Titanium 표면거칠기에 따른 세포분화와 부착 유전자 발현 비교 연구

김병수 전남대학교 대학원 2003 국내석사

뼈 유착성 임플란트에서 뼈와 임플란트 표면 사이의 초기 뼈 형성과 긴밀한 접촉이 장기적인 임플란트의 성공을 위하여 필수적이다. 임플란트 주위에 뼈가 형성되는 과정에는 재료의 성질 외에 임플란트 자체의 표면 특성, 즉 표면거칠기 및 topography는 세포 반응에 영향을 미친다. 뼈모세포 또는 뼈모세포계열의 세포와 임플란트 표면과의 특이 반응은 궁극적으로 세포 표현형의 변화를 수반하게 된다. 현재까지 여러 형태의 임플란트 표면에 반응하는 세포 변화 및 변화 기전에 대하여는 알려진 바 없다. 본 연구는 MG 63 preosteoblast 세포주에서 상대적으로 매끈한 표면(smooth surface)과 거친 표면(rough surface)을 갖는 titanium 임플란트 재료에서 세포 분화와 기능 변화를 세포증식, 주사전자현미경 및 중합효소반응을 이용하여 구명하고자 시도되었다. 유전자 발현 변화는 COX-2, ERK-1, ERK-2, Type Ⅰ collagen, β-catenin, PLC-γ2, β-actin 등 세포 분화와 부착에 관여하는인자를 대상으로 하였다. 배양접시의 polystylene well 표면과 rough surface titanium과 smooth surface titanium의 표면거칠기 Ra 값은 각각 0.16±0.03 ㎛, 0.24±0.04 ㎛, 2.93±0.21 ㎛로 각 군간에 유의하게 차이가 있었다. 배양 18시간과 5일 모두에서 rough surface titanium의 세포 수는 smooth surface titanium에 비하여 유의하게 세포수가 적었다(p<0.01). 주사전자현미경적 소견에서 smooth surface titanium의 세포는 방추형으로 rough surface titanium에 비하여 세포 경계가 매끈하고 titanium 표면에 납작하게 부착되어 있었다. rough surface titanium의 세포는 smooth surface titanium에 비하여 세포경계가 비교적 거칠고 외형은 titanium 표면의 돌출부와 함몰부 사이를 따라 납작하지 않으며, 세포 윤곽이 뚜렷한 소견을 보였다. 상기 검사한 유전자 중 배양 18시간에서 erk2의 발현이, 배양 5일에서 erk1과 type Ⅰ collagen 유전자의 발현이 rough surface titanium에서 증가되어 있었다(p<0.05). 이상의 결과는 rough surface titanium(Ra = 2.93±0.21 ㎛)에서 세포는smooth surface titanium(Ra = 0.24±0.04 ㎛)에 비교하여 세포 증식보다는 분화를 향하며, 이 과정에 erk1과 erk2 등의 유전자가 관여할 것으로 사료된다. Early stage of bone formation and close contact between implant and tissue bed are important factors for successful osseointegrated dental implants. Surface characteristics of implant materials such as roughness and topography have effects on peri-implant tissue reaction in addition to chemical properties of dental implants. The specific reactions of osteoblasts or their lineages to implant surface accompany changes of their phenotype, even though their cellular mechanisms of changes have not been fully elucidated to date. This study was undertaken to unravel cell differentiation and functional changes, responding to implant surfaces, which are comparatively rough (Ra = 0.24±0.04 ㎛) and smooth (Ra = 2.93±0.21 ㎛). Cell proliferation, scanning electron microscopy and RT-PCR analyses for COX-2, ERK-1, ERK-2, Type I collagen, β-catenin, PLC-γ2, β-actin were carried using MG 63 preosteoblastic cells at 18 hours and 5 days of culture in vitro. The number of attached cells on rough surface titanium was less than that on smooth surface titanium at both 18 hours and 5 days of culture(p<0.01). Cells on smooth surface titanium were flat and spindle shaped and their margin was smooth. In contrast, cells on rough surface titanium seemed to be thicker and shaped following irregular pits and projections of the surface and their margin was irregular with many processes. At 18 hours of culture, erk2 gene expression in rough surface titanium was more than that in smooth. Similarly at 5 days of culture, erk1 and collagen I genes were more expressed than those of smooth surface titanium (p<0.05). These results suggest that rough surface titanium (Ra = 2.93±0.21 ㎛) directs preosteoblasts toward differentiation rather than cell proliferation, comparing smooth surface titanium (Ra = 0.24±0.04 ㎛), and several genes such as erk1 and erk2 would be involved in the cellular changes.

