Preparation of low-crystalline apatite nanoparticles and their coating onto quartz substrates

Abstract

We prepared low-crystalline apatite nanoparticles and coated them onto a surface of a Au/Cr-plated quartz substrate by the electrophoretic deposition (EPD) method or by using a self-assembled monolayer of 11-mercaptoundecanoic acid (SAM method). Low-crystalline apatite nanoparticles around 10 nm in size with extremely low contents of undesirable residual products were obtained by adding (NH(4))(2)HPO(4) aqueous droplets into a modified synthetic body fluid solution that contained Ca(CH(3)COO)(2). The apatite nanoparticles were successfully coated by either the EPD method or the SAM method; the nanoparticle coating achieved by the SAM method was more uniform than that achieved by the EPD method. The present SAM method is expected to be a promising technique for obtaining a quartz substrate coated with apatite nanoparticles, which can be used as a quartz crystal microbalance device.

Solid-state 1H and 31P NMR and FTIR spectroscopy study of static and dynamic structures in sol-gel derived calcium hydroxyapatites

“…The signal at 2.6 ppm is dominating in the 31 P MAS NMR spectra of CaP and gel/CaP, similarly to pure HA [10]. Therefore this peak was also attributed to PO 4 3groups. However, the signal shapes in both CaP and gel/CaP are asymmetric and significantly broader, demonstrating structural inhomogeneities, which can include the presence of an additional phase difference from pure crystalline HA.…”

“…3). The signal maxima at 3.5-3.9 ppm (MAS) and 4.7-4.8 ppm (static) get into the range of 31 P chemical shifts of bulk and surface PO 4 3groups in the related systems reviewed above [8][9][10][11][12]. Much more interesting seem the signal shape and width evolution observed upon MAS.…”

“…It should be noted that for several systems decomposition of the observed 31 P signal into 2-3 spectral components was obtained [9][10][11][12]. These components have been attributed to bulk PO 4 3-(2.5-3.2 ppm), surface unprotonated PO 4…”

“…A single 31 P signal centered at 2.3 ppm is also displayed in fluoroapatite (FAp) gelatin nano-composite [9]. This signal was attributed to PO 4 3− groups in crystalline FAp. Its Δν 1/2 of 178 Hz is typical of that of pure HA and deviates significantly from that observed in HAbased nano-composite prepared by direct precipitation in a solution (373 Hz).…”

“…Moreover, current artificial bone substitutes are inferior to the auto-graft with respect to osteoconductivity (property to form a new bone on the surface of materials). It has been also reported that cell attachment, proliferation and differentiation behaviour is regulated on the crystallinity [4,5]. Thus, one of the objectives of this work was to fabricate low crystalline CaHA, which is thought to show higher osteoconductivity and thus can be used as an artificial bone substitute.…”