The paper describes perspective technology for deposition of inorganic-organic coatings used for biomedical
application. Synthetic hydroxyapatite was used as inorganic compound, due to the similarity of the
main component to bone tissue. As organic components we used chitosan and alginate – natural biopolymers,
which widely used for bioactive and biocompatible composites formation. Thermal substrate method
used for coatings deposition based on principle of decreasing solubility of hydroxyapatite with increasing of
substrate temperature and allow to deposit coatings at substrate temperatures below 100 °C. Porous composite
hydroxyapatite-chitosan and hydroxyapatite-alginate coatings were obtained on Ti-6Al-4V substrates.
Morphology, phase composition and adhesion to the substrate surface were investigated.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3529

Kuznetsov, V.M.

Stanislavov, O.S.

Sukhodub, Leonid Fedorovych

Yanovska, G.O.

Суходуб, Леонид Федорович

Суходуб, Леонід Федорович

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 2, 02FNC09(2pp) (2013) 
 
 
2304-1862/2013/2(2)02FNC09(2) 02FNC09-1  2013 Sumy State University 
Functional Coatings Based on Hydroxyapatite and Polymers  
Formed on Ti-6Al-4V Substrates 
 
G.O. Yanovska1,* V.M. Kuznetsov1,, O.S. Stanislavov1, L.F. Sukhodub2,† 
 
1 Institute of Applied Physics, 58, Petropavlovskaya Str., 40000 Sumy, Ukraine  
2 Sumy State University, 2, Rymsky Korsakov Str., 40007 Sumy, Ukraine 
 
(Received 20 May 2013; published online 31 August 2013) 
 
The paper describes perspective technology for deposition of inorganic-organic coatings used for bio-
medical application. Synthetic hydroxyapatite was used as inorganic compound, due to the similarity of the 
main component to bone tissue. As organic components we used chitosan and alginate – natural biopoly-
mers, which widely used for bioactive and biocompatible composites formation. Thermal substrate method 
used for coatings deposition based on principle of decreasing solubility of hydroxyapatite with increasing of 
substrate temperature and allow to deposit coatings at substrate temperatures below 100 C. Porous com-
posite hydroxyapatite-chitosan and hydroxyapatite-alginate coatings were obtained on Ti-6Al-4V sub-
strates. Morphology, phase composition and adhesion to the substrate surface were investigated.   
 
Keywords: Hydroxyapatite, Chitosan, Alginate, Thermal substrate method, Composite coatings. 
 
 PACS numbers: 82.45.Qr, 61.43.Gt 
 
 
                                               
* biophy@yandex.ru 
† l_sukhodub@yahoo.com 
1. INTRODUCTION 
 
Metal ion release and bacterial infection of medical 
implants lead to inflammatory effects and infections in 
bone-implant interface in the physiological environ-
ment. That’s why the application of bioactive coatings 
is very promising way to solve this problem. Polymeric 
materials are widely used in the field of medical im-
plantology, due to their similarity to the physical-
chemical properties of the living tissues which are 
mainly composed of biopolymers. 
Chitosan (CS) and hydroxyapatite (HA) are among 
the best bioactive biomaterials in bone tissue engineer-
ing due to their excellent biocompatibility in the physi-
ological environment [1]. Hydroxyapatite, 
Ca10(PO4)6(OH)2, is widely used in dentistry and ortho-
pedics. It is one of the most thermodynamically stable 
forms of calcium phosphate which occurs in the bone as 
a major component (60 to 65 %) [2]. Chitosan is an al-
ternative polymer using in orthopedic applications due 
to its good biocompatibility, biodegradability, porous 
structure, suitability for cell growth, osteoconduction 
and intrinsic antibacterial nature [3-5]. Chitosan is an 
N-deacetylation product of chitin. It is a copolymer con-
sisting of -(1 → 4)-2-acetamido-d-glucose and -
(1 → 4)-2-amino-D-glucose unit linkages [6]. 
Alginates – are the monovalent salts formed of  
alginic acid is a linear block copolymer composed of β-
D-mannuronate (M-block) and -L-guluronate  
(G-block) linked by 1,4-glycoside linkage. [7] The  
G-block of alginate has correspondingly high affinities 
for divalent ions such as calcium (Ca2 +) at room tem-
perature and thus in an aqueous solution of divalent 
ions, the alginate chains are rapidly cross-linked via 
the stacking of G-blocks to form gel [7].  
In our work, nano-composite coatings consist of hy-
droxyapatite, chitosan and alginate were deposited by 
wet synthesis from aqueous solutions using thermal 
substrate method that allows obtaining coatings at 
temperatures below 100 C which are favorable for final 
biomedical application. 
 
