• 대한의용생체공학회:의공학회지
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• 제16권1호
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• pp.9-16
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• 1995

Biodegradable poly (I ,4-butanediol succinate) (PBS) was synthesized from 1,4-butanediol and succinic anhydride. The glass transition temperature of poly (I, 4-butanediol succinate) was revealed at $73^{\circ}C$. The crystallization and cold crystallization of the polymers were investigated as a function of holding time in melt state, cooling rate. reheating, and molecular weight. Chain scission and/or cmsslinking did not occur in the melt state at var.ious holding times. Slower scanning rate can allow more times for nucleation, rearrangement, and packing of the polymer chain, so the onset temperature of crystallization from the melt was increased. PBS crystallized from the melt was found to have spherulitic structure. The degradation behavior of PBS was studied under basic conditions and with microorganisms using the modified ASTM method. In the basic solution. PBS lost up to 85% of its mass within two days. Based upon visual observation, the crystalline structure of films composed of larger molecular weight polymers retained their crystallinity longer than similar structures in low molecular weight samples.

• 대한의용생체공학회:의공학회지
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• 제15권3호
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• pp.259-264
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• 1994

혈액으로부터 헤파린을 선택적으로 제거하기 위하여 cellulose 기질에 양이온 고분자인 poly(allylamine)(PALA)을 새로운 방법으로 고정화하여 헤파린 제거제를 제조한 다음 in vitro 헤파린 용액내에서 흡착실험을 행하여, 미처리 cellulose control과의 흡착능을 비교하였다. 제조된 헤파린 제거제와 미처리 cellulose의 표면적은 각각 1.36 및 $2.56m^2$/g로 개질처리된 경우의 표면적이 약 1/2로 감소하였다. 또한 제조된 헤파린 제거제에 흡착된 헤파린의 양은 개질 방법에 따라 0.16~$0.03{\mu} g$/$cm^2$로 미처리 celluose($0.03{\mu} g$/$cm^2$)보다 월등히 우수한 헤파린 흡착능을 나타내었다.

• 대한의용생체공학회:의공학회지
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• 제28권4호
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• pp.484-493
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• 2007

Two polymeric prodrugs of PGE1 (prodrugs IVg and PNg) were newly synthesized. The drug conjugation proceeded in quantitative yield without decomposition of PGE1 to PGA1. With two types conjugates, PEG-PGE1 and PN-PGE1 with different spacer groups, we first discovered a possibility of slow release of PGE1 in blood circulatory system. PGE1 is conjugated with PEG and PN through the long alkylene spacers, and their availability as polymeric prodrugs is evaluated. Their drug-releasing behavior was examined both in phosphate buffer (pH=7.4) and rat plasma. Each prodrug was known to be highly stabile in the buffer solution. The drug-releasing rate became much faster in rat plasma than in the buffer solution due to the acceleration by the plasma enzymes. The drug-release was found to reach a plateau in rat plasma because the released PGE1 or its derivatives may be captured or decomposed by the plasma proteins. The slower drug-releasing rate of pro drug PNg in rat plasma is reasonably attributed to the molecular aggregation due to the hydrophobic bonding between the PGE1 moieties and spacers.

• Macromolecular Research
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• 제10권2호
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• pp.115-121
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• 2002

Synthesis of polymers with controlled thermosensitive properties was carried out by conventional radical copolymerization of N-isopropylacrylamide (NIPAAm) with N-vinylpyrrolidone (NVP) taken as a hydrophilic comonomer. Lower activity of NVP rather than NIPAAm was revealed by gravimetric and $^1$H NMR analysis. Thermosensitive properties of the copolymers were investigated. It was found that aqueous solutions of the copolymers undergo thermo-induced phase transition and become opaque, precipitate or gel with heating. After formation of the gels their significant contraction was observed at storage. Swelling degree and amount of expelled water were measured in dependence on the copolymer composition, temperature and ionic strength of environment medium and concentration of the solution. It was determined that in collapsed state gels exhibit quite high water content. According to physico-chemical properties of the copolymers observed they could be suitable for biomedical application as an injectable implant material.

• Multiscale and Multiphysics Mechanics
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• 제1권4호
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• pp.327-340
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• 2016

Poly(${\epsilon}$-caprolactone) (PCL) diol, with good biodegradation and biocompatibility, is one of the widely used soft segments (SSs) in composing bio-polyester-urethanes (Bio-PUs), which show great potential in both biomedical and tissue engineering applications. Properties of Bio-PUs are tunable by combining SS monomers with different molecular weights, structures, modifications, and ratio of components. Although numbers of research have reported many Bio-PUs properties, few studies have been done at the molecular scale. In this study, we use molecular dynamic (MD) simulation to construct atomistic models for two commonly used PCL diol SSs with different molecular weights 1247.58 Da and 1932.42 Da. We compare the simulation results by using two widely used classical force fields for organic molecules: Consistent Valence Force Field (CVFF) and CHARMM General Force Field (CGenFF), and discuss the validity and accuracy. Melt density, volume, polymer conformations, transition temperature, and mechanical properties of PCL diols are calculated and compared with experiments. Our results show that both force fields provide accurate predictions on the properties of PCL diol system at the molecular scale and could help the design of future Bio-PUs.

