Preparation and Surface Characterization of Calcium Hydroxyapatite Grafting of Phosphoethanolamine

Abstract

Calcium hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 : Hap) particles grafting of O-phosphoethanolamine (NH 2 (CH 2 ) 2 OPO 3 H 2 : PEA) were prepared by a coprecipitation method with a mixture of Ca(OH) 2 , H 3 PO 4 and PEA at different PEA/(PEA+H 3 PO 4 ) molar ratios in aqueous media at 85°C. The crystallinity and particle size of Hap were decreased with an increase of PEA/(PEA+H 3 PO 4 ) ratio, revealing that the crystal and particle growth of Hap were inhibited by grafting of PEA. The surface aminoethyl groups were generated by substituting the surface PO 4 3-of Hap with PEA ions, giving rise to the decrease of surface P-OH groups of Hap. The number of surface aminoethyl groups was increased with increasing the PEA/(PEA+H 3 PO 4 ) ratio and was ranged from 0.08 to 0.56 molecules/nm 2 . The surface aminoethyl groups would act as the irreversible adsorption sites of CO 2 .

Facile preparation in synthesizing nano-size hollow silicate particles by encapsulating colloidal-hydroxyapatite nanoparticles

“…Here, two aspects are demonstrated: encapsulation of HAp nanoparticles with an amorphous SiO 2 shell (HAp@SiO 2 ), and production of unique NSHSPs. At this point, the concern is developing less than 60 nm-scale hollow silicate particles using colloidal-HAp particles (Ca(OH) 2 : H 3 PO 4 ¼ 1.75 : 1, synthesized by Tanaka et al 11,12 ) The advantages in utilizing HAp particles include the following: they are easily dissociated at mild acid concentrations 12 and no special equipment is needed to recycle the dissolved HAp particles. There were other studies pertaining to modifying and coating HAp particles 13,14 but in attempting to use them as template-colloidal HAp solution (1.75 Ca/P) to form <60 nm NSHSPs (as far as we know) we were the first group to do it successfully.…”