Summary of Doctoral thesis in Chemistry: Synthesis and characterization of trace elements co-doped Hydroxyapatite on 316L stainless steel application in bone implant

VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY
GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
-----------------------

Vo Thi Hanh

SYNTHESIS AND CHARACTERIZATION OF TRACE
ELEMENTS CO-DOPED HYDROXYAPATITE ON 316L
STAINLESS STEEL APPLICATION IN BONE IMPLANT

Major:
Code:

Theoretical and Physical Chemistry
62 440119

SUMMARY OF DOCTORAL THESIS IN CHEMISTRY

Hanoi – 2018


The thesis has been completed at:
Department of Corrosion and Protection of Metals - Institute for
Tropical Technology - Vietnam Academy of Science and Technology
Scientific Supervisors:
Assoc. Prof. Dr. Dinh Thi Mai Thanh, Institute for Tropical Technology Vietnam Academy of Science and Technology
Reviewer 1:

Reviewer 2:

Reviewer 3:

The thesis was defended at Evaluation Council held at Graduate
University of Science and Technology - Vietnam Academy of Science
and Technology
on
, 2018.

Thesis can be further referred at:
- The Library of Graduate University of Science and Technology.
- National Library of Vietnam.


INTRODUCTION
1. The necessary of the thesis
Nowadays, 316L stainless steel (316LSS), titanium and alloys of titanium
are widely used in orthopedic surgery with the purpose of splinting bone.
Materials made of titanium and titanium alloy have a good mechanical
properties and good biocompatibility but they have a high cost. Therefore, in
Vietnam, to reduce the cost of medical services, most of the splints are made of
316L stainless steel. However, 316L stainless steel could be corroded and
limited the ability of biological compatibility in the biological environment. To
improve these problems, 316LSS is generally coated biomaterials such as
hydroxyapatite (Ca10(PO4)6(OH)2, HAp).
HAp has chemical composition and biological activity similar to the
natural bone. HAp could stimulate the bonding between the host bone to
implant materials and make bone healing ability faster. Moreover, HAp also
protects for the metal surfaces against corrosion and prevents the release of
metal ions from the substrates into the environment.
However, pure HAp has been dissolved in the physiological environment
which may lead to the disintegration of the coatings and affects the implant

fixation. These disadvantages could deal with doping some trace elements in
the HAp structure by replacing Ca2+ ions with cations and substituting OHgroup with anions. In addition, the present of trace element such as magnesium,
sodium, strontium, fluorine, zinc … has also the role to stimulate the new bone
formation and provides minerals for bone cells to grow. Besides, the problem of
postoperative infection should be concerned. Thus, antibacterial elements such
as copper, silver and zinc are also being studied to incorporated into HAp.
Based on the reasons mentioned above, the research topic of thesis is
chosen as following: “Synthesis and characterizations of trace elements codoped hydroxyapatite coatings on 316L stainless steel application in bone
implaint”
2. The objectives of thesis:
- Trace elements (sodium, magnesium, strontium, fluorine, copper, silver and
zinc) doped NaHAp coatings are synthesized sucessfully on the 316LSS
substrates, separately and simultaneously.
- Research on the physical and chemical characteristics, cytotoxicity and
antibacterial ability, biological compatibility of the NaHAp coating doping
some trace elements separately and simultaneously.
3. Research contents of the thesis:
- Investigating and selecting of optimal conditions for the synthesis of NaHAp
coatings and NaHAp coatings doping magnesium, strontium and fluorine
separately and simultaneously by cathodic scanning potential method.
1


- Investigating and selecting of optimal conditions for the synthesis of NaHAp
coatings doping copper, siliver and zinc separately and simultaneously by
ion exchange method.
- The HAp coatings doping 7 elements simultaneously: Mg, Sr, F, Na, Cu, Ag,
Zn are studied to synthesize by the combination two methods:
electrodeposition and ion exchange.
- Studying on the biological activity of materials: 316LSS, NaHAp/316LSS,

MgSrFNaHAp/316LSS and HApđt/316LSS in simulated body fluid (SBF)
solution.
- Studying on the cytotoxicity ability of powder: NaHAp, MgSrFNaHAp.
- Studying on antibacterial ability of powder: NaHAp, MgSrFNaHAp,
AgNaHAp, CuNaHAp, ZnNaHAp và HApđt.
- Evaluation of the biological compatibility of materials: 316LSS,
NaHAp/316LSS, MgSrFNaHAp/316LSS on dog’s body.
CHAPTER 1. OVERVIEW OF HAp AND DOPED HAp
1.1. The properties and synthesized methods of HAp and doped HAp coatings
Some trace elements doped HAp coatings have more advantages than
pure HAp coatings, such as: decrease of the dissolution, increase of the
metabolism, antibacterial ability and compatibility.
HAp coatings is deposited on the substrates by many methods: plasma,
magnetron and electrodeposition … These methods have advantages and
disadvantages. The electrodeposition has an important technology because of
the advantages: the low temperature, easily controlling the coatings thickness,
the high purity, high bonding strength and low cost of the equipment.
Furthermore, it is easy to substitute some trace elements ions (Mg2+, Na+, K+,
Sr2+ and F- …) into HAp coatings by addiction M(NO3)n or NaX into the
electrolyte. Dope HAp is producted according to the chemical reaction:
(10-x)Ca2+ + 6PO43- + (2-y)OH- + xM2+ + yX-  Ca10-x M x(PO4)6(OH)2-yXy
1.2. In vitro and in vivo test of HAp
The compatibility of materials is studied by immersion them in SBF
solution and investigate the formation of apatite on the material surface.
Besides, the compatibility of materials is also studied by in vivio test on the
animal.
1.4. The application of HAp, doped HAp
HAp and doped HAp are used as:
- The medicine of calcium supplements: the composition of HAp contains
a lot of calcium and be absorbed directly without transformation.

- Material for implantation: repair of the teeth and bone defects.
1.5. The situation of HAp research in the country
2


Basic on the overview of HAp and doped HAp, it can be seen that there is
no published report about doped HAp coatings in our country; in the world, the
trace elements doped HAp coatings have been only synthesized separately.
Thus, in this doctoral thesis, some trace elements (sodium, magnesium,
strontium, fluorine, copper, silver and zinc) doped HAp coatings were
synthesized separately and simultaneously. The HAp obtained coatings have
many good properties, such as: decrease of the dissolution and increase of the
metabolism, antibacterial ability and compatibility for HAp coatings.
CHAPTER 2. EXPERIMENT AND RESEARCH METHODS
2.1. Synthesis of doped HAp
2.1.1. By the electrodeposition method (cathodic scanning potential)
2.1.1.1. Electrochemical cells
The electrodeposition was carried out in a three-electrode cell with
316LSS as the working electrode, platinum foil as the counter electrode and a
saturated calomel electrode (SCE) as the reference electrode.
2.1.1.2. Synthesis of NaHAp coatings
- NaHAp coatings were synthesized on the 316LSS by cathodic scanning
potential method in 80 mL solution containing Ca(NO3)2 3×10-2 M + NH4H2PO4
1.8×10-2 M and NaNO3 with different concentrations: 4.10-2 M (DNa1), 6.10-2
M (DNa2) và 8.10-2 M (DNa3).
- NaHAp coatings were synthesized under following conditions as
follows: the different scanning potential ranges: 0 to -1.5, 0 to -1.7, 0 to -1.9
and 0 to -2.1 V/SCE; reaction temperatures: 25, 35, 50, 60 and 70 oC; pH = 4.0,
4.5, 5.0 and 5.5; scanning time: 1, 3, 5, 7 and 10; scanning rate: 3, 4, 5, 6 and 7
mV/s.

