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pH-controllable cell-penetrating polypeptide that exhibits cancer targeting
Lee, DaeYong,Noh, Ilkoo,Yoo, Jisang,Rejinold, N. Sanoj,Kim, Yeu-Chun Elsevier 2017 ACTA BIOMATERIALIA Vol.57 No.-
<P><B>Abstract</B></P> <P>Helical peptides were naturally-occurring ordered conformations that mediated various biological functions essential for biotechnology. However, it was difficult for natural helical polypeptides to be applied in biomedical fields due to low bioavailability. To avoid these problems, synthetic alpha-helical polypeptides have recently been introduced by further modifying pendants in the side chain. In spite of an attractive biomimetic helical motif, these systems could not be tailored for targeted delivery mainly due to nonspecific binding events. To address these issues, we created a conformation-transformable polypeptide capable of eliciting a pH-activated cell-penetrating property solely at the cancer region. The developed novel polypeptide showed that the bare helical conformation had a function at physiological conditions while the pH-induced helical motif provided an active cell-penetrating characteristic at a tumor extracellular matrix pH. The unusual conformation-transformable system can elicit bioactive properties exclusively at mild acidic pH.</P> <P><B>Statement of Significance</B></P> <P>We developed pH-controllable cell-penetrating polypeptides (PCCPs) undergoing pH-induced conformational transitions. Unlike natural cell-penetrating peptides, PCCPs was capable of penetrating the plasma membranes dominantly at tumor pH, driven by pH-controlled helicity. The conformation of PCCPs at neutral pH showed low helical propensity because of dominant electrostatic attractions within the side chains. However, the helicity of PCCPs was considerably augmented by the balance of electrostatic interactions, thereby inducing selective cellular penetration. Three polypeptides undergoing different conformational transitions were prepared to verify the selective cellular uptake influenced by their structures. The PCCP undergoing low-to-high helical conformation provided the tumor specificity and enhanced uptake efficiency. pH-induced conformation-transformable polypeptide might provide a novel platform for stimuli-triggered targeting systems.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Lee, Jinwoo,Bong, Hyuk Jong,Kim, Se-Jong,Lee, Myoug-Gyu,Kim, Daeyong Elsevier 2020 International journal of plasticity Vol.126 No.-
<P><B>Abstract</B></P> <P>In this study, a new material model for hexagonal close-packed (HCP) metals for predicting their flow responses under monotonic/cyclic loadings at various temperatures is proposed. The temperature-dependent constitutive model is re-formulated using a continuum-based distortional hardening law, which affects the shape of the yield surface depending on the loading direction, and also uses the concept of the dominant deformation modes in magnesium alloys: twin, untwin, and slip-dominate modes, considering the role of the twins in plastic deformation. In terms of the material asymmetry in yield strength, the Cazacu–Barlat–Plunkett (CPB) ’06 yield criterion is extended to include thermal effects. A numerical formulation of the material model has also been developed to allow its implementation into finite element analysis software via a user-defined material subroutine (UMAT). The predicted results of stress–strain response for monotonic and cyclic loadings are excellent agreement with the experimental data. Moreover, the simulated results show the strength differential (SD) effect and unusual flow responses of AZ31B magnesium alloy sheets at room temperature, as well as the variation in the SD effect and anisotropic hardening behavior at elevated temperatures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Enhanced distortional hardening law for HCP metals, particularly for targeting Mg alloys at warm temperatures, is proposed. </LI> <LI> The stress integration algorithm based on predictor-corrector scheme are formulated for the proposed constitutive model. </LI> <LI> Experimental results under strain path changes at various temperatures are accurately predicted using the proposed law. </LI> <LI> The Bauschinger effect under cyclic loadings is quantified, and the proposed constitutive model lead better prediction. </LI> </UL> </P>
