Synthesis and Characterization of Brush Polymers Bearing Various Biomolecule Bristle Ends

DoctorPolymeric materials of any dimensions, including miniaturized and multilayer structure, can easily be processed at low cost and have high flexibility, high mechanical strength, and good scalability. Furthermore, their properties can easily be tailored through chemical synthesis. Through chemical bonding of specific molecules to the polymer backbone or side chain, the function of polymer can be changed. With such advantages, there has been significant research effort in recent years in the field of brush polymer.Brush polymers were first reported in the 1940s with the synthesis of a polyvinyl polymer with n-alkyl side groups. Brush polymers have since received significant attention from both academia and industry because their numerous end groups permit high loading of desirable functional groups onto the polymer. Research efforts developed synthetic routes to new functional brush polymers, and the structures and properties of these new polymers have been investigated. Several interesting brush polymer systems have been described as potential candidate materials for applications in a range of fields, such as biomaterials, microelectronics, flat panel displays, optics and optoelectronics, solar cells, adhesives, and gas separation techniques.In the area of biomaterials, biomolecule-mimicking brush polymers may be useful in a variety of solid forms as biocompatible coating materials, tissue culture materials, biomedical sensor materials, protein separation membranes, and gene delivery carriers. Most of these applications require formation of nanoscale thin films with control over the nanostructures.In Chapter II, New DNA-mimicking brush polymers were synthesized: poly[oxy(11-(3-(9-adeninyl)propionato)-undecanyl-1-thiomethyl)ethylene] (PECH-A), poly[oxy(11-(thyminyl- 1-aceto)-undecanyl-1-thiomethyl)ethylene] (PECH-T), poly[oxy(11-(3-(9-guanyl)propionato)-undecanyl-1-thiomethyl)ethylene] (PECH-G), poly[oxy(11-(N4-acetylcytosinyl-1-aceto)-undecanyl-1-thiomethyl)ethylene] (PECH-C), and poly[oxy(11-(urasilyl-1-aceto)-undecanyl-1-thiomethyl)ethylene] (PECH-U). These polymers were found to be thermally stable up to 220 C and could be applied easily by conventional coating processes to produce good quality films. Interestingly, brush polymers formed molecular layer structures to provide nucleobase-rich surfaces. The nucleobase-rich surfaces of the polymer films demonstrated selective protein adsorption, suppressed bacterial adherence, facilitated HEp-2 cell adhesion, and exhibited good biocompatibility in mice.In Chapter III, We synthesized two new DNA-mimicking brush polymers: poly[oxy(11-(3-(9-adeninyl)propionato)-undecanyl-1-thiomethyl)ethylene] (PECH-AP) and poly[oxy(11-(5-(9-adenylethyloxy)-4-oxopentanoato)undecanyl-1-thiomethyl)ethylene] (PECH-AS). These polymers were found to be thermally stable up to 220 C and could be applied easily by conventional coating processes to produce good quality films. Interestingly, both brush polymers formed molecular multi-bilayer structures to provide an adenine-rich surface. Despite the structural similarities, PECH-AS surprisingly exhibited higher hydrophilicity and better water sorption properties than PECH-AP. These differences were attributed to the chemical structures in the bristles of the polymers. The adenine-rich