2.1.1.3. Synthesis of Mg2+, Sr2+ or F- doped NaHAp coatings (ĐNaHAp)
ĐNaHAp were deposied at 50 oC in 80 mL solution containing at the Table
2.1 and under following conditions: the different scanning potential ranges: 0 to
-1.5, 0 to -1.7, 0 to -1.9 and 0 to -2.1 V/SCE; scanning time: 1, 3, 5, 7 and 10;
scanning rate: 3, 4, 5, 6 and 7 mV/s.
Table 2.1. Chemical composition of the electrolyte
ĐNaHAp
MgNaHAp

SrNaHAp

Notation
DMg1
DMg2
DMg3
DMg4
DSr1
DSr2

Chemical composition
DNa2+ Mg(NO3)2 1x10-4 M
DNa2+ Mg(NO3)2 5x10-4 M
DNa2+ Mg(NO3)2 1x10-3 M
DNa2+ Mg(NO3)2 5x10-3 M
DNa2 + Sr(NO3)2 1x10-5 M
DNa2 + Sr(NO3)2 5x10-5 M
3


FNaHAp

DSr3
DSr4
DF1
DF2
DF3

DNa2 + Sr(NO3)2 1x10-4 M
DNa2 + Sr(NO3)2 5x10-4 M
DNa2 + NaF 5x10-4 M
DNa2 + NaF 1x10-3 M
DNa2 + NaF 2x10-3 M

2.1.3.4. Synthesis of Mg2+, Sr2+ and F- co-doped NaHAp coatings (MgSrFNaHAp)
MgSrFNaHAp were synthesized in 80 mL solution containing at DNa2 +
NaF 2.10-3 M + Sr(NO3)2 5.10-5 M + Mg(NO3)2 1.10-3 M and under following
conditions as follows: the different scanning potential ranges: 0 to -1.5, 0 to 1.7, 0 to -1.9 and 0 to -2.1 V/SCE; reaction temperatures: 25, 35, 50, 60 and 70
o
C; scanning time: 3, 4, 5, 6, 7 and 10; scanning rate: 3, 4, 5, 6 and 7 mV/s.
2.1.2. By the ion exchange method
Preparing material of NaHAp/316LSS: NaHAp coatings were synthesized
on the 316LSS substrates by cathodic scanning potential method in the otimal
condiction: the scanning potential range of 0 to -1.7 V/SCE, the reaction
temperatures of 50 oC, the scanning time of 5 and the scanning rate of 5 mV/s
in 80 mL DNa2 solution.
2.1.2.1. Synthesis of Cu2+, Ag+ or Zn2+ doped NaHAp coatings
Material of NaHAp/316LSS with mass of 2.45x10-3 g was immersed in 4
mL M(NO3)n solutions with variable concentration showed on Table 2.2 and at
different time immersions: 0; 2.5; 5; 10; 20; 30; 60 and 80 minutes at room
temperature.

Table 2.2. The initial concentration of Mn+ (mol/L)
M(NO3)n
Concentration (mol/L)
Cu(NO3)2
0.005
0.01
0.02
0.05
0.1
AgNO3
0.0012 0.0022 0.005
0.01
Zn(NO3)2
0.01
0.05
0.1
0.15
2.1.2.2. Synthesis of Cu2+, Ag+ and Zn2+ co-doped NaHAp coatings
CuAgZnHAp coatings was synthesized by the way: immersion the
material of NaHAp/316LSS about 30 minutes at room temperature in 4 mL
solutions containing simultaneously: Cu(NO3)2 0.02 M + AgNO3 0.001 M +
Zn(NO3)2 0.05 M.
2.1.3. Synthesis of Mg2+, Sr2+, Na+, Cu2+, Ag+, Zn2+ and F- co-doped HAp
coatings (HApđt)
- Preparing material of MgSrFNaHAp/316LSS: MgSrFNaHAp coatings
were synthesized on the 316LSS substrates by cathodic scanning potential
method in the otimal condiction: the scanning potential range of 0 to -1.7
V/SCE; reaction temperatures of 50 oC; scanning time of 5; scanning rate of 5
4

mV/s in 80 mL the solution containing: DNa2 + NaF 2.10-3 M + Sr(NO3)2 5.10-5
M + Mg(NO3)2 1.10-3 M.
- HApđt coatings was synthesized by the way: immersion the material of
MgSrFNaHAp/316LSS about 30 minutes at room temperature in 4mL solutions
containing simultaneously: Cu(NO3)2 0.02 M + AgNO3 0.001 M + Zn(NO3)2
0.05 M.
2.2. Research method
2.2.1. Electrochemical method
Methods of scanning potential, potential applied, open circuit potential
and electrochemical impedance spectra which were carried out on AUTOLAB
equipment at Institute for tropical Technology.
2.2.2. Ion exchange method
Ion exchange was done by immersing the meterial of NaHAp/316LSS or
MgSrFNaHAp/316LSS in solution containing Mn+ with different concentrations.
2.2.3. Coatings characterization
The composition and structure of doped HAp obtained coatings were
analyzed by the method: IR, XRD, SEM, AFM, EDX (or AAS or ICP-MS),
UV-VIS.
Physical properties of the coatings was determined by: mass, thickness,
adhesion strength. The dissolution behavior of the coatings were studied by
measuring the concentration of Ca2+ dissolved from the coatings and iron
released from 316LSS substrates when the samples immersed into the 0.9 %
NaCl solution or SBF solution.
2.2.5. In vitro and in vivo Test
2.2.5.1. Invitro test in simulated body fluid (SBF) solutions
The in vitro tests in SBF solution investigated by the apatite formed
ability and the protection substrates ability of meterials and using the method:
open circuit potential (OCP), electrochemical impedance measurements at the
OCP and the polarized Tafel curves.

