• Journal of Microbiology and Biotechnology
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• 제11권2호
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• pp.259-265
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• 2001

Staphylococal infection still remains to be one of the most serious infections, having various complications in the clinical use of indwelling polymeric medical devices. However, there are a few promising systems showing a high antibacterial effect without causing any demage of polymer backbone under biological environments such as blood or body fluid. In order to resolve this problem, we have designed a new antibiotic releasing system via a hydrolysis mechanism. The surface of biomedical polyurethane (PU) was modified by using 1,6-diisocyanatohexane (HMDI) to immobilize the rifampicon. Also, the immobilized rifampicin was designed to be released by a selective cleavage of the unstable carbamate linkage that exists on the rifampicin-immobilized polyurethane (PHR). The immobilization of rifampicin on the surface of polyurethane was confirmed by the disappearance of the characteristics IR absorbance peak of the isocyanate (-NCO) group at $2,267\;cm^{-1}$. The PHR showed a continuous rifampicin release profile under an aqueous environment of 10 mM of PBS (phosphate-buffered saline) for ove 6 days. The rifampicin molecules, which are released from PHR under an optimal bacterial infection environment, had a higher antibacterial activity against both S. aureus and S. epidermidis than rifampicin-incorporated polyurethane (RIP). In addition, the PHR maintained a stable antibacterial effect under a blood-mimic aqueous environment such as bovine calf serum.

• 대한의생명과학회지
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• 제19권1호
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• pp.41-47
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• 2013

Pluripotent stem cells (PSCs) have lots of potential in biomedical sciences owing to its potential to differentiate into any kind of cells in the body. However, it is still a challenge to culture PSCs on a large scale for application to regenerative medicine. Herein, we introduce a synthetic polymer that enables large-scale suspension culture of human PSCs. By employing suspension culture, it became unnecessary to use conventional substrata such as mouse embryonic fibroblast (MEF) or Matrigel$^{TM}$, which are believed to be main causative sources of xenogeneic contamination in cultured human PSCs in vitro. Human PSCs were cultured in the medium in which elastin-like polypeptide (ELP) dissolved. The ELP in the medium became harden as temperature increases by transforming the medium into a semi-solid gel that supported growth of human PSCs in suspension. Gel-sol transition temperature of ELP can be adjusted by modifying the peptide sequence in which 5 amino acids, Val-Pro-Gly-Xaa-Gly, repeated sequentially. We constructed 3D suspension media having transition temperature around $33{\sim}35^{\circ}C$ using an ELP consisted of 40, 60, or 80 repeats of a monomer, which was Val-Pro-Gly-Val-Gly. Among the ELPs, ELP80 was chosen as the best ELP to support growth of human PSCs in suspension culture. This result suggests that the ELP80 can be a medium component for culturing human PSCs in large-scale.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.337-342
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• 1997

Dental implant has been increasingly used to recover the masticatory unction of tooth. It has been well known that the success of dental implant is heavily dependent on initial stability and long-term osseointegration due to optimal stress distribution in the surrounding bones. The role of periodontal ligament, removed during operation, is to absorb impact force and to distribute them to alveolar bone. or this reason, the study for artificial periodontal ligament has become an important issue in this field. In this study, chitosan was coated on dental implant or the purpose of replacing the role of intact periodontal ligament. The results by experiment and FEM analysis showed : I) Initial stability of dental implant was significantly increased(35%) when the implant was coated with chitosan. II) The coated implant showed higher impact absorption, more even stress distribution and lower stress magnitude under impact force than uncoated implant. Accordingly, the micro-fracture of the surrounding bones due to impact force would be lessened by chitosan coating on dental implant.