surfaces of the polymer films demonstrated selective protein adsorption, suppressed bacterial adherence, facilitated HEp-2 cell adhesion, and exhibited good biocompatibility in mice. However, the high hydrophilicity and good water sorption characteristics of the PECH-AS film suggest that this brush polymer is better suited to applications requiring good biocompatibility and reduced chance of bacterial infection compared with the PECH-AP film.In Chapter IV, we synthesized novel brush polymers bearing thymine moieties in which the chemical loading of thymine moieties is maximized and that self-assemble into molecular layer-by-layer structures (i.e., molecular lamellar structures) and provide thymine-rich surfaces: poly(oxy(11-thyminoacetyloxyundecylthiomethyl)ethylene) (PECH(S)-T) and poly(oxy(11-thyminoacetyloxyundecylsulfonylmethyl)ethylene) (PECH(SO2)-T). These brush polymers are thermally stable up to around 225C. PECH(S)-T exhibits relatively high water sorption whereas PECH(SO2)-T exhibits low water sorption. The synchrotron grazing incidence X-ray scattering (GIXS) analysis found that thin films of PECH(S)-T are amorphous but that it forms a molecular lamellar structure in water as well as in metal ion solutions, whereas thin films of PECH(SO2)-T always have molecular lamellar structures providing thymine-rich surfacesthis lamellar structure is retained in water and metal ion solutions. Surface plasmon resonance spectroscopy (SPRs) analysis was performed and it was found that PECH(SO2)-T exhibits excellent sensitivity, selectivity, and reversibility in sensing mercury ions in aqueous solutions, with properties that are superior to those of PECH(S)-T. We propose a strategy based on the control of morphological nanostructure for developing high performance polymers for the chemical monitoring of metal ions.In Chapter V, we synthesized novel poly(ethylene oxide) based brush polymers with glucose bristle end. The brush polymers are thermally stable up to 200 °C and present excellent processabilitynanometer-scale thin films of the polymers with smooth surfaces are easy to produce through simple spin-, roll- and dip-coating, and subsequent drying process. In thin film states, brush polymers exhibit molecular layer structures with stable glucose-rich surfaces. Surfaces of brush glycopolymers suppressed protein adsorption and promoted HEp-2 cell adhesion. Furthermore, the brush polymer revealed biocompatibility in mice.In Chapter VI, A series of well-defined brush polymers, poly(oxy(11-(3-sulfonylpropyltrimethyl-glycinyl)undecylesterthiomethyl)ethylene-co-oxy(n-dodecylthio-methyl)ethylene)s (PECH-DMAPSm, where m is the mol% of DMAPS (sulfobetaine) end group) were synthesized. The thermal properties and phase transitions of these polymers were investigated. The polymers were thermally stable up to 185 C. The polymers were found to form favorably into multi-bilayer structures, always providing hydrophilic, zwitterionic sulfobetaine end groups at the film surface. Because of the sulfobetaine groups present at the surface, the polymer films promoted HEp-2 cell adhesion and revealed biocompatibility in mice but significantly suppressed protein adsorption. These results collectively indicate that the sulfobetaine-containing brush polymers are suitable for use in biomedical applications, including medical devices and biosensors that require biocompatibility

