Less is more: silicate in the crystallization of hydroxyapatite in simulated body fluids

Abstract

Dilute silicate (0.05–0.5 mM) promoted the nucleation of hydroxyapatite (HAP) in simulated body fluids, while a higher level of silicate (3–8 mM) inhibited it.

Effect of the aggregation state of amorphous calcium phosphate on hydroxyapatite nucleation kinetics

“…Meanwhile, this transformation of HAP at ACP-solution interface was also frequently observed and reported in previous work. [15][16][17][18]27,30,31…”

“…However, these disadvantages can be avoided by direct TEM observations. 31 Herein, we used TEM (see ESI for details †) to determine the specic surface area of ACP. As a results (Fig.…”

Amorphous Phase Mediated Crystallization: Fundamentals of Biomineralization

“…To keep the ionic product of ACP, {Ca 2+ } needs to be increased, which can promote the ACP-mediated crystallization ( Figure 8). This model can also be applied to explain the stability change of ACP by its aggregation state [86] and its size [85]. It should be noted that our model is applicable when a crystal phase is nucleated directly from an amorphous phase.…”

“…This model can also be applied to explain the stability change of ACP by its aggregation state [86] and its size [85]. system, the effective supersaturation can be taken as a constant regardless of how much calcium and phosphate ions were initially put into solution.…”

“…The surface area of ACP and the activity of calcium ions in solution are the key factors for controlling nucleation kinetics [6,7]. Citrate [84], poly-Asp [11], silicate [85], solution pH [10], and the aggregation stated of ACP [86] can either modify the ACP surface or the surface area or change the activity of calcium in solution that leads to the inhibition or promotion of ACP phase transformation. In addition to the surface-mediated nucleation pathway, ACP-HAP crystallization might also go through other pathways, such as multiple sites nucleation inside ACP [58], HAP nucleation at ACP inter-particles boundary [87], and structure-rearrangement of the Ca 9 (PO 4 ) 6 unit (called Posner cluster) in ACP [33,61], which indicate that the CaP crystallization pathway is solution chemical-sensitive.…”