• Journal of Pharmaceutical Investigation
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• 제24권1호
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• pp.41-48
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• 1994

A new local drug delivery device to treat otitis media (OM) has been developed. This device consists of a biodegradable poly(L-lactic acid) (PLLA) film containing antibiotic (ampicillin, AMP), which can be placed into the middle ear cavity and release the therapeutic concentration of AMP for prolonged period. Biodegradable films containing AMP (10 w/w%) were prepared by solution casting method using a suspension of the drug in a $PLLA/CH_{2}Cl_{2}$ solution (molecular weight of PLLA, 100,000 (100 K) and 300,000 (300 K), respectively). PLLA-AMP films were characterized by FTIR, DSC, and SEM. In vitro release of AMP from AMP-PLLA films were examined. The release pattern of AMP from AMP-PLLA films remained consistent from 1 day to 14 days, and the release rates of AMP from AMP-100K-PLLA film and AMP-300K-PLLA film were $0.7384\;{\mu}g/ml/day$, $0.4107\;{\mu}g/ml/day$, respectively.

• 대한기관식도과학회지
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• 제12권2호
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• pp.19-25
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• 2006

There have been numerous modalities to recover blink function of orbicularis oculi muscle in patients with facial paralysis. However, there is still no optimal method for reanimation of eyelid. In this study, we tried to recover blink function of paralyzed rabbit's eyelid with the ion polymer metal composite (IPMC) which is one of the electroactive polymers that is spotlighted as artificial muscle. We manufactured IPMC by plating the platinum over perfluorosulphonic acid polymer ($Nafion^{(R)}$). IPMC was coated by Norland optical adhesive for the purpose of insulation and keeping it from dry. IPMC modifications by roughening the surface of Nafion, repetitive plating (maximum 4 times) with platinum, and lengthening the width of IPMC were done. The facial paralysis was induced in the rabbit by sectioning of facial nerve at the main trunk. After minimum period of 4 weeks, IPMC was inserted in the paralyzed rabbit's eyelid. By modification, the force generated by IPMC was enhanced. Restoration of blink function in paralyzed rabbit was achieved on electrical stimulation of the IPMC by 5 voltage direct current. IPMC can be promising option for facial reanimation, but further studies are needed to enhance the efficiency of IPMC.

• 폴리머
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• 제35권5호
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• pp.419-423
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• 2011

항균제 대체제로 응용하기 위하여 다양한 저분자량 수용성 키토산(LMWSC; MW1, MW3, MW5, MW10)을 제조하였으며, 이들의 항균제 대체제 사용 가능여부와 그 작용 기작에 대하여 연구하였다. 먼저, 다양한 분자량 형태의 LMWSC를 이용하여 사람에게 유해한 각종 박테리아를 이용하여 항균효과를 확인하였고, 그 중 MW10의 항균효과가 가장 우수한 것으로 확인되었다. 그 반면 사람의 적혈구를 이용한 용혈활성 실험에서 독성을 나타내지 않았다. MW10의 항균 효과가 세균의 어느 부분에서 일어나는지 확인하기 위해 박테리아의 세포막 조건(PE/PG=7/3, w/w)으로 인공리포좀을 만들었고, 여기에 MW10을 처리한 결과 세균 막에서 항균효과를 나타냄을 추론할 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제18권2호
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• pp.187-196
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• 1997

The three-dimensional flow analysis using the finite volume method is presented to compare the steady flow characteristics of blood with those of blood substitutes such as water and aqueous polymer solution in an idealized double branching model. The model is used to simlllate the region of the abdominal aorta near the celiac and superior mesenteric branches. Apparent viscosities of blood and the aqueous Separan solution are represented as a function of shear rate by the Carreau model, Water and aqueoiu Separan AP-273 500wppm solution are frequently used as blood substitutes in vitro experiments. Water is a typical Newtonian fluid and blood and Separan solution are non-Newtonian fluids. Flow phenomena such as velocity distribution, pressure variation and wall shear stress distribution of water, blood and polymer solution are quite different due to differences of the rheological characteristics of fluids. Flow phenomena of polymer solution are qualitatively similar to those of blood but the phenomena of water are quite different from those of blood and polymer solution. It is recommended that a lion-Newtonian fluid which exhibits very similar rheological behavior to blood be used in vitro experiments. A non-Newtonian fluid whose rheological characteristics are very similar to those of blood should be used to obtain the meaninylll hemodynamic data for blood flow in vitro experiment and by numerical analysis

