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Anhydrous Alum Inhibits α-MSH-Induced Melanogenesis by Down-Regulating MITF via Dual Modulation of CREB and ERKby Kyu-Ree In, Mi Ae Kang, Su Dong Kim, Jinho Shin, Sung Un Kang, Tae Jun Park, Seung-Joo Kim and Jong-Soo LeeInternational Journal of Molecular Sciences 2023, 24(19), 14662; https://doi.org/10.3390/ijms241914662AbstractMelanogenesis, the intricate process of melanin synthesis, is central to skin pigmentation and photoprotection and is regulated by various signaling pathways and transcription factors. To develop potential skin-whitening agents, we used B16F1 melanoma cells to investigate the inhibitory effects of anhydrous alum on melanogenesis and its underlying molecular mechanisms. Anhydrous alum (KAl(SO4)2) with high purity (>99%), which is generated through the heat-treatment of hydrated alum (KAl(SO4)2·12H2O) at 400 °C, potentiates a significant reduction in melanin content without cytotoxicity. Anhydrous alum downregulates the master regulator of melanogenesis, microphthalmia-associated transcription factor (MITF), which targets key genes involved in melanogenesis, thereby inhibiting α-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis. Phosphorylation of the cAMP response element-binding protein, which acts as a co-activator of MITF gene expression, is attenuated by anhydrous alum, resulting in compromised MITF transcription. Notably, anhydrous alum promoted extracellular signal-regulated kinase phosphorylation, leading to the impaired nuclear localization of MITF. Overall, these results demonstrated the generation and mode of action of anhydrous alum in B16F1 cells, which constitutes a promising option for cosmetic or therapeutic use.Keywords: anhydrous alum; melanogenesis; MITF; CREB; ERK
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Cu(triNHC)-catalyzed polymerization of glycidol to produce ultralow-branched polyglycerolby Kihyuk Sung, Jinsu Baek, Soonyoung Choi, Byeong-Su Kim, Sang-Ho Lee, In-Hwan Lee and Hye-Young JangRSC Advances 2023, 13(34), 24071-24076; https://doi.org/10.1039/D3RA04422JAbstractWe have successfully synthesized a novel form of polyglycerol with an unprecedentedly low degree of branching (DB = 0.08–0.18), eliminating the need for glycidol protection. Leveraging the remarkable efficiency and selectivity of our Cu(triNHC) catalyst, comprising copper(I) ions and NHC ligands, we achieved a highly selective polymerization process. The proposed Cu-coordination mechanisms presented the formation of linear L1,3 units while effectively suppressing dendritic units. Consequently, our pioneering approach yielded polyglycerol with an ultralow DB and exceptional yields. To comprehensively assess the physical properties and topology of the synthesized polyglycerol, we employed 1H diffusion-ordered spectroscopy, size-exclusion chromatography, and matrix-assisted laser desorption/ionization-time of flight spectrometry. Remarkably, the ultralow-branched cyclic polyglycerol (DB = 0.08) synthesized at 0 °C showcased extraordinary characteristics, exhibiting the lowest diffusion coefficient and the highest molecular weight. This achievement establishes the significant potential of our polyglycerol with a low degree of branching, revolutionizing the field of biocompatible polymers.
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Recent advances in organelle-specific two-photon small-molecule fluorescent probes for bioanalysis in live tissuesby Hyo Won Lee, Vinayak Juvekar, Dong Joon Lee, Hwan Myung KimTrAC Trends in Analytical Chemistry 2023, 165, 117128; https://doi.org/10.1016/j.trac.2023.117128AbstractBiological events occur in specific cellular organelles to perform specialized roles in cells and collaborate with other organelles. Various methods have been used to study organelle dynamics, including two-photon microscopy. This technique uses two near-infrared photons as an excitation source to generate high-resolution images over an extended period with minimal photo-toxicity and background noise. This review highlighted the design strategies, photo-physical properties, and bioimaging applications of recent two-photon probes for organelles in live samples. In this review, we focused on the development of two-photon probes specifically localized in the endoplasmic reticulum, Golgi, lipid droplets, lysosomes, plasma membrane, and mitochondria. The summary was limited to research from 2017 onwards.Keywords: Bioanalysis; Live tissues; Organelles; Two-photon microscopy; Two-photon probes
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Results on bar-core partitions, core shifted Young diagrams, and doubled distinct coresby Hyunsoo Cho, JiSun Huh, Hayan Nam, Jaebum SohnDiscrete Mathematics 2023, 346(7), 113387; https://doi.org/10.1016/j.disc.2023.113387AbstractSelf-conjugate core partitions, bar-core partitions, core shifted Young diagrams (or CSYDs), and doubled distinct core partitions have been studied independently. In this paper, we show that doubled distinct cores and CSYDs are special cases of bar-core partitions. From this fact together with the abacus construction, we find path interpretations of bar-cores, CSYDs, and doubled distinct cores on (s, t)-cores and (s,s+d,s+2d)-cores, respectively. As a result, we get the number of these core partitions.Keywords: Bar-core partitions; Core shifted young diagrams; Doubled distinct core partitions; Simultaneous core partitions; Free Motzkin paths
