Nghiên cứu kết tủa điện hóa màng hydroxyapatit ống nano carbon biến tính trên nền hợp kim định hướng ứng dụng trong cấy ghép xương tt tiếng anh

This study aims are selection of suitable conditions to synthesize HAp-CNTcoating on the surface of 316LSS, Ti6Al4V substrates by scanning potential method.. 9 formation of surface inter

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GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY

INSITUTE FOR TROPICAL TECHNOLOGY

SUMMARY OF PhD THESIS IN CHEMISTRY

ELECTRODEPOSITION OF HYDROXYAPATITE/MODIFY CARBON NAOTUBES ON

ALLOYS TO APPLY FOR BONE IMPLANTS

Specialization: Theoretical and Physical chemistry Code: 9 44 01 19

Hanoi 2019

The dissertation completed at:

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INTRODUCTION

 Reason to choose the topic

bones and teeth, has high biocompatibility HAp is applied in medicine with different forms: powder, ceramic, composite and coating Synthetic HAp has the same composition in natural bone and has good biocompatibility However, pure HAp coating has a relatively high solubility in physiological environment and poor mechanical properties leading to faster degradation of the material and reducing the fixed ability between the implant material and the host tissue Some reports show that the doping of carbon nanotubes to create HAp-CNTcomposite significantly improves the mechanical properties of materials such as corrosion resistance and mechanical strength The thesis: "Electrodeposition of hydroxyapatite/modify carbon nanotubes coating on alloys to apply for bone implants"

 Objectives of the thesis:

316LSS and Ti6Al4V

comparison with HAp coating

• Main content of the thesis:

2 Determination of roughness, elastic modulus and hardness of 316LSS, Ti6Al4V,

3 Research on biocompatibility and electrochemical behavior of 316LSS, Ti6Al4V,

solution

CHAPTER 1: OVERVIEW 1.1 Overview for Hydroxyapatite

1.1.1 Properties of Hydroxyapatite

1.1.1.1 Structural properties

Hydroxyapatite (HAp) exists in two structural forms: hexagonal (hexagonal) and monoclinic (monoclinic) Hexagonal HAp is usually formed during synthesis at temperatures between

25 and 100 °C The monoclinic form is mainly created by heating the hexagonal HAp at

850 °C in air, then cooling to room temperature

1.1.1.2 Physical properties

rod-shape, needle-rod-shape, scale-rod-shape, fibrous-rod-shape, spherical-rod-shape, and cylindrical-shape

1.1.1.3 Chemical properties

• HAp reacts with acids to form calcium salts and water

• HAp is relatively thermally stable, which is decomposed slowly at temperature range of 800°C ÷ 1200°C, to form oxy-hydroxyapatite

b Electrochemical method

Electrochemical method has many advantages in making thin coating on metal or alloys for biomedical applications Electrochemical technique is a simple technique that allows the synthesis of HAp coating at low temperatures The obtained HAp coating is of high purity, good adhesion to the substrate and we can control the coating thickness HAp coating with thickness of nm size are synthesized on different substrates by electrochemical method such as: Electrophoresis method, Anode method, Cathode deposition method

1.1.3 Application of HAp

1.1.3.1 Application of HAp powder

HAp powder with nano size is mainly used for medicine and calcium supplements In addition, HAp is used as a slow-release nitrogen fertilizer for plants

1.1.3.2 Application of HAp porous ceramic

Porous ceramic of HAp is used in making dentures and repairing dental defects, making artificial eyes, making bone graft details and repairing bone defects

1.2.3.3 Application of HAp composite

HAp is combined with biodegradable polymers such as polylactic acid, polyacrylic acid, chitosan to create replacement materials for bone

1.2.3.4 Application of HAp coating

HAp coating on the suface of biomedical materials is applied in dentistry, orthopedic bone

1.2 Overview of carbon nano tubes materials

1.2.1 Properties

1.2.1.1 Structure of CNT: CNT are graphene sheets which are rolled up to form a hollow

cylinder Depending on rolling direction, CNT materials are divided into armchair, zigzag and chiral types