인간 중간엽 줄기세포에 재조합 Fibronectin 과 Elastin 으로 티타늄 표면의 생체 기능화와 생체 외 평가

박보현 인하대학교 대학원 2022 국내석사

티타늄은 우수한 기계적, 화학적 특성을 포함한 여러 중요한 요건을 충족하지만 생체 활성이 낮은 생체재료이다. 티타늄 표면에 대한 세포 반응과 골유착을 향상시키기 위해, 티타늄 표면의 생체기능화는 인간 줄기세포의 거동에 긍정적인 영향을 미치는 세포외 기질(ECM)과 유사한 미세환경을 모방하도록 활용되었다. ECM 중 Fibronectin과 Elastin은 생물학적 미세환경을 지원하여 줄기세포 분화를 조절하는 요소이다. 그러나 각각의 고유 ECM은 높은 생산 비용과 면역원성으로 인해 적합하지 않다. 이러한 문제점을 극복하기 위해 재조합 키메라 FNIII9-10 및 Elastin-like peptide 단편 (FN9-10ELP)을 개발하여 티타늄 표면의 생체 기능화에 적용하였다. 뼈 재생에 관한 생물학적 활성 및 세포 반응은 초기 폭발 효과 없이 FN9-10ELP 기능화 티타늄 표면에서 4주 동안 지속성을 나타냈다. 특히 FN9-10ELP가 코팅된 티타늄이 코팅되지 않은 티타늄보다 human mesenchymal stem cell (hMSCs)의 부착 및 증식을 향상시키는 것을 확인했으며, alkaline phosphatase (ALP) 활성 및 광물화 활성과 같은 골 분화 활성에 더 효과적인 것을 확인했다. 또한 collagen type I (Col I), Runt-related transcription factor 2 (RUNX2), osteopontin (OPN), osteocalcin (OCN), bone sialo protein (BSP), PDZ-binding motif (TAZ) 등 골 생성 관련 유전자의 발현을 향상시켰다. 따라서 생체 외 FN9-10ELP 기능화 티타늄은 생체활성을 지속시킬 뿐만 아니라 인간 줄기세포의 부착, 증식, 분화와 같은 세포 반응을 향상시킴으로써 골 재생을 위해 효과적인 것을 나타낸다. Titanium is a biomaterial that meets a number of important requirements, including excellent mechanical and chemical properties, but has low bioactivity. To improve cellular response onto titanium surfaces and hence its osseointegration, the titanium surface was bio-functionalized to mimic an extracellular matrix (ECM)-like microenvironment that positively influences the behavior of stem cells. In this respect, fibronectin and elastin are important components of the ECM that regulate stem cell differentiation by supporting the biological microenvironment. However, each native ECM is unsuitable due to its high production cost and immunogenicity. To overcome these problems, a recombinant chimeric fibronectin type III9-10 and elastin-like peptide fragments (FN9-10ELP) was developed herein and applied to the bio-functionalized of the titanium surface. An evaluation of the biological activity and cellular responses with respect to bone regeneration indicated a 4-week sustainability on the FN9-10ELP functionalized titanium surface without an initial burst effect. In particular, the adhesion and proliferation of human mesenchymal stem cells (hMSCs) was significantly increased on the FN9-10ELP coated titanium compared to that observed on the non-coated titanium. The FN9-10ELP coated titanium induced osteogenic differentiation such as the alkaline phosphatase (ALP) activity and mineralization activity. In addition, expressions of osteogenesis-related genes such as a collagen type I (Col I), Runt-related transcription factor 2 (RUNX2), osteopontin (OPN), osteocalcin (OCN), bone sialo protein (BSP), and PDZ-binding motif (TAZ) were further increased. Thus, the in vitro FN9-10ELP functionalization titanium not only sustained bioactivity but also induced osteogenic differentiation of hMSCs to improve bone regeneration.

Effect of silver addition on corrosion resistance and biocompatibility of Nickel-Titanium alloy

