• Journal of Sensor Science and Technology
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• v.14 no.3
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• pp.137-143
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• 2005

Research in the field of biosensor has enormously increased over the recent years. The metal-oxide semiconductor field effect transistor (MOSFET) type protein sensor offers a lot of potential advantages such as small size and weight, the possibility of automatic packaging at wafer level, on-chip integration of biosensor arrays, and the label-free molecular detection. We fabricated MOSFET protein sensor and proposed the gold-black electrode as the gate metal to improve the response. The experimental results showed that the output voltage of MOSFET protein sensor was varied by concentration of albumin proteins and the gold-black gate increased the response up to maximum 13 % because it has the larger surface area than that of planar-gold gate. It means that the expanded gate allows a larger number of ligands on same area, and makes the more albumin proteins adsorbed on gate receptor.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.19-23
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• 1998

We enhanced the sensitivity of surface plasmon resonance biosensor by the conversion of the real-time direct binding immunoassay into the sandwich immunoassay, in which colloidal gold particles coated with anti-mouse IgG was used. By the immobilization of anti-mouse IgG onto the carboxymethyl dextran surface of thin gold film, the direct binding of analyte(mouse IgG) onto the sensor chip, and the injection of colloidal gold particles coated with anti-mouse IgG, about 100 times of sensitivity enhancement was obtained. This result suggests that nanoparticles, which has a high refractive index, homogeneous ultrafine structure and capability of size control, would be applicable for the detection of very small quantity of biomaterial.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.106-110
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• 2009

An amperometric glucose biosensor has been developed using viologen derivatives as a charge transfer mediator between a glucose oxidase (GOD) and a gold electrode. A highly stable self-assembled monolayer (SAM) of thiol-based viologen was immobilized onto the gold electrode of a quartz crystal microbalance (QCM) and GOD was immobilized onto the viologen modified electrode. This biosensor response to glucose was evaluated amperometrically in the potential of -300mV. Upon immobilization of the glucose oxidase onto the viologen modified electrode, the biosensor showed rapid response towards glucose. Experimental conditions influencing the biosensor performance, such as pH potential, were optimized and assessed. This biosensor offered excellent electrochemical responses for glucose concentration below ${\mu}$ mol level with high sensitivity and selectivity and short response time. The levels of the RSDs (<5%) for the entire analyses reflected the highly reproducible sensor performance. A linear calibration range between the current and the glucose concentration was obtained up to $4.5{\times}10^{-4}M$. The detection limit was determined to be $3.0{\times}10^{-6}M$.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4171-4175
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• 2011

Bio-functionalized gold nanoparticles (AuNPs), which bio-specifically interact with biotin-(strept)avidin, were investigated in this study. AuNPs were functionalized with a synthetically-provided biotin-linked thiol (BLT), which was synthesized by amidation of the active ester of biotin with 2-mercaptoethylamine. The BLT-attached AuNP was bio-specific for streptavidin, making it potentially useful for biosensor applications. To test the bio-specific interactions, the colors, absorption spectra and TEM images were investigated for proteins such as streptavidin, cytochrome C, myoglobin and hemoglobin. The colors and absorption spectra changed when streptavidin was added to the BLT-attached AuNP solution. However, the color and spectra did not change when the other proteins were added to the same solution. These results show that the AuNPs provided a colloidal solution with excellent stability and highly selective absorption characteristics for streptavidin as a target molecule. Proteins were also screened in order to identify a general strategy for the use of optical biosensing proteins based on AuNPs. In addition, TEM images confirmed that streptavidin led the BLT-attached AuNPs to aggregate or precipitate.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.228-234
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• 2023

