• International Journal of Industrial Entomology and Biomaterials
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• 제37권2호
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• pp.36-42
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• 2018

Recently, silk sericin has attracted attention because of its unique properties as a biomaterial, including its UV resistance, moisturizing effect on skin, and wound-healing effect. Therefore, the preparation of sericin in various forms such as gel, film, fiber, and sponge is studied for cosmetic and biomedical applications, and the effect of the preparation conditions on the structure and properties of sericin forms is examined to maximize its performance. In this study, silk sericin films were prepared under different preparation conditions and heat-treated at high temperatures ($100-250^{\circ}C$) to examine the effect of heat treatment on the film structure. The order of the crystallinity index of the untreated sericin film is as follows: F25 (sericin film cast from formic acid) > WE25 (ethanol treated sericin film cast from water at $250^{\circ}C$) > W25 (sericin film cast from water at $250^{\circ}C$) > W100 (sericin film cast from water at $100^{\circ}C$). As the heat-treatment temperature was increased, the color of the sericin films changed gradually from colorless to yellow, brown, and black depending on the temperature. The crystallinity of the sericin film changed after the heat treatment, depending on the preparation condition. Whereas a sericin film cast from formic acid (F25) started to lose its crystallinity at $200^{\circ}C$, thus undergoing the highest loss of crystallinity among the sericin films studied, the rest (W25, WE25, and W100) showed a decrease in crystallinity at $250^{\circ}C$, owing to the disruption of the ${\beta}$-sheet crystallites due to heat.

• 대한의용생체공학회:의공학회지
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• 제40권1호
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• pp.1-6
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• 2019

Human mesenchymal stem cells (hMSC) are multipotent stromal cells that have great potential to differentiate into a variety of cell types such as osteocytes, chondrocytes, and myocytes. Although there have been many studies on their clinical availability, little is known about how intracellular signals can be modulated by topographic features of the extracellular matrix (ECM). In this study, we investigated whether and how microwavy-patterned extracellular matrix (ECM) could affect the signaling activity of focal adhesion kinase (FAK), a key cellular adhesion protein. The fluorescence resonance energy transfer (FRET)-based FAK biosensor-transfected cells are incubated on microwavy-patterned surfaces and then platelet derived growth factor (PDGF) are treated to trigger FAK signals, followed by monitoring through live-cell FRET imaging in real time. As a result, we report that PDGF-induced FAK was highly activated in cells cultured on microwavy-patterned surface with L or M type, while inhibited by H type-patterned surface. In further studies, PDGF-induced FAK signals are regulated by functional support of actin filaments, microtubules, myosin-related proteins, suggesting that PDGF-induced FAK signals in hMSC upon microwavy surfaces are dependent on cytoskeleton (CSK)-actomyosin networks. Thus, our findings not only provide new insight on molecular mechanisms on how FAK signals can be regulated by distinct topographical cues of the ECM, but also may offer advantages in potential applications for regenerative medicine and tissue engineering.

• Biomedical Engineering Letters
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• 제8권4호
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• pp.365-371
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• 2018

Uninterrupted monitoring of multiple subjects is required for mass causality events, in hospital environment or for sports by medical technicians or physicians. Movement of subjects under monitoring requires such system to be wireless, sometimes demands multiple transmitters and a receiver as a base station and monitored parameter must not be corrupted by any noise before further diagnosis. A Bluetooth Piconet network is visualized, where each subject carries a Bluetooth transmitter module that acquires vital sign continuously and relays to Bluetooth enabled device where, further signal processing is done. In this paper, a wireless network is realized to capture ECG of two subjects performing different activities like cycling, jogging, staircase climbing at 100 Hz frequency using prototyped Bluetooth module. The paper demonstrates removal of baseline drift using Fast Fourier Transform and Inverse Fast Fourier Transform and removal of high frequency noise using moving average and S-Golay algorithm. Experimental results highlight the efficacy of the proposed work to monitor any vital sign parameters of multiple subjects simultaneously. The importance of removing baseline drift before high frequency noise removal is shown using experimental results. It is possible to use Bluetooth Piconet frame work to capture ECG simultaneously for more than two subjects. For the applications where there will be larger body movement, baseline drift removal is a major concern and hence along with wireless transmission issues, baseline drift removal before high frequency noise removal is necessary for further feature extraction.

