A Model System to Provide a Good in Vitro Simulation of Biological Mineralization

The in vivo process of biological mineralization can be successfully simulated in vitro by a slow crystallization of a nonstoichiometric carbonated apatite from revised simulated body fluid (rSBF) carried out in a constant-composition double-diffusion (CCDD) device under physiological conditions (temperature 37 °C, solution pH within 7.2−7.4). The substitution of an organic buffer (Hepes) by permanent carbon dioxide bubbling to keep the pH constant has no strong influence on the crystallization. By increasing the overall concentration, calcification can be easily induced on porous bioinert surfaces such as cellulose or cholesterol that normally cannot be coated with calcium phosphates from supersaturated solutions without additional promoters.