2.2.5.2. Cytotoxicity ability test
The safety and biocompatibility of NaHAp and MgSrFNaHAp powder
were tested on fibroblasts cells by two methods: the Trypan Blue and the MTT.
2.2.5.3. Antibacterial ability test
The antibacterial ability of NaHAp, MNaHAp, MgSrFNaHAp and
HApđt powder were tested on three strains: E.faecalis, E.coli, C.albicans và
P.aerugimosa by the disk diffusion agar method.
2.2.5.4. In vivo test
Healthy dogs are divided to 3 groups, each group of 6 dogs, which are
implanted with 3 splint made of: 316LSS, NaHAp/316LSS and
5


MgSrFNaHAp/316LSS by two methods: implantation the materials on the thigh
and on the femur. The material compatibility is evaluated by observation of the
situation the incision, the general images and the microscope images at transplant
location.
CHAPTER 3. RESULTS AND DISCUSSION

2

i (mA/cm )

3.1. Synthesis and characterization of doped HAp coatings
3.1.1. Electrodeposition of doped HAp coatings
3.1.1.1. NaHAp coatings
a. The cathodic polarization curve
The cathodic polarization curve of 316LSS substrates at the potential
range 0 ÷ -2.1 V/SCE are shown in Figure 3.1. With this potential range, there
are several electrochemical reactions, such as:

2H+ + 2e-  H2
(3.1)
O2 + 2H2O + 4e  4OH
(3.2)

3
H 2 PO4 + 2e  PO4 + H2
(3.3)

2
2 H2 PO4 + 2e  2 HPO4 + H2
(3.4)
2 HPO24 + 2e- 2 PO34 + H2
(3.5)


NO3 + 2H2O + 2e  NO2 + 2OH
(3.6)
2H2O + 2e  H2 + 2OH
(3.7)

2
H 2 PO4 + OH  HPO4 + H2O
(3.8)
HPO24 + OH-  PO34 + H2O
(3.9)
3
2+
+
−

10(Ca , Na ) + 6 PO4 + 2OH → (Ca, Na)10(PO4)6(OH)2
(3.10)
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
-5.0
-5.5
-6.0
-2.2 -2.0 -1.8 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0

E (V/SCE)

Figure 3.1. The cathodic polarization curve of 316LSS substrates in the
DNa2 solution
b. Effect of Na+ concentration
The ratio of (Ca+0.5Na+Mg)/P in all obtained coatings samples at DNa1,
DNa2 and DNa3 solutions is the same the ratio of Ca/P in the natural bone
(1.67) (Table 3.1). However, to reach the Na/Ca ratio similar to its in natural
bone, the deposited NaHAp coatings in the DNa1 and DNa2 solution are
suitable. Therefore, DNa2 was chosen for the next experiments.
6

Table 3.1. The component of elements of NaHAp deposited on 316L SS in
DNa1, DNa2 and DNa3 solutions
Weigh (%)
DD
Na / Ca
(0.5 Na+ Ca)/ P
P
Ca
Na
DNa1 17.25
36.09
0.32
0.0155
1.63
DNa2 16.80
33.20
1.50
0.0785
1.61
DNa3 16.60
33.09
2.20
0.1156
1.58
3-

PO4

2-

CO3

3

3500

447
603

Intensity

PO4

874

1384

2

1
11
1

1

1

1

1

1

1

566

NaHAp

HAp (NIST)

1036
4000

(a)

2

3-

OH

1641

H2O
3441

Tranmistance (a.u)

-

CO3

2-

1. HAp; 2. CrO.FeO.NiO; 3. Fe

3000

2500

2000

1500

1000

500

10

-1

Wave number (cm )

20

30

40

50

60

70

degree

Figure 3.2. IR spectra and XRD patterns of NaHAp deposited in DNa2
solution
Both IR spectra and XRD patterns of NaHAp deposited in DNa2 solution
exhibit that NaHAp coatings have crystals structure and single phase of HAp
(Figure 3.2).
c. Effect of the scanning potential range
The charge, mass, thickness and adhesion strength of NaHAp coatings at
the different potential ranges show that the thickness and adhesion strength of
NaHAp coatings reaches the maximum value at potential range of 0 ÷ -1.7
V/SCE (Table 3.2). Thus, the potential range 0 to -1.7 V/SCE is chosen for
NaHAp coatings electrodeposition.
Table 3.2. The variation of charge, mass, thickness and adhesion strength
of obtained NaHAp coatings at the different scanning potential ranges
Scanning potential ranges Charge
Mass
Thickness Adhesion
2
(V/SCE)
(C)
(mg/cm )
(µm)

(MPa)
0 ÷ -1.5
0.41
1.00
3.2
0 ÷ -1.7
3.23
2.45
7.8
7.2
0 ÷ -1.9
4.29
1.82
5.8
7.1
0 ÷ -2.1
6.57
1.67
5.3
7.0
d. Effect of electrodeposition temperature
The SEM images of NaHAp coatings deposited in DNa2 at different
temperatures show that the temperature have an effected on the morphology of
obtained coatings.
The XRD diffraction data of NaHAp coatings at the different temperatures
are shown in Figure 3.4. The typical peaks of the 316LSS substrates were
7


observed in all samples. At 25 and 35 oC, the obtained coatings is mostly

dicalcium phosphate dehydrate (CaHPO4.2H2O, DCPD) with the typical peaks
at 2 12o and 24o. With temperature from 50°C, the peaks of DCPD are not
detected and there are only characteristic peaks of HAp phase at 2  26o (002),
32o (211), 33o (300), 46o (222) and 54o (004). Thus, 50 oC is chosen to prepare
NaHAp coatings.

Figure 3.3. The SEM images of deposited NaHAp coatings at different
temperatures
34

1. HAp; 2. DCPD
3. CrO.FeO.NiO; 4. Fe
1

3
1

1
1

Intensity

1

0

60 C

0

50 C
2
0

35 C

0

25 C

2

10

20

30

40

50

60

70

degree

Figure 3.4. XRD patterns of NaHAp deposited at different temperatures
e. Effect of pH

Results of mass and thickness of NaHAp coatings with pH solusions from
4.0 to 5.5 show on table 3.3. The results indicate that their values reaches the
highest value at pH0=4.5. Thus, pH0 is chosen for NaHAp coatings
electrodeposition.
Table 3.3. The variation of mass and thickness of obtained NaHAp coatings at
pH solutions difference
pH
4.0
4.5
5.0
5.5
2
Mass of NaHAp coatings (mg/cm )
2.05
2.43
1.54
1.31
Thickness of NaHAp coatings (µm)
6.55
7.80
4.92
4.19
g. Effect of the scanning times
The charge, mass, thickness and adhesion strength of NaHAp coatings at
the different scanning times show that the thickness and adhesion strength of
NaHAp coatings are highest at 5 scanning times (Table 3.4).
Table 3.4. The variation of charge, mass, thickness and adhesion strength
of obtained NaHAp coatings at the different scanning times
Scanning times
(times)

Charge
(C)

Mass
(mg/cm2)
8

Thickness
(µm)

Adhesion
(MPa)


1
3
5
7
10

0.74
2.21
3.23
4.07
5.20

0.52
1.50
2.45

1.27
1.05

1.6
4.7
7.8
4.1
3.4

7.2
7.2
6.3
6.0

The SEM images of obtained NaHAp coatings show that: they have slate
shapes with large size at 3 scanning times; plate shapes and denser with the size of
150×25 nm at 5 scanning times; both slate and plate shapes at 7 scanning times
(figure 3.5).
Based on the above results, 5 scanning times is selected for NaHAp
coatings electrodeposition.

