Interaction between nanosized crystalline components of a composite based on <Emphasis Type="Italic">Acetobacter xylinum</Emphasis> cellulose and calcium phosphates

A composite consisting of two nanosized biocompatible components, Acetobacter xylinum cellulose and calcium phosphate, is prepared through aggregation in an aqueous suspension. The structures of initial components and composite are investigated by the methods of X-ray and electron diffraction and electron microscopy. The mineral component consists of two crystalline phases, hydroxyapatite and whitlockite (magnesium-containing tricalcium phosphate), which are nanosized platelike crystals. The composite preserves the crystalline structures of initial calcium phosphates and cellulose. In the course of composite formation, hydroxyapatite and whitlockite crystallites are adsorbed on the surfaces of nanofibrillar cellulose ribbons. Whitlockite nanocrystals are predominantly deposited on the surface of cellulose ribbons. The mutual orientation of the surfaces of crystalline structures of cellulose and two types of calcium phosphates, hydroxyapatite and whitlockite, is analyzed by means of computer simulation, and the variants of mutual arrangement of their surfaces during formation of the interfacial boundary are suggested.