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Han, Sanghun,Kim, Donghun,Han, So-hee,Kim, Nam Hee,Kim, Sun Hee,Lim, Yong-beom American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.38
<P>Understanding the dynamic behavior of nanostructural systems is important during the development of controllable and tailor-made nanomaterials. This is particularly true for nanostructures that are intended for biological applications because biomolecules are usually highly dynamic and responsive to external stimuli. In this Article, we investigated the structural and conformational dynamics of self-assembling bioactive β-sheet peptide nanostructures using electron paramagnetic resonance (EPR) spectroscopy. The model peptide nanostructures are characterized by the cross-β spine of β-ribbon fibers and multiple RNA-binding bioactive peptides that constitute the shell of the nanostructures. We found first, that bioactive peptides at the shell of β-ribbon nanostructure have a mobility similar to that of an isolated monomeric peptide. Second, the periphery of the cross-β spine is more immobile than the distal part of surface-displayed bioactive peptides. Third, the rotational dynamics of short and long fibrils are similar; that is, the mobility is largely independent of the extent of aggregation. Fourth, peptides that constitute the shell are affected first by the external environment at the initial stage. The cross-β spine resists its external environment to a certain extent and abruptly disintegrates when the perturbation reaches a certain degree. Our results provide an overall picture of β-sheet peptide nanostructure dynamics, which should be useful in the development of dynamic self-assembled peptide nanostructures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-38/ja307493t/production/images/medium/ja-2012-07493t_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja307493t'>ACS Electronic Supporting Info</A></P>
Cell-Penetrating Cross-β Peptide Assemblies with Controlled Biodegradable Properties
Han, Sanghun,Lee, Mun-kyung,Lim, Yong-beom American Chemical Society 2017 Biomacromolecules Vol.18 No.1
<P>Although self-assembled peptide nanostructures (SPNs) have shown potential as promising biomaterials, there is a potential problem associated with the extremely slow hydrolysis rate of amide bonds. Here, we report the development of cell-penetrating cross-beta SPNs with a controllable biodegradation rate. The designed self-assembling beta-sheet peptide incorporating a hydrolyzable,ester bond (self-assembling depsipeptide; SADP) can be assembled into bilayer beta-sandwich one-dimensional (1D) fibers similarly to conventional beta-sheet peptides. The rate of hydrolysis can be controlled by the pH, temperature, and structural characteristics of the ester unit. The ID fiber of the SADP transforms into vesicle-like 3D structures when the hydrophilic cell-penetrating peptide segment is attached to the SADP segment. Efficient cell internalization of the 3D nanostructures was observed, and we verified the intracellular degradation and disassembly of the biodegradable nanostructures. This study illustrates the potential of biodegradable cross-beta SPNs and provides a valuable toolkit that can be used with self assembling peptides.</P>
Spread current spectrum method based on model predictive control with double sampling
Sanghun Han,Seungil Choi,Younghoon Cho 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.1
This paper proposes a model predictive control (MPC) with a double-sampling technique to spread the current spectrum. Finite control set MPC has the characteristic of a switching frequency that fluctuates. Thus, the components of the switching frequency and harmonics are reduced in the current spectrum. When MPC is utilized to control current, virtual vectors are added to ensure a low current total harmonic distortion (THD). However, increasing the voltage vector reduces the switching frequency variation, which leads to degradation of the spread-spectrum performance. The proposed method allows MPC to have an additional feature to change the harmonic components while reducing the current THD. To verify the proposed scheme, a comparison of its performance according to the sampling techniques and number of the voltage vectors has been conducted. The simulation and experimental results demonstrate the effectiveness of the proposed method.