Figure 3.5. The SEM images of NaHAp coatings deposited at different
scanning times
h. Effect of the scanning rate
The thickness of obtained NaHAp coatings is highest at 5 mV/s scanning
rates (Table 3.5) so it is chosen to deposite the HAP coatings.
Table 3.5. The variation of charge, mass, thickness and adhesion strength
of obtained NaHAp coatings at the different scanning rates
Scanning rates
Charge

Mass
Thickness
Adhesion
2
(times)
(C)
(mg/cm )
(µm)
(MPa)
3
5.09
1.95
6.2
6.2
4
4.11
2.15
6.9
6.5
5
3.23
2.45
7.8
7.2
6
2.21
1.27
4.1
7.8
7

1.85
0.93
3.0
10.6
3.1.1.2. Synthesis of Mg2+, Sr2+ or F- doped NaHAp coatings (ĐNaHAp)
a. Effect of concentration
The cathodic polarization curve of 316LSS substrates in the different
solusions shows on figure 3.6. Concentration increasing of Mg2+, Sr2+ or F- ion
in the solution leads improving ionic strength of the electrolyte and the
reducting speed of NO3- to OH- raise. Thus, the cathodic current density
increases.
9


In the potential range of 0 ÷ -1,7 V/SCE, the reducted reactions are listed
at section 3.1.1. Then, doped HAp coatings (MgNaHAp, SrNaHAp or FNaHAp)
is producted on the cathode substrates according to the chemical reaction:
10(Ca2+,Mg2+,Na+) + 6PO43− + 2OH− → (Ca,Mg,Na)10(PO4)6(OH)2
(3.12)
2+
2+
+
3−
−
10(Ca ,Sr ,Na ) + 6PO4 + 2OH → (Ca,Sr,Na)10(PO4)6(OH)2
(3.13)
+
(Ca,Na)10(PO4)6(OH)2 + xF + xH  (Ca,Na)10(PO4)6(OH)2-xFx + xH2O (3.14)
0

(a)

0

0

(b)

2

i (mA/cm )

-1

-2 DNa2
2

DMg1
-3 DMg2

-4 DMg3

-2
DNa2
DSr1

-3 DSr2

-5
-6

(c)

-1

i (mA/cm )

2

i (mA/cm )

-1

DSr3

DMg4

-4

-1.8 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2
E (V/SCE)

0.0

DSr4

-1.8

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

E (V/SCE)

-0.4

-0.2

0.0

-2
DNa2

-3
-4

DF1

-5

DF2

-6

DF3

-1.8 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2
E (V/SCE)

0.0

Figure 3.6. The cathodic polarization curve of 316LSS substrates in the
solusions with different concentrations of Mg2+ (a), Sr2+ (b) và F- (c) ions
Table 3.6 shows that the concentration of doped ions in the solution
increases leading to the increase of their components and the atomic ratios of
X/Ca in obtained coatings. However, to reach the X/Ca similar to its in natural
bone, the soluion of DMg1, DMg2, DMg3, DSr1 or DSr2 are suitable to
deposite the MgNaHAp or SrNaHAp coatings. The ratio of F/Ca is smaller than
its in natural bone but the extension of F- concentration is more than 2.10-3 M
leading to precipitation of CaF2 in the solution. Therefore, DMg3 or DSr2 or
DF3 is chosen to deposite the MgNaHAp or SrNaHAp or FNaHAp coatings.
Table 3.6. The element components of obtained coatings at diffrent
solutions
Weigh (%)
Solutions
Ca
P
Na
Mg
Sr
F
DMg1

34.12
17.18
1.21
0.06
DMg2
35.20
17.90
1.13
0.12
DMg3
34.60
18.10
1.20
0.20
DMg4
34.20
18.50
1.10
0.40
-4
DSr1
34.19
17.25
1.27
1.74.10
-4
DSr2
34.72
17.96
1.22

3.68.10
-4
DSr3
33.34
17.46
1.16
6.30.10
-3
DSr4
33.32
17.36
1.12
1.00.10
DF1
38.40
18.90
1.15
1.01
DF2
37.20
18.01
1.50
1.30
DF3
33.10
16.80
1.90
1.55

10

Table 3.7. The atomic ratios of X/Ca, Y/P and the formula of
ĐNaHAp coatings
The formula (expectation)
DD
Na/Ca
X/Ca
Y/ P
-3
DMg1 0.062 2.90x10
1.59
Ca9.403Mg0.027Na0.570(PO4)6(OH)2
-3
DMg2 0.056 5.70x10
1.58
Ca9.438Mg0.052Na0.510(PO4)6(OH)2
-3
DMg3 0.060 9.60x10
1.54
Ca9.378Mg0.086Na0.536(PO4)6(OH)2
-2
DMg4 0.056 1.95x10
1.50
Ca9.352Mg0.168Na0.480(PO4)6(OH)2
-4
DSr1
0.065 1.74x10
1.64
Ca9.403Sr0.002Na0.595(PO4)6(OH)2

-4
DSr2
0.061 3.68x10
1.59
Ca9.447Sr0.003Na0.549(PO4)6(OH)2
-4
DSr3 0.0605 6.30x10
1.57
Ca9.457Sr0.006Na0.537(PO4)6(OH)2
-3
DSr4
0.049 1.00x10
1.58
Ca9.469Sr0.009Na0.521(PO4)6(OH)2
-2
DF1
0.052 5.50x10
1.66 Ca9.508Na0.492(PO4)6(OH)1.477F0.523
-2
DF2
0.070 7.40x10
1.67 Ca9.326Na0.674 (PO4)6(OH)1.293F0.707
-2
DF3
0.099 9.90x10
1.67 Ca9.085Na0.915(PO4)6(OH)1.097F0.903
(X/Ca = Mg/Ca or Sr/Ca or F/Ca; Y/P = (0,5Na+ Ca + Mg + Sr)/P)
b. The effect of scanning potential range
Table 3.8 shows that the scanning potential range of 0 ÷ -1.7 V/SCE for
MgNaHAp + SrNaHAp and at 0 ÷ -1.8 V/SCE for FNaHAp, the mass, thickness

and adhension strength of obtained ĐNaHAp coatings are best. Thus, the
scanning potential range of 0 ÷ -1.7 V/SCE is selected to synthesize the MgNaHAp
+ SrNaHAp coatings and 0 ÷ -1.8 V/SCE for FNaHAp coatings.
Table 3.8. The variation of charge, mass, thickness and adhesion strength
of deposited ĐNaHAp coatings at the different scanning potential ranges
Scanning
ĐNaHAp potential ranges
(V/SCE)
0 ÷ -1.5
0 ÷ -1.7
MgNaHAp
0 ÷ -1.9
0 ÷ -2.1
0 ÷ -1.5
0 ÷ -1.7
SrNaHAp
0 ÷ -1.9
0 ÷ -2.1
0 ÷ -1.6
0 ÷ -1.7
FNaHAp
0 ÷ -1.8
0 ÷ -1.9

Charge
Mass
Thickness
2
(C)
(mg/cm )

(µm)
0.42
3.56
4.52
6.85
0.31
3.51
4.32
6.69
0.50
3.63
4.25
4.97

1.21
2.63
1.96
1.41
1.12
2.35
1.91
1.45
1.40
2.40
2.90
1.80
11

5.5
8.1

6.3
4.5
5.2
7.6
6.1
4.7
4.2
7.8
8.3
5.4

Adhesion
(MPa)
7.3
7.2
7.1
7.0
7.4
7.3
7.1
7.0
7.6
7.1
6.9
5.5


3-

2-

PO4

3-

CO3

PO4

-

OH

CO3

H2O

F

11

FNaHAp

1

Intensity

1

874

NaHAp

2500

2000

1500
-1

Wave number (cm )