2. MATERIALS AND METHODS 
 
2.1 Materials 
 
Ti-6Al-4V specimens, 36  1.9  0.36 mm in size, 
were used as substrates for CS-HA coatings deposition. 
They were first polished with sandpaper than washed in 
acetone (15 min) and 96 % ethanol (15 min) and in the 
end three times rinsed with distilled water under ultra-
sound. Biomedical grade chitosan (200 kDa molecular 
weight) was supplied by the Haidebei Marine Bio Ltd. 
(Jinan, China) with 9 % degree of the deacetylation. So-
lutions with various chitosan concentrations were pre-
pared by dissolving the 1 g of chitosan fibers in 1 liter of 
1 % CH3COOH solution with vigorous stirring. Chitosan 
solution with concentration of 1 g/l was diluted to the 
required CS concentrations: 0.001; 0.025; 0.05; 0.1 g/l by 
mixing with the initial solution for HA synthesis which 
contains CaCl2 (10 mmol/dm3) and NaH2PO4 
(6 mmol/dm3). Sodium alginate with concentrations from 
0.001 to 0.1 g/l was used for HA-alginate composite coat-
ings formation. 
 
2.2 Methods  
 
The thermal substrate method for obtaining HA 
coatings based on the main principle that the solubility 
of HA in aqueous solution decreases with increasing 
substrate temperature [2]. 
Microstructure characterization and morphology 
analysis on the composite coatings were conducted using 
scanning electron microscopy (SEM), X-ray diffractome-
try (XRD), adhesion testing were studied by “tape-test 
method”. 
 G.O. YANOVSKA, V.M. KUZNETSOV, O.S. STANISLAVOV, L.F. SUKHODUB PROC. NAP 2, 02FNC09 (2013) 
 
 
02FNC09-2 
Chitosan and alginate were inserted into hydroxyap-
atite coatings by the co-deposition onto titanium sub-
trate from aqueous solutions having chitosan (alginate) 
concentrations of 0.001, 0.025, 0.05, 0.1 g/l under follow-
ing conditions: substrate temperature 80-100 ºC, pH of 
the initial solution 6.5-6.8, time of deposition 180 min. 
 
3. RESULTS AND DISCUSSION  
 
Simultaneously, the following reaction of hydroxy-
apatite formation takes place on the substrate surface: 
 
 
   
2 + –  –
2 4 
10 4 26 2
10Ca  + 6H PO  + 14OH
 Ca PO OH  + 12H O
 (3.1) 
 
The variation in coatings morphology is observed 
depending on the initial CS concentration in the solu-
tion (Fig. 1).  
 
 
 
Fig. 1 – Morphology of the HA-CS coatings co-deposited by 
TSM method from aqueous solutions having chitosan concen-
trations of 0.1 g/l (a), 0.05 g/l (b), 0.025 g/l (c), 0.001 g/l (d) 
 
For coatings obtained from solutions having CS 
concentrations of 0.001 and 0.025 g/l a homogeneous 
surface morphology is observed. The intensities of HA 
peaks are significantly higher for coatings having lower 
chitosan concentrations (Fig. 2) which can be explained 
by higher HA crystallinity.  
 