1.2.1.2 Physical properties

1.2.1.2.1 Mechanical properties

CNT have a good mechanical property, durable and low density So, they are used as reinforcement for rubber, polymer, and metals to improve durability and abrasion resistance for materials

1.2.1.2.2 Electrical properties

About chemical property, CNT are relatively inert To improve the chemical activity

of CNT, CNT usually are modified to create surface defects

1.2.2 Application of CNT materials

CNT are used in energy storage, electronic, reinforcing materials and medical applications (CNT are used in biosensors, drug delivery, and nanotechnology application for bone implants)

1.2.3 Modification of CNT

- CNT is modified by oxidizing agents, a combined reaction, and substitution reaction

1.3 Composite of hydroxyapatite/carbon nano tubes (HAp-CNT bt )

show that the presence of CNT improved the mechanical properties for HAp by the increase

of elastic modulus and the hardness

1.4 In vitro and In vivo tests

The results of biocompatibility of HAp-CNT in Hanks solution or simulated body fluid solution (SBF) show that the material has good biocompatibility with the development

of new apatite crystals The results of in vitro test by cells (osteoblast) showed that there is a

good growth

1.5 Investigation in Vietnam

In Vietnam, there are some reports about HAp powder, coating, ceramic and composite Since 2011, Dinh Thi Mai Thanh et al (Institute of Tropical Technology) investigated on HAp powder, PLA/HAp composite and HAp coating on the surface of 304LSS, 316LSS, TiN/316LSS, Ti6Al4V and CoNiCrMo

We realize that, investigation of HAp-CNT coating is quite new in Vietnam This study aims are selection of suitable conditions to synthesize HAp-CNTcoating on the surface of 316LSS, Ti6Al4V substrates by scanning potential method

Chapter 2 CONDITION AND EXPERIMENTAL METHOD 2.1 Chemicals and experimental conditions

2.1.1 Chemicals

Material Science

- The materials of 316LSS (100×10×2 mm) and Ti6Al4V (12×10×2 mm) were purchased from Gloria Technology Material Company (Taipei, Taiwan) with element components are listed in Table 2.1 and 2.2

Table 2.1 The element component of 316LSS

Table 2.2 The element component of Ti6Al4V

2.1.2 Electrodeposition of HAp-CNTon 316LSS or Ti6Al4V

* Preparation of substrate: 316LSS and Ti6Al4V were polished by SiC paper of 600, 800

and 1200 (Japan) After that, they were clearned and dried The working area was limited of

* Modification of CNTs:

316LSS or Ti6Al4V, The counter electrode of Platinium; and reference electrode of Ag/AgCl (SCE) The factors investigated:

0 ÷ -2.0 V (for Ti6Al4V); 5 scans,

0 ÷ -2.0 V (for Ti6Al4V); 5 mV/s;

2.1.3 In vitro test in SBF solution

Dynamic scanning method, Method of measuring open-circuit potential and

Electrochemical Impedance Spectroscopy

2.2.2 Analysis methods

Characteristics of these materials were determined by IR, SEM, EDX, TEM, XRD,

AFM, TGA, measuring adhesion, determination of coating mass and thickness,

CHƯƠNG 3: RESULTS AND DISCUSSTION 3.1 Modification of CNTs

C=O and C-OH The results confirm that CNTs was modified successfully

Figure 3.2 shows that after 7 days soaked in water, CNTs was clumped by Van der

4000 3500 3000 2500 2000 1500 1000 500

1385 1630 1720

EDX spectrum of CNTs (Figure 3.4) shows

characteristic peaks of C, O, Fe, Al and Pt

characteristic peaks of C and O The

modification process of CNTs removed heavy

metal catalysis

3.2 Synthesis and characterization of HAp-CNTs bt composite

3.2.1 Effect of snanning potential range

Cathode polarization curves of 316LSS and Ti6Al4V (Fig 3.5): 0 ÷ -0,7 V/SCE, i≈ 0 because no reaction occurs -0,7 ÷ -1,2 V/SCE, i increases slightly corresponding to

