효소를 이용한 뼈 성장 인자 (BMP-2)의 TiO₂표면 고정화 방법
Novel enzyme-mediated BMP-2 immobilization onto TiO₂surface for bone tissue regeneration
- 주제(키워드) surface modification , TiO₂ , BMP-2 , bone tissue regeneration
- 발행기관 아주대학교
- 지도교수 박기동
- 발행년도 2012
- 학위수여년월 2012. 2
- 학위명 석사
- 학과 및 전공 일반대학원 분자과학기술학과
- 실제URI http://www.dcollection.net/handler/ajou/000000012317
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Titanium oxide (TiO₂) has been widely used as implant materials for bone tissue engineering in orthopaedic and dental fields due to its various advantages such as good biocompatibility and suitable mechanical strength. However, one of the main concerns of TiO₂ implants is lack of biological activities which can lead to failure of implantation by not integrating well with surrounding bone tissues. In this study, we report a novel surface modification method using an enzymatic reaction to develop bioactive TiO₂ implants. Tyramine (TA) was conjugated to poly(ethylene glycol) (PEG) as a hydrophilic linker and then the resulting material (PTA) was chemically immobilized onto the TiO₂ substrates via a Tyrosinase-mediated reaction. Bone morphogenetic protein-2 (BMP-2), which is known to enhance bone regeneration, was subsequently immobilized onto the PTA-modified TiO₂ substrates via Schiff base and Michael-type addition reaction. The changes in atomic compositions and hydrophilicity of the BMP-2 immobilized TiO₂ were monitored by X−ray photoelectron spectroscopy (XPS) analysis and contact angle measurement. The immobilized amounts of BMP-2 on TiO₂ quantified by a Sandwich-ELISA assay were found to be 30−170 ng/cm2, depending on the feed amounts of PTA and BMP-2. The obtained results demonstrate that this facile BMP-2 immobilization method onto TiO₂ via an enzymatic reaction can be employed as a versatile surface modification technique to improve bioactivity of the metallic implants for efficient bone tissue regeneration.
more목차
I. INTRODUCTION 1
A. Biomaterials 1
1. Metallic biomaterials 2
2. Titanium oxide 3
B. Surface modification to deliver the growth factor 5
1. Growth factor immobilization 6
2. Bone morphogenetic protein-2 9
C. Tyrosinase-mediated reaction 11
D. Objectives 13
II. EXPERIMENTALS 14
A. Materials 14
B. Synthesis of TA-PEG-TA (PTA) conjugates 15
C. PEG grafting onto TiO₂ surfaces 17
D. Immobilization of BMP-2 onto TiO₂ surfaces 18
E. Surface characterization of BMP-2 immobilized TiO₂ 19
1. Water contact angle measurement 19
2. X-ray photoelectron spectroscopy 20
F. Quantitative analysis of BMP-2 21
III. RESULTS AND DISCUSSIONS 23
A. Structural characterization 23
B. Characterization of BMP-2-immobilized TiO₂ surfaces 25
1. Surface hydrophilicity; water contact angle 25
2. Chemical composition; XPS 28
C. Quantitative analysis of BMP-2; Sandwich-ELISA assay 32
1. Concentration of PTA conjugates 32
2. Incubation time of BMP-2 34
3. Feed amounts of BMP-2 36
D. In vitro stability test of immobilized BMP-2 38
IV. CONCLUSIONS 40
V. REFERENCES 41