602

MgNaHAp

1000

565

1035

1390

3445

3000

SrNaHAp

437

MgNaHAp

3500

2

1

SrNaHAp

4000

23

1. HAp; 2. CrO.FeO.NiO; 3. Fe

-

1645

Tranmistance (a.u)

FNaHAp

2-

c. The effect of the scanning times
The results of the mass and thickness of ĐNaHAp coatings at the

different scanning times show on Table 3.9. The mass, thichness and adhesion
strength of deposited ĐNaHAp coatings at 5 scanning times are higher than
othes scanning times so 5 scanning times is chosen to deposited the ĐNaHAp
coatings.
Table 3.9. The variation of charge, mass, thickness and adhesion strength
of deposited ĐNaHAp coatings at the different scanning times
Scanning Charge
Mass
Thickness Adhesion
ĐNaHAp
2
times
(C)
(mg/cm )
(µm)
(MPa)
1
0.76
0.57
1.6
3
2.40
1.72
5.5
7.3
MgNaHAp
5
3.51
2.63
8.1

7.2
7
4.61
1.41
4.5
6.3
10
6.33
0.98
3.1
5.7
1
0.56
0.37
1.2
3
2.13
1.51
5.2
10.0
SrNaHAp
5
3.51
2.35
7.6
7.3
7
4.02
1.51
4.8

7.5
10
4.98
1.12
3.7
5.2
1
0.78
0.62
1.8
3
2.61
1.80
5.6
7.4
FNaHAp
5
3.82
2.40
7.8
7.1
7
5.14
1.52
4.9
6.1
10
6.96
1.26
4.1

5.8
d. Characterization of ĐNaHAp coatings
The analysed results of IR spectra, XRD patterns and SEM images show
that deposited ĐNaHAp coatings have crystals structure and single phase of
HAp (Figure 3.7) and the morphology change because of the presence of Mg,
Sr or F into NaHAp coatings (Figure 3.8).

NaHAp

500
10

15

20

25

30

35

40

45

50

55

60

65

70

degree

Figure 3.7. IR spectra and XRD patterns of ĐNaHAp coatings

12


Figure 3.8. SEM images of NaHAp and ĐNaHAp coatings
3.1.1.3. Synthesis of Mg2+, Sr2+and F- co-doped NaHAp coatings (MgSrFNaHAp)
a. The effect of the scanning potential range
The MgSrFNaHAp coatings is produced on the cathode substrates
according to the chemical reaction:
10(Ca2+,Na+,Mg2+,Sr2+) + 6 PO34 + 2OH-  (Ca,Na,Mg,Sr)10(PO4)6(OH)2 (3.15)
(Ca,Na,Mg,Sr)10(PO4)6(OH)2 + x F- + x H+  (Ca,Na,Mg,Sr)10(PO4)6(OH)2- xFx
+ xH2O (3.16)
The change of charge, mass, thickness and adhesion strength of
MgSrFNaHAp coatings with the different potential ranges shows on Table 3.10.
The mass and thickness of MgSrFNaHAp coatings are highest at 0 ÷ -1,7
V/SCE.
Table 3.10. The variation of charge, mass, thickness and adhesion
strength of deposite MgSrFNaHAp coatings with the different scanning
potential ranges
Scanning potential
Charge

Mass
Thickness
2
ranges (V/SCE)
(C)
(mg/cm )
(µm)
0 ÷ -1.5
1.13
1.01
3.1
0 ÷ -1.7
4.32
3.17
8.9
0 ÷ -1.8
5.08
2.54
7.8
0 ÷ -1.9
5.92
1.95
5.9
0 ÷ -2.1
7.84
1.47
4.2
SEM images of MgSrFNaHAp coatings deposited with different potential
ranges are presented in Fig. 3.9. With potential ranges of 0 ÷ -1.7 và 0 ÷ -1.8
V/SCE, the deposited coatings are denser with cylinder shapes.

Therefore, the potential ranges of 0 ÷ -1,7 V/SCE is selected to
electrodeposited MgSrFNaHAp coatings.

Figure 3.9. SEM images of MgSrFNaHAp coatings deposited with the
potential ranges: (a) 0 ÷ -1,5; (b) 0 ÷ -1,7; (c) 0 ÷ -1,8; (d) 0 ÷ -1,9 (V/SCE)
13


b. Effect of electrodeposition temperature
At 25 and 35 oC, the deposited coatings are mostly DCPD. With higher
temperature, the peaks of DCPD are not detected and there are only peaks of
HAp phase (Figure 3.10a). Thus, 50 oC is chosen to prepare MgSrFNaHAp
coatings.
c. The effect of the scanning times
The XRD patterns indicate that the phase of deposited coatings at one
scanning times is only DCPD without HAp. At 3 scanning times, it appears the
phase of HAp but DCPD is still the mainly component. From 5 scanning times,
the obtained coatings have single phase of HAp (Figure 3.10b). Thus, 5
scanning times is chosen for MgSrFNaHAp coatings electrodeposition.
d. Effect of the scanning rate
Figure 3.10c presents the XRD patterns of MgSrFNaHAp coatings
deposited at different scanning rates. Both XRD patterns exhibit the
hydroxyapatite phase with the typical peaks at 2 of 32o and 26o. However, with
the scanning rate at 6, 7 mV/s, there are also appear peaks of DCPD at 2 of
12o. Thus, scanning rate 5 mV/s is chosen to deposite of MgSrFNaHAp
coatings.
1

1. HAp; 2. DCPD; 3. CrO.FeO.NiO; 4. Fe
3 4

(c)
1
1

0

70 C

Intensity

1

0

60 C

0

1

1

1

13

1

5 lÇn quÐt

50 C

1 3 1

1

10 lÇn quÐt

7 lÇn quÐt

Intensity

34

1

1. HAp; 2. DCPD; 3. CrO.FeO.NiO; 4. Fe
34

(b)

1. HAp; 2. DCPD; 3. CrO.FeO.NiO; 4. Fe
1
11 1

3 mV/s

Intensity

1

(a)
1

4 mV/s

5 mV/s

2

2

3 lÇn quÐt

6 mV/s

2

0

35 C

2

7 mV/s
1 lÇn quÐt

0

25 C
10

20

30

40

degree

50

60

70

10

20

30

40
degree

50

60

70

10

20

30

40

degree

50

60

Figure 3.10. XRD patterns of deposited coatings with the change:
(a) temperature, (b) scanning time, (c) scanning rate
e. Characterization of MgSrFNaHAp coatings
The EDX spectra of MgSrFNaHAp coatings shows that: the presence of 7
main elements doped in HAp including: Ca, O, P, Mg, Na, F and Sr (Table
3.11). These results have been used to calculate the atomic ratios of M/Ca, (Ca
+ M)/P (Table 3.12). The ratios suggest that the components of the elements in
the coatings are similar to component of mineral phase in natural bone .
Table 3.11. The element component of MgSrFNaHAp coatings deposited
on 316L SS
Elements
O Ca
P
Na