주욱현 Graduate School, Yonsei University 2007 국내박사

Nickel-titanium 합금은 형상기억효과와 초탄성 특성을 가진 재료로서, 항공산업 분야, 일반 산업 분야, 의료 분야 등에서 많이 사용되고 있다. Nickel-titanium 합금은 nickel과 titanium의 정확한 원자수 비, 제 3 원소 첨가, 가공 공정 등에 매우 민감한 재료로서, 반복 하중에 대한 피로특성 개선 등의 목적으로 Cu, Fe 등 제 3원소를 첨가하기도 한다. 그러나 합금 원소 첨가에 따라 불안정한 피막을 형성, 내식성을 감소시키는 문제점이 있으며, 높은 내식성을 요구하는 의료 분야에서는 그 사용에 있어 주의가 요구되고 있다. 본 연구에서는 nickel-titanium 합금에 소량의 은 (Ag) 첨가에 다른 합금의 부식저항성, 생체적합성에 미치는 영향을 알아보고자 하였다. 합금은 아크 용해로에서 제조하여, 균질화 열처리, 열연공정, 용체화 열처리 등의 과정을 거쳐 판상 형태로 제작하였다. 원자수비 1:1인 nickel-titanium 합금과 은 (Ag)이 첨가된 nickel-titanium 합금에 대하여, 일반적인 특성을 평가하고자 상 분석, 미세조직관찰, 변태온도 측정, 경도 시험을 실시하였으며, 전기화학적 특성 분석을 통하여 실험합금의 내식성을, 표면 분석, Ni 이온 용출 실험, 세포독성 평가 등을 통해 생체적합성 평가를 시행하였다.은(Ag)이 첨가된 nickel-titanium 합금은 Ni이나 Ti에 비해서 낮은 은(Ag) 회수율(28.5~41.5%)을 나타내었으며, 오스테나이트와 마르텐사이트 상이 혼합된 구조를 나타내었다. 은(Ag)이 첨가됨에 따라 마르텐사이트 상의 비율이 증가하였다. 은(Ag)이 첨가된 nickel-titanium 합금은 첨가되지 않은 nickel-titanium 합금과 비교 시 변태온도가 증가하였으며, 경도값은 증가하지 않았다(p>0.05). 전기화학적 특성 실험을 통해 합금의 내식성을 평가한 결과, 동전위 실험에서는 10 ㎂/cm2 이하의 낮은 부동태 전류밀도를, 정전위 실험 상에서는 시간이 지남에 따라 1 ㎂/㎠ 이하의 안정된 전류밀도 분포를 나타내었다.XPS를 통해 얻어진 스펙트럼을 분석한 결과, 실험 합금 표면 피막 층은 주로 TiO2 등의 티타늄 산화물로 구성되어 있었다. 은(Ag)이 첨가된 nickel-titanium 합금의 피막 바깥층에서는 Ni이 관찰되지 않았으며, 피막 안쪽층에서 금속 상태의 Ni과 Ag이 존재하는 것으로 관찰되었다.은(Ag)이 첨가된 nickel-titanium합금은 첨가되지 않은 nickel-titanium 합금과 비교 시 Ni 이온 용출량에 대한 유의차가 없었으며(p>0.05), 세포 독성을 나타내지 않았다.이상의 결과로 은(Ag)이 첨가된 nickel-titanium 합금은 변태온도를 높이고, 내식성을 향상시키며, 안정된 산화막을 구성하여, 생체재료로 사용이 가능할 것으로 판단된다. 앞으로 다양한 분야에 생체재료로 사용하기 위해서, 은(Ag)이 첨가된 nickel-titanium 합금에 대한 화학적 안정성, 변태온도 조절, 가공 공정에 대한 연구가 더 필요할 것으로 생각된다. The equiatomic or near-equiatomic nickel-titanium alloys are unique materials which possess a shape memory effect and superelasticity and they have come to be widely used not only in aerospace engineering but also in industrial and medical fields. However the properties of such alloys are extremely sensitive to the precise nickel-titanium ratio, the addition of alloying elements and processing etc.. For the purpose of improving fatigue property, a third element such as Cu and Fe is added to nickel-titanium alloy. But because nickel-titanium alloys form unstable passive film or reveal lowered corrosion resistance depending on third elements, a cautious approach is needed in medical applications which require high corrosion resistance. The purpose of this research was to investigate the effect of silver addition to nickel-titanium alloys on corrosion resistance and biocompatibility for biomedical application. Arc melting, homogenization, hot rolling and solution heat treatment were performed to prepare silver added nickel-titanium alloys. First, the physical properties of the experimental nickel-titanium alloys were investigated by phase identification, phase transformation temperature and microhardness. The corrosion resistance was evaluated by electrochemical test. The effect of silver addition on the biocompatibility of the alloys was studied by surface characterization, ion release test and cytotoxicity.In the case of silver added nickel-titanium alloys, the actual silver contents were less than the silver contents added in this study. The recovery rate for silver range was 28.48 ~ 41.50%. The silver added nickel-titanium alloys had mixed austenitic and martensitic phase and exhibited high martensitic fraction. Silver added nickel-titanium alloys increased the transition temperature range and did not show an increase in hardness value, compared with nickel-titanium alloy (p>0.05). From the results of the electrochemical test, the silver addition was considered to improve corrosion resistance and form a stable passive film. In potentiodynamic test, silver added nickel-titanium alloys had low passive current densities below 10 ㎂/cm2. Also, the current densities of alloys rapidly decreased with immersion time and subsequently showed a stable potentiostatic behavior below 1 ㎂/㎠. According to high resolution spectral analyses for spectra, the surface film formed on experimental nickel-titanium alloys was mainly titanium oxide, such as TiO2. For the silver added nickel-titanium alloys, nickel element was not observed in the outer layer of the passive film and the silver existed as metallic state in the inner layer of the passive film. From the results of ion release test, there was no significant difference in nickel ion release depending on silver content, compared to nickel-titanium alloy (p>0.05). The silver added nickel-titanium alloys showed almost no toxicity and the cell viability above 80%, compared to nickel-titanium alloy.From the above results, we concluded that silver added nickel-titanium alloys increased their transformation temperatures, strengthened their corrosion resistance and formed a stable oxide film. Further study on the biocompatibility, the chemical stability of the passive film, transformation temperature change, and the working process for these alloys is necessary to ensure that these materials can be safely used in the dental and medical fields.

