Biomedical subjects

Kwang W Oh

Publications and source records attributed to Kwang W Oh.

4 recordsLinked to original sources

PubMed2005

Clinical evaluation of micro-scale chip-based PCR system for rapid detection of hepatitis B virus.

The polymerase chain reaction (PCR) is widely used to amplify a small amount of DNA in samples for genetic analysis. Rapid and accurate amplification is prerequisite for broad applications including molecular diagnostics of diseases, food safety, and biological warfare tests. We have developed a rapid real-time micro-scale chip-based PCR system, which consists of six individual thermal cycling modules capable of independent control of PCR protocols. The PCR volume is 1 microl and it takes less than 20 min to complete 40 thermal cycles. To test utility of a chip-based PCR system as a molecular diagnostic device, we have conducted the first large-scale clinical evaluation study. Three independent clinical evaluation studies (n = 563) for screening the hepatitis B virus (HBV) infection, the most popular social epidemic disease in Asia, showed an excellent sensitivity, e.g. 94%, and specificity, e.g. 93%, demonstrating micro-scale chip-based PCR can be applied in molecular diagnostics.

DNA, Viral↗

PubMed2005

World-to-chip microfluidic interface with built-in valves for multichamber chip-based PCR assays.

We report a practical world-to-chip microfluidic interfacing method with built-in valves suitable for microscale multichamber chip-based assays. One of the primary challenges associated with the successful commercialization of fully integrated microfluidic systems has been the lack of reliable world-to-chip microfluidic interconnections. After sample loading and sealing, leakage tests were conducted at 100 degrees C for 30 min and no detectable leakage flows were found during the test for 100 microchambers. To demonstrate the utility of our world-to-chip microfluidic interface, we designed a microscale PCR chip with four chambers and performed PCR assays. The PCR results yielded a 100% success rate with no contamination or leakage failures. In conclusion, we have introduced a simple and inexpensive microfluidic interfacing system for both sample loading and sealing with no dead volume, no leakage flow and biochemical compatibility.

DNA, Viral↗

PubMed2003

DNA hybridization electrochemical sensor using conducting polymer.

We report the use of poly(thiophen-3-yl-acetic acid 1,3-dioxo-1,3-dihydro-isoindol-2-yl ester (PTAE) for application to electrochemical hybridization sensor. A synthetic route for the thiophen-3-yl-acetic acid 1,3-dioxo-1,3-dihydro-isoindol-2-yl ester (TAE) is described, which is used as a monomer of conducting polymer sensor. A direct chemical substitution of probe oligonucleotide to good leaving group site in the PTAE is carried out on the conducting polymer film. A biological recognition can be monitored by comparison with the electrochemical signal (cyclic voltammogram) of single and double strand state oligonucleotide. The sensitivity of the electrochemical sensor is 0.62 microA/nmole and the detection limit is 1 nmole. The oxidation current of double strand state oligonucleotide is a half of that of single strand, that is corresponding to the decrease of electrochemical activity of conducting polymer with increase of stiffness of side group of the polymer. The oxidation current decreasing ratios of perfect matched and single nucleotide mismatched samples are 52 and 25-30%, respectively. The more decreasing ratio is attributable to the more steric hindrance of single nucleotide mismatched sample.

Biosensing Techniques↗

PubMed2001

An integrated microfluidic biochemical detection system for protein analysis with magnetic bead-based sampling capabilities.

This paper presents the development and characterization of an integrated microfluidic biochemical detection system for fast and low-volume immunoassays using magnetic beads, which are used as both immobilization surfaces and bio-molecule carriers. Microfluidic components have been developed and integrated to construct a microfluidic biochemical detection system. Magnetic bead-based immunoassay, as a typical example of biochemical detection and analysis, has been successfully performed on the integrated microfluidic biochemical analysis system that includes a surface-mounted biofilter and electrochemical sensor on a glass microfluidic motherboard. Total time required for an immunoassay was less than 20 min including sample incubation time, and sample volume wasted was less than 50 microl during five repeated assays. Fast and low-volume biochemical analysis has been successfully achieved with the developed biofilter and immunosensor, which is integrated to the microfluidic system. Such a magnetic bead-based biochemical detection system, described in this paper, can be applied to protein analysis systems.

Electrochemistry↗