Enzymatic synthesis of calcium phosphates: A review

Abstract

Biochemical synthesis of calcium phosphates (CaP) with use of enzymes is a novel trend in the synthesis of hydroxyapatite (HA) and other biocompatible calcium salts and composites. These compounds are biocompatible, possess good mechanical properties, and are suitable for a variety of purposes in bone tissue engineering. In this review, we discuss the biosynthesis (or enzymatic synthesis) of calcium phosphates and its comparison with conventional chemical methods. Main attention is paid to properties of CaP compounds for biochemical applications, classification and role of various enzymes in the biomineralization processes, role of bacteria and fungi, mechanisms of mineralization in several steps and possible real-time monitoring. A large number of morphologies of biochemically obtained CaP is shown, in particular for nanoscale range. Enzymes in natural biomineralization processes with participation of common bacteria, possessing a periplasmic alkaline phosphatase, are discussed in the point of view of their contribution in formation of fossils and rocks. CaP composites with natural biopolymers (chitosan, polysaccharides, cellulose) and synthetic polymers are described, as well as CaP compounds, functionalized with a series of biomolecules. The use of biowaste (animal, plant and aquatic origin, such as bone waste, eggshells, naturally derived biomolecules and biomembranes, marine organisms, etc.), used as raw materials for the preparation of CaP, is also shown.