타이타늄 터닝 스크랩의 전처리 및 Ca-Mg 복합 탈산을 활용한 저산소 분말 제조

채지광 전북대학교 일반대학원 2021 국내석사

Titanium is widely used in aerospace and medical implants due to its high specific strength and excellent corrosion resistance. Accordingly, the generation of titanium scrap after mechanical processing or use is also increasing. These titanium scraps are exported to foreign countries at a low price and are being imported again as titanium ingots at high prices. In addition, the demand for metal powder according to the recent development of the additive manufacturing method is increasing. Therefore, in this study, hydrogenation-dehydrogenation comparison experiment was conducted between titanium turning scrap and titanium ingot for recycling of titanium alloy scrap. The titanium turning scrap was pretreated to remove impurities, and the pretreated scrap was used to cast an ingot through arc melting. The cast titanium ingot and compressed titanium turning scrap were charged into a hydrogenation furnace, and the hydrogenation effect according to hydrogen pressure was compared. The hydrogenated titanium turning scrap and ingot were pulverized to prepare powder, and dehydrogenation was performed in a vacuum heat treatment furnace. The powder thus prepared was pickled and washed with water, and then the titanium powder was dried in a vacuum chamber. The dried powder was subjected to XRD, SEM, and oxygen/nitrogen analysis to compare hydrogenation-dehydrogenation behavior. To manufacture titanium scrap into powder, a hydrogenation-dehydrogenation (HDH) process is used to increase the oxygen content of titanium. To solve this, calcium is used, but there is a disadvantage that the deoxidation temperature is relatively high. Therefore, in this study, magnesium was mixed with calcium and deoxidation was carried out at a low temperature. The titanium scrap was hydrogenated and pulverized to prepare titanium hydrogenated powder, and the powder was deoxidized at a temperature of 600°C to 800°C through steam deoxidation in a vacuum atmosphere using a composite deoxidizer mixed with calcium and magnesium. In addition, the hydrogenation powder and the dehydrogenation powder were deoxidized, and the final oxygen content was comparatively analyzed by deoxidation with the powder before and after dehydrogenation.