In this study, the performance of a gold biosensor combined with light microscope imaging system (GB-LMIS) was comparatively evaluated against enzyme-linked immunosorbent assay (ELISA) for detecting Salmonella under simulated chilling condition. The optimum concentration of antiSalmonella polyclonal antibodies (pAbs) was determined to be 12.5 and 100 ㎍/ml for ELISA and GBLMIS, respectively. GB-LMIS exhibited a sufficient and competitive specificity toward three tested Salmonella among only. To mimic a real-world situation, chicken was inoculated with Salmonella cocktail and stored under chilling condition for 48 h. The overall growth of Salmonella under chilling condition was significantly lower than that under non-exposure to the chilling condition (p < 0.05). No significant differences in bacterial growth were observed between brain heart infusion and brilliant green broth during the enrichment period (p > 0.05). Finally, both GB-LMIS and ELISA were employed to detect Salmonella at every 2-h interval. GB-LMIS detected Salmonella with a competitive specificity by the direct observation of bacteria on the sensor using a charge-coupled device camera within a detection time of ~2.5 h. GB-LMIS is a feasible, novel, and rapid method for detecting Salmonella in poultry facilities.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.472-477
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• 2014

A voltammetric investigation of Au assay was conducted at a low cost, using Nafion and DNA immobilized on a graphite Pencil working electrode (NDP) with a black lead counter and reference. The following optimal parameters were found: 0.4 V amplitude, 500 Hz frequency, -0.7 V initial potential, and 0.015 V increment potential. These optimal conditions were also applied to sand obtained from the river site. The aforementioned technique is simpler and less costly compared to the common voltammetry and spectrophotometric methods.

• Polymer(Korea)
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• v.38 no.6
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• pp.809-814
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• 2014

An array structure of conducting polymer microtubule was fabricated for an amperometric biosensor. 3,4-Ethylenedioxythiophene (EDOT) was electropolymerized in the microporous template membrane with poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonic acid) (PEDOT/PSS) composite as a binder. The array structure can provide enhanced current collecting capability due to large active surface area compared to the macroscopic area of the electrode itself. For a biosensor application, the array electrode was tested for $H_2O_2$ detection and showed very sluggish electrochemical response to $H_2O_2$. To enhance the detection efficiency to the oxidation of $H_2O_2$, gold was treated on the electrode by two different approaches: sputtering and electrochemical deposition. Gold treatment with either method greatly enhanced the sensitivity of the electrode to $H_2O_2$. So, conducting polymer microtubule array with gold treatment was expected to be a sensitive amperometric biosensor system based on the detection of $H_2O_2$.

• 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.

• Journal of Biosystems Engineering
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• v.28 no.2
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• pp.167-172
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• 2003

This study was performed to fabricate a batch-type SPR biosensing system using a thiolated E. coli antibody coupling, and to explore the feasibility of real-time detection of E. coii in a stagnant sample solution. In advance. “O” and “K” antigenic serotype E. coli antibodies were thiolated with sulfo-LC-SPDP and dithiothreitol, and immobilized by chemisorption in the gold surface of compact SPR sensors. When the SPR biosensor immobilized with E. coli antibody monitored a E. coli solution, it took 3 to 5 min to stabilize. The SPR biosensing system developed in this study was able to detect E. coli in the range above 10$^4$ CFU/mL at the 0.05 significant level. Also, the SPR biosensor had possibility to significantly detect E. coli in the range of 10$^2$ to 10$^4$ CFU/mL in E. coli solutions. Meanwhile, when the SPR biosensor immobilized with 5. coli antibody was cleaned with NaOH solutions, its ability to detect E. coli largely decreased due to wash-out of the immobilized antibody. In order to reuse the SPR sensor, it should be antibody-immobilized newly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.3
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• pp.267-272
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• 2006

Optical waveguide based on symmetric and asymmetric Mach-Zehnder interferometer(MZI) type was designed, fabricated and measured the optical characteristics for the application of biosensor. The wavelength of the input optical signal for the device was 1550 nm. And the difference of refractive index was $0.45\;{\Delta}\%$ between core and cladding of the device. The TM(Transverse Magnetic) mode optical properties of the biosensor were analyzed with the refractive index variation of gold thin film deposited for overclad. Nowadays, nano-photonic crystal structures have been paied much attention for its high optical sensitivity. There is a technique to realize the structure, which is called Dip-Pen Nanolithography(DPN) process. The process requires a nano-scale process patterning resolution and high reliability. In this paper, two dimensional nano-photonic crystal array on the surface was proposed for improving the sensitivity of optical biosensor. And the Dip-Pen Nanolithogrphy process was investigated to realize it.