The Effect of Different Surface Modification Agents on the Dispersion of Nano-Hydroxyapatite (n-HA) Crystallites

Y.M. Jiang; Xiao Hong Li; Bo Feng; Jie Weng

doi:10.4028/www.scientific.net/KEM.284-286.55

Paper Titles

HAp Protein Composites Formed by Hydrolysis of α-TCP
p.39

XRD, SEM/EDX and FTIR Characterization of Brazilian Natural Coral
p.43

Effect of Some Physical-Chemical Variables in the Synthesis of Hydroxyapatite by the Precipitation Route
p.47

Effect of Operation Conditions on HA Synthesized by the Hydrothermal Method
p.51

The Effect of Different Surface Modification Agents on the Dispersion of Nano-Hydroxyapatite (n-HA) Crystallites
p.55

Synthesis and Characterisation of Hydroxyapatite Nano-Rods/Whiskers
p.59

Protein Loading and Solubility of Apatite Hydrogel
p.63

A Method for Simultaneously Precipitating and Dispersing Nano-Sized Calcium Phosphate Suspensions
p.67

A New Synthetic Route to Calcium Polyphosphates
p.71

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The Effect of Different Surface Modification Agents on the Dispersion of Nano-Hydroxyapatite (n-HA) Crystallites

Abstract:

The surface of synthetic calcium hydroxyapatite (HA, Ca10(PO4)6(OH)2) was modified through combining freeze-drying, solvent replacement and surface modification methods in an effort to obtain the deaggregative n-HA crystallites. Three surface modification agents: Polyethylene glycol (PEG, Mw: 6000), poly(propyl oxide)-poly (ethyl oxide)-co-poly(propyl oxide)(Pluronic F-127, Mw: 12,000) and poly(d, l-lactide)-co-poly (ethylene glycol) (PELA, Mw: 20,000)were selected. The dispersion of the modified n-HA was characterized by sedimentation time in distilled water, acetone and dimethyl formamide (DMF). The results indicate that the three surface modification agents influence the dispersion of n-HA crystallites in various solvent based on different mechanisms. Transmission electron microscopy (TEM) observation shows that the dried and acetone-replacement powders are composed of needle-like HA crystallites isolated individually. The chosen solvents have a profound effect on the sedimentation time. In distilled water, the dispersion of as-synthesized n-HA crystallites is increased greater by F127 than by PEG. After freeze-drying, the two n-HA particles show homogeneous dispersion in acetone. The colloid stability of freeze-dried HA/PEG, solution-replaced HA/F127 and solution-replaced HA/PELA in DMF were improved significantly. The suspensions remained stable after 30 days with only a blue transparent sol being observed.