• Journal of the Korean Electrochemical Society
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• v.16 no.4
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• pp.217-224
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• 2013

In this paper, we have investigated the characteristics of cyclic voltammetry of a self-assembled mono-layer(SAM) electrode which was modified by 3-Mercaptopropionic acid (3-MPA) on gold nanoparticle(AuNP)-deposited electrode. Also, the transport phenomena of electrons and ions around the electrode have been analyzed. The governing equation and its boundary conditions by adopting the semi-infinite diffusion model were formulated for the mass-transfer dominant system. In order to obtain the numerical solutions of cyclic voltammetry(CV) on SAM electrodes, MATLAB program was implemented by applying the explicit finite difference method. Resulting CV program for the SAM-modified electrode was verified in good agreements with the experimental CV results for the 3-MPA on AuNP electrode.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2421-2429
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• 2018

Thiol-based self-assembled anchor linked to glucose oxidase (GOx) and gold nanoparticle (GNP) cluster is suggested to enhance the performance of glucose biosensor. By the adoption of thiol-based anchors, the activity of biocatalyst consisting of GOx, GNP, polyethyleneimine (PEI) and carbon nanotube (CNT) is improved because they play a crucial role in preventing the leaching out of GOx. They also promote electron collection and transfer, and this is due to a strong hydrophobic interaction between the active site of GOx and the aromatic ring of anchor, while the effect is optimized with the use of thiophenol anchor due to its simple configuration. Based on that, it is quantified that by the adoption of thiophenol as anchor, the current density of flavin adenine dinucleotide (FAD) redox reaction increases about 42%, electron transfer rate constant ($k_s$) is $9.1{\pm}0.1s^{-1}$ and the value is 26% higher than that of catalyst that does not use the anchor structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1539-1542
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• 2005

Self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols, $HS(CH_2)_nX$, where X is an organic functional group, onto gold surfaces have attracted widespread interest as templates for the fabrication of molecular and biomolecular microstructures. Previously photopatterning has been thought of as being restricted to the micron scale, because of the wellknown diffraction limit. So, we have explored a novel approach to nanofabrication by utilizing a femtosecond laser coupled to a near-field scanning optical microscope (NSOM).

• Macromolecular Research
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• v.15 no.3
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• pp.211-215
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• 2007

Hybrid thin film nanostructures composed of metal nanoparticles (NPs) and self-assembled polymer films with different spatial distributions of NPs were analyzed by optical waveguide spectroscopy (OWS). Specifically, the dielectric constants were calculated using effective medium theory for the incorporation of 1 vol% Au NP into the block copolymer (BCP) films having a cylindrical nanodomain morphology. Three cases were considered: uniform distribution of NPs in the film; selective distribution of NPs only in the cylindrical domains; and segregation of NPs to the center of the cylindrical domains. The optical waveguide spectra derived from the calculated dielectric constants demonstrate the feasibility of experimentally distinguishing the composite nanostructures with different inner morphologies in the hybrid metal NP-BCP nanostructures, by the measurement of the dielectric constants using OWS.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.618-624
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• 2013

We demonstrated unique inter- and intra-plasmonic coupling effects in bimetallic Au@Ag core-shell NP arrays which are regularly or randomly arranged on self-assembled block copolymer (BCP) inverse micelle monolayers. Polyvinylpyrrolidone (PVP)-stabilized Au@Ag core-shell NP arrays in regular or disordered configuration were incorporated and assembled on reconstructed PS-b-P4VP inverse micelle templates through two types of processes. The intensively enhanced LSPR coupling properties of individual and assembled Au@Ag NPs were evaluated by UV-visible spectroscopy in terms of the type of ligand stabilizer, coupling between Au and Ag, thickness of Ag shell, and type of array configuration. Finally, Au@Ag core-shell NP arrays were employed as active substrates for surface enhanced Raman spectroscopy (SERS) and a significantly enhanced signal enhancement was observed in accordance with the coupling intensity of Au@Ag NPs patterns.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.237-242
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• 2006