Sr
Mg
F
Weigh (%) 39.34 32.65 15.76 0.56 0.03
0.14 1.50
Atomic (%) 68.20 18.00 11.20 0.99 0.01 0.13 1.47

14

70


Table 3.12. The atomic ratios of M/Ca and M/P in MgSrFNaHAp
coatings and in natural bone
M/Ca (M: Na, Mg, Sr, F) MgSrFNaHAp
In natural bone
-2
Na/ Ca
8.8×10
0.102
-3
Mg/Ca
1.2×10
6.7×10-3÷ 1.7×10-2
Sr/ Ca
8.9×10-4
2.7×10-4 ÷ 9.8×10-4
F/ Ca
1.3×10-2
0.024 ÷ 0.15

(0,5 Na + Mg + Sr + Ca)/P
1.664
SEM and AFM images of deposited coatings are shown in Figure 3.11. At
the same conditions, MgSrFNaHAp coatings with the presence of Mg, Sr, F
are high density, uniform and has a rod shape, while HAp coatings has a plate
shape. The roughness value (Ra) of MgSrFNaHAp coatings is less 2 times than
its of NaHAp coatings.

Figure 3.11. SEM (a) and AFM (b) images of NaHAp and MgSrFNaHAp coatings
3.1.2. Synthesis of doped HAp by ion exchange method
3.1.2.1. Synthesis of Cu2+, Ag+ or Zn2+ doped NaHAp coatings
a. Effects of M2+ concentration
For the ion exchange between HAp and Cu2+, the initial concentration of
Cu2+ increases from 0.005 M ÷ 0.02 M, the ion exchange capacity rises rapidly.
When the concentration of Cu2+ was elevated to 0.05 M and 0.1 M, the capacity
altered slightly, as the ion exchange process had reached trace of the
equilibrium. Therefore, 0.02 M Cu2+ solution is used to synthesize CuHAp
coatings (Table 3.13).
For ion exchange between HAp coatings with Ag+ and Zn2+ ions, ion
exchange capacity increased simutaneously as Ag+ and Zn2+ concentration
increased. Xray diffraction of the obtained samples after ion exchange are
presented in Fig. 1. With concentration of Ag+ from 0.001 M to 0.005 M and
Zn2+ from 0.01 M to 0.1 M, all the samples have crystals structure and single
phase of HAp. Contrary, with the Ag+ concentration of 0.01 M, the obtained
coatings have mainly the phase of Ag3PO4. Therefore, 0.001 M Ag+ and 0.05 M
Zn2+ solutions are used to synthesize AgHAp and ZnHAp coatings.

15

Table 3.13. Ion exchange capacity and the formula of MHAp
Ion

Cu2+

Ag+

Zn2+

Concentration
Mn+ (M)
0.005
0.01
0.02
0.05
0.1
0.001
0.002
0.005
0.01
0.01
0.05
0.1

The formula
MNaHAp (expectation)
Ca9.278Na0.722 Cu0.065(PO4)6(OH)2
Ca9.162Na0.722 Cu0.116(PO4)6(OH)2
Ca9.113Na0.722 Cu0.165(PO4)6(OH)2
Ca9.076Na0.722 Cu0.202(PO4)6(OH)2

Ca9.064Na0.722 Cu0.214(PO4)6(OH)2
Ca9.021Na0.722 Ag0.257(PO4)6(OH)2
Ca8.907Na0.722 Ag0.371(PO4)6(OH)2
Ca8.714Na0.722 Ag0.564(PO4)6(OH)2
Ca8.783Na0.722 Zn0.495(PO4)6(OH)2
Ca8.040Na0.722 Zn1.238(PO4)6(OH)2
Ca5.452Na0.722 Zn3.826(PO4)6(OH)2

Q (mmol/g)
0.065
0.117
0.166
0.204
0.216
0.259
0.374
0.569
2.470
0.499
1.248
3.858

1. HAp; 2. CrO.FeO.NiO; 3. Fe; 4. Ag 3PO4
4

4
4
4

g

3
2

1

Intensity

23
1

4

4

4
2

1

4

1

f
e
d

c
b

a

10

15

20

25

30

35

40

45

50

55

60

65

degree

Figure 3.12. XRD patterns of the obtained samples after ion exchange
between HAp and solution containing: 0.01 M Zn2+ (a), 0.05 M Zn2+ (b), 0.1 M

Zn2+ (c) and 0.001 M Ag+ (d), 0.002 M Ag+(e), 0.005 M Ag+ (f), 0.01 M Ag+ (g)
b. Effect of contact time
The change in ion exchange capacity folowing the contact time are
presented in Fig. 2. The results show that: after 10 minutes contact with Ag+ ion
and after 30 minutes contact with Cu2+ or Zn2+, the ion exchange capacity has
reached equilibrium trace (figure 3.13); if the contact time is longer, this value
changes light. Thus, the contact time is selected to synthesize CuNaHAp or
ZnNaHAp of 30 minutes and AgNaHAp coatings of 10 minutes.

16


0.55

0.45

+

0.16

0.50

0.15
0.14
0.13

0.40
0.35

+

NaHAp + Ag 0,001M

2+

NaHAp + Cu 0,02M
0.12

1.4
1.2

2+

0.17

1.6
Q (mmol Zn /g NaHAp)

0.60

0.18
Q (mmol Ag /g NaHAp)

2+

Q (mmol Cu /g NaHAp)

0.19

1.0

0.8
0.6

2+

NaHAp + Zn 0,05M

0.30
0

10

20

30

40

50

60

70

80

90

0

10

20

Time (min)

30

40

50

60

70

80

90

0

10

20

30

40

Time (min)

50

60

70

80

90

Time (min)

Figure 3.13. The change in ion exchange capacity of the HAp coatings
with Mn+ solutions
c. Characterization of CuNaHAp, AgNaHAp, ZnNaHAp coatings
3

CuHAp

1

Intensity

1390

AgHAp

(a)

2
1

1

PO4

3-

PO4

H2O

Tranmistance (a.u)

3-

CO3

-

OH

2

1. HAp; 2. CrO.FeO.NiO; 3. Fe

2-

NaHAp

1

11

ZnNaHAp
AgNaHAp

ZnHAp

CuNaHAp
1643
3430

602

565

NaHAp

1034
4000

3500

3000

2500

2000

1500

1000

500

10

-1

Wave number (cm )

20

30

40

degree

50

60

Figure 3.14. IR spectra and XRD patterns of NaHAp and MNaHAp
coatings
Both IR spectra and XRD patterns of MNaHAp coatings exhibit that
NaHAp coatings have crystals structure and single phase of HAp (Figure 3.14).

SEM images of HAp and MHAp coatings show that with the present of
Cu, Ag, Zn in HAp structure, the morphology changes from plate shape of HAp
to rod shape of CuHAp; fiber shape of AgHAp and coral-shape of ZnHAp
(Figure 3.15).

