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This article can be downloaded from http://www.ijerst.com/currentissue.php
Int. J. Engg. Res. & Sci. & Tech. 2014 A Ragu et al., 2014
SYNTHESIS AND CHARACTERIZATION OF NANOHYDROXYAPATITE WITH POLY VINYL ACETATE
NANOCOMPOSITE FOR BONE TISSUEENGINEERING
A Ragu1*, K Senthilarasan1 and P Sakthivel1
Synthetic hydroxyapatite (HAp) nano particle were synthesized by a wet chemical precipitationtechnique using calcium hydroxide and ammonium dihydrogen phosphate at room temperaturecondition. Nano hydroxyapatite (nHAp) materials consisting of biocompatible polymers havebeen widely used in orthopedic, dental, hard human tissue and nano filler applications. Syntheticbone graft substitute based on polymer have been largely studied during the past decade. In thiswork, hydroxyapatite (HAp)/Poly vinyl acetate (PVAc) nano composite were synthesized andcharacterized physical-chemically by X-ray diffraction (XRD), Fourier Transform Infraredspectroscopy (FTIR), Transmission Electron Microscopy (TEM), Energy Dispersive Analysis ofX-rays techniques (EDAX) and Micro Hardness test.
Keywords: XRD, FT-IR, TEM, EDAX, Hardness
*Corresponding Author: A Ragu [email protected]
INTRODUCTIONIn this paper, Hydroxyapatite (HAp) has received
considerable attention as a bone substitute due
to its similar biocompatibility, bioactivity,
osteoconductivity and tunable degradability to
bone (Legeros, 1991). The use of bioactive filler
such as hydroxyapatite (HAp), ceramic or
bioglass particle to reinforce a polymer may
improve both the mechanical properties and the
bone bonding properties (LIU, 1997). Bone is an
active, hard and strong living tissue that not only
supports and protects our internal organs, but is
1 Research Scholar, Department of Physics, Urumu Dhanalakshmi College, Kattur, Tiruchirappalli, India.
Int. J. Engg. Res. & Sci. & Tech. 2014
ISSN 2319-5991 www.ijerst.comVol. 3, No. 4, November 2014
© 2014 IJERST. All Rights Reserved
Research Paper
also essential for however; it is susceptible to
fracture as results of traumatic or non-traumatic
events (Turner, 2002). When there is a change in
external stimuli (or) stress, the bone either
remodels itself to sustain such forces or it
fractures ‘breaks’ when the energy from the
impact exceeds the energy the bone can absorb
(Turner, 2002). The conventional treatment for
fracture healing involves immobilization of the
bone/ joint with a cast, brace, split or a sling, while
the bone repair itself to resolve the fracture.
Bone tissue engineering aims to restore
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Int. J. Engg. Res. & Sci. & Tech. 2014 A Ragu et al., 2014
skeleton function in the field of orthopedic and
oral maxillofacial surgery, augmentation of
fracture healing, and reconstruction of bone
defects resulting from ageing, osteoporosis,
trauma tumor, infections, biochemical disorder,
or abnormal skeletal development. It facilitates
the repair and remodeling of bone tissue biological
and synthetic substitutes to restore regenerate
and improve bone function ((Bock A K et al., 2003;
Meijer et al., 2007). Bone graft are the second
most common transplantation tissue, where
more than 2.2 million bone grafting procedures
occur worldwide to repair bone defect worldwide
(Giannoudis et al., 2005). Current therapies in
bone tissue engineering, classified as naturally
or synthetically derived biocompatible bone graft,
have drawbacks which limit their potential use.
Natural bone grafts are used for autologous and
allologous transplants, while synthetic bone
grafts, such as permanent artificial bone
substitute, are fabricated with biocompatible
materials. Bone consists of two major structural
components: cortical bone and cancellous bone.
Cortical bone forms the hard, outer, compact layer
of the bone while the cancellous bone form an
inner, porous network containing bone marrow
(Seeley et al., 2005).
Poly Vinyl Acetate (PVAc) is one of the most
widely used biodegradable polymers in synthetic
bone tissue scaffolds. Poly Vinyl acetate (PVAc),
a biocompatible and biodegradable (owing to the
hydrolyzable groups in the side chain) polymer,
has also been used in biomedical applications,
including drug, cell carriers and tissue engineering
(Silvalingam, 2003; Novoa et al., 2005). The
polymers commonly used in these applications
are poly(glycolic acid), poly(lactic acid) (PLA) and
their copolymer poly(lactide-co-glycoide),
polydioxanone, poly(ethylene oxide) and
poly(trimethylene carbonate) (James et al., 2011;
Pielchowska et al., 2010). In addition, poly(€-
caprolactoone) (PCL), polyanhydrides, poly (vinyl
alcohol) (PVA) and polyurethane have also been
investigated for bone regeneration (Pielchowska
et al., 2010). However, out of these polymers,
PLA, poly(glycolic acid) and poly(lactide-co-
glycoide) have received the highest interest
because the architectures and properties of these
polymers can be easily controlled. Various
materials of biological and synthetic origins, such
as metals, ceramic and polymers have been
used for bone tissue regeneration. Moreover, it’s
known that natural polymers including properties
such as collagen and alginate, chitosan are also
attractive, since they exhibit superior
biocompatibility and can facilities cell growth.
