New Functional Amorphous Calcium Phosphate Nanocomposites by Enzyme-Assisted Biomineralization

Abstract

In the present study, we report on enzyme-assisted formation of biomineralized amorphous calcium phosphate nanocomposites (ACP-NCs). About 100–200 nm sizes of the spherical porous enzyme-assisted ACP-NCs were successfully synthesized via double reverse microemulsion, but no ACP-NCs formed without the enzyme. It is believed that the enzyme was used as an organic template or additive that could regulate the biomineralization process. The enzyme-assisted ACP-NCs were well characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, dynamic light scattering, and Brunauer–Emmett–Teller (BET) criteria. The BET surface area, total pore volume, pore size from adsorption, and pore size from desorption of the ACP-NCs were 163 m² g^–1 or 0.37 cm³ g^–1, 8.87 nm, and 7.48 nm, respectively. The enzyme-assisted ACP-NCs retained about 43% of the catalytic activity of free carboxyl esterase. Furthermore, they preserved their bioactivity even after the 10th reuse and were stable over 10 days even under a stringent shaking conditions. The reported method paves the way for novel biomineralization via enzyme molecules to form functional enzymes containing nanocomposites.