A NOVEL METHOD OF ADVANCED MATERIALS PROCESSING
J MATER SCI 41 (2006) 1341–1344
Hydrothermal preparation of tailored hydroxyapatite
, G. KAWACHI, S. SASAKI
Graduate School of Environmental Studies, Tohoku University, Aoba 6-6-20 Aramaki, Aoba-ku,
Sendai 980-8579, Japan
H. FUJIMORI, S. GOTO
Graduate School of Medicine, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan
Hydrothermal vapor treatment method was applied for preparation of ceramic biomaterials.
; HA) ceramics prepared by sintering with random crystal
surface have already been used as bone-repairing materials which can directly bond to natural
bones. If materials of HA could have the tailored speciﬁc crystal surface, they should have the
advantage of adsorptive activity and osteoconductivity in comparison with the sintered HA. In
the present study, porous HA sheets of about 50 µm to 1 mm in thickness and porous HA
granules of about 50 µm to 1 mm in size with tailored crystal surface were prepared by the
hydrothermal vapor exposure method at temperatures below 200
C. Porous sheets and porous
granules of HA with controlled crystal surface should be suitable for scaffold of cultured bone,
for bone graft material and for drug delivery system (DDS).
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; HA) is known as ma-
jor component of human hard tissue such as bones and
teeth. Sintered HA has already been used as a bone-
repairing material which can directly bond to natural
bones in bony defect. It has been known to be biocompati-
ble and osteoconductive , but newly bone formation on
HA is not quick in comparison with the autograft. If mate-
rials of HA could have the tailored speciﬁc crystal surface,
they should have the quick bone formation because of the
advantage of adsorptive activity.
The authors reported various kinds of HA materials
prepared by the unique hydrothermal methods [2–8]. In
the present investigation, porous HA sheets of about
50 µm to 1 mm in thickness and porous HA granules
of about 50 µm to 1 mm in size with tailored crystal sur-
face were prepared by the hydrothermal vapor exposure
method [9–12]. This hydrothermal method is the strong
technique for control the crystal surface.
The sheets and granules of HA must be suitable as
scaffold for cultured bone, for bone graft material and for
drug delivery system (DDS).
Author to whom all correspondence should be addressed.
2. Experimental methods
2.1. Preparation of HA sheets
Commercial powders of α-tricalcium phosphate (α-
: α-TCP, Taihei Chemical Industrial Co., Ltd.,
Japan) and polyvinyl alcohol (PVA, Wako Pure Chemical
Industries Ltd., Japan) were used as the starting materi-
als. The slurry of α-TCP with PVA was prepared by using
10 mass% PVA aqueous solution at room temperature.
To remove bubbles, the slurry was kept under vacuum
condition. Films of α-TCP with PVA were prepared from
this slurry by spin overcoat method. This method is very
popular technique to preparing polymer ﬁlm . The
glass dish was set on a turntable, and then the slurry
was cast in the glass dish and twiddled. Films of α-TCP
with PVA were dried at room temperature for 12 h. In
order to control the thickness of ﬁlms, rotation speed of
the turntable was controlled. After heating at 1200
5 min in air, the samples were set in a 105 cm
clave with 30 cm
of pure water, and then they were
exposed to vapor of the pure water at the temperatures
from 105 to 200
C under the saturated vapor pressure for
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