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Propagation of Dirac waves through various temporal interfaces, slabs, and crystalsby Seulong Kim and Kihong KimPhys. Rev. Research 2023, 5(2), 023162; https://doi.org/10.1103/PhysRevResearch.5.023162AbstractWe investigate the influence of the temporal variations of various medium parameters on the propagation of Dirac-type waves in materials where the quasiparticles are described by a generalized version of the pseudospin-1/2 Dirac equation. Our considerations also include the propagation of electromagnetic waves in metamaterials with the Dirac-type dispersion. We focus on the variations of the scalar and vector potentials, mass, Fermi velocity, and tilt velocity describing the Dirac cone tilt. We derive the scattering coefficients associated with the temporal interfaces and slabs analytically and find that the temporal scattering is caused by the changes of the mass, Fermi velocity, and vector potential, but does not arise from the changes of the scalar potential and tilt velocity. We also explore the conditions under which the temporal Brewster effect and total interband transition occur and calculate the change in total wave energy. We examine bilayer Dirac temporal crystals where parameters switch between two different sets of values periodically and prove that these systems do not have momentum gaps. Finally, we assess the potential for observing these temporal scattering effects in experiments.
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Developing a Novel Terahertz Fabry–Perot Microcavity Biosensor by Incorporating Porous Film for Yeast Sensingby Hwan Sik Kim, Seung Won Jun and Yeong Hwan AhnSensors 2023, 23(13), 5797; https://doi.org/10.3390/s23135797AbstractWe present a novel terahertz (THz) Fabry–Perot (FP) microcavity biosensor that uses a porous polytetrafluoroethylene (PTFE) supporting film to improve microorganism detection. The THz FP microcavity confines and enhances fields in the middle of the cavity, where the target microbial film is placed with the aid of a PTFE film having a dielectric constant close to unity in the THz range. The resonant frequency shift increased linearly with increasing amount of yeasts, without showing saturation behavior under our experimental conditions. These results agree well with finite-difference time-domain (FDTD) simulations. The sensor’s sensitivity was 11.7 GHz/μm, close to the optimal condition of 12.5 GHz/μm, when yeast was placed at the cavity’s center, but no frequency shift was observed when the yeast was coated on the mirror side. We derived an explicit relation for the frequency shift as a function of the index, amount, and location of the substances that is consistent with the electric field distribution across the cavity. We also produced THz transmission images of yeast-coated PTFE, mapping the frequency shift of the FP resonance and revealing the spatial distribution of yeast.Keywords: Fabry–Perot cavity; microorganisms; porous film
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Elucidating atomistic mechanisms of the formation of phase-controlled ultrathin MoTe2 films and lateral hetero-phase MoTe2 interfacesby Hyeonkyeong Kim, Jooyong Bhang, Taejoon Park, Jae-Hyun Lee, Hosung Seo, Youngdong YooSurfaces and Interfaces 2023, 40, 103040; https://doi.org/10.1016/j.surfin.2023.103040AbstractMolybdenum ditelluride (MoTe2) is gaining great attention because of its phase tunability. However, the precise control of the phase of ultrathin MoTe2 films is quite challenging, and the atomistic mechanism has not been fully elucidated. Here, we establish phase-controlled growth of ultrathin MoTe2 films by independently adjusting the Te atomic flux. We employed a chemical vapor deposition method that uses Mo nanolayers as a precursor to synthesize ultrathin MoTe2 films with a thickness of 4 − 7 nm. We found that ultrathin 1T’ MoTe2 films were formed with low Te atomic flux, whereas ultrathin 2H MoTe2 films were obtained with high Te atomic flux. Lateral metal–semiconductor hetero-phase 1T’/2H MoTe2 ultrathin films with seamless interfaces were synthesized with medium Te atomic flux. Furthermore, we performed density functional theory calculations to elucidate the detailed mechanisms of the phase transition between 1T’ and 2H MoTe2 driven by Te vacancy as well as the property of the 1T’/2H MoTe2 interface. This work provides a full understanding of the formation of phase-controlled ultrathin MoTe2 films and lateral metal–semiconductor hetero-phase MoTe2 interfaces.Keywords: Ultrathin MoTe2 films;Hetero-phase interfaces;Phase control;Te vacancies
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