Development of Titanium-Organic Materials as Porous Photocatalysts

Yesub Keum DGIST 2022 국내박사

광촉매 TiO₂ 나노 튜브의 제조와 특성

기범수 國民大學校 大學院 2007 국내석사

Titanium은 산소와 쉽게 반응하여 산화 피막을 형성하며 이러한 피막은 내식성 및 생체 적합성 특성이 있으며, 광촉매용 TiO_(2)는 반도체특성을 가지고 있어 촉매 표면에서 밴드 갭(band gab)에너지 이상의 광 에너지를 받으면, valence band에서 전자가 반응하여 conduction band로 여기 된다. 이때 활성산소의 생성과 물 분자의 배위가 일어나 산소로부터는 슈퍼 옥사이드 (O_(2)^(-)), 물로부터는 수산화 라디칼(·OH)이 생성된다. 이렇게 생성된 인자는 유기물 분해 기능이 있어, 환경정화, 탈취, 항균, 자정(self-cleaning) 등에 이용되고 있다. 또한 최근에는 TiO_(2) 피막의 나노 기공 구조를 이용하여 정보 통신 및 에니지 분야에 대한 활용 연구가 활발히 진행되어 수소 저장장치에 응용을 하거나 태양전지의 활용의 응용으로도 많은 연구를 하고 있다. 한편으로 나노 튜브 구조의 응용에 관한 연구도 많은 관심의 대상이 되고 있다. 그러나 TiO_(2) 나노 튜브 제조 및 공정 조건에 따른 나노 튜브의 형성 및 성장에 미치는 영향에 대한 보고가 아직 많지 않은 실정이다. 이러한 광촉매 재료의 실용화를 위해서는 기지재료와의 밀착성과 이용광원의 가시광화가 이루어져야 한다. 양극 산화에 의해 제조된 산화 타이타늄의 피막은 밀착성의 측면에서 우수한 특성을 가질 뿐만 아니라, 간단한 장치만으로 그 제조가 가능한 장점을 가지고 있어 이러한 전기화학적 방법으로 광촉매용 튜브를 제조할 경우 광 에너지와의 반응으로 이루어지는 특징 때문에 표면적을 극대화한 것은 광촉매 반응 또한 극대화 되리라 여겨져 연구를 시작하였으며 제조 과정에서 생기는 변수를 제어하기 위해 조건들을 찾아 나갔다. 본 실험에서는 양극 산화법을 이용하여 HF를 전해액으로 사용하고 전압과 시간에 변화를 주어 티타늄 산화 튜브의 전해 조건에 따른 산화 튜브의형성과 성장 거동에 대하여 조사하였다. 기본적인 실험방법은 전처리 과정으로 상업용 Ti(99.9%)를 acetone으로 탈지를 하였으며 기계적 연마와 HF, HNO_(3) 혼합 용액에서 화학적 연마를 실시하였고 전압, 전류, 극간간격(WD), 전해액의 농도, 열처리 온도조건 등을 변화시켜 제조의 최적의 조건을 찾았다. 하지만 전해액으로 사용한 HF는 생체에 미치는 악영향으로 다른 전해액을 사용하여 titanium oxide nano tube를 제조하기 위한 연구도 병행하였다. 전해액으로는 HF를 대신하여 Glycerol / HN_(4)F, Ethylene Glycol / HN_(4)F, (NH_(4))_(2)SO_(4) / HN_(4)F, Glycerol/ HN_(4)F와 Ethylene Glycol/HN_(4)F는 표면에 산화물이 많이 형성되어 후처리가 요구되며 HF는 강한 부식성을 가지고 있어 표면에 산화물이 형성되지 않았지만 산화물을 용해시켜 tube의 두께가 짧은 것으로 나타났다. 또한 (NH_(4))_(2)SO_(4) / HN_(4)F는 titanium oxide nano tube의 길이가 길어졌으며 표면에 산화물이 형성되지 않지만 tube중간 중간에 hole이 생기는 것으로 확인 되였다. 양극산화에 의해 제조된 TiO_(2) nano tube는 온도 조건에 따라 광촉매 반응을 일으키는anatase type과 Rutile type의 결정형이 나타났으며, 이러한 방법에 의해 제조된 TiO_(2) nano tube를 광촉매 특성중 하나인 분해효율성을 알아보기 위하여 aniline blue 용액에서의 90min 동안 자외선을 조사 시킨 후 spectrometer로 분석하였다. Titanium oxide is one of the most widely studied chemical substances because of its variety of application in catalytic, gas-sensing and corrosion-resistance materials. Moreover, it is gaining considerable interest due to unique and excellent properties in optics, electronics, photochemistry and biology. Anodic oxidation is a commonly used surface treatment method especially in forming porous alumina structure; which has been widely studied. Many kinds of nano-structures including nano-wires, nano-rods and nano-tubes have been fabricated by taking nano-porous alumina as templates. Titanium and aluminum are both classified as'valve metals' because their surfaces are immediately covered with a native oxide film of a few nano meters when these metals are exposed to oxygen-containing surroundings. Naturally it is a meaningful work to investigate whether other valve metals such as Ti can also be used as nano template materials. There were a few attempts to compare anodic oxide growth on other value metals with porous alumina. Electrochemical oxidization of titanium has been studied in sulfuric acid, phosphoric acid, acetic acid and chromic acid with or without HF solution. Different morphologies were obtained in oxidized titanium compared with alumina can not be copied in the forming of porous titanium oxide. This study investigates the oxidation process of titanium in HF electrolyte via constant-voltage experiments. Undered nanotubes of titanium oxide were fabricated. TiO_(2) oxide nano tube with the thickness of approximately 2㎛ was fabricated to analyze the micro structure and phocatalytic characteristics of anodic oxide nano tube under the different conditions, including an applied voltage, anodizing time in constant voltage region and constant current region. It was considered that the pore diameter and micro structure variations were largely controlled by an applied voltage, anodizing time, electrolyte concentration, waking distance(WD), kind of electrolyte. A possible growth mechanism is presented. The nano tube arrays of titanium oxide are very interesting and may have many potential applications in catalytic micro structure and growth behaviors of anodic oxide layers on titanium were investigated. The anodic TiO_(2) layer formed at the photocatalytic efficiencies of TiO_(2) were evaluated by the rate of decomposition of aniline blue, which depended on the surface condition of an anodic oxide film. The decomposition rate of aniline blue for the TiO_(2) film formed at 20V was higher than that of the TiO_(2) film formed at 20V. Also, TiO_(2) nano tube was produced under 20V in the anodic oxidation using the HF and kind of electrolyte. The thickness of TiO_(2) oxide film was about 2㎛ on pure titanium. The micropores began to be clearly observed as the applied voltage approched to the voltage, and the pore diameter increasing voltage. Thus, titanium was anodized using the D.C.-constant voltage method to form an anodic oxide nano tube with the thickness of approximately 2㎛ on titanium. The pore diameter and the cell size were proportional to the anodizing voltages, and it was indicated that the pore initiation and growth were largely controlled by the field-assisted oxide dissolution. Meanwhile, the micro structure and growth behaviors of anodic oxide layers on titanium were investigated. The anodic TiO_(2) layer formed at 20V showed a cell structure with more irregular pore shapes around the interface between the TiO_(2) nano tube.

