Mesocrystal aggregation of biological apatite nanocrystals

Abstract

Bone is a composite structure that is composed of calcium phosphate mineral, type I collagen, water and extracellular matrix proteins that interact over several levels of hierarchy from the macroscale to nanoscale. Early crystallographic studies on bone biominerals identified that they are calcium deficient and carbonate substituted biosynthesized hydroxyapatite (BHAp) (Trautz, 1955;Zapanta-LeGeros, 1965). The shape of the nanocrystals is generally plate-like with particle size in the range of 30-50 nm (length), 10-30 nm (width) and 2-10 nm (thickness) (Heywood et al., 1990;Sakae et al., 2015). The extensive shape and small size of BHAp have triggered high research interest in its mechanism of crystallization in terms of nucleation and growth. Understanding the formation of BHAp in a biological environment is essential for studies in bone healing, remodelling and regeneration and provides a sound foundation for advancing future endeavours in the design of bone biomaterials (Combes et al., 2016).Additional benefits can be derived from these studies in material design related to drug and gene delivery, nutritional supplements, health products and analytical tools to probe nanoscale phenomena such as hydroxyapatite based Quartz Crystal Microbalance (QCM) adsorption systems with enhanced sensitivity (REF).

Electrospun Scaffolds of Polylactic Acid, Collagen, and Amorphous Calcium Phosphate for Bone Repair

“…ACP has a structural unit similar to HAP, which allows it to play a critical role in apatite formation both in vitro and in vivo. ACP has a disordered structure that confers high reactivity in body fluids, resulting in high solubility and the rapid precipitation of apatite [56].…”

Hydroxyapatite-Tethered Peptide Hydrogel Promotes Osteogenesis

“…However, HAp is very stable with low solubility in physiological conditions. Nanosized HAp tends to aggregate due to its high surface energies [ 9 ], impeding its osteoinduction efficacy. What is worse, inhomogeneous aggregation of HAp is risky to bone malformation during bone regeneration [ 10 ].…”