전곡리 고고학 유적지에서의 지질연대와 퇴적물의 지구 화학적 특성 연구

Thesis(doctors) --서울대학교 대학원 :지구환경과학부,2009.8.Docto

북한의 사회불평등 구조화 요인과 특성에 관한 연구 : 주민 성분분류사업을 통한 사회적 자원의 배분 문제를 중심으로

학위논문(석사) --서울대학교 대학원 :사회학과,2010.2.Maste

임플란트-지대주 연결 구조에 따른 골반응의 임상적 현상

학위논문 (석사)-- 서울대학교 대학원 : 치의학대학원 치의과학과, 2018. 8. 여인성.-ABSTRACT- Clinical phenomena of bone responses depending on implant-abutment connection structures Jin-Cheol Kim, D.D.S. Department of Prosthodontics, Graduate School, Seoul National University (Directed by Professor In-Sung Yeo, D.D.S., M.S.D., Ph.D.) 1. Purpose This study aimed to evaluate the effect of two different implant–abutment connection structures with identical implant design on peri-implant bone level. 2. Materials and Methods This clinical study was a randomized controlled trial following the CONSORT 2010 checklists. Implants with internal friction connection were compared to implants with external hex connection. Eleven external hex and eleven internal friction implants were analyzed in this study. These implants had the same design except the connection structure. One implant for each patient was installed, replacing the second molar in the maxilla or mandible. Cement-retained crowns were delivered at four months after implant insertion. Standardized periapical radiographs were taken at prosthesis delivery (baseline), and one year after delivery. On the radiographs, distance from implant shoulder to first bone-to-implant contact (DIB) and peri-implant area (PA) were measured. These measurements were compared between two connections using the independent t-test, which was evaluated at 0.05 significance level. Also, this study measured strain around the implant–abutment joint area at an in vitro bone model setting under 100,000 cyclic loading 3. Results Mean changes of DIB from baseline to 1-year loading were 0.59 ± 0.95 mm for the external, and 0.01 ± 0.68 mm for the internal connection. Although no significant differences were found between two groups in the change of PA and DIB, medium effect size was found in DIB between the connections (Cohens d=0.67). The internal friction connection displayed higher values of strain than the external hex connection. Internal friction connections strain was measured 993 µm/m and external connection registered 904 μm/m. 4. Conclusions Within the limitation of this study, the results of this one-year comparative clinical trial suggested the possibility of internal friction connection in more effective preservation of marginal bone despite of no significant differences in the bone level between the implant-abutment connection structures, considering the effect size in the vertical bone level change. Keywords: Clinical trialsBone implant interactionsPeriodontologyImplant–abutment connectionMarginal bone level Student Number : 2016-29016CONTENTS Ⅰ. INTRODUCTION Ⅱ. MATERIALS AND METHODS Ⅲ. RESULTS Ⅳ. DISCUSSION Ⅴ. CONCLUSIONS REFERENCES FIGURES AND TABLES ABSTRACT IN KOREANMaste

Comparison of tensile and knot stability properties of surgical suture materials

Thesis(master`s)--서울대학교 대학원 :치의학과 치과생체재료과학전공,2006.Maste

A Study on the spray characteristics of volatile lubricants for dry metal forming

본 논문에서는 액체 이산화탄소(CO2)의 윤활 성능에 대한 연구를 위해 다양한 마이크로 홀 형상(Confusor, Straight, Diffuser)을 가진 적층 제조된 노즐의 분사 특성 분석이 수행되었다. 분사 과정에서 액체 CO2 는 Joule-Thomson 효과로 인해 분사 노즐 출구에서 드라이 아이스로 전환된 후 대기압 및 대기 온도 조건에서 기체로 증발한다. 분사 노즐 출구에서 생성된 드라이 아이스는 성형 소재와 금형을 분리해주는 역할로 윤활을 함과 동시에 기화하는 과정에서 열을 흡수하여 소재를 냉각시키게 된다. 실험 결과는 액체 CO2 의 윤활 및 냉각이 마이크로 홀 형상에 크게 의존하는 것이 확인되었다. 특히, confusor 형상의 마이크로 홀은 straight, diffuser 형상보다 분사 폭 및 드라이 아이스 생성 면적이 크다는 결과가 나타났다. 냉각 속도 또한 confusor 형상의 마이크로 홀에서 나오는 분사 및 드라이 아이스 면적이 가열된 시트의 냉각에 효과적인 냉각을 기여하며, AA6061-T6 의 고용체 처리를 위한 냉각 속도인 -66 ℃/s 보다 2.24 배 높은 냉각 속도를 보였다. 본 연구는 마이크로 홀 형상을 최적화함으로써 액체 CO2 의 윤활 및 냉각 성능이 쉽게 향상될 수 있음을 증명되었다.Maste