Titanium 화합물의 카르보닐기에 대한 화학적 입체적 선택성에 관한 연구

김주경 建國大學校 大學院 1991 국내석사

유기금속화합물은 유기합성 분야에서 중요한 역할을 하고 있다. 그러나 고전적 유기금속인 Benzyl magnesium chloride처럼 반응성은 높으나 화학적 선택성이 낮은 결점이 있다. 이러한 문제점을 해결하기 위해 본 연구에서는 Benzyl magnesium chloride에 Titanium tetrachloride를 첨가하여 화학적 선택성을 가진 Benzyl titanium trichloride를 만들어 이 화합물의 선택성을 규명하고자 하였다. 또한, 광학활성을 가진 Titanium-complex 촉매를 만들어 Enantiselectivity를 높이기 위해 Triisopropoxy titanium chloride, Titanium tetrachloride, Diisopropoxytitanium dichloride를 L-(+)Tatrate와 반응시켜 광학활성을 가진 phenylallyl alcohol과 mandelonitrile을 만드는 과정을 규명하였는데 앞으로 광학활성을 가진 물질을 개발하기 위한 새로운 방법들이 연구되어야 할 것이라 생각된다. Though the classical carbanion, for example, alkyllithium or Grignard reagent, show high reactivity for the carbonyl compound, they react with low selectivity. On the other hand, it is well known that organotitanium compounds generally expressed as RTiX_(3) or R_(2)TiX_(2)( R = Alkyl, Alkoxy ) have high chemo and streoselectivity. In this study, benzyl titaniumtrichloride(Ⅳ) was prepared from benzyl magnesium chloride and titanium tetrachloride in situ and was added to the mixture of carbonyl compounds in other to investigate its reactivity. And titanium-L-(+) tatrate catalyst was prepared from L-(+) diisopropyl tatrate and titanium compounds in situ and was added benzaldehyde in other to investigate its enantioselectivity. As a result, bengyl titanium trichloride(Ⅳ) reagent was proved to have the same aldehydes reactivity selectivity in competition reaction between aldehydes and ketones as the other organotitanium compounds but it was not revealed that titanium-L-(+) tatrate catalyst has enantioselectivity in cyanohydrine synthesis.

타이타늄 스크랩을 활용한 저산소 타이타늄 합금 분말의 제조 및 탈산 거동

김태헌 전북대학교 일반대학원 2019 국내석사

Titanium and titanium alloys boast excellent performance in aerospace, biomaterials and military industries due to their high strength-to-weight ratio and good corrosion resistance, but are limited by high cost issues. For this reason, researches are actively conducted to solve the problem of the cost of titanium by recycling a large amount of scraps. The most economical way to recycle titanium scraps is the HDH process, which is called the hydrogenation-dehydrogenation process. However, due to the increase of the oxygen content in the pulverization process, the sintering density is decreased and the adverse effect of physical properties. The deoxidation process must be accompanied  Studies on the deoxidation of titanium powders have made considerable progress, but most studies have been limited to pure titanium. As a result, studies on oxygen control of titanium alloy powders have not been studied so far, and studies on deoxidation of titanium alloy powder are indispensable to utilize titanium alloys used in various industrial fields.  Therefore, this study recycled titanium scraps to fabricate titanium alloy powder and deoxidation using calcium vapor to produce extra low oxygen titanium alloy powder and investigate the change of properties accordingly.

생체응용을 위한 티타늄 표면의 개질: 물리화학적 특성과 생물학적인 평가

매드하프라사드 전북대학교 대학원 2009 국내박사

Metallic titanium and its alloys have become key materials for biomedical applications, mainly owing to their compatibility with human tissues and their mechanical strength. They are used as implant materials such as dental implants and various orthopedic and osteosynthesis systems in contact with bone. Titanium covered with a passive oxide film, is a rather bioinert material. Titanium and its alloys have high enough strength and toughness to bear loads. In order to obtain the favorable properties of titanium metal as implantation, titanium surfaces are modified with different methods. A number of different surface modification methods have been invented and developed; of which many suffer from low durability and relatively low adhesion of coating on the metal substrate. This thesis deals with the modification of pure titanium surface by different methods anodic oxidation, quenching, and cyclic voltammetry to obtain favorable properties of titanium surface with improved coating integrity and adhesion. The resulting modified surfaces were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometer (EDS), X-ray Diffraction (XRD), and surface roughness test by using Surftest Formtracer. Also after modifying the titanium surfaces the biological in vitro evaluation was performed. Chapter I of this thesis highlights literature overview of history and types of methods of surface modification of titanium, applications, and effects of surface characteristics on biological responses with modified surfaces. Remaining chapters demonstrate the modification, characterization and their potential applications in in vitro biological evaluation. Chapter II highlights the control quenching of titanium metal to obtain metal products having particular surface properties. Quenching of metal also relive the internal stresses of metal. This chapter focuses on surface topography, roughness, crystallite size, and crystal intensity of quenched surface with heating temperature. Cytotoxicity of the quenched surface was evaluated with MTT assay. The surface roughness and crystallite size was increased and cytotoxicity of quenched surface was decreased as the heating temperature increased. Similarly, crystalline intensity was varied at different temperature. In chapter III, micro-arc oxidation (MAO) surface modification method is evaluated as a technique to obtain the favorable properties of titanium with improved coating integrity and adhesion. MAO, an advanced anodization method, allows for anodic oxide layer formation and incorporation of P ions from electrolyte in one single process step. The method exploits the dielectric breakdown of anodic oxide film at high electrical field strength to produce a porous oxide layer with a thickness of a few micrometers that contains different amounts of P ions. A major advantage is the interfacial integrity as a result of the electrochemical reaction between titanium metal and electrolyte. Additionally, MAO is a fast single-step process that is less expensive and much more suited to coat implants than other deposition process such as plasma spraying. This chapter focuses on two main topics: ● The investigation of the MAO surface modification process, also known as anodic spark deposition, interms of process mechanism and the influence of process parameter “electrolyte pH” on the resulting MAO coating properties. ● The development of bioactive coating consisting of a phosphated titanium oxide matrix that facilitates possible growth of hydroxyapatite as well as osteoblast response. Firstly, the influence of the process parameter “electrolyte pH” on the dielectric breakdown properties, the coating structure, crystallinity, and chemical composition were investigated by using phosphate buffer electrolyte. The resulting coatings were characterized using SEM, EDS, XRD and surface roughness test. It was illustrated that the parameter “electrolyte pH” influences the surface topography, crystallinity, and surface roughness of modified surface. Secondly, the phosphate buffer electrolyte with different pH was found to incorporate P ions in MAO coatings with different quantity. A cell-culture study was carried out with MC3T3 mouse osteoblasts in order to test the biocompatibility of the coating with different pH modified surfaces in comparison to uncoated CP titanium surfaces. The results indicated that the MAO coatings are not less biocompatible than the commercially available implant surfaces with respect to cell growth and cytotoxicity evaluation. Finally, the MAO process was investigated by means of a high-resolution SEM to study the mechanism of film formation. Chapter IV deals the formation of titanium oxide nanotubes in acidic fluoride solution by anodic oxidation. After the formation of nanotubes its stability and crystal phase transition was studied at different temperatures. Finally, formation model of titanium oxide nanotube was proposed. At the end, chapter V demonstrates the corrosion of titanium metal at different electrolyte pH. Also the numbers of potentiodynamic cycles were applied on previously formed oxide film. The corrosion of metal linearly depends on electrolyte pH as well as number of potentiodynamic cycles. In summary, the thesis will direct the idea of different surface modification methods, which can provide a better method as compared to either one method. And it also appreciates to use those modified implant materials that comes from the different modification methods would be the best candidate in the future for dental and orthopedic implant.

