https://dspace.ewha.ac.kr/handle/2015.oak/171702 2026-04-05T10:28:21Z 2026-04-05T10:28:21Z 이영미 https://dspace.ewha.ac.kr/handle/2015.oak/274962 2026-04-02T16:31:09Z 2026-01-01T00:00:00Z

Title: Triple Amperometric Microsensor for Simultaneous Real-Time In Vivo Monitoring of NO, CO, and H2S During Epileptic Seizures Ewha Authors: 이영미 Abstract: Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are endogenous gaseous signaling molecules, playing crucial roles in a wide range of biological processes. This study presents the fabrication and evaluation of a triple amperometric microsensor capable of the simultaneous and selective detection of NO, CO, and H2S for in vivo applications. The sensor integrates three platinum working electrodes into a single device. Each electrode was independently modified with specific metal deposits and selective membranes optimized to enhance specificity toward its target analyte. The sensor’s excellent performance in terms of sensitivity, linearity, and selectivity was confirmed. To demonstrate in vivo applicability, the sensor was positioned on the cortical surface of a living rat brain, where it successfully monitored real-time concentration changes of NO, CO, and H2S during seizure events induced by 4-aminopyridine: NO exhibited the earliest concentration increase, followed sequentially by CO and H2S, providing the first temporally resolved evidence of in vivo gasotransmitter crosstalk during neural hyperactivity. This work establishes a powerful electrochemical platform for probing multigasotransmitter dynamics in real time. © 2025 American Chemical Society

2026-01-01T00:00:00Z 윤주영 https://dspace.ewha.ac.kr/handle/2015.oak/274956 2026-04-02T16:31:08Z 2026-01-01T00:00:00Z

Title: Near-Infrared Ratiometric Fluorescent Probe for Monitoring Hypochlorous Acid in Ferroptosis Models Ewha Authors: 윤주영 Abstract: Ferroptosis is an iron-dependent, regulated cell death caused by the disruption of the oxidation–reduction balance. The hypochlorous acid (HClO) levels are closely correlated with the onset and progress of ferroptosis. Hence, investigating the underlying relationships between HClO changes and ferroptosis is particularly vital. To this end, we presented a new near-infrared (NIR) ratiometric fluorescent probe (BV-HD) based on the oxidation of the phenothiazine moiety for imaging HClO variations in ferroptosis models. Employing this BV-HD, the exogenous and endogenous HClO concentrations were consecutively detected in cells via ratiometric fluorescent intensity. Moreover, by virtue of NIR ratiometric fluorescent values, the up-regulated HClO fluxes were clearly observed in Erastin-induced ferroptosis cells. Upon exposure to ferrostatin-1 or glutathione or N-acetylcysteine, the ratiometric fluorescent intensity and NIR fluorescence intensity of Erastin-induced cells were both dramatically suppressed. Importantly, high levels of HClO were subsequently detected in drug-induced liver injury and ferroptosis mice. Therefore, this is an effective method based on this NIR ratiometric fluorescent probe, which was used for rapidly monitoring HClO concentrations and uncovering in-depth biological mechanisms in ferroptosis-related diseases. © 2025 American Chemical Society

2026-01-01T00:00:00Z 남원우 Shunichi Fukuzumi 이용민 Akhilesh Kumar https://dspace.ewha.ac.kr/handle/2015.oak/274948 2026-04-02T16:31:07Z 2026-01-01T00:00:00Z

Title: High oxidizing reactivity of mononuclear nonheme Iron(V)-oxo complexes Ewha Authors: 남원우; Shunichi Fukuzumi; 이용민; Akhilesh Kumar Abstract: Mononuclear nonheme iron(V)-oxo complexes bearing a tetraamido-macrocyclic (TAML) ligand ([FeV(O)(TAML)]-) are well characterized and the high oxidizing reactivity has been examined. In contrast, the oxidizing reactivity of mononuclear nonheme iron(V)-oxo complexes with neutral ligands, has yet to be studied because of the extreme short lifetimes of the iron(V)-oxo complexes (ca. several microseconds). We report herein systematic studies on the oxidizing reactivity of formal mononuclear nonheme iron(V)-oxo complexes, [FeV(O)(L)](n+1)+ [n = 2 where L is neutral ligand or n = 1 where L is monoanion ligand], by using laser-induced transient absorption measurements. The [FeV(O)(L)](n+1)+ complexes were produced by electron transfer from [FeIV(O)(L)]n+ to the triplet excited state of 2,3-dichloro-5,6-dicyano-p-benzoquinone (3DDQ*), which was generated by laser excitation. [FeV(O)(L)](n+1)+ reacts with H2O to produce [FeIII(OOH)(L)]n+, which was further oxidized by DDQ to evolve O2, accompanied by regeneration of [FeII(L)]n+. The decay rates of [FeV(O)(L)](n+1)+ became faster in the presence of substrates via oxidation of substrates by [FeV(O)(L)](n+1)+. Plots of logarithm of the rate constants vs the one-electron oxidation potentials of donor substrates were evaluated in light of the Marcus theory of outer-sphere electron transfer to afford the one-electron reduction potentials and reorganization energies of [FeV(O)(L)](n+1)+, which have been compared with those of other iron(V)-oxo complexes. The large reorganization energies of the electron-transfer reduction of the one-electron oxidized species of [FeIV(O)(L)]n+ indicate that electron-transfer oxidation of [FeIV(O)(L)]n+ occurs at the metal center to produce [FeV(O)(L)](n+1)+ rather than [FeIV(O)(L•+)](n+1)+. Copyright © 2025 Elsevier Inc. All rights reserved.

2026-01-01T00:00:00Z 남원우 이용민 https://dspace.ewha.ac.kr/handle/2015.oak/274932 2026-04-02T16:30:06Z 2026-01-01T00:00:00Z

Title: Electronic Configurations Modulated by Heterometallic Orbital Interactions of Spinel Cocatalysts in Covalent Organic Framework-Based Dyads for Photocatalytic Hydrogen Evolution Ewha Authors: 남원우; 이용민 Abstract: Metal sulfides are promising cocatalysts in covalent organic framework (COF)-based photocatalytic systems. It is of paramount importance to fine-tune the electronic configurations of these cocatalysts for enhancing the efficiency of photocatalytic hydrogen evolution. Herein, we report a strategy aimed at regulating heterometallic electron configuration of the cocatalysts to construct noble-metal-free photocatalytic systems, which is achieved by combining spinel sulfides (NiCo2S4) with the ketoenamine-linked COFs (TpPa). In NiCo2S4, the 3d orbital electrons of tetrahedral Ni sites (NiTd) and octahedral Co sites (CoOh) interact with the p orbital electrons of sulfur. Such interactions result in strong d–p orbital hybridization that triggers the electron migration from NiTd to CoOh sites, which improves the electron delocalization and facilitates the formation of hydrogen intermediates, thereby significantly boosting the kinetics of the photocatalytic hydrogen evolution reaction. The hydrogen evolution rate in the NiCo2S4/TpPa system is as high as 9160 μmol g–1 h–1, which outperforms that of Ni3S4/TpPa (700 μmol g–1 h–1), Co3S4/TpPa (2511 μmol g–1 h–1), and even Pt-loaded TpPa (5548 μmol g–1 h–1). This work presents a rational and effective approach to develop noble-metal-free, COFs-based photocatalytic systems for ameliorating hydrogen evolution performance. © 2026 American Chemical Society

2026-01-01T00:00:00Z