 
 
Fig. 2 – X-ray diffraction patterns of HA-CS coatings obtained 
by TSM from aqueous solutions with chitosan concentrations 
of 0.1 g/l (a), 0.05 g/l (b), 0.025 g/l (c), 0.001 g/l (d)  
When chitosan is dissolved in acetic acid its ami-
no groups are protonated (CS−NH3+) and bonds 
with carboxyl groups (CH3COO −) presented in solu-
tion. If other ions Ca2+, HPO4 − are also presented in 
the initial solution some positively charged complex-
es for example CH3COO− −Ca2+ and HPO4− −Ca2+ 
can be formed in the solution. Such complexes can 
absorb negatively charged PO43 − with following 
crystal growth of HA. The presence of Ca2+ ions in 
the initial solution leads to chemical interaction be-
tween the calcium ions on HA surface and the amino 
groups in a chitosan molecule. In general, chitosan 
forms a chitosan-metal complex in which the metal 
ion coordinates the amino group in chitosan mole-
cules. We suggest that small HA crystallites are able 
to align along the chitosan molecule upon aggrega-
tion through the interaction between the Ca2+ ions 
on the HA surface and the amino groups of the chi-
tosan molecule. In other words, the c-axes of HA 
nano-crystals are parallel to the chitosan molecules 
due to formation of complexes of Ca2+ and amino 
groups of chitosan, which are the nucleation centers 
for HA crystals. 
It has been observed that in preparing HA/alginate 
composites, Ca2+ ions present on the hydroxyapatite 
surface cross-link the alginate chains to produce a ma-
terial with various morphology and adhesion to the 
substrate surface, both functions of the HA/alginate 
weight ratio. In vitro tests were performed on different 
samples in terms of both the HA/alginate ratio and 
synthesis temperature. 
The results of adhesion testing by “tape-test” meth-
od show that HA-polymer coatings adhesion strength is 
greater than for simple HA coatings.   
 
4. CONCLUSIONS 
 
Composite coatings based on hydroxyapatite and 
natural polymers (chitosan and alginate) were deposited 
by thermal substrate method from aqueous solutions. 
The organic components affect the formation of HA coat-
ings with various surface morphology depending on pol-
ymer concentration in the initial solution. Adhesion 
strength for polymer-HA coatings is also increased. 
Following incorporation of antibiotics and antibacte-
rial components into the matrix of CS or alginate can 
promote cell proliferation, faster and more efficient min-
eralization and bone formation.  
 
 
 
REFERENCES 
 
1. M. Wang, Biomaterials 24 (2003). 
2. J.C. Elliott, Structure and Chemistry of the Apatites and 
Other Calcium Orthophosphates (Elsevier: London: 1994). 
3. P.J. Vande Vord, H.W.T. Matthew, S.P. Desilva, 
L. Mayton, B. Wu, P.H. Wooley, J. Biomed. Mater. Res. 59 
(2002). 
4. K. Eugene, Y.L. Lee, Biomaterials 24 (2003).  
5. A. Di Martino, M. Sittinger, M.V. Risbud, Biomaterials 26 
(2005). 
6. J. Je, S. Kim, Bioorg. Med.  Chem. 13 (2005). 
7. A. Tampieri, et al., Acta Biomaterialia 1 (2005). 
 
d c b a 


Functional Coatings Based on Hydroxyapatite and Polymers Formed on Ti-6Al-4V Substrates

