
authors.affiliation: Faculdade de Engenharia Química, Unicamp, CP6066 CEP13083-970, Campinas, SP, Brazil.
authors.forename: Cassiano Gomes
authors.initials: CG
authors.lastname: Aimoli
authors.forename: Marisa Masumi
authors.initials: MM
authors.lastname: Beppu
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D011232:Chemical Precipitation; D048271:Chitosan / Q000737:chemistry*; D008567:Membranes, Artificial; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D008567:Membranes, Artificial; D048271:Chitosan; D002119:Calcium Carbonate