Physicochemical regularities of the sorption of amino acids on the surface of hydroxylapatite

Biogenic and pathogenic mineral formations contain calcium phosphates. It is known that hydroxylapatite is the main mineral component of bone tissue, tooth enamel, and dentin. The basis of the processes of mineralization is proposed to be in the adsorption interaction of free amino acids and associated protein molecules with inorganic components in body fluids and emerging phases. However, the mechanism of their interaction is not fully understood. In this paper the adsorption of amino acids on the surface of hydroxylapatite has been studied. The synthesis of calcium phosphates from solution has been carried out. According to the results of XRD and IR spectroscopy it has been established that precipitation is represented by the phase of hydroxylapatite. The adsorption of amino acids in a wide range of variation of their concentrations and the pH of the solution has been investigated. It has been established that adsorption of amino acids on the surface of hydroxylapatite reaches saturation. The effect of pH on the maximum adsorption of amino acids on hydroxylapatitehas been considered. It has been established that adsorption of amino acids is described by the Langmuir model. The result of IR spectroscopy confirmed adsorption. It has been determined by the sign of the surface charge of the solid phase of hydroxylapatite. The values of the Gibbs energy have been calculated. It has been revealed that the interaction of amino acids with the surface of the hydroxylapatiteis characterized by physical adsorption.