$Fe_3O_4$ and $CoFe_2O_4$ magnetic nanoparticles have been synthesized successfully in aqueous solution and coated with oleic acid. The solid and organic solution of the synthesized nanoparticles was obtained. Self-assembled monolayer films were formed using organic solution of these nanoparticles. The crystal sizes determined by Debye-Scherre equation with XRD data were found close to the particle sizes calculated from TEM images, and this indicates that the synthesized particles are nanocrystalline. Especially, EDS, ED, FT-IR, TGA/DTA and DSC were used to characterize the nanoparticles and the oleic acid adsorption, and it was found that oleic acid molecule on the $Fe_3O_4$ nanoparticle is a bilayer adsorption, while that on $CoFe_2O_4$ nanoparticle is single layer adsorption. The superparamagnetic behavior of the nanoparticles was documented by the hysteresis loop measured at 300 K.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.515-520
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• 2012

In this review, the fabrication of silicon based memory capacitor and organic memory thin film transistors (TFTs) was discussed for their potential identification tag applications and biosensor applications. Metal or non-metal nanoparticles (NPs) could be capped with chemicals or biomolecules such as protein and oligo-DNA, and also be self-assembly monolayered on corresponding target biomolecules conjugated dielectric layers. The monolayered NPs were formed to be charging elements of a nano floating gate layer as forming organic memody deivces. In particular, the strong and selective binding events of the NPs through biomolecular interactions exhibited effective electrostatic phenomena in memory capacitors and TFTs formats. In addition, memory devices fabricated as organic thin film transistors (OTFTs) have been intensively introduced to facilitate organic electronics era on flexible substrates. The memory OTFTs could be applicable eventually to the development of new conceptual devices.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.36-44
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• 2015

This article describes synthesis and electrochemical properties of layer-by-layer self-assembled multilayer film composed of polyaniline (PANi), graphene oxide (GO) and phytic acid (PA), whereby the GO was electrochemically reduced to ERGO, resulting in $(PANi/ERGO/PANi/PA)_{10}$ film electrode. Especially, we examined the possibility to improve the volumetric capacitive property of $(PANi/ERGO)_{20}$ film electrode via combining a spherical hexakisphosphate PA nanoparticle into the multilayer film that would dope PANi properly and also increase the porosity and surface area of the electrode. The electrochemical performances of the multilayer film electrodes were investigated using a three-electrode configuration in 1 M $H_2SO_4$ electrolyte. As a result, the $(PANi/ERGO)_{20}$ electrode showed the volumetric capacitance of $666F/cm^3$ at a current density of $1A/cm^3$, which was improved to the volumetric capacitance of $769F/cm^3$ for the $(PANi/ERGO/PANi/PA)_{10}$ electrode, in addition to the cycling stability maintained to 79.3% of initial capacitance after 1000 cycles. Thus, the electrochemical characteristics of the $(PANi/ERGO)_{20}$ electrode, which was densely packed by ${\pi}-{\pi}$ stacking between the electron-rich conjugate components, could have been improved through structural modification of the multilayer film via combining a spherical hexakisphosphate PA nanoparticle into the multilayer film.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.468-468
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• 2013

Self-assembled silver nanoparticles were synthesized on a graphene film to investigate plasmonic effect. Graphene was synthesized on glass substrate using chemical vapor deposition method and transfer process. Silver nanoparticles were formed using thermal evaporator and post-annealing process. The shape of silver nanoparticles was measured using a scanning electron microscopy. The resonance wavelength of plasmonic effect on graphene-silver nanoparticles was measured using transmittance spectra. The plasmon resonance wavelength was increased from 400 nm to 424 nm according to the lateral dimension of silver nanoparticles. Also we confirmed a strong plasmon effect form Raman spectra, which were measured on graphene-silver nanoparticles. The result shows that plasmon resonance wavelength could be controlled by lateral dimension of silver nanoparticles, and transparent conductive films based on plasmonic graphene could be developed.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.360-360
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• 2011

We demonstrated the fabrication method of superhydrophobic nanocoating through a facile spin-coating and the chemical modification. The resulting coating showed a tremendous water repellency with a static water contact angle (CA) of 158$^{\circ}$ and a hysteresis of 1$^{\circ}$. The number of ZnO nanoparticle (NP) coating cycles affected on the surface roughness, which is key role for superhydrophobic surface, and thus the CA can be modulated by changing the ZnO NP coating cycles. The CA can be controlled by changing the carbon length of Self-Assembled Monolayers(SAM). This simple ZnO coating is substrate-independent including flexible surfaces, papers and cotton fabrics, which can effectively be used in various potential applications. We also observed the thermal and dynamic stabilities of SAM on ZnO nanoparticles. The superhydrophobicic surface maintained its superhydrophobic properties below 250$^{\circ}C$ and under dynamic conditions.