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Prof. Jinwoo Cheon
講演題目：“ Advances of Non-graphene 2D TMC Nanoparticles and Bio-sensing/actuation of Magnetic Nanostructures”
Two-dimensional (2D) layered transition metal chalcogenides (TMCs) are of significant interest due to their novel materials properties that are lacking from other 2D materials such as graphene. However, the understanding of chemical reactivity of 2D TMSs such as surface reactions and structural effects of chemical environments is poor. In this talk, I will discuss the chemistry of 2D layered TMCs with an emphasis on the chemical parameters which can promote structural transformation and composition reactions. In specific, upon exposure to water (nucleophile) and oxygen (electrophile), 2D TiS2 nanodisc transforms to either entirely new toroid or shape preserved disc TiO2 nanocrystals. Our study is one of the rare observations on the unique characteristics of 2D layered nanomaterials. In addition, the investigation described in the manuscript has led to a new concept of functionalizing the 2D TMCs as one of the intermediate TiS2(disc)-TiO2(shell) hetero-structure nanocrystals possess type II electronic band alignment with near infrared absorption (0.76 eV) which induce increased solar energy conversion rate. As a second theme, magnetic nanoparticles will be described as an new tool that can turn on cell signaling for wide variety cells such as cancer and sensory (auditory) cells in a remote and noninvasive manner. For example, the magnetic switch consists of iron oxide magnetic nanoparticles, conjugated with a targeting antibody for receptor 4 (DR4) of DLD-1 cells. The magnetic switch, in its “On” mode when a magnetic field is applied to aggregate magnetic nanoparticle bound DR4s, promotes sequential cascades of apoptosis signaling pathways. In this study, we have also demonstrated that the magnetic switch is operable in a micrometer scale controlled manner for promoting cell death and that it can be applied in an in vivo system.