• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1968-1976
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• 2006

Recombinant E. coli ACV 1003 (recA:: lacZ) was used to measure low concentrations of DNA-damaging chemicals, which produce $\beta$-galactosidase via an SOS regulon system. Very low $\beta$-galactosidase activities of less than 0.01 unit/ml, $\beta$-galactosidase produced through an SOS response corresponding to the 10 ng/ml (ppb) of DNA damaging chemicals in the environment, can be rapidly determined by using an alternative interferometric biosensor with optically flat thin films of porous silicon rather than by the conventional time-consuming Miller's enzyme assay as well as the ELISA method. fu order to enhance the sensitivity in the interferometry, it needs to obtain more uniform distribution and higher biolinking efficiency, whereas interferometric sensing is rapid, cheap, and advantageous in high throughput by using a multiple-well-type chip. In this study, pore size adjusted to 60 nm for the target enzyme $\beta$-galactosidase to be bound on both walls of a Si pore and a calyx crown derivative was apllied as a more efficient biolinker. Furthermore, anti-$\beta$-galactosidase was previously functionalized with the biolinker for the target $\beta$-galactosidase to be specifically bound. When anti-$\beta$-galactosidase was bound to the calyx-crown derivative-linked surface, the effective optical thickness was found to be three times as high as that obtained without using anti-$\beta$-galactosidase. The resolution obtained was very similar to that afforded by the time-consuming ELISA method; however, the reproducibility was still unsatisfactory, below 1 unit $\beta$-galactosidase/ml, owing to the microscopic non-uniform distribution of the pores in the etched silicon surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.549-549
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• 2012

Early detection of cancer biomarkers in the blood is of vital importance for reducing the mortality and morbidity in a number of cancers. From this point of view, immunosensors based on nanowire (NW) and carbon nanotube (CNT) field-effect transistors (FETs) that allow the ultra-sensitive, highly specific, and label-free electrical detection of biomarkers received much attention. Nevertheless 1D nano-FET biosensors showed high performance, several challenges remain to be resolved for the uncomplicated, reproducible, low-cost and high-throughput nanofabrication. Recently, two-dimensional (2D) graphene and reduced GO (RGO) nanosheets or films find widespread applications such as clean energy storage and conversion devices, optical detector, field-effect transistors, electromechanical resonators, and chemical & biological sensors. In particular, the graphene- and RGO-FETs devices are very promising for sensing applications because of advantages including large detection area, low noise level in solution, ease of fabrication, and the high sensitivity to ions and biomolecules comparable to 1D nano-FETs. Even though a limited number of biosensor applications including chemical vapor deposition (CVD) grown graphene film for DNA detection, single-layer graphene for protein detection and single-layer graphene or solution-processed RGO film for cell monitoring have been reported, development of facile fabrication methods and full understanding of sensing mechanism are still lacking. Furthermore, there have been no reports on demonstration of ultrasensitive electrical detection of a cancer biomarker using the graphene- or RGO-FET. Here we describe scalable and facile fabrication of reduced graphene oxide FET (RGO-FET) with the capability of label-free, ultrasensitive electrical detection of a cancer biomarker, prostate specific antigen/${\alpha}$ 1-antichymotrypsin (PSA-ACT) complex, in which the ultrathin RGO channel was formed by a uniform self-assembly of two-dimensional RGO nanosheets, and also we will discuss about the immunosensing mechanism.

• Korean Journal of Optics and Photonics
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• v.30 no.2
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• pp.59-66
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• 2019

We report highly sensitive detection of myocardial infarction biomarkers, such as myoglobin and cTnI, within several hundred seconds using a rotating-analyzer ellipsometer and a biosensor with biochips fabricated on a $SiO_2$-coated tilted silicon substrate. We choose the running buffer to be pure phosphate-buffered saline (PBS) or 10% mixed human serum. When we choose the running buffer to be pure PBS, we obtain diagnostic densities of pure myocardial infarction biomarkers of up to 1 ng/ml and 5 pg/ml respectively. Meanwhile, when we use PBS with 10% human serum, the measured densities of myoglobin and cTnI were up to 1 ng/mL and 1 pg/mL respectively. The measured diagnostic densities are less than 1/15 and 1/80 (in cases of myoglobin and cTnI respectively) of those referenced by the World Health Organization.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2134-2136
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• 2004

A microcantilever-based biosensor with piezoresistor has been fabricated using surface micromachining technique, which is cost effective and simplifies a fabrication procedure. To evaluate the characteristics of the cantilever, the cystamine terminated with thiol was covalently immobilized on the gold-coated side of the cantilever and glutaraldehyde that would be bonded with amine group in the cystamine was injected subsequently. This process was characterized by measuring the deflection of the cantilever in real time monitoring. Using a piezoresistive read-out and a well-known optical beam deflection method as well carried out the measurement of deflection.