Figure 3.15. SEM images of NaHAp and MnaHAp coatings
3.1.2.2. Synthesis of Cu2+, Ag+ and Zn2+ co-doped NaHAp coatings
The ion exchange capacity of NaHAp coatings with the solution
containing simultaneously: Cu2+ 0.02 M + Ag+ 0.001 M + Zn2+ 0.05 M at 30
minutes is smaller than its with the solution containing separately: Cu2+ 0.02 M
or Ag+ 0.001 M or Zn2+ 0.05 M (Table 3.14).
Table 3.14. The ion exchange capacity and the fomular of CuAgZnNaHAp coatings
Ion
Cu2+

Concentration Mn+
(M)
0.02

Q (mmol/g)
0.121
17

The formula
MNaHAp (expectation)
Ca8.550Na0.722 Cu0.121


Ag+
0.001

0.207
Ag0.208Zn1.121(PO4)6(OH)2
2+
Zn
0.05
1.117
Results of IR spectra, XRD patterns and SEM images demonstrate that
CuAgZnNaHAp obtained coatings have crystals structure with slate shape and
single phase of HAp (Figure 3.16).
3

1. HAp; 2. CrO.FeO.NiO; 3. Fe

1
1

1390

Intensity

Tranmistance (a.u)

(a)

1643

(b)
3432

602

565

2
2

1

2

1

1

1

(b)

(a)

1034

4000

3000
2000
-1
Wave number (cm )

1000

10

15

20

25

30

35

40

45

50

55

60

65

degree

Figure 3.16. IR spectra and XRD patterns of NaHAp (a) and
CuAgZnNaHAp (b) coatings and SEM images of CuAgZnNaHAp coatings
3.1.3. Synthesis of Mg2+, Sr2+, Na+, Cu2+, Ag+, Zn2+ and F- co-doped HAp
coatings (HApđt)

The EDX spectra of HApđt coatings obtained shows that: There are the
presence of 10 main elements doped in HAp, including: Ca, O, P, Mg, Na, F,
Sr, Cu, Ag and Zn with their components listed at table 3.15. The atomic ratios
of X/Ca and (0,5Na+Ca+Mg+Sr+Cu+0,5Ag+Zn)/P (symbol Z/P) are calculated
and show on Table 3.16. To compare with component of mineral phase in
natural bone, the element components of Mg, Sr, F and Na in the coatings are
similar to but this values of Cu, Ag and Zn and Na are higher to increase the
antibacterial ability of the coatings.
Table 3.15. The element component of HApđt coatings
Elements
O
P
Ca
Na Mg
Sr
F
Cu Ag Zn
Weigh (%) 29.01 14.67 52.83 0.15 0.04 0.03 1.07 0.18 0.39 1.06
Atomic (%) 49.17 12.63 35.82 0.18 0.05 0.008 1.53 0.08 0.1 0.44
Table 3.16. The atomic ratios of X/Ca and Z/P in HApđt coatings and in
natural bone
The atomic
F/Ca Mg/Ca Sr/Ca Na/Ca Cu/Ca Ag/Ca Zn/Ca Z/P
ratios
HApđt
0.0646 2x10-3 4x10-4 8x10-3 3x10-3 4x10-3 0.0187 1.65
coatings
Natural bone 0.149 0.176 4x10-4 0.102 1x10-4 1x10-6 6x10-4 1.67
The fomular
Ca9.005Mg0.019Sr0.004F0.638Cu0.032Ag0.041Zn0.185Na0.074(PO4)6(OH)2

(expectation)
IR spectra, XRD patterns and SEM images of HApđt obtained coatings
demonstrate that they have crystals structure with slate shape and single phase
of HAp (Figure 3.17).
18


3

1. HAp; 2. CrO.FeO.NiO; 3. Fe
1

(a)

1390
1643

(b)

1
1

2
1

(b)

1

1

Intensity

Tranmistance (a.u)

2

3432

(a)

602
565
1034

4000

3000
2000
-1
Wave number (cm )

10

1000

15

20

25

30

35

40

45

degree

50

55

60

65

Figure 3.17. IR spectra and XRD patterns of NaHAp (a) and HApđt (b)
coatings and SEM images of HApđt coatings
The dissolution behaviors of HApđt, MgSrFNaHAp and NaHAp coatings is
studied by immersions materials in 0.9% NaCl and SBF solutions. For all
samples, the dissolved amount of Ca2+ ions from these coatings increases with
immersion time. However, The dissolution of HApđt coatings is slowest and of
NaHAp is faster at any time (Figure 3.18a). The release concentration of iron
ions from substrates increases according to time for all sample. Because HApđt
coatings play as a barrier to protect the substrates and the dissolution of the
coatings decreases with the presence of the trace elements in HAp structure so

the iron ion release is arranged in order: 316LSS > NaHAp/316LSS >
MgSrFNaHAp/316LSS > HApđt/316LSS.
This suggested that the protect ability for the substrates of the coatings:
HApđt > MgSrFNaHAp > NaHAp.
200

a: NaHAp/TKG316L
b: MgSrFNaHAp/TKG316L
c: HAp®t /TKG316L

7

a
Concentration Fe (ppb)

2+

Concentration Ca (ppm)

8

6

b
5

c
4
3

150

a: TKG316L
b: NaHAp/TKG316L
c: MgSrFNaHAp/TKG316L
d: HAp®t /TKG316L

a
b

100

c
d

50

2
0

2

4

6

8

10

12

14

16

0

18

7

Time (days)

14

21

28

Time (days)

Figure 3.18. The release concentration of Ca2+ (1) and Fen+ (2)
3.2. The in vitro and in vivo test
3.2.1. The in vitro test
3.2.1.1. Invitro test in simulated body fluid (SBF) solutions
a. The variation of the pH and the open circuit potential (OCP - Eo) value
With 316LSS sample, the pH solution decreases and Eo tends to increase
during immersion time (Figure 3.19).

19


8.2

7.6

80
E0 (V/SCE)

7.8

7.4

pH

7.2
7.0

(a)
(b)
(c)

6.8
6.6

(d)

(c)

40
(b)

0
-40

(a)

-80
-120

(d)

6.4

(a): TKG316L
(b): NaHAp/TKG316L
(c): MgSrFNaHAp/TKG316L
(d): HAp®t/TKG316L

120

(a): TKG316L
(b): TKG316L/NaHAp
(c): TKG316L/MgSrFNaHAp
(d): TKG316L/HApdt

8.0

-160

6.2
0

5

10

15

20

0

25

2

4

6

8

Time (days)

10 12 14
Time (days)

16

18

20

22

Figure 3.19. The variation of pH (1) and Eo (2) vs. different immersion
times in SBF solution
With doped HAp/316LSS materials, pH solution and value of Eo have
fluctuated which shows the formation of new apatite crystals or the dissolution
of the coatings in the immersion process. The dissolution HAp causes to
increase pH solution Eo. In the process of forming apatite, OH- as Ca2+, PO43- is
consumed large quantities leading to reduce pH and rise Eo.
b. The electrochemical impedance
During 21 immesion days, the impedance of 316LSS increases, these
values of doped HAp coated 316LSS changes, but they are much higher than
316LSS because of protection ability of coatings and tend to increase which
demonstrates that the rate of the formation is higher than the rate of the
dissolution of the coatings (Figure 3.20).
Moreover, the variations of impedance modulus at 100 mHz frequency
show that the values of impedance modulus of MgSrFNaHAp/316LSS and
HApđt/316LSS material are higher than of NaHAp/316LSS and 316LSS which
indicates that HAp doped with the present of some trate elements have the
protection ability better than NaHAp coatings.
5