Several reports have indicated blood compatibility
of PVAc. PVAc has also been applied in many
medical fields because of its biocompatibility.
MATERIALS AND METHODS
Chemicals
All chemicals used were of analytical grade.
Calcium hydroxide Ca(OH)2 (99%), Ammonium
dihydrogen phosphate (NH4) H2PO4 (99%) and
Poly vinyl acetate (mol.wt 190.000) were procured
from Sigma Aldrich. Deionized water, ethanol,
toluene were used as the solvent.
Methods
Preparation of nHAp
Nano hydroxyapatite powder was synthesized
by wet chemical precipitation method through
microwave accelerated in room temperature
condition. Calcium hydroxide solution was
dissolved in 100 mL volume of an ethanol-water
mixture (50:50%, v/v) and was stirred for 3 h. A
solution of Ammonium dihydrogen phosphate was
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Int. J. Engg. Res. & Sci. & Tech. 2014 A Ragu et al., 2014
(b)
dissolved in 100ml volume of water and then
added to the Ca (OH)2 solution over a period of
24 h. The amount of reagents in the solution was
calculated to obtain a Ca/P molar ratio value equal
1.67, corresponding to a stoichiometric HAp. The
PH of the slurry was measured digitally during
the precipitation reaction, reaction a final value of
PH11.
Synthesis of nHAp/PVAc
The nHAp powder was prepared by wet chemical
precipitation method in an aqueous medium. At
first the PVAc was dissolved in toluene, and then
nHAp was added slowly with help of magnetic
stirrer. After addition of the entire nHAp powder to
the polymer solution, the milky white coloration
was observed almost instantaneously. The
solution was dried using micro wave exposure at
900C.
RESULTS AND DISCUSSION
XRD
The XRD patterns of nHAp/PVAc nano
composites were taken. The pattern indicates the
presence of amorphous nHAp. The broad peaks
reveal that the particles size is very small in the
range 5 nm to 9 nm. The reflection planes
corresponding to the characteristic XRD spectral
peaks of pure nano HAp and PVAc nano
composites as shown in Figure 1. The observed
diffraction peaks are identified by standard
JCPDS file no. 09-0432 and are arranged as
crystalline nHAp. The main (h k l) indices for
nanometer sized HAp: (211),(300), and (200) are
indicated in Figure 1. The crystalline size, t(hkl), of
the synthesized nano HAp powder is calculated
using the Debye-Scherrer equation.
)(
9.0)( hklBCOS
t hkl
Figure 1: XRD Pattern of nHAp /PVAc
10 20 30 40 50 60 70 80 90
0
50
100
150
200
250
300
350
Inte
nsi
ty (
a.u
)
( 2 Theta )
HAp-PVAc
( 1
1 0
)
( 2
2 0
)(
1 0
2)
( 2
1 1
)(
3 0
0 )
( 2
0 0
)
( 2
2 2
)(
1 3
0 )
( 3
2 1
)(
1 0
4 )
( 5
0 2
)(
3 0
4 )
( 4
3 1
)(
4 0
4 )
where, is the wavelength of the monochromatic
X-ray beam, B is the Full Width at Half Maximum
(FWHM) intensity, (hkl) is the peak diffraction angle
that satisfies Bragg's law for the (hkl) plane and
t(hkl) is the crystalline size. The XRD patterns show
diffraction peaks with high intensities, which
confirm the nano size with crystalline nature.
FTIR
The FTIR spectrums of pure HAp/PVAc
nanocomposites are shown in Figure 2. The FTIR
spectrum investigation was carried out using
PERKIN ELEMER spectrometer in the range of
400 cm-1 to 4000 cm-1. The functional groups were
identified using peak assignments. A absorption
at 3642.47 cm-1 and 3416.17 cm-1 indicates the
presence of alcohol O-H group. The strong band
at 2934.18 cm-1 was assigned the C-H stretching
in alkane. The frequency at 1741.02 cm-1 shows
stretching of aliphatic carbonyl group. The
medium peak appeared at 1435.08 cm-1 indicates
the presences of C-C stretching of aromatic
group. A strong peak at 1246.08 cm-1 exhibits the
C-O stretching of aliphatic group. The presences
of strong peak at 1035.52 cm-1 indicate the
presence of C-O stretching of aliphatic amines.