Enhancing Biological Activity of Porous Titanium Scaffolds via Functional Surface Treatments

이현 서울대학교 대학원 2019 국내박사

Porous titanium (Ti) scaffolds have been widely used for orthopedic and dental applications because merits of titanium, which is represented by excellent mechanical properties, chemical stability, and good biocompatibility and porous structure are combined. Especially for porous structure, this could reduce stress shielding effect resulting from reduced elastic modulus, and infiltration of body fluid through pores leads to homogeneous bone regeneration. However, the improvement of effective osseointegration ability is still required to accomplish sufficient fixation between the scaffolds and surrounding bone. Thus, various surface treatments have been adopted to modify surface and pore characteristics. In the first study, porous Ti6Al4V scaffolds with enhanced biocompatibility were obtained by coupling dynamic freeze casting (DFC) method with modified micro-arc oxidation process (MAO). The fabricated scaffolds exhibited tailored pore characteristics with interconnected pores. Compressive strength and elastic modulus were controlled by adjusting the porosity of the scaffolds. Modified MAO process was successfully performed on the porous Ti6Al4V scaffolds by inhibiting gaseous emission from the electrolysis of water with the addition of ethanol to the MAO solution. Moreover, the biological response of pre-osteoblast cells on the MAO-treated porous Ti6Al4V scaffolds was enhanced owing to their porous topography and modified chemical composition. In the second study, functionally graded porous Ti scaffolds generated by two body combination with densification process were developed, which can simultaneously release growth factor (rhBMP-2) and antibiotics (TCH). Inner dense and outer porous scaffolds were successfully fabricated and significantly different pore characteristics were observed by scanning electron microscopy (SEM) and micro CT. Mechanical properties of them proved their applicability as bone substitutes with sufficient strengths and elastic modulus in the range of real bone. Sustained release of rhBMP-2 was obtained by altered tortuosity through densification, whereas TCH was released in relatively earlier stage. To monitor effectiveness of remaining biomolecules inside the scaffolds, series of in vitro cell tests and anti-microbial tests were conducted using the scaffolds after releasing for certain time intervals. Notable differences in the degree of cell differentiation were observed in functionally graded porous Ti scaffolds compared to control groups resulted from higher amount of remaining rhBMP-2. And anti-microbial properties appeared in relatively short period of time, which is essential to reduce early stage inflammation reaction after surgery. In the third study, acidic solution combined with HF and HNO3 was treated to efficiently modify pore characteristics and mechanical properties of porous Ti scaffolds. The porosity, pore size, wall thickness, and pore neck size were easily controlled by varying the acid treatment time, which produced scaffolds with mechanical properties