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 2, 02FNC09(2pp) (2013)   2304-1862/2013/2(2)02FNC09(2) 02FNC09-1  2013 Sumy State University Functional Coatings Based on Hydroxyapatite and Polymers  Formed on Ti-6Al-4V Substrates  G.O. Yanovska1,* V.M. Kuznetsov1,, O.S. Stanislavov1, L.F. Sukhodub2,†  1 Institute of Applied Physics, 58, Petropavlovskaya Str., 40000 Sumy, Ukraine  2 Sumy State University, 2, Rymsky Korsakov Str., 40007 Sumy, Ukraine  (Received 20 May 2013; published online 31 August 2013)  The paper describes perspective technology for deposition of inorganic-organic coatings used for bio-medical application. Synthetic hydroxyapatite was used as inorganic compound, due to the similarity of the main component to bone tissue. As organic components we used chitosan and alginate – natural biopoly-mers, which widely used for bioactive and biocompatible composites formation. Thermal substrate method used for coatings deposition based on principle of decreasing solubility of hydroxyapatite with increasing of substrate temperature and allow to deposit coatings at substrate temperatures below 100 C. Porous com-posite hydroxyapatite-chitosan and hydroxyapatite-alginate coatings were obtained on Ti-6Al-4V sub-strates. Morphology, phase composition and adhesion to the substrate surface were investigated.    Keywords: Hydroxyapatite, Chitosan, Alginate, Thermal substrate method, Composite coatings.   PACS numbers: 82.45.Qr, 61.43.Gt                                                  * biophy@yandex.ru † l_sukhodub@yahoo.com 1. INTRODUCTION  Metal ion release and bacterial infection of medical implants lead to inflammatory effects and infections in bone-implant interface in the physiological environ-ment. That’s why the application of bioactive coatings is very promising way to solve this problem. Polymeric materials are widely used in the ﬁeld of medical im-plantology, due to their similarity to the physical-chemical properties of the living tissues which are mainly composed of biopolymers. Chitosan (CS) and hydroxyapatite (HA) are among the best bioactive biomaterials in bone tissue engineer-ing due to their excellent biocompatibility in the physi-ological environment [1]. Hydroxyapatite, Ca10(PO4)6(OH)2, is widely used in dentistry and ortho-pedics. It is one of the most thermodynamically stable forms of calcium phosphate which occurs in the bone as a major component (60 to 65 %) [2]. Chitosan is an al-ternative polymer using in orthopedic applications due to its good biocompatibility, biodegradability, porous structure, suitability for cell growth, osteoconduction and intrinsic antibacterial nature [3-5]. Chitosan is an N-deacetylation product of chitin. It is a copolymer con-sisting of -(1 → 4)-2-acetamido-d-glucose and -(1 → 4)-2-amino-D-glucose unit linkages [6]. Alginates – are the monovalent salts formed of  alginic acid is a linear block copolymer composed of β-D-mannuronate (M-block) and -L-guluronate  (G-block) linked by 1,4-glycoside linkage. [7] The  G-block of alginate has correspondingly high affinities for divalent ions such as calcium (Ca2 +) at room tem-perature and thus in an aqueous solution of divalent ions, the alginate chains are rapidly cross-linked via the stacking of G-blocks to form gel [7].  In our work, nano-composite coatings consist of hy-droxyapatite, chitosan and alginate were deposited by wet synthesis from aqueous solutions using thermal substrate method that allows obtaining coatings at temperatures below 100 C which are favorable for final biomedical application.  2. MATERIALS AND METHODS  2.1 Materials  Ti-6Al-4V specimens, 36  1.9  0.36 mm in size, were used as substrates for CS-HA coatings deposition. They were first polished with sandpaper than washed in acetone (15 min) and 96 % ethanol (15 min) and in the end three times rinsed with distilled water under ultra-sound. Biomedical grade chitosan (200 kDa molecular weight) was supplied by the Haidebei Marine Bio Ltd. (Jinan, China) with 9 % degree of the deacetylation. So-lutions with various chitosan concentrations were pre-pared by dissolving the 1 g of chitosan fibers in 1 liter of 1 % CH3COOH solution with vigorous stirring. Chitosan solution with concentration of 1 g/l was diluted to the required CS concentrations: 0.001; 0.025; 0.05; 0.1 g/l by mixing with the initial solution for HA synthesis which contains CaCl2 (10 mmol/dm3) and NaH2PO4 (6 mmol/dm3). Sodium alginate with concentrations from 0.001 to 0.1 g/l was used for HA-alginate composite coat-ings formation.  