• Archives of Plastic Surgery
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• 제33권1호
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• pp.21-30
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• 2006

Alginate, a polymer of guluronic and mannuronic acid, is used as a scaffolding material in biomedical applications. The research was to produce highly-purified alginate from seaweeds and to evaluate the efficacy of alginate as dermal substrate. Our alginate purification method showed a production rate as high as 25%. The purified alginate contained little polyphenol contents and endotoxin, proteins. For study of wound healing, full thickness skin defects were made on the dorsal area of the animal models. And then alginate, fibroblast-growth-factor mixed alginate, alginate-collagen complex, vaseline gauze as control were applied on the wound, respectively, and were evaluated grossly and histopathologically. For biocompatibility test, alginate and alginate-collagen complex discs were implanted on the back of Sprague-Dawly rats. Four weeks after implantation, the animals were examined immunologically against alginate and collagen. Alginate and FGF-mixed alginate, alginate-collagen complex group showed statistically higher percentage of wound contraction and wound healing than control group(p<0.05). Alginate-collagen complex group and FGF-mixed alginate group showed statistically higher percentage of wound healing than alginate group. The experiment of biocompatibility and immunologic reaction against impanted alginate or collagen needs more investigation. Highly-purified alginate from seaweeds by our purification method, showed the effect of wound healing, and addition of FGF or collagen increases the alginate's wound healing effect. It shows the possibility of alginate as a dermal substrate.

• 공업화학
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• 제4권1호
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• pp.188-195
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• 1993

생체의료용 재료로서 응용 가능한 고분자 전해질복합체와 그라프트 공중합체를 수용성 고분자 유도체로부터 제조하였다. 고분자 전해질 복합체들은 카르복시메틸 셀룰로오즈(CMC)와 젤라틴으로부터 제조하였다. 그라프트 공중합체는 메틸셀룰로오즈(MC)에 아크릴산을 그라프트반응시켜 합성하였고, 이 그라프트 공중합체와 젤라틴의 고분자 전해질 복합체도 제조하였다. 그라프트 공중합체와 고분자 전해질 복합체들을 화학가교법과 열처리법으로 제조시 최적조건들을 조사하였다. 예비실험 결과 이들 재료들이 생체의료용 재료로서의 응용 가능성이 있는 것을 알았다.

• Macromolecular Research
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• 제14권1호
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• pp.73-80
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• 2006

Sulfonated poly(ethylene glycol) (PEG-$SO_{3}$) grafted polyrotaxanes (PRx-PEG-$SO_{3}$) were prepared in order to utilize the unique properties of PEG-$SO_{3}$ and the supramolecular structure of PRx, in which PEG-$SO_{3}$ grafted $\alpha$-cyclodextrins ($\alpha$-CDs) were threaded onto PEG segments in a PEG-b-poly(propylene glycol) (PPG)-b-PEG triblock copolymer (Pluronic) chain capped with bulky end groups. Some of the PRx-PEG-$SO_{3}$ demonstrated a higher anticoagulant activity in case of PRx-PEG-$SO_{3}$ (P 105), and compared with the control they showed a lower fibrinogen adsorption in PRx-PEG-$SO_{3}$ (F68) and a higher binding affinity with fibroblast growth factor. The obtained results suggested that polyrotaxane incorporated with PEG-$SO_{3}$ may be applicable to the surface modification of clinically used polymers, especially for blood/cell compatible medical devices.

• Macromolecular Research
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• 제12권4호
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• pp.379-383
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• 2004

Poly(ethylene glycol)s (PEGs) are unique in their material properties, such as biocompatibility, non-toxicity, and water-solublizing ability, which are extremely useful for a variety of biomedical applications. In addition, a variety of functional PEGs with specific functionality at one or both chain ends have been synthesized for many specialized applications. Surface modifications using PEG have been demonstrated to decrease protein adsorption and platelet or cell adhesion on biomaterials. Furthermore, PEGs having anionic sulfonate terminal units have been proven to enhance the blood compatibility of materials, which has been demonstrated by the negative cilia concept. The preparation of telechelic PEGs having a sulfonic acid group at one end and a polymerizable methacryloyl group at the other is an interesting undertaking for providing macromers that can be used in various vinyl copolymerization and gel systems. In this paper, preliminary results on the synthesis and polymerization behavior of a novel PEG macromer is described with the aim of identifying a biocompatible material for applications in various blood-contacting devices.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2002년도 정기총회 및 추계학술연구발표회
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• pp.54-55
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• 2002

The fabrication, characterization and manipulation of nanoparticle system brings together physics, chemistry, materials science and biology in an unprecedented way. Phenomena occurring in such systems are fundamental to the workings of electronic devices, but also to living organisms. The ability to fabricate the surface of nanoparticles Is essential in the further development of functional devices that incorporate nanoscale features. Even more essential is the ability to introduce a wide range of chemical and materials flexibility into these structures to build up more complex nanostructures that can ultimately rival biological nanosystems. In this respect, polymers are potentially ideal nanoscale building blocks because of their length scale, well-defined architecture, controlled synthesis, ease of processing and wide range of chemical functionality that can be incorporated. In this presentation, we will look at a number of promising polymer-based nanoparticle fabrication strategies that have been developed recently, with an emphasis on those techniques that incorporate nanostructured polymeric particles into electronic devices or biomedical applications. And functional nanoparticles deliberately designed using several powerful process methods and their application will be discussed. Nanostructured nanoparticles, what we called, implies dispersed colloids with the size ranged from several nanometers to hundreds of nanometer. They have extremely large surface area, thus it is very important to control the morphology or surface functionality fitted for adequate objectives and properties. Their properties should be controlled for various kind of bio-related technologies, such as immunomagnetic cell separation, drug delivery systems, labeling and identification of lymphocyte populations, extracorporeal and hemoperfusion systems, etc. Well-defined polymeric nanoparticles can be considered as smart bomb or MEMS.