that were suitable for bone tissue engineering. As the mixed acid treatment time increased, internal isolated pores were gradually interconnected with adjacent pores. After 10 min of treatment, nearly all the pores were interconnected. The post-treatment with HF/HNO3 also affected the surface properties. Surface carbon contaminants were significantly reduced after treatment with no hydride formation. Micron-scale surface roughness was uniformly generated across the whole surface. The actual cell penetrability of the Ti scaffold was evaluated using a perfusion-based in vitro cell test. Over 90% of the surface pores depict cell penetrability with a sufficient number of cells attached to the wall surface of the pore after performing acid treatment for 12 min. In conclusion, these researches adopted different techniques to enhance functional ability of porous titanium and titanium alloy for biomedical applications. Enhanced biological properties were obtained by adopting modified MAO process to porous Ti6Al4V scaffolds and drug loading in functionally graded porous titanium scaffolds. Improved pore interconnectivity for cell penetration through porous titanium scaffolds were achieved through simple HF/HNO3 treatment for short period of time. 다공성 티타늄 (Ti) 지지체는 우수한 기계적 성질, 화학적 안정성, 우수한 생체 적합성으로 대표되는 티타늄의 장점과 다공성 구조가 결합되어 정형 외과 및 치과 용으로 광범위하게 사용되어 왔다. 특히 다공성 구조의 경우, 탄성 계수 감소로 인하여 응력 차폐 효과를 감소시킬 수 있으며, 기공을 통한 체액의 침투는 균질 한 골 재생을 유도한다. 그러나 효과적인 골 유착 능력의 향상은 지지체와 주위 뼈 사이에 충분한 고정을 이루기 위해 여전히 요구된다. 따라서 다양한 표면 처리가 표면 및 기공 특성을 변화시키기 위해 도입되었다. 첫 번째 연구에서는 동적 동결 주조 (DFC) 방법과 마이크로 아크 산화 공정 (MAO)을 결합한 다중 다공성 Ti6Al4V 지지체를 제조하였다. 제작된 지지체는 상호 연결된 조절된 기공 특성을 보였다. 압축 강도와 탄성 계수는 지지체의 기공률을 조절하여 조절하였다. MAO 용액에 에탄올을 첨가하여 물의 전기 분해로부터 발생하는 기체 방출을 억제함으로써 다공성 Ti6Al4V 지지체상에 MAO 공정을 성공적으로 도입하였다. MAO 처리된 다공성 Ti6Al4V 지지체에 대한 조골세포의 생물학적 반응은 다공성 형상 및 변화된 화학 조성으로 인해 향상되었다. 두 번째 연구에서는 치밀화 공정이 도입된 이체 조합 방법을 이용하여 성장 인자 (rhBMP-2)와 항생제 (TCH)를 동시에 방출할 수 있는 기능성 경사능 다공성 티타늄 지지체를 개발하였다. 내부의 고밀도 구조 및 외부의 다공성 구조를 갖는 지지체가 성공적으로 제조되었으며 주사 전자 현미경 (SEM) 및 마이크로 CT를 통하여 현저히 다른 기공 특성을 관찰하였다. 이들의 기계적 특성은 충분한 강도의 탄성 계수를 나타내며 이는 실제 골의 범위 내에 존재하여 골 대체제로서의 적용 가능성을 입증하였다. rhBMP-2의 지속적인 방출은 치밀화를 통한 변화된 기공 복잡도에 의해 얻어졌고 TCH는 비교적 초기 단계에서 방출되었다. 지지체 내부의 잔류 생체 분자의 유효성을 확인하기 위해 일련의 세포 시험 및 항균능 시험이 일정 시간 간격 동안 방출이 진행된 지지체를 사용하여 수행되었다. 잔류 rhBMP-2의 양이 대조군에 비하여 기능성 다공성 티타늄 지지체 내부에 더 많아 세포 분화 정도에서 현저한 차이를 보였다. 그리고 항균성은 수술 후 초기 염증 반응을 줄이는데 필수적인 비교적 단기간에서 나타났다. 세 번째 연구에서, HF와 HNO3가 결합된 산성 용액은 다공성 Ti 지지체의 기공 특성과 기계적 성질을 효과적으로 변화시키기 위해 처리되었다. 다공성, 기공 크기, 벽 두께 및 공경 (pore neck)의 크기는 산처리 시간을 변화하여 쉽게 제어할 수 있었으며 기계적 성질 역시 갖는 경조직 공학에 적합한 정도로 조절할 수 있었다. 혼합된 산처리 시간이 증가함에 따라, 내부 분리된 기공이 인접한 기공과 점진적으로 상호 연결되었다. 10 분간의 처리 후 거의 모든 기공이 서로 연결되었다. HF/HNO3를 사용한 후 처리는 표면 특성에도 영향을 미쳤다. 표면 탄소 오염물은 처리 후 수소화물 형성 없이 현저히 감소되었다. 마이크로 단위의 표면 굴곡이 전체 표면에 걸쳐 균일하게 생성되었다. Ti 지지체의 실제 세포 침투성은 관류 기반 세포 시험을 사용하여 평가되었다. 표면 기공의 90 % 이상에서 세포가 관찰되었으며 12 분 동안 산처리가 된 시편에서 기공의 표면에 충분한 수의 세포가 부착된 것을 확인하였다. 결론적으로, 이러한 연구는 다공성 티타늄 및 티타늄 합금의 생체의료용 응용을 위하여 기능적 능력을 향상시키는 다양한 기술을 도입하였다. MAO 과정을 다공성 Ti6Al4V 지지체에 적용하여 향상된 생물학적 성질을 얻었으며, 약물이 탑재된 기능성 경사능 다공성 티타늄 지지체도 성공적으로 제조되었다. 짧은 시간 동안 간단한 HF/HNO3 처리를 통해 세포가 침투할 수 있는 향상된 기공 연결도를 달성하였다.