2.2 Methods   The thermal substrate method for obtaining HA coatings based on the main principle that the solubility of HA in aqueous solution decreases with increasing substrate temperature [2]. Microstructure characterization and morphology analysis on the composite coatings were conducted using scanning electron microscopy (SEM), X-ray diffractome-try (XRD), adhesion testing were studied by “tape-test method”.  G.O. YANOVSKA, V.M. KUZNETSOV, O.S. STANISLAVOV, L.F. SUKHODUB PROC. NAP 2, 02FNC09 (2013)   02FNC09-2 Chitosan and alginate were inserted into hydroxyap-atite coatings by the co-deposition onto titanium sub-trate from aqueous solutions having chitosan (alginate) concentrations of 0.001, 0.025, 0.05, 0.1 g/l under follow-ing conditions: substrate temperature 80-100 ºC, pH of the initial solution 6.5-6.8, time of deposition 180 min.  3. RESULTS AND DISCUSSION   Simultaneously, the following reaction of hydroxy-apatite formation takes place on the substrate surface:      2 + –  –2 4 10 4 26 210Ca  + 6H PO  + 14OH Ca PO OH  + 12H O (3.1)  The variation in coatings morphology is observed depending on the initial CS concentration in the solu-tion (Fig. 1).     Fig. 1 – Morphology of the HA-CS coatings co-deposited by TSM method from aqueous solutions having chitosan concen-trations of 0.1 g/l (a), 0.05 g/l (b), 0.025 g/l (c), 0.001 g/l (d)  For coatings obtained from solutions having CS concentrations of 0.001 and 0.025 g/l a homogeneous surface morphology is observed. The intensities of HA peaks are significantly higher for coatings having lower chitosan concentrations (Fig. 2) which can be explained by higher HA crystallinity.     Fig. 2 – X-ray diffraction patterns of HA-CS coatings obtained by TSM from aqueous solutions with chitosan concentrations of 0.1 g/l (a), 0.05 g/l (b), 0.025 g/l (c), 0.001 g/l (d)  When chitosan is dissolved in acetic acid its ami-no groups are protonated (CS−NH3+) and bonds with carboxyl groups (CH3COO −) presented in solu-tion. If other ions Ca2+, HPO4 − are also presented in the initial solution some positively charged complex-es for example CH3COO− −Ca2+ and HPO4− −Ca2+ can be formed in the solution. Such complexes can absorb negatively charged PO43 − with following crystal growth of HA. The presence of Ca2+ ions in the initial solution leads to chemical interaction be-tween the calcium ions on HA surface and the amino groups in a chitosan molecule. In general, chitosan forms a chitosan-metal complex in which the metal ion coordinates the amino group in chitosan mole-cules. We suggest that small HA crystallites are able to align along the chitosan molecule upon aggrega-tion through the interaction between the Ca2+ ions on the HA surface and the amino groups of the chi-tosan molecule. In other words, the c-axes of HA nano-crystals are parallel to the chitosan molecules due to formation of complexes of Ca2+ and amino groups of chitosan, which are the nucleation centers for HA crystals. It has been observed that in preparing HA/alginate composites, Ca2+ ions present on the hydroxyapatite surface cross-link the alginate chains to produce a ma-terial with various morphology and adhesion to the substrate surface, both functions of the HA/alginate weight ratio. In vitro tests were performed on different samples in terms of both the HA/alginate ratio and synthesis temperature. The results of adhesion testing by “tape-test” meth-od show that HA-polymer coatings adhesion strength is greater than for simple HA coatings.    4. CONCLUSIONS  Composite coatings based on hydroxyapatite and natural polymers (chitosan and alginate) were deposited by thermal substrate method from aqueous solutions. The organic components affect the formation of HA coat-ings with various surface morphology depending on pol-ymer concentration in the initial solution. Adhesion strength for polymer-HA coatings is also increased. Following incorporation of antibiotics and antibacte-rial components into the matrix of CS or alginate can promote cell proliferation, faster and more efficient min-eralization and bone formation.     REFERENCES  1. M. Wang, Biomaterials 24 (2003). 2. J.C. Elliott, Structure and Chemistry of the Apatites and Other Calcium Orthophosphates (Elsevier: London: 1994). 3. P.J. Vande Vord, H.W.T. Matthew, S.P. Desilva, L. Mayton, B. Wu, P.H. Wooley, J. Biomed. Mater. Res. 59 (2002). 4. K. Eugene, Y.L. Lee, Biomaterials 24 (2003).  5. A. Di Martino, M. Sittinger, M.V. Risbud, Biomaterials 26 (2005). 6. J. Je, S. Kim, Bioorg. Med.  Chem. 13 (2005). 7. A. Tampieri, et al., Acta Biomaterialia 1 (2005).  d c b a 

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Functional Coatings Based on Hydroxyapatite and Polymers Formed on Ti-6Al-4V Substrates

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