• KSBB Journal
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• v.15 no.5
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• pp.423-427
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• 2000

Intense research on biosensors has been performed in a number of different institution over the past 15 years, but relatively few commercial products have resultingly, the blood glucose sensor is a good example of a product which penetrated the market. However recently, the development of electrochemical and optical technologies has accelerated the turnover of the research as is illustrated by a rapid increase in the number of point-of-care diagnostic systems and analytical devices. Examples of such biosensors used in the fields of medical diagnostics, bioprocess control, and environmental monitoring are described, and summarized in an introduction to their characteristics, structures, and functions, given.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1412-1415
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• 2008

A glucose biosensor using a microdisk resonator in polymeric waveguides was developed by observing either the shift in the resonant wavelength or the variation in the optical power. The deformation in the transfer curve of the vertically coupled resonator sensor resulting from the variation in the disk-to-ring coupling, which was incurred by the application of the target analyze, was suppressed. And the refractive index of the polymeric waveguide was devised to closely follow that of the analyze itself for enhancing the sensitivity of the sensor. The sensitivity and measurement range were observed to be respectively 0.14 pm/(mg/dL) and 1500 mg/dL (theoretically up to 4700 mg/dL, for the wavelength shift method and 0.04 dB/(mg/dU and 140 mg/dL the power variation scheme.

• Journal of the Korean Chemical Society
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• v.60 no.1
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• pp.28-33
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• 2016

The spiropyran is a typical material having photodegradation properties in the process of photochromism. The spiropyran has been utilized in various applications such as optical switch, optical memories, and biosensor because of its remarkable stability, fast responsive time, stronger color change, and photo-induced controllability. However, the spriropyran is photodegraded by the repetitive optical irradiation. The photodegradation of spiropyran have been investigated by using UV-Visible spectroscopy, nuclear magnetic resonance (NMR), and Raman spectroscopy. Herein, the properties of spiropyran were characterized by using terahertz time-domain spectroscopy (THz-TDS) in the terahertz frequency region. In terahertz region, the measured absorbance of spiropyran was increased due to the photodegradation induced by the repetitive UV irradiation. The absorbance tendency of spiropyran in the terahertz frequency region was compared with that in the visible region, and they were completely opposite to each other.

• Journal of the Korean Society of Visualization
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• v.15 no.2
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• pp.41-47
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• 2017

Microring/nanoring structure has high applicability for nano-antenna and biosensor thanks to its superior optical characteristics. Although coiling nanowires manufactured using immiscible emulsion droplets have an advantage in mass production, this process also forms nanowire bundles. In this study, we solved the nanowire bundle problem by size-selective sorting of the emulsion droplets in a pinched flow fractionation microchannel. Utilizing silver nanowires and immiscible emsulsion droplets, we investigated the correlation between the size of ring droplets and bundle droplet. We visualized the sorting process for glass particles and microring-containing emulsion droplets. Droplets were sorted based on their size, and the ratio of bundle droplets in solution decreased. This droplet-sorting strategy has potential to help the printing and coating process for manufacturing of ring structure patterns and developing of functional materials.

• Vacuum Magazine
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• v.2 no.1
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• pp.10-16
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• 2015

With the recognition of nanotechnology as one of the future strategic technologies, the R&D efforts have been performed under exclusive supports of governments and private sectors. At present, nanotechnology is at the focus of research and public attention in almost every advanced country including USA, Japan, and many others in EU. Keeping tracks of such technical trends, center for nanoscale mechatronics and manufacturing (CNMM) was established in 2002 as a part of national nanotechnology promotion policy led by ministry of science and technology (MOST) in Korea. It will hold widespread potential applications in electronics, optical electronics, biotechnology, micro systems, etc, with the promises of commercial visibility and competitiveness. In this paper, wafer scale multilayer nanoimprint lithography technology which is well-known the next generation lithography, roll-typed nanoimprint lithography (R-NIL), roll-typed liquid transfer imprint lithography (R-LTIL), the key technology for nanomanufacturing and nanoscale measurement technology will be introduced. Additionally, its applications and some achievements such as solar cell, biosensor, hard disk drive, and MOSFET, etc by means of the developed multilayer nanoimprint lithography system are introduced.

• KSBB Journal
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• v.20 no.2 s.91
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• pp.123-128
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• 2005

We have addressed two important issues of immunosensing biochips, including the construction of antibody functionalized suface for efficient affinity reactions and the development of a signal registration strategy that converts biospecific reactions into highly quantifiable electrochemical and/or optical signals. The developed immunoassay reaction is an integrated version of enzyme-mediated immunoprecipitaion reaction, which is widely used in immunohistochemistry, and electrochemical signaling reaction. For the evaluation of analytical performance of fabricated immunosensing biochips, signaling for mouse IgG in antiserum was conducted. Applications of the developed strategy have been found for the evaluation of histology chemicals and for the signal amplification for array-type biochip analysis.