• 대한화학회지
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• 제53권5호
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• pp.547-552
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• 2009

천연고분자물질인 키토산은 생체적합성과 생체활성이 좋은 특성을 가지고 있기 때문에 생체 의료용 재료로 중요하게 다루어지고 있다. 본 연구는 수용성 키토산을 교차결합제인 EGDMA (ethylene glycol dimethacrylate)와 HEMA (2-hydroxyethyl methacrylate), MMA (methylmethacrylate), MA (methacrylic Acid) 그리고 개시제인 AIBN을 사용하여 공중합 하였다. 공중합한 안의료용 재료의 물리적 특성을 측 정한 결과 함수율 24$\sim$59%, 가시광선 투과율 88$\sim$89%, 인장강도 0.1$\sim$2.4 Kgf를 나타내었다. 또한 포도 상구균, 녹농균에 대한 항균성 시험 결과 키토산을 포함하지 않은 고분자에 비해 높은 항균성을 나타내 어 향후 이 공중합체가 고기능성을 가진 안의료용 재료로 사용될 수 있을 것으로 기대된다.

• 폴리머
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• 제32권2호
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• pp.131-137
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• 2008

전기방사법에 의해 폴리스테렌 나노섬유 부직포를 제조하였고, 간세포의 접착을 유도하기 위해 간세포접착 리간드인 Poly[N-p-vinylbenzyl-O-$\beta$-D-galactopyranocyl-($1{\rightarrow}4$)-D-gluconamide](PVLA)를 나노섬유의 표면에 코팅하였다. 얻어진 나노섬유는 평균직경이 500 nm이었고 분광학적인 방법을 통해 PS 나노섬유 표면의 개질 여부를 확인하였다. 장기간 배양시의 간세포 생존율을 MTT법으로 조사한 결과 기존의 세포배양접시에서는 급격하게 세포생존율이 감소함에 비해 PVLA가 코팅된 나노섬유상에서는 생존율이 서서히 감소하였으며 약 3주간에 걸쳐 간세포가 생존율이 유지되었다. 간세포의 대표적인 기능인 알부민분비 및 요소분해능을 측정한 결과 기존의 세포배양접시에서는 급격하게 간세포기능이 저하되었지만, PVLA가 코팅된 나노섬유상에서는 약 3주정도 초기의 간세포기능을 유지하는 것이 밝혀졌다.

• 폴리머
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• 제36권5호
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• pp.586-592
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• 2012

산화철($Fe_3O_4$은 세포에 의해 섭취된 후 대사반응에 의해 분비되므로 세포독성을 나타내지 않는다. 따라서 산화철 나노입자는 MRI 촬영을 하기에 앞서 조영제로서 널리 사용되고 있다. 본 연구에서는 통상의 공침법으로 산화철 나노입자를 합성하고 폴리에틸렌글리콜을 스페이서로 하여 혈관내피세포 및 방광암 세포막의 IL-4 리셉터에 특이적으로 반응하는 homing 펩타이드(AP)를 고정화하였다. AP를 고정화한 산화철 나노입자의 크기는 수용액 상에서 약 39 nm이었다. 섬유아세포 및 방광암세포를 이용하여 AP고정화 산화철 나노입자의 uptake를 조사한 결과 섬유아세포에는 선택적 uptake를 발견할 수 없었으나 방광암세포에는 선택적으로 uptake됨을 알 수 있었다. 따라서 AP 고정화 산화철 나노입자는 조기 암진단용 조영제로서 가능성을 지니고 있다고 할 수 있다.