Potential <-1.2 V /SCE, i increases

the formation of hydrogen bonds between

2 6 4 10 3

4 2

) ( ) ( 2

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(3.9)

mass increased and reached a maximum at 0 ÷ -1.9 V/SCE The mass and thickness decreases when it synthesized at 0 ÷ -2 V/SCE At 0 ÷ -1.6 and 0 ÷ -1.65 V/SCE, the obtained materials had the same adhesion The adhesion decreased about twice for the materials synthesized at 0 ÷ -2.0 V/SCE Therefore, 0 ÷ -1.65 V/SCE was chosen to

increased and reached at 0 ÷ -2.1 V/SCE The adhesion between the coating and substrate decreased at large potential range Therefore, 0 ÷ -2.0 V/SCE was chosen to synthesize

in solution On the other hand, the large cathode potential was favorable for the electrolysis

Mass (mg/cm2) Thickness (µm) Adhesion strength (MPa)

solution interacted with oxide layer of 316LSS, so they accumulate on the surface and

large, the surface of 316LSS gradually charged positively and combined with negatively

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formation of surface interaction between 316LSS and HAp, improving the adhesion of HAp coating to the substrate [98-101]:

For Ti6Al4V substrate, the mechanism of the adhesion between HAp coating and

synthesis process, some reactions occured leading to the presence of corrosive products 101]:

FTIR spectra showed that potential range does not affect to the characteristic peaks of

và 0 ÷ -1.7 V/SCE was observed phase of DCPD At larger potential range, the obtained coating composed phases of HAp and CNTs

synthesized at 0 ÷ -1.6 V/SCE; 0 ÷ - 1.65 V/SCE and has plate shapes with large size when

scales-shapes and uniform when they were synthesized in small potential ranges At 0 ÷ -2.1 V /

Fig 3.11 SEM images of HAp-CNTs bt /316LSS synthesized at different potential range

Fig 3.12 SEM images of HAp-CNTs bt /Ti6Al4V synthesized at different potential range

3.2.2 Effect of temperature

Cathodic polarization curves of 316LSS and Ti6Al4V at different temperature were the same (Fig 3.20 and 3.21) The temperature increased leading to the increase of reaction rate and current density The temperature increased leading to the mass, thickness increased but

-35 -30 -25 -20 -15 -10 -5 0 5

-0.6 -0.4 -0.2 0.0

Fig 3.20-21 Cathodic polarization curves of

316LSS and Ti6Al4V at different temperature

Fig 3.22-23 XRD paterns of HAp-CNTs bt on 316LSS and Ti6Al4V at different temperature Table 3.5 Mass, thickness and adhesion strength of HAp-CNTs bt followed temperature

Mass (mg/cm2) Thickness (µm) Adhesion strength (MPa) Temperature

(oC) 316LSS Ti6Al4V 316LSS Ti6Al4V 316LSS Ti6Al4V

XRD paterns showed that the temperature đo not affect to phase component of the

o

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Fig 3.24 SEM images of HAp-CNTs bt /316LSS at different temperature

Fig 3.25 SEM images

of HAp-CNTs bt /Ti6Al4V

at different temperature

voluminous molecular structure of CNTs which prevented the formation of HAp in the

further investigation

-1.8 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 -9

-8 -7 -6 -5 -4 -3 -2 -1 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 -45

-40 -35 -30 -25 -20 -15 -10 -5 0 5

1 g/L CNTs

Fig 3.13 TEM images of HAp-CNTs bt on

316LSS (A) and Ti6Al4V (B)

Fig 3.14-15 Cathodic Polarization curves of 316LAA and Ti6Al4V in electrolyte with the different CNTs bt amount Table 3.4 The variation of mass, thickness and adhesion strength of HAp-CNTs bt synthesized at different

Fig 3.16-17 IR spectra of HAp-CNTs bt

with different amount of CNTs bt

Fig 3.24 TG/DTG diagram 0f HAp/316LSS (a) and

HAp/Ti6Al4V (b)

Fig 3.25 TG/DTG diagram of Hap-CNTs bt /316LSS synthesized at 0 ÷ -1,65 V; 5 mV/s, 5 scans; 45 o C with

