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상분리 영역 관찰 장치 및 방법

Title: 상분리 영역 관찰 장치 및 방법 Author(s): 이원희; 안용덕; 진시우; 서대하; 박지성 Abstract: 일실시예에 따른 상분리 영역 관찰 장치는 프로브 입자의 산란신호로부터 획득된 이미지 데이터를 수집하는 이미지 데이터 수집부; 상기 수집된 이미지 데이터에 기초하여 상기 프로브 입자의 위치 또는 경로를 결정함으로써 상기 이미지 데이터에서 프로브를 추적하는 프로브 추적부; 상기 프로브 입자의 결정된 위치 또는 경로에 기초하여 상분리 영역을 분류하는 영역 분류부; 상기 분류된 상분리 영역에 대한 크기를 추정하는 영역 크기 추정부; 및 상기 크기가 추정된 영역에 대한 정보를 제공하는 정보 제공부를 포함한다.

Fluorescence Modulation in UiO-66-NH2 via Photooxidation and Selective Reduction

2025-08-31T15:00:00Z

Title: Fluorescence Modulation in UiO-66-NH2 via Photooxidation and Selective Reduction Author(s): Ahn, Yongdeok; Park, Minsoo; Son, Younghu; Cho, Juhyeong; Park, Min Jeong; Seo, Daeha; Yoon, Minyoung Abstract: Metal-organic frameworks with emissive ligands offer tunable photophysical properties that are sensitive to their coordination environment and structural configuration. In this study, we demonstrate that the fluorescence of UiO-66-NH2 can be modulated through photo-oxidation-induced quenching and subsequent solvent-mediated recovery. Upon visible-light irradiation, reactive oxygen species induce two distinct oxidation pathways: irreversible oxidation of the ligand and reversible oxidation of the metal-oxo cluster. These redox events lead to partial disruption of the coordination environment and result in fluorescence loss. Reduction using mild alcohols selectively removes adsorbed oxidative species from Zr6O4(OH)4, leading to partial recovery of fluorescence and porosity. The extent of fluorescence restoration correlates with both the reducing strength and molecular size of the alcohol, reflecting its ability to penetrate internal pores and access to redox-active sites. Notably, some alcohol-treated samples exhibited nitrogen uptake beyond that of pristine UiO-66-NH2, suggesting redux-induced structural reorganization and defect-assisted pore expansion. These results establish a structure-function relationship in MOFs governed by localized redox chemistry, providing a platform for designing reconfigurable optical materials with switchable photophysical and porous characteristics.

Real-Time Visualisation of Reaction Kinetics and Dynamics: Single-Molecule Insights into the Iminium-Catalysed Diels-Alder Reaction

2025-10-31T15:00:00Z

Title: Real-Time Visualisation of Reaction Kinetics and Dynamics: Single-Molecule Insights into the Iminium-Catalysed Diels-Alder Reaction Author(s): Park, Minsoo; Ahn, Yongdeok; Cho, Juhyeong; Jang, Juhee; Lee, Wonhee John; Seo, Sangwon; Lee, Sunggi; Seo, Daeha Abstract: Investigation of the fundamental microscopic processes occurring in organic reactions is essential for optimising both organocatalysts and synthetic strategies. In this study, single-molecule fluorescence microscopy was employed to study the Diels-Alder reaction catalysed by a first-generation MacMillan catalyst, providing direct insights into its kinetic dynamics. This reaction proceeds via a series of reversible processes under equilibrium conditions (S -><- IM1 -><- IM2 -> P, IM1 and IM2: N,O-acetal and iminium ion intermediates, respectively). The individual reaction trajectories of single molecules were directly observed in real-time, and the kinetic transitions between the different states were quantitatively analysed using a hidden Markov model, thereby enabling precise determination of the kinetic rate constants and transition probabilities at the single-molecule level. In particular, the unique structural features of the MacMillan catalyst were probed to reveal how specific interactions stabilise the reaction intermediates and influence their kinetic behaviours. These findings highlight the importance of single-molecule fluorescence microscopy in understanding the fundamental mechanisms of organic reactions and guiding the rational design of more effective catalysts.

Reconciling a Kinetic Model for Dimerization of the EGFR Using Single-Molecule Tracking in Living Cells

2025-08-31T15:00:00Z

Title: Reconciling a Kinetic Model for Dimerization of the EGFR Using Single-Molecule Tracking in Living Cells Author(s): Kim, Kiwook; Jang, Juhee; Cho, Juhyeong; Ahn, Yongdeok; Jeong, Seunghyeon; Shin, Jiwon; Yea, Kyungmoo; Lee, Wonhee John; Seo, Daeha Abstract: Epidermal growth factor receptor (EGFR) dimerization plays a pivotal role in cellular signaling, influencing proliferation and disease progression, particularly in cancer. Despite extensive studies, the quantitative relationship between EGFR expression levels and dimerization efficiency remains incompletely understood. In this study, we investigated EGFR dimerization kinetics using ensemble-level biochemical assays and single-molecule tracking (SMT) in living cells. Our findings revealed noncanonical negative cooperative dimerization, where the monomer-to-dimer transition rate decreased as EGFR expression increased, challenging the assumptions of a simplistic reaction model. Furthermore, we identified a dimer-specific degradation pathway highlighting the open-system nature of the plasma membrane environment. These findings establish a quantitative framework for understanding EGFR dimerization dynamics, offering insights into the complex regulatory principles governing membrane protein interactions. This model not only improves our understanding of EGFR-mediated signaling but also suggests broader applicability for the therapeutic targeting of membrane protein systems.