https://scholar.dgist.ac.kr/handle/20.500.11750/13676 2026-10-03T23:47:38Z https://scholar.dgist.ac.kr/handle/20.500.11750/60888 Title: Polyproline Modulates Membrane Translocation of Arginine-Rich Cell-Penetrating Peptides: Insights from Molecular Dynamics Simulations Author(s): Choe, Seungho; Mariam, Afira; Ejaz, Maheen Abstract: Recent experiments have shown that incorporating polyproline segments into arginine (R)-rich cell-penetrating peptides (CPPs) enhances membrane penetration. Here, we employ molecular dynamics (MD) simulations combined with the weighted ensemble approach to investigate how a polyproline segment influences the free-energy barrier for membrane translocation in the designed peptide P9R9. Our results indicate that the extended, conformationally constrained nature of the P9 segment facilitates early membrane engagement and promotes the formation of a hydrated translocation pathway. This behavior is associated with a reduced desolvation penalty during insertion of the arginine-rich (R9) segment. Consistent with this interpretation, the solvent-accessible surface area (SASA) of R9 exhibits a non-monotonic trend, suggesting partial rehydration within the membrane interior. Together, these findings support a sequential translocation mechanism in which P9 interacts with the membrane prior to R9, thereby facilitating subsequent insertion and lowering the free-energy barrier relative to peptides lacking polyproline segments. This work provides a molecular-level perspective on how polyproline segments modulate membrane translocation and offers useful insights for designing more effective CPPs. 2026-05-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60686 Title: Spontaneous Penetration of Carbon Nanotubes through Lipid Bilayers: A Computational Perspective Author(s): Choe, Seungho; Mariam, Afira; Ejaz, Maheen Abstract: Carbon nanotubes (CNTs) have been widely explored for applications ranging from drug delivery to energy conversion. To evaluate their potential as drug-delivery agents, it is essential to understand the molecular mechanisms governing their interactions with, and possible transport across, cell membranes. Molecular dynamics (MD) simulations provide a powerful framework for probing these processes at molecular resolution. In this study, we investigate the spontaneous membrane insertion and deep penetration of pristine CNTs (p-CNTs) using the weighted ensemble (WE) method combined with all-atom MD simulations. Two p-CNTs with similar diameters but different lengths were examined to elucidate how nanotube length influences membrane-interaction behavior. Both p-CNTs readily insert into the hydrophobic core of the membrane; however, they exhibit distinct behaviors near the lower leaflet. Although neither p-CNT fully escapes into the opposite aqueous phase due to strong hydrophobic interactions, the WE approach enables detailed characterization of their penetration pathways and the associated free-energy landscape within the bilayer. 2026-03-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59990 Title: Decoding Diluent-Driven Solvation Dynamics in Locally Concentrated Ionic Liquid Electrolytes Author(s): Akter Shanjida; Mariam Afira; Lim, Minhong; Lee, Hongkyung; Choe, Seungho Abstract: The interplay between lithium salts and anions critically influences the electrochemical and physicochemical properties of locally concentrated ionic liquid electrolytes (LCILEs), a promising class of materials for next-generation lithium-ion batteries. Here, we investigate how varying diluent concentrations modulate lithium-anion interactions, ion dynamics, and transport properties in LCILEs. Using molecular dynamics (MD) simulations combined with density functional theory (DFT) calculations, we show that incorporating 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as a diluent minimally perturbs the solvation structure while effectively weakening Li+-anion interactions and promoting ionic dissociation. Adjusting the lithium salt-to-ionic liquid (IL) ratio alters the coordination environment of bis(fluorosulfonyl)imide anions (FSI-). It reduces the presence of pyrrolidinium cations in the lithium solvation shell. Beyond solvation effects, we further demonstrate that introducing lithium hexafluorophosphate (LiPF6) enhances ionic conductivity and increases the lithium-ion diffusion coefficient. By systematically exploring the impacts of diluent concentration and ionic additives, our theoretical framework offers molecular-level insights into how electrolyte composition influences lithium-ion mobility and interfacial stability, key factors in designing high-performance electrolytes for next-generation energy storage systems. 2025-09-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58553 Title: Interfacial impacts of diluent-mediated anion conformational changes in locally concentrated ionic liquid electrolytes Author(s): Lim, Minhong; Chang, Hongjun; Kim, Gunyoung; Seo, Jiyeon; Kim, Beomjun; Choe, Seungho; Lee, Hochun; Moon, Janghyuk; Lee, Hongkyung Abstract: Dilution methods employing weaker-solvating solvents as diluents have shown promise in reducing the viscosity of liquid electrolytes without disrupting the coordination between Li⁺ and anions. However, diluents alter the FSI− coordination conformation in locally concentrated ionic liquid electrolytes (LCILEs) by occupying the interstitial space between the Li+−FSI− complex and Pyr13+. The Li+−FSI− bond exhibits various energy states depending on the anion coordination conformation. By regulating the dilution extent, the HOMO level can be reduced, enabling higher voltage tolerance with fewer side reactions. Given that reinforcing the Li+−FSI− binding can contribute to reducing the HOMO level, TTE in-between Pyr13+ and FSI− possibly changes the anion conformation from bidentate to ambidentate coordination. Furthermore, moderate dilution promoting bidentate coordination facilitates the formation of a LiF-rich solid-electrolyte interphase (SEI). Herein, we present an optimally diluted CILE (LCILE-T1) that demonstrates superior cycle stability in a pouch-type full cell operating at 4.7 V, achieving over 240 cycles. © 2025 2025-05-31T15:00:00Z