Abstract: Silicate-substituted calcium phosphates have been shown to result in enhanced biological
performance compared to the corresponding, silicate-free, calcium phosphates. We have produced a
range of silicate-substituted alpha-TCP compositions using two different synthesis methods and two
different substitution mechanisms. Single phase compositions were only observed for a silicate
substitution of 1.3 wt% by both solid state synthesis and aqueous precipitation synthesis, although
the latter was the result of a design composition with a higher silicate substitution (3 wt%). The
silicate substitution resulted in small changes in the unit cell parameters of the alpha-TCP. More
importantly, this small level of silicate substitution had a strong effect on the thermal stability of the
alpha-TCP phase, with the silicate substitution stabilising the alpha-polymorph to lower
temperatures. This has an immediate advantage in that the quenching conditions are not as critical
for the production of silicate-substituted alpha-TCP compositions compared to silicate-free alpha-
Abstract: Micrometer-sized hydroxyapatite (HA) with rod-shape was prepared to investigate
protein adsorption onto its crystal face, through hydrothermal processing. Adsorption of Bovine
serum albumin (BSA) and Lysozyme from chicken egg white (LSZ) on rod-shaped HA crystals with
approximately 50 μm in length and 1 μm thickness was examined in phosphate buffer solution. The
amount of adsorbed BSA was decreased with increasing phosphate concentration in the examined
solution. Adsorption of LSZ was increased with increasing phosphate concentration in the buffer
solution up to 50 mmol/L (mM), while it was remarkably decreased when the phosphate
concentration reached approximately 100 mM. These phenomena lead to understanding of
chromatographic characters of HA for separation of acidic and basic proteins.
Abstract: The infrared and Raman spectra of Na substituted β-TCP are presented for various levels
of substitution. The influence of Na content on main vibrational modes appears significant and
among them the ν1 symmetric stretching band is very sensitive to PO4
3- tetrahedrons environment.
Thus, this mode was particularly investigated and has been decomposed using Lorentzian shapes
components. We assigned the calculated components to the different types of PO4
present in the crystalline structure.
Abstract: The interaction of calcium phosphates with biological molecules under controlled
conditions permits the formulation of meaningful conclusions concerning the driving forces. The
uptake and release at the material-solution interface is the result of the various interactions between
and within the system components which include the solid surface, the adsorbate, the solvent and
other solutes present. The understanding of adsorption and desorption mechanisms with respect to
active molecules can be exploited for the development of drug delivery applications.
Abstract: The present study examined the possibility of using spherical porous granules of hydroxyapatite
(HA, Ca10(PO4)6(OH)2) composed of rod-shaped particles as the drug delivery system. The granules
composed of rod-shaped HA were successfully prepared by an emulsion method and a hydrothermal
treatment. When the rod-shaped granules were soaked in phosphate buffer salines containing lysozyme
chloride or albumin, the granules of rod-shaped HA adsorbed more albumin than lysozyme. On the other
hand, the HA granules prepared by a normal sintering method adsorbed little lysozyme chloride or albumin.
The HA granules composed of rod-shaped particles are expected to be useful as carriers of negatively
Abstract: In this work, we studied the surface/water interaction properties of a pure calcium
hydroxyapatite (HA) and their modifications as a consequence of the partial Ca2+/Mg2+ (MHA)
substitution by means of IR spectroscopy and microcalorimetry of adsorbed water. IR data
indicated that water molecules in direct contact with the surface of HA are coordinated to surface
cations and experience H-bond significantly stronger than in liquid water. The heats of adsorption
associated to such interactions are very high, being twice-triple the heat of liquefaction of water.
Interestingly, water experiences H-bond higher than in its bulk liquid state also in the second layer.
Finally the entering in the material of Mg2+ ions was shown to significantly affect the affinity of the
material toward water and the properties of its hydration layers.
Abstract: Two-step sintering was performed to prepare hydroxyapatite (HAp) with a high density
and a fine microstructure utilizing hydrothermally synthesized nano powders. Its effectiveness was
dependent on starting chemicals for precursors of HAp, powder processing condition, initial
temperature in the two-step sintering, heating rate to the initial temperature, and holding time at
final temperature. HAp powder, hydrothermally treated after aging of precipitate of Ca(OH)2 and
H3PO4 for 48 h, led to HAp having a high phase stability at elevated temperatures, a high density,
and a fine microstructure after two-step sintering with heating rate of 10°C/min to 1275°C.
Abstract: Both biochemical cell functional test and animal implantation test were done to investigate
the reaction to fine particles. Particles cause nonspecifically phagocytosis to cells and inflammation
to tissue for the size below 10m. With the size below 50nm particles may invade into the internal
body through the respiratory or digestive system and diffuse inside body. Ti mapping by XSAM after
the compulsory exposure test to the respiratory system showed the internal diffusion of 30nm TiO2
particles. They diffused with time course to lung, liver and spleen after injection from caudal vein.
Nanoparticles might be the objects whose existence has not been assumed by the biophylactic system.
Abstract: Hydroxyapatite (HA) and barium titanate (BT) powders were mixed and sintered to form
hydroxyapatite – barium titanate (HABT) ceramics. These materials were then poled and their
piezoelectric properties were measured. The microstructure of unpoled samples was examined
using scanning electron microscopy (SEM).The piezoelectric constants (d33 and d31) of the ceramics
were found to be dependent on the proportion of BT in the ceramic In materials containing less
than 70% BT, no piezoelectric effect was found. Above this value, the piezoelectric constant
increased with the addition of BT up to a value of 108pCN-1 for pure BT. Values of d33 for
ceramics containing more than 80% BT are above values previously shown to have a positive
influence on bone growth in vivo. SEM analysis indicated that the grain size within the materials
decreased as the proportion of BT in the material was reduced. Examination of the microstructure
of the ceramics indicated the presence of electrical domains in the 100% BT and 95% BT ceramics.
Domains were not visible below 95% BT. The reduction in grain size may influence the reduction
in piezoelectric activity within the materials but cannot be considered to be the only cause.
Abstract: Dense bioceramics made of pure hydroxyapatite (HA) was prepared and characterized.
The cylindrical samples were compacted from HA powders of diverse pretreatments; namely, from
spray-dried HA, calcined HA and mixtures thereof. The samples were prepared by a hydraulic press
under different compaction loads both with and without auxiliary compounds (a binder and a
lubricant). Both the total mass and geometrical dimensions of the prepared cylinders were
measured. Then, the cylindrical samples were sintered at 1200 °C for 4 hours. After cooling down
to ambient temperature, the sintered cylinders were weighed and their geometrical dimensions were
measured once again. Mass decreasing and the shrinkage degree were calculated as a result.
Afterwards, the compression strength of the sintered cylinders was measured by an Instron 5587
machine. Preparation of dense HA bioceramics possessing the highest possible compression
strength was the purpose of this study. The necessary processing parameters were discovered.