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Han, Uiyoung,Park, Hee Ho,Kim, Yu Jin,Park, Tai Hyun,Park, Ju Hyun,Hong, Jinkee American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.30
<P>Basic fibroblast growth factor (bFGF) has an established pivotal function in biomedical engineering, especially for the human pluripotent stem cells (iPSCs). However, the limitation of bFGF is the ease of denaturation under normal physiological conditions, inducing loss of its activity. In this study, we designed multi-trilayered nanofilm composed of a repeating polycation/polyanion/bFGF structure, which has high loading efficiency and short buildup time. We also investigated that the loading and release of bFGF from the nanofilm with two parameters (counter-polyanion and film architectures). Then, we prepared the optimized nanofilm which maintains a sustained bFGF level in physiological condition to apply the nanofilm to human iPSCs culture. The amount of bFGF release from 12 trilayer nanofilm was 36.4 ng/cm(2), and activity of bFGF encapsulated into the nanofilm was maintained (60%) until 72 h during incubation at 37 degrees C. As a result, the iPSCs grown in the presence of the nanofilm with tridaily replacement of growth medium maintained undifferentiated morphology and expression levels of pluripotency marker proteins.</P>
Han, Uiyoung,Kim, Yu Jin,Kim, Wijin,Park, Ju Hyun,Hong, Jinkee Royal Society of Chemistry 2019 Nanoscale Vol.11 No.28
<P>Interactions with peripheral environments, such as extracellular matrix (ECM) and other cells, and their balance play a crucial role in the maintenance of pluripotency and self-renewal of human pluripotent stem cells. In this study, we focused on a nano-sized artificial cellular environment that is directly attached to the cytoplasmic membrane as a facile method that can effect intercellular interactions at the single-cell level. We designed multilayered nanofilms that are self-assembled on the surface of human induced pluripotent stem cells (iPSCs), by repetitive adsorption of fibronectin and heparin or chondroitin sulfate. However, the surface modification process could also lead to the loss of cell-cell adhesion, which may result in apoptotic cell death. We investigated the proliferation and pluripotency of the iPSCs coated with the nanofilm in order to establish the suitable nanofilm structure and coating conditions. As a result, the cell viability reduced with the increase in the duration of the coating process, but the undifferentiated state and proliferation of the cells were maintained until 2 bilayers were coated. To suppress the dissociation-induced apoptosis, Y-27632, the Rho-associated kinase inhibitor (ROCKi), was added to the coating solution; this allowed the coating of up to 4 bilayers of the nanofilm onto the iPSCs. These results are expected to accelerate the pace of iPSC studies on 3-dimensional cultures and naïve pluripotency, in which the regulation of cellular interactions plays a critical role.</P>
박소현,Uiyoung Han,최다희,홍진기 한국생체재료학회 2018 생체재료학회지 Vol.22 No.4
Background: The main purpose of drug delivery systems is to deliver the drugs at the appropriate concentration to the precise target site. Recently, the application of a thin film in the field of drug delivery has gained increasing interest because of its ability to safely load drugs and to release the drug in a controlled manner, which improves drug efficacy. Drug loading by the thin film can be done in various ways, depending on type of the drug, the area of exposure, and the purpose of drug delivery. Main text: This review summarizes the various methods used for preparing thin films with drugs via Layer-by-layer (LbL) assembly. Furthermore, additional functionalities of thin films using surface modification in drug delivery are briefly discussed. There are three types of methods for preparing a drug-carrying multilayered film using LbL assembly. First methods include approaches for direct loading of the drug into the pre-fabricated multilayer film. Second methods are preparing thin films using drugs as building blocks. Thirdly, the drugs are incorporated in the cargo so that the cargo itself can be used as the materials of the film. Conclusion: The appropriate designs of the drug-loaded film were produced in consideration of the release amounts and site of the desired drug. Furthermore, additional surface modification using the LbL technique enabled the preparation of effective drug delivery carriers with improved targeting effect. Therefore, the multilayer thin films fabricated by the LbL technique are a promising candidate for an ideal drug delivery system and the development possibilities of this technology are infinite.