Lee, DaeYong,Lee, Soo-Hwan,Na, Youjin,Noh, Ilkoo,Ha, JongHoon,Yoo, Jisang,Bang, Hyun Bae,Park, Jong Hyun,Jeong, Ki Jun,Yun, Chae-Ok,Kim, Yeu-Chun Elsevier Science Publishers 2017 Journal of controlled release Vol.264 No.-
<P><B>Abstract</B></P> <P>Artificial cationic helical peptides possess an enhanced cell-penetrating property. However, their cell-penetrability is not converted by cellular environmental changes resulting in nonspecific uptake. In this study, pH-sensitive anion-donating groups were added to a helical polypeptide to simultaneously achieve tumor targeting and pro-apoptotic activity. The mitochondria-destabilizing helical polypeptide undergoing pH-dependent conformational transitions selectively targeted cancer cells consequently disrupting mitochondrial membranes and subsequently inducing apoptosis. This work presents a promising peptide therapeutic system for cancer therapy.</P> <P><B>Graphical abstract</B></P> <P>Mitochondria-destabilizing helical polypeptide undergoing a pH-activated conformational transition selectively perturbed the mitochondrial outer membranes thereby inducing pro-apoptosis.</P> <P>[DISPLAY OMISSION]</P>
Lee, Yunju,Park, Joonam,Jeon, Hyunkyu,Yeon, Daeyong,Kim, Byung-Hyun,Cho, Kuk Young,Ryou, Myung-Hyun,Lee, Yong Min Elsevier 2016 Journal of Power Sources Vol.325 No.-
<P><B>Abstract</B></P> <P>To establish an accurate correlation between a separator’s pore structure and the electrochemical performance of a lithium-ion battery (LIB), we fabricate well defined polyethylene (PE) separators on the same production line while maintaining most processing variables, except for composition. Four PE separators having different thicknesses and porosities (16 μm/37%, 16 μm/40%, 16 μm/47%, 22 μm/47%, respectively) are physically and electrochemically evaluated in detail. Although thickness and porosity remain good parameters by which to represent the separators’ characteristics, both the normalized Gurley number and ionic conductance are found to have much stronger relationships with the rate capability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Well-defined polyethylene separators are fabricated with the same raw materials. </LI> <LI> Normalized Gurley number and ionic conductance can predict the cell performance. </LI> <LI> Correlation map on separators’ physical and electrochemical properties is proposed. </LI> </UL> </P>
초등학교 교사, 학생 및 학부모들의 교육공동체 형성을 위한 요구도 분석
이대용(Lee, Daeyong),박한숙(Park, Han-Sook) 학습자중심교과교육학회 2017 학습자중심교과교육연구 Vol.17 No.10
The purpose of this study was to investigate factor of educational community which members of elementary school(teachers, students and parents) recognized and to explore their needs on building warm educational community. For this purpose, t-test, Borich priority formula and the Locus for Focus Model method were used. The result of this study were following: first, in total their needs analysis, needs of ‘democratic participation’ and ‘relation care’ category were highest. Second, needs of elementary school teachers on warm educational community were highest about ‘communication’ and ‘democratic participation’. Third, ‘democratic participation’ and ‘relation care’ category were highest in needs of elementary school students on warm educational community. Finally, needs of elementary school parents on warm educational community were highest about ‘democratic participation’ and ‘relation care’ category. Based on the review, findings and implications are discussed. 본 연구는 초등학교 교사, 학생 및 학부모들의 교육공동체 형성에 있어 어떤 요구 들을 가지고 있는지를 밝히는데 그 목적이 있다. 이를 위해 본 연구는 t-검증, Borich의 요구도와 The Locus for Focus 모델을 활용하여 우선순위 분석을 실시하 였다. 연구 결과는 다음과 같다. 첫째, 전체 구성원의 요구도 조사에서는 민주적 참여와 관계적 돌봄 요인들의 요구도가 높게 나타났다. 둘째, 초등학교 교사들은 민주적 참여와 연대적 협력 요인들의 요구도가 높은 것으로 밝혀졌다. 셋째, 초등학교 학생들은 민주적 참여와 관계적 돌봄 요인에서의 요구도가 가장 높게 나타났다. 마지 막으로 초등학교 학부모들도 학생과 마찬가지로 민주적 참여와 관계적 돌봄 요인들 에서 요구도가 높게 나타났다. 학생들과 달리 학부모의 요구는 다양하고 구체적인 것으로 판단된다. 이러한 결과를 바탕으로 논의 및 제언을 제시하였다.