• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.121-124
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• 1996

It is well known that the metallo- phthalocyanine (MPcs) are sensitive to toxic gaseous molecules such as NO$_2$and also chemically and thermally stable. Therefore, lots of MPcs have been studied for the potential chemical sensor for NO$_2$gas using quartz crystal microbalance(QCM) or electrical conductivity. In this study, thin films of octa(2-ethylhexyloxy) copper-phthalocyanine were prepared by Langmuir -Blodgett method and characterized by using UV-VIS spectroscopy and ellipsometry. Transfer condition, and characterization of LB films were investigated and preliminary results of current-voltage(I-V) characteristics of these films exposed to NO$_2$gas as a function of film thickness, temperature and temperature were discussed.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.291-294
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• 2003

A highly interferent-resistive membrane, poly-5-amino-1-naphthol (poly-5A1N), underlied beneath enzymeembedded poly-1,3-phenylendiamine (poly-m-PD) network for miniturized continuous monitoring glucose sensors. The enzyme layer was prepared from a mixed solution of glucose oxidase (GOx) and m-PD monomer by simple electrolysis. The mass change of poly-5A1N was monitored by electrochemical quartz crystal microbalance (EQCM) in situ and the corresponding thickness was measured. Successive electropolymerization of poly-5A1N and poly-m-PD create a several tens nm-thick bilayer showing excellent selectivity for $H_2O_2$ and low activity loss of immobilized enzymes.

• Journal of Electrochemical Science and Technology
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• v.1 no.1
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• pp.1-9
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• 2010

Conducting polymer films grown from various aromatic compounds have been evaluated as overcharge protecting additives for lithium ion rechargeable batteries. The polymer films were grown electrochemically under the conditions similar to those encountered during the overcharging processes of lithium batteries and subsequently characterized by potentiodynamic, electrochemical quartz crystal microbalance, electrochemical impedance spectroscopic, and scanning electron microscopic experiments. Results indicate that bicyclic and polycyclic aromatic hydrocarbons would be poor candidates for inhibitors, while biphenyl, terphenyl, and benzene derivatives displayed excellent performances. Mixed polymer films grown from o-terphenyl and p-xylene show the best performance among the candidates.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.4
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• pp.161-164
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• 2005

Viologen has been extensively investigated in the paper because their well-behaved electrochemistry has led to their use in a variety of theses, including the electron acceptor for the electric charge delivery mediation of the devices. It was formed monolayer in QCM by self-assembly method. We could know the adsorbed mass of viologen molecules from the frequency shift. We calculated that the adsorbed mass was about 196 [$ng/cm^2$]. We studied the electron transfer property of viologen by the cyclic voltammetry among the electrochemical process so we changed an anion like 0.1 M $NaClO_4$ and $Na_3PO_4$ electrolyte solution and investigated the interrelationship between scan rate and peak current when scan rates were increased twice.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.786-790
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• 2004

2-Aminoethanethiol (aet) has been used to make self-assembled monolayer (SAMs) on gold electrodes, which are subsequently modified with 3,4-dihydroxy phenylalanine (dpa). Such modified electrodes having various types of Au/aet-dpa were employed in the electrocatalytic oxidation of NADH. The purpose of this study to characterize the responses of such modified electrodes in terms of the immobilization procedure, pH of the solution and applied potential. The reaction of the surface immobilized dpa with NADH was studied using the rotating disk electrode technique and a value of $2.2{\times}10^4M^{-1}s^{-1}$ was obtained for the second-order rate constant in 0.1 M Tris/$NO_3^-$buffer (pH=8.0). The hydration behavior of the films was characterized by quartz crystal microbalance. When used as a NADH sensor, the Au/aet-dpa electrode exhibited good sensitivity and an excellent correlation (r ${\geq}$ 0.99) for NADH concentration which extended to $3.8{\times}10^{-3}$ M.

• Bulletin of the Korean Chemical Society
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• v.22 no.11
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• pp.1192-1196
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• 2001

A diaphorase enzyme electrode for the catalytic reduction of NAD+ , the oxidized form of nicotinamide adenine dinucleotide, has been prepared. The enzyme layer grew spontaneously over an aminoethanethiol self assembled monolayer on a go ld plate electrode. The growth was accomplished by simply dipping the electrode covered by the aminoethanethiol monolayer into a solution containing both glutaraldehyde and diaphorase. We suggested that the glutaraldehyde as a cross-linking reagent was attached to the amino groups of the aminoethanethiol monolayer and the diaphorase enzyme molecules were bound to free aldehyde groups of the glutaraldehyde. Further attachments of the enzyme molecules over the bound enzyme molecules continued with the bridging of the glutaraldehyde. In frequency measurements with a quartz crystal microbalance, the frequency decrease was much more than it was for that of the enzyme monolayer formation, and an enzyme layer thicker than a monolayer was formed. The modified electrode was employed to reduce NAD+ , using diffusional methyl viologen as an electron transfer mediator. The NAD+ was electrocatalytically reduced, and the catalytic current was almost equivalent to that with the multilayered electrode of ten enzyme layers.

• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.276-280
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• 2001

The self-assembled formation of octadecanethiol (CH3(CH2)17SH) on a gold substrate was studied using a quartz crystal microbalance (QCM) and a scanning tunneling microscope (STM). From the QCM measurements at vario us concentrations of octadecanethiol solutions in hexane and alcohol, the adsorption process of octadecanethiol onto Au was confirmed to consist of two steps as follows: (i) fast but disordered adsorption and (ii) a thermodynamically controlled rearrangement for uniform packing of octadecanethiol. Also, it was revealed that the adsorption rate became faster in ethanol than in hexane since less solubility of octadecanethiol in ethanol could help the formation of the monolayers. At 5 ${\times}$10-7 M solution, the monolayer formation was monitored by STM. The morphology of monolayer region was initially circular (diameter size: 7.26 $\pm$ 2.1 nm) and gradually changed to a stripe type after several minutes. At higher concentration, the self-assembled monolayer was formed immediately after the solution was introduced to a substrate.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9375-9378
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• 2014

Background: A piezoelectric immunosensor for early cervical cancer detection was developed involving short analyis time and less invasive technique for $p16^{INK4a}$, a protein that has been linked to cervical cancer. Materials and Methods: $5{\mu}L$ of 5.0 mg/mL $p16^{INK4a}$ antibody and then supernatant from different clinical samples from West China Second University Hospital (Sichuan, China) were dripped on the center of the AT-cut crystal through a micro-injector. Absorption of the $p16^{INK4a}$ by antibody caused a shift in the resonant frequency of the immunosensor, and the resonant frequency was correlated to the amount of the $p16^{INK4a}$ in the supernatant. Results: The greater severity of lesion grading, the greater the expression level of $p16^{INK4a}$. Conclusion: Degree of cervical cancer lesion development could be determined by detected amount of $p16^{INK4a}$ in different clinical samples.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1295-1296
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• 2008

Hydrogen peroxide ($H_2O_2$) biosensor is one of the most developing sensors because this kind of sensors is highly selective and responds quickly to the specific substrate. Hemoglobin (Hb) has been used as ideal biomolecules to construct hydrogen peroxide biosensors because of their high selectivity to $H_2O_2$. The direct electron transfer of Hb has widely investigated for application in the determination of $H_2O_2$ because of its simplicity, high selectivity and intrinsic sensitivity. An electrochemical detection for hydrogen peroxide was investigated based on immobilization of hemoglobin on DNA/Fe(pyterpy)$^{2+}$ modified gold electrode. The pyterpy monolayers were firstly an electron deposition onto the gold electrode surface of the quartz crystal microbalance (QCM). It is offered a template to attach negatively charged DNA. The fabrication process of the electrode was verified by quartz crystal analyzer (QCA). The experimental parameters such as pH, applied potential and amperometric response were evaluated and optimized. Under the optimized conditions, this sensor shows the linear response within the range between $3.0{\times}10^{-6}$ to $9.0{|times}10^{-4}$ M concentrations of $H_2O_2$. The detection limit was determined to be $9{\times}10^{-7}$ M (based on the S/N=3).

• Journal of the Korean Applied Science and Technology
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• v.12 no.1
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• pp.125-131
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• 1995

Ultra thin films of Tetra-3-hexadecylsulphamoylcopperphthalocyanine(HDSM-CuPc) were formed on various substrates by Langmuir-Blodgett method, where HDSM-CuPc was synthesized by attaching long-chain alkylamine(hexa-decylamine) to CuPc. The reaction product was identified with FT-IR, UV-visible absorption spectroscopies, elemental analysis and thin layer chromatography. The formation of Ultrathin Langmuir-Blodgett(LB) films of HDSM-CuPc was confirmed by FT-IR and UV-visible spectroscopies. A quartz piezoelectric crystal coated with LB films of HDSM-CuPc was examined as a gas sensor for $N0_2$ gas. HDSM-CuPc LB films were transferred to a quartz crystal microbalance(QCM) in the form of Z-type multilayers. Response characteristics of film-coated QCM to $NO_2$ gas concentrations over a range of $100{\sim}600ppm$ have been tested with a thickness of $5{\sim}20$ layers of HDSM-CuPc. Changes in frequency by adsorption of $NO_2$ were increased With the number of LB layers and $NO_2$ concentration, but the response time was slow.