Publications by authors named "Young Koan Ko"

We investigate the effects of the frequency and density of a nanomechanical stimulus on nucleation and growth of silk-elastin-like protein polymer (SELP) nanofibers. Repetitive tappings are crucial to create nucleation areas and a potential molecular level mechanism was proposed. Using this technique mechanically guided nanofiber patterns were successfully created.

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Carbon nanotubes (CNTs) have attracted considerable attention for applications using their superior mechanical, thermal and electrical properties. A simple method to controllably align single-walled CNTs (SWNTs) by using magnetic particles embedded with superparamagnetic iron oxide as an accelerator under the magnetic field was developed. The functionalization of SWNTs using biotin, interacted with streptavidin-coupled magnetic particles (micro-to-nano in diameter), and layer-by-layer assembly were performed for the alignment of a particular direction onto the clean silicon and the gold substrate at very low magnetic forces (0.

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We developed a novel method of vertical alignment of SWNTs using a single-step process for the simultaneous vertical alignment of the SWNTs by a magnetic field and the fixation of their alignment by means of the direct evaporation of the films. We fabricated Fe-oxide/SWNT samples that are reacted by iron-oleate complex, oleic acid and cut SWNTs in 1-octadecene. The Fe-oxide/SWNT samples are dispersed in N,N-dimethylformamide and the resulting solution was deposited on an ITO glass substrate using the spraying method with magnetic field.

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We investigated the effects of the alignment and ordering of pi-conjugated perfluorinated dendrimers containing pyrene moieties in their cores on their photoluminescence (PL) properties. The pyrene molecules are stacked in columns surrounded by aromatic and semifluorinated tails, which can be conjugated and act as chromophores. Polarized light microscopy (PLM), cross-sectional scanning electron microscopy (SEM), and atomic force microscopy (AFM) results show that variation of the cooling rate of the dendrimers produces variation in their orientation and ordering: Slow cooling (approximately <0.

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Single-walled carbon nanotubes (SWNTs) have been chemically attached with high density onto a patterned substrate. To form the SWNT pattern, the substrate was treated with acid-labile group protected amine, and an amine prepattern was formed using a photolithographic process with a novel polymeric photoacid generator (PAG). The polymeric PAG contains a triphenylsulfonium salt on its backbone and was synthesized to obtain a PAG with enhanced efficiency and ease of spin-coating onto the amine-modified glass substrate.

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DNA oligonucleotides were covalently immobilized to prepatterned single-walled carbon nanotube (SWNT) multilayer films by amidation. SWNT multilayer films were constructed via consecutive condensation reactions creating stacks of functionalized SWNT layers linked together by 4,4'-oxydianiline. Aminated- or carboxylated-DNA oligonucleotides were covalently immobilized to the respective carboxylated or aminated SWNT multilayer films through amide bond formation using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride.

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Carbon nanotube conducting arrays were constructed via consecutive amidation reactions with the aid of a linker molecule and a condensation agent on a patterned amine-terminated glass substrate. The electrical resistivity of the nanotube films was sensitive to the degree of coverage for the substrate, making it possible to tailor nanotube multilayers suitable for use in micro- or nanoscale electronic devices and circuits.

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