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Int. J. Engg. Res. & Sci. & Tech. 2014 A Ragu et al., 2014
Figure 2: FTIR Spectrum of nHAp/PVAc
ACIC
St.Joseph's College ( Autonomous)
Trichy-2Spectrum Name: NHAP-PVAc.sp
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
0.0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100.0
cm-1
%T
3642.47
3416.17
2934.18
2472 .59
1741 .02
1561.96
1435.08
1377.12
1246.08
1035.52
949 .99
872 .20
797.57
606 .27568.58
469.75
The strong band at 949.99 cm-1 was assigned to
carboxylic acid group. The peak at 606.27 cm-1
indicates the presence of phosphate group in
nHAp.
TEM
The Transmission Electron Microscopy (TEM)
showed a nHAp/PVAc as shown in Figure 3 with
average grain size 5 nm to 9 nm. TEM microscopy
depicted the precipitation of hydroxyapatite
aggregates in porous poly vinyl acetate. TEM
studies showed a distribution of nanoHAp with self
assembled and aggregates of uniform sized. The
morphology due to the very f ine size of
precipitated particles present in the aggregates
could not be ascertained through selected area.
The different size of nano HAp particle with
homogeneous dispersion are well identified in
case of the nHAp/PVAc nanocomposite Figure 3
(a), (b) The particle size of nHAp is controlled by
the polymer (PVAc) in the composite as depicted
in the TEM image. The Selected Area Electron
Diffraction (SAED) Figure 3(c) results of nano HAp
and PVAc are good agreement with the lattice
structure of hydroxyapatite and exhibit excellent
crystallinity. In addition to this, there is almost no
Figure 3: (a), (b) TEM Image of nHAp/PVAc
Figure 3: (c) Selected Electron AreaDiffraction (SAED) of HAp/PVAc
Nano Composite
40
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Int. J. Engg. Res. & Sci. & Tech. 2014 A Ragu et al., 2014
agglomeration, which may be due to reduction of
surface energy.
EDAX
The Energy Dispersive Analysis of X-rays (EDAX)
of nHAp/PVAc is shown in Figure 4. The mineral
composition of Ca, O, P and organic content C
present in both nano composite are tested. The
EDAX results confirmed the existence of the
elements such as Ca, P and O Figure 4. The Ca/
P value of synthesized HAp with PVAc
nanocomposite to be 1.72 which is closer to the
Ca/P ratio of human bone (Trommer et al., 2007).
implanted HAp were used to measure the
hardness of bone by means of an indentation test
(Micro hardness MVHT; Wilson Wolpert-
Germany). Brief measurements of micro
hardness were made tangential to the interface
with a Vickers indenter applied to the bone at a
load of 50 g. For the load of 10 g, 25 g, 50 g and
100 g the harness number was in the range 20.1,
21.0, 35.0 and 16.9. The hardness of the
specimens used in this study increase with the
increasing test load and is comparable with other
having reported. The tendency of hardness of
materials decrease with the increasing test load
above 50 g.Figure 4: EDAX of HAp/PVAc Nano Composite
Micro Hardness Test
The micro hardness tests are used to determine
the resistance of a deformation. This test can be
performed on a macroscopic or microscopic
scale. The pellet indentation hardness correlates
linearly with tensile strength. With the controlled
test force, the specimen is pressed by using the
indenter with a dwell time of 10 to 15 s. Micro
hardness of pure nHAp/PVAc based composites
(HAp/PVAc-10 g to 100 g) is shown in Figure 5. A
maximum increasing of the peak value (35 HV
50 g) is observed for the composition. The same
blocks containing the residual part of the
Figure 5: Micro Hardness Test of nHAp/PVAc
CONCLUSIONPVAc is a synthetic polymer that has been used
for the past 30 years in several medical and
nonmedical devices Nano Hydroxyapatite has
been successfully synthesized using the wet
chemical precipitation techniques. This process
showed that high purity product of nano
hydroxyapatite powders could be obtained at room
temperature. Hydroxyapatite with polymer
nanocomposites offers a robust system to
engineer synthetic bone substitute for orthopedic
implant fixation, synthetic bone graft substitute
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Int. J. Engg. Res. & Sci. & Tech. 2014 A Ragu et al., 2014
and tissue because of their biocompatibility and
osteoconductivity properties. The formation of
hydroxyapatite nanoparticle was confirmed by X-
Ray Diffraction (XRD) and functional groups of
the compound are identif ied using Fourier
Transforms Infrared Spectroscopy (FTIR). The
elemental compositions were examined using
the EDAX analysis. The size and morphology of
the sample characterized using Transmission
Electron Microscopy (TEM) analysis confirms the
presence of HAp/PVAc nano particles with the
particle size of around 5 nm to 9 nm. Many aspects
of the composite structure can be tailored in order
to design for specific mechanical, biological and
surgical functions. Nano hydroxyapatite with
polymer will remain a fruitful and active area of
biomaterials research for the foreseeable future.
ACKNOWLEDGMENTThe management of Urumu Dhanalakshmi
College, Tiruchirappalli for providing research
facilities in the campus.
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