CNT bt : 0,25 g/L (a); 0,5 g/L (b); 0,75 g/L (c) and 1 g/L (d)

Fig 3.26 TG/DTG diagram of HAp-CNT bt /Ti6Al4V synthesized at 0 ÷ -2 V; 5 mV/s, 5 scans; 45 o C with

CNT bt : 0,25 g/L (a); 0,5 g/L (b); 0,75 g/L (c) and 1 g/L (d)

3.2.4 Effect of number scans

The number of scans increased, mass and thickness increased but the adhesion strength

which was similar with adhesion of substrate and glue When the number of scans increased

the substrate Continue to increase the scans to 6 times the adhesion between the coating and substrate was strongly reduced Therefore, 5 scans were selected to synthesize

Table 3.6 Mass thickness and adhesion strength of HAp-CNTs bt followed number scans

XRD paterns showed that number scans does not affect to phase component of the

and CNTs (Fig 3.27 and 3.28)

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Fig 3.27-28 XRD paterns of HAp-CNTs bt

on 316LSS and Ti6Al4V at the different

number scans

3.2.5 Effect of scanning rate

Fig 3.29 and 3.30 showed that scanning rate increased i cathode decreased Scanning rate increased from 2 to 7 V/s the coating massdecreased but the adhesion increased It can be

-2.2 -2.0 -1.8 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 -35

-30 -25 -20 -15 -10 -5 0

1: HAp; 2: CNTs 1 1 1 1,2

1: HAp; 2: CNTs 1 1 1 1,2

7 mV/s

Fig 3.29-30 Cathodic polarization curves of

316LSS Ti6Al4V with different scanning rate

Fig 3.31-32 XRD of HAp-CNTs bt /316LSS and CNTs bt /Ti6Al4V with different scanning rate

with different scanning rate

Mass (mg/cm2) Adhesion (MPa)

XRD paterns showed that the scanning rate doex not affect to phase component of the

3.2.6 Determination of mechanical and dissolution of materials

 Surface roughness

than that of the substrate

Fig 3.33 AFM images of 316LSS (a), HAp/316LSS (b) and HAp- CNTs bt /316LSS (c)

Fig 3.34 AFM images of Ti6Al4V (a), HAp/Ti6Al4V (b) and HAp-CNTs bt /Ti6Al4V (c)

 Modulus

20 60 100 140 180 220 260

40 80 100 120 160

20 60 100 140 180 220 260

20 60 100 140 180 220

 Dissolution of materials

from the coating after these materials were immersed into 20 mL of 0.9 % NaCl with

together to make obtained tighter coating

Ca2+ concentration (mg/L) Material

HAp/316LSS 20.6 ± 0.3 25.3 ± 0.2 30 ± 0.2 HAp-CNTs bt /316LSS 13 ± 0.5 16.5 ± 0.2 19.4 ± 0.2

HAp/Ti6Al4V 21.3 ± 0.3 25 ± 0.4 29.5 ± 0.3 HAp-CNTs bt /Ti6Al4V 12.5 ± 0.4 16.3 ± 0.3 17.7 ± 0.3

3.3 Electrochmical behavior in SBF solution

3.3.1 The variation of pH solution

containing 316LSS and Ti6Al4V, pH slight change during immersion period and pH solution trend to decrease at long immersion time After 21 imersed days, pH values of SBF solutions were 7.28 and 7.22 corresponding to the SBF containing 316LSS and Ti6Al4V

equations of (3.10) and (3.11) The decrease of pH solution was explained by the formation

pH values is the same, pH value increased after 1 soaked day and strongly decreased after 5 soaked days Aterthat, pH solution continue to increase and trend to strongly decrease after

HAp/316LSS were 6.5 and 6.9, respectively

For HAp/Ti6Al4V, pH solution increased from 7.4 to 7.75 when immersion time increased from 1 to 5 days At longer immersion times, pH solution decreased This value was 6.86 after 21 soaked days

immersion period pH solution increased at the first times and strongly decreased after 21