• Biomedical Engineering Letters
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• 제8권4호
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• pp.337-344
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• 2018

Additive manufacturing (AM) is an alternative metal fabrication technology. The outstanding advantage of AM (3D-printing, direct manufacturing), is the ability to form shapes that cannot be formed with any other traditional technology. 3D-printing began as a new method of prototyping in plastics. Nowadays, AM in metals allows to realize not only net-shape geometry, but also high fatigue strength and corrosion resistant parts. This success of AM in metals enables new applications of the technology in important fields, such as production of medical implants. The 3D-printing of medical implants is an extremely rapidly developing application. The success of this development lies in the fact that patient-specific implants can promote patient recovery, as often it is the only alternative to amputation. The production of AM implants provides a relatively fast and effective solution for complex surgical cases. However, there are still numerous challenging open issues in medical 3D-printing. The goal of the current research review is to explain the whole technological and design chain of bio-medical bone implant production from the computed tomography that is performed by the surgeon, to conversion to a computer aided drawing file, to production of implants, including the necessary post-processing procedures and certification. The current work presents examples that were produced by joint work of Polygon Medical Engineering, Russia and by TechMed, the AM Center of Israel Institute of Metals. Polygon provided 3D-planning and 3D-modelling specifically for the implants production. TechMed were in charge of the optimization of models and they manufactured the implants by Electron-Beam Melting ($EBM^{(R)}$), using an Arcam $EBM^{(R)}$ A2X machine.

• 대한수의학회지
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• 제58권4호
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• pp.183-192
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• 2018

Although hyaluronic acid (HA) has been developed as a nanoparticle (NP; 320-400 nm) for a drug delivery system, the tissue targeting efficacy and the pharmacokinetics of HA-NPs are not yet fully understood. After a dose of 5 mg/kg of cyanine 5.5-labeled HA-NPs or HA-polymers was intravenously administrated into mice, the fluorescence was measured from 0.5 h to 28 days. The HA-NPs fluorescence was generally stronger than that of HA-polymers, which was maintained at a high level over 7 days in vivo, after which it gradually decreased. Upon ex vivo imaging, liver, spleen, kidney, lung, testis and sublingual gland fluorescences were much higher than that of other organs. The fluorescence of HA-NPs in the liver, spleen and kidney was highest at 30 min, where it was generally maintained until 4 h, while it drastically decreased at 1 day. However, the fluorescence in the liver and spleen increased sharply at 7 days relative to 3 days, then decreased drastically at 14 days. Conversely, the fluorescence of HA-polymers in the lymph node was higher than that of HA-NPs. The results presented herein may have important clinical implications regarding the safety of as self-assembled HA-NPs, which can be widely used in biomedical applications.

• 공업화학
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• 제30권2호
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• pp.254-259
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• 2019

본 연구에서는 마그네슘-층상규산염(MgP) 층간에 솔잎 추출물(PLE)이 삽입되어 겹겹이 쌓여있는 샌드위치 구조의 나노입자(PLE/MgP)를 one-pot으로 합성하였다. XRD 분석을 통해 팔면체와 사면체 구조로 MgP가 성공적으로 합성되었으며, PLE가 층간에 삽입되어 MgP 간의 층간거리(d-spacing)가 벌어진 것을 확인하였다. HR-TEM을 통해 모폴로지 변화를 관찰하였으며, 열중량분석법을 통해 PLE가 MgP 대비 10%까지 함유된 것을 확인하였다. 최소저해농도(MIC) 및 최소 사멸농도(MBC) 분석을 통해 피부 상재균에 대한 항균 활성을 검토한 결과 MgP 또는 PLE보다 PLE/MgP의 항균 활성이 더욱 향상된 것을 확인하였다. 이러한 결과는 본 연구에서 개발한 PLE/MgP 유/무기 복합 소재가 화장품 소재, 의료용 소재 등의 다양한 분야에 적용 가능함을 확인하였다.