22

12

316LSS

NaHAp/316LSS

11

x : 100 mHz
4

18

2

Z'' (.cm )

2

1 day
3 days
5 days
7 days

1

10 days
14 days
17 days
21 days

7

6
5
4
3

1

2

3

4

1

5

0

1

2

3

4

5

2

Z' (.cm )

HAp®t/316LSS

x : 100 mHz
2

IZI (k.cm )

22
2

Z'' (.cm )

20
18
16
14
12
10
8

1 day
3 days
5 days
7 days

4
2

0
0

2

4

6

8

10

12

14

16
2

Z' (.cm )

8

9

10

11

18

20

10 days
14 days
17 days
21 days
22

24

26

28

30
28
26
24
22
20
18
16
14
12
10
8
6
4

2

(d)

(a)

6

8

10 12 14
Time (days)

20

2

4

6

8

10

12

14

16

18

20

22

Figure 3.20. Nyquist plots
and the variation of
impedance modulus at 100
mHz versus immersion time
in SBF solution

(b)

4

0

10 days
14 days
17 days
21 days

2

(c)

2

1 day
3 days
5 days
7 days

Z' (.cm )

a: 316LSS
b: NaHAp/316LSS
c: MgSrFNaHAp/316LSS
d: HApdt/316LSS

0

8

0

12

Z' (.cm )

24

6

7

10

2

2

28
26

6

12

4

0

0

14

6

10 days
14 days
17 days
21 days

1 day
3 days
5 days
7 days

2

0

x : 100 mHz

16

8

2

Z'' (.cm )

2

Z'' (.cm )

9

3

MgSrFNaHAp/316LSS

20

x : 100 mHz

10

16

18

20

22


c. The polarized Tafel curves
The presence of trace elements in HAp structure leads to move the
corrosion potential (Ecorr) toward the positive side and reduce the corrosive
current density (icorr) in comparation with 316LSS (Figure 3.21 and Table 3.17).
This indicates that the protection ability for the substrates of doped HAp
coatings is better than that of NaHAp one.
Table 3.17. The values of the corrosion current
density (icorr) and the corrosion potential (Ecorr)
of meterials after immersion in SBF solution
-3.5

(a): 316LSS
(b): NaHAp/316LSS
(c): MgSrFNaHAp/316LSS
(d): HAp®t/316LSS

-4.0

-5.0

lg(i), A/cm

2

-4.5

-5.5
-6.0

Materials

-6.5
-7.0

a
b

-7.5
-8.0
-8.5
-0.8

c
d

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

E (V/SCE)

Figure 3.21. The polarized
Tafel curves of materials

316LSS
NaHAp/316LSS
MgSrFNaHAp/316LSS
HApđt/316LSS

Ecorr
(V)
-0.424
-0.354
-0.258
-0.213

icorr
(µA/cm2)
2.773
0.842

0.355
0.193

d. The SEM images
Figure 3.22 presents SEM images of 316LSS, NaHAp/316LSS,
MgSrFNaHAp/316LSS and HApđt/316LSS before and after immersion in SBF
solution. After immersion, the formation of new apatite crystals is observed on
the surface of all materials.

Figure 3.22. SEM images of materials before (above) and after (under)
21 immersion days in SBF solution
3.2.1.2. Cytotoxicity ability test
Results of the cytotoxicity ability test by Trypan Blue and the MTT method
show that NaHAp or MgSrFNaHAp powder with different concentrations are safe
for fibroblasts and lymphocyte cells.
3.2.1.3. Antibacterial ability test
The results of antibacterial ability test with three strains (P.aerugimosa,
E. coli and E.faecalis) show that: AgHAp and HApđt have good resistance to all
21


of them; CuHAp has a good effect on P. aerugimosa; the HAp and ZnHAp
have no effect on all strains;
3.2.2. In vivo test on the dog
3.2.2.1. Results of implantation at the thigh
At the first 3 days, the wound at implantation area has been edema but not
bleeding. After 1 month, the skin was almost completely covered (Figure 3.23).

Figure 3.24. The woud at implantation area
Microscopic images at implantation area shows that all implanted animals

have the same results. The area of the direct contact with the material is forming
a membrane link. However, some lymphocyte cells appear on 316LSS and
NaHAp/316LSS materials but in contrast, they are completely not observed on
MgSrFHAp/316LSS material.
3.2.2.2. Results of transplantation on the femur
The wound has been edema but not bleeding at the first 3 days and after 1
month, the skin was almost completely covered at the location of transplantation.
Microscopic images at transplantation area shows that:
- After 1 week: all transplanted animals have the same results. At the
transplantation area, many osteoblasts cells are observed but acute inflammation
cells still exist (Figure 3.24).

Figure 3.24. Images of NaHAp/316LSS after 1 week transplantation
- After 1 month: the acute inflammation cells have absented and the
necrosis have not observed on all transplanted materials. There are many
osteoblasts cells on 316LSS and NaHAp/316LSS but still have the lymphocyte
cells (Figure 3.25a). With MgSrFNaHAp/316LSS, the osteoblast concentrate on
the location of the bone edge to form bone (Figure 3.25b) and form a membrane
link attached on the surface of this material (Figure 3.25c).

22


Figure 3.25. Images of the osteoblast near the location of transplanted
materials: 316LSS (a), MgSrFNaHAp/316LSS (b, c) after 1 month
- After 2 months: There are many osteoblasts cells on 316LSS and
NaHAp/316LSS but still have few the lymphocyte cells (Figure 3.26a). The
tissues adhese on the surface of NaHAp/316LSS better than the 316LSS. On the
surface of MgSrFNaHAp/316LSS, the lymphocyte cells have not observed
(Figure 3.26b) and a new bone layer is produced (Figure 3.26c)

Figure 3.26. Images of the osteoblast near the location of transplanted
materials: 316LSS (a), MgSrFNaHAp/316LSS (b, c) after 2 months
- After 3 months: on all transplanted materials, there are not the
lymphocyte cells (Figure 3.27a, b). On the surface of MgSrFNaHAp/316LSS, a
thick new bone is formed which are rarely found out on 316LSS and
NaHAp/316LSS (Figure 3.27c).

Figure 3.27. Images of the osteoblast near the location of transplanted
materials: 316LSS (a), MgSrFNaHAp/316LSS (b, c) after 3 months
CONCLUSIONS
1. The optimal conditions is selected to synthesize the NaHAp coatings and
NaHAp coatings doping magnesium, strontium and fluorine separately and
simultaneously by cathodic scanning potential method: the scanning
potential range of 0 to -1.7 V/SCE (0 ÷ -1.8 V/SCE for FNaHAp); the
reaction temperatures of 50 oC; the scanning time of 5; the scanning rate of
5 mV/s in DNa2, DMg3, DSr3, DF3 và DNaMgSrF, respectively. The dope
deposited HAp have crystals structure and single phase of HAp with the
thickness about 7,6 ÷ 8,1 µm. The component wt% of the elements Na, Mg,
23