재형성 가능한 조성 고분자의 합성과 형광의 광스위칭 특성 분석

학위논문 (석사)-- 서울대학교 대학원 : 재료공학부, 2011.2. 박수영.Maste

Studies on the recovery of burst strength in the alloxan-treated rats

의학과/박사[한글]당뇨병으로 인한 이차적 병변으로 신기능부전, 실명, 고혈압등 소혈관 병변들이 나타나며 말초신경염, 감염, 골절치유장애, 수술후 창상치유 지연등을 볼 수 있다. 당뇨병에서 창상치유 지연은 외과영역에서 흔히 볼 수 있는 증상의 하나이며, 이러한 창상치유 지연은 체내외의 여러 가지 요인들에 의해 영향을 받으나 현재까지 각 요인의 상호작용은 정확히 알지 못하고 있다. Alloxan은 취소도의 β세포에 선택적 괴사를 일으켜 실험적 당뇨병을 유발하며, 이는 창상치유 과정중 초기 염증반응기를 억제함으로 섬유아세포와 교원섬유의 형성을 억제시켜 창상치유를 억제시킨다고 한다. Vitamin A 및 그 유도체는 lysosomal membrane에 대하여 완화제로서 섬유아세포와 교원섬유이 형성을 촉진시켜 창상치유를 촉진시키고, 이에 반하여 hydrocortisone은 lysosomal membrane의 안정제로서 작용함으로써 창상치유 과정중 초기 염증반응기를 억제하여 창상수축 및 장력회복을 지연시킨다고 한다. 그 외 물리적인 요인으로서 고정(immobilization)도 감염된 상처에서는 중요한 역할을 하는데 이는 임파량이 감소되어 상처부위의 정상균의 전파를 감소시킴으로써 창상치유에 도움을 준다고 한다. 따라서 본 실험은 흰쥐에서 alloxan으로 실험적 당뇨병을 유발시킨 상태에서 창상치유에 미치는 vitamin A 및 그 유도체와 hydrocortisone 및 물리적인 요인인 고정의 영향을 검색하여 다음과 같은 결과를 얻었다. 1. 대조군의 창상파열력은 시일이 경과함에 따라 급격히 증가되며, 특히 5일과 1주일 사이의 증가가 현저하였다. 2. Alloxan 당뇨병은 흰쥐의 창상파열력을 현저히 감소시켰다. 3. Alloxan당뇨병으로 인한 창상파열력 감소는 retinold 및 retinoic acid 투여로 회복되어지나 대조군보다는 낮았으며, 그 회복정도는 retinoic acid 투여군이 다소 빨랐다. 4. Hydrocortisone 투여는 alloxan 당뇨병의 창상파열력을 더욱 감소시켰으며 retinoic acid 첨가로 약간 상승하나, alloxan 단독투여군 보다는 낮았다. 이상의 실험결과를 종합하여 볼 때 당뇨병은 창상치유를 지연시키며, retinoid 및 retinoic acid 투여는 당뇨병에 의한 창상치유 지연을 완화시키나 hydrocortisone은 이를 더욱 지연시킴을 알 수 있다. [영문]Diabetes mellitus, characterized by metabolic derangement due to insuin deficiency, can cause many functional disturbances. Surgeon has encountered many troblesome experiences in operated diabetic patient. Wound healing is influenced by various factors, and the process and mechanism of that is still unclear. But there are evidences that stability of lysosomal membrane is important to early inflammatory phases of wound healing processes, and representatively, corticosteroid suppresses wound healing by reinforcing the lysosomal membrane integrity, on the other hand, vitamin A promotes the wound healing by labilizing the lysosmal membrane. It is also reported that impaired wound healing in diabetes is related to depression of early inflammatory phase, thus delaying the fibroblastic proliferation, and collagen formation. Present study, therefore, was undertaken to investigate the effects of retinoid, retinoic acid, hydrocortisone, and immobilization on wound healing in alloxan-treated rats. The results are summerized as follows: 1) The burst strength of the wound in control group were increased with time, especially, more prominent during 5 and 7 days. 2) The burst strength of the wound were remarkably decreased in alloxan-treated rats. 3) The development of burst strength in alloxan-treated rats was accelerated by retinoid or retinoic acid, and retinoic acid was rather effective than retinoid. 4) The burst strength of the wound in alloxan-treated rats was significantly decreased by hydrocortisone, which was partially recovered by addition of retinoic acid. From these results, it is suggested that impaired wound healing in diabetes mellitus can be ameliorated by retinoid or retinoic acid, but aggravated by hydrocortisone.restrictio

고출력 레이저와 플라즈마를 이용한 레이저 증폭과 이온 가속 과정에서 나타나는 비선형 현상의 이론적 연구

Docto

Hierarchical optimization of the PCB assembly line including non-identical surface mounting machines

학위논문(박사)--서울대학교 대학원 :전기·컴퓨터공학부,2003.Docto