• Korean Chemical Engineering Research
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• 제59권4호
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• pp.639-643
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• 2021

본 연구에서는 3차원 다층 미세유체 디바이스를 제작하기 위한 접착제로서 불소화 에틸렌 프로필렌(fluorinated ethylene propylene, FEP) 나노입자를 연구하였다. FEP 분산 용액을 1500 rpm에서 30초 동안 단순 스핀 코팅하여 기판에 3 ㎛ 두께의 균일하게 분포된 FEP 나노 입자 층을 형성하였다. FEP 나노입자는 300 ℃에서 1시간 동안 열처리 후 소수성 박막으로 변형되었으며, FEP 나노입자를 이용하여 제작된 폴리이미드 필름 기반 미세유체 디바이스는 최대 2250 psi의 압력을 견디는 것을 확인하였다. 마지막으로 기존의 포토리소그래피로 제작하기 어려운 16개의 마이크로 반응기로 구성된 3차원 다층 미세유체 디바이스를 FEP가 코팅된 9개의 폴리이미드 필름을 간단한 1단계 정렬로 성공적으로 구현하였다. 개발된 3차원 다층 미세유체 디바이스는 화학 및 생물학의 다양한 응용을 위한 고속대량 스크리닝, 대량 생산, 병렬화 및 대규모 미세유체 통합과 같은 강력한 도구가 될 가능성이 있습니다.

• 멤브레인
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• 제31권5호
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• pp.293-303
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• 2021

물 여과, 단백질 정제 또는 생체 의학 여과 장치에 사용되는 분리막은 여러 가지 이유로 막 파울링을 거치게 된다. 박테리아에 의한 막 표면의 바이오필름 형성은 분리막의 내구성에 심각한 문제를 초래한다. 단백질 정제의 경우, 소수성인 막의 표면으로 인해 막의 기공이 막히게 된다. 분리막의 파울링을 조절하는 방법에는 여러 가지가 있는데, 그 중 하나가 은나노 입자의 도입이다. 은나노 입자의 항균 특성은 잘 알려져 있고 따라서 여러 응용에 사용되고 있다. 본 총설에서는 은나노 입자 또는 그 유도체가 박막 활성층에 도입되거나 또는 복합막 전체에 균일하게 분포된 분리막에 초점을 두었다.

• 멤브레인
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• 제31권4호
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• pp.241-252
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• 2021

급격한 산업화와 인구수 증가로 인한 환경 수질 오염이 발생하고 있다. 더불어 날씨 패턴의 변화로 인해 빗물이 부족해지자, 폐수를 깨끗한 물로 재활용하기 위한 요구가 나날이 늘어나고 있다. 색변화를 이용한 수중 속 중금속 검출은 아주 간단하고 효과적인 기술이다. 본 논문에는 멤브레인을 이용한 수은 이온 색검출에 대해 자세하게 논의되어 있다. 셀룰로스, 폴리카프로락톤, 키토산, 폴리설폰 등의 멤브레인이 금속 이온 검출을 지지체로서 사용되었다. 지지체로서 사용된 멤브레인들은 나노 섬유를 기반으로 하며 표면적이 크며, 중금속 검출의 활성 부위로 사용하기에 탁월하다. 나노 섬유를 기반으로 한 재료는 에너지, 환경, 그리고 바이오메디컬 연구에서 다양하게 응용될 수 있다. 나노 섬유로 이루어진 멤브레인들은 폴리머에 있는 적용기를 많이 받아들일 수 있으며, 표면적이 넓고 다공성이라는 장점이 있다. 이로 인해 멤브레인의 표면 구조를 변화시키거나 리간드를 섬유 표면에 부착해 나노 입자 결합을 더 쉽게 해준다.

• Current Optics and Photonics
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• 제6권6호
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• pp.550-564
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• 2022

Optical microscopy is a useful tool for study in the biological sciences. With an optical microscope, we can observe the micro world of life such as tissues, cells, and proteins. A fluorescent dye or a fluorescent protein provides an opportunity to mark a specific target in the crowd of biological samples, so that an image of a specific target can be observed by an optical microscope. The optical microscope, however, is constrained in resolution due to diffraction limit. Super-resolution microscopy made a breakthrough with this diffraction limit. Using a super-resolution microscope, many biomolecules are observed beyond the diffraction limit in cells. In the case of volumetric imaging, the super-resolution techniques are only applied to a limited area due to long imaging time, multiple scattering of photons, and sample-induced aberration in deep tissue. In this article, we review recent advances in super-resolution microscopy for volumetric imaging. The super-resolution techniques have been integrated with various modalities, such as a line-scan confocal microscope, a spinning disk confocal microscope, a light sheet microscope, and point spread function engineering. Super-resolution microscopy combined with adaptive optics by compensating for wave distortions is a promising method for deep tissue imaging and biomedical applications.