Preparation of multifunctional micelles from two different amphiphilic block copolymers
Tanum, Junjira,Han, Uiyoung,Shin, Jong wook,Hong, Jinkee Elsevier 2018 Colloids and surfaces. A, Physicochemical and engi Vol.537 No.-
<P><B>Abstract</B></P> <P>Micelles are widely used in drug delivery owing to their attractive properties such as controllable drug release rates and the ability to target certain locations by conjugating with specific molecules. However, with the current state of understanding, only the core–shell and corona sites of micelles can be utilized. To form a micelle, each block copolymer was dissolved in DMF and then dropped into a polar solvent. Polymer micelles were formed through the agglomeration of the hydrophobic part that constituted a non-polar core and a hydrophilic corona. In this study, poly(styrene)-<I>block</I>-poly(4-vinylpyridine) (PS-<I>b</I>-P4VP) and poly(styrene)-<I>block</I>-poly(acrylic acid) (PS-<I>b</I>-PAA) formed micelles with a PS core in water. The hydrophobic PS domains were insoluble in the aqueous phase, which led to aggregation. Furthermore, from the pH-sensitive characteristic of weak polyelectrolyte, the changing of pH condition has an affected to the degree of ionization. Due to their characteristics, we prepared micelles from block copolymers at various pH values to increase the functionality of the micelles.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Hwang, Jun-Ha,Han, Uiyoung,Yang, Miso,Choi, Yonghyun,Choi, Jonghoon,Lee, Jong-Min,Jung, Han-Sung,Hong, Jinkee,Hong, Jeong-Ho Elsevier 2019 ACTA BIOMATERIALIA Vol.86 No.-
<P><B>Abstract</B></P> <P>In regenerative medicine, the generation of therapeutic stem cells and tissue engineering are important for replacing damaged tissues. Numerous studies have attempted to produce cellular components that mimic the native tissue for gaining optimal function. Particularly, the extracellular matrix (ECM) composition plays an important role in cellular functions including determining the fates of mesenchymal stem cells (MSCs). Here, we evaluated the osteogenic effects of a nanofilm in which oppositely charged polyelectrolytes were alternately adsorbed onto the cell surface to create an artificial ECM environment for single MSCs. Interestingly, nanofilm composed of collagen (Col) and alginate (AA) showed relatively high stiffness and MSCs coated with the Col/AA nanofilm showed increased osteogenic differentiation efficiency compared to other nanofilm-coated MSCs. Further analysis revealed that the Col/AA nanofilm coating stimulated osteogenesis by activating transcriptional coactivators with the PDZ binding motif through extracellular signal-related kinase and p38 MAPK signaling. This nano-sized cellular coating will facilitate the development of nanotechnology for controlling cellular functions and advance stem cell-based clinical applications for regenerative medicine.</P> <P><B>State of Significance</B></P> <P>In this study, we developed an artificial cellular nano-environment formed by multilayer nanofilms. We demonstrated that the nanofilms introduced to mesenchymal stem cells (MSCs) stimulate osteogenic differentiation by regulating intracellular signaling. Among the various nanofilm combinations, the induction of osteogenic gene transcription in collagen (Col) and alginate (AA) film-coated MSCs was the most pronounced compared to that on other nanofilms. A minimum number of Col/AA nanofilm bilayers (n = 2) was required for effective induction of MSC osteogenic differentiation. In addition, we observed the correlation between the promoting effect of osteogenic differentiation and stiffness of the nanofilm. Our results may be useful for developing a cell coating model system widely applicable in bioengineering and regenerative medicine.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
비밀 중간키를 이용한 소프트웨어적 전력분석공격 방어대책
박영구,김형락,이훈재,한덕찬,박의영,Park, YoungGoo,Kim, HyeongRag,Lee, HoonJae,Han, DeokChan,Pak, UiYoung 한국정보통신학회 2013 한국정보통신학회논문지 Vol.17 No.12
전력분석공격은 알려진 값과 마스터키로부터 생성된 숨겨진 값을 입력 받아 연산하는 시점에서 이루어진다. 연산 결과값과 연산 중에 측정된 전력신호의 상관도를 분석하여 숨겨진 값을 찾아내고, 이 찾아낸 값으로 부터 마스터키를 추정할 수 있다. 그러나 전력분석을 가능하게 하는 조건을 바꾸어, 알려진 값과 연산자를 숨기거나, 숨겨진 값으로부터 마스터키의 추정이 불가능하게 하거나, 연산 결과 값과 전력신호간의 상관도를 매우 낮게 하면 전력분석공격이 매우 어렵게 된다. 이와 같은 전력분석공격을 어렵게 하는 조건을 적용한 비밀 중간키를 이용한 소프트웨어적 방어 대책을 제안한다. Correlation power analysis attack takes place at the point of operating a known value and a hidden value from a master key as an input. The hidden value can be found by analyzing a correlation between the result value and the measured power signal during the operation, witch makes it possible to estimate the master key from the hidden value. However, the correlation power analysis attack can be very difficult by changing the conditions that make the power analysis possible, when the known value and the operation is hidden, when it is impossible to estimate the master key from the hidden value, or when the correlation between the result value and the power signal is considerably lowered. Therefore this study proposes a software countermeasure using a secrete intermediate key to witch these conditions are applied.