• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.427-430
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• 2014

We developed a novel immunochromatographic assay (ICA) (EZ-Step VanA rapid kit; Dinona, Korea) for the detection of VanA ligase from vancomycin-resistant enterococci (VRE). Of eight monoclonal antibodies screened by ELISAs, the VanA ligase ICA constructed with 1H9 plus 3G11 showed the greatest reactivity. The detection limit of the kit was $6.3{\times}10^6$ CFU per test. Of 127 vancomycin-resistant microorganisms, 100 vanA VRE were positive in the VanA ligase ICA, and 27 non-vanA vancomycin-resistant isolates were negative. These results were consistent with those of the PCR analyses. Thus, our ICA is a reliable and easy-to-use immunological assay for detecting VanA-producing VRE in clinical laboratories.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.210-217
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• 2018

A one-step multiplex reverse transcription PCR (RT-PCR) method comprising six primer sets (for the detection of norovirus GI and GII, hepatitis A virus, rotavirus, and astrovirus) was developed to simultaneously detect four kinds of pathogenic viruses. The size of the PCR products for norovirus GI and GII, hepatitis A virus (VP3/VP1 and P2A regions), rotavirus, and astrovirus were 330, 164, 244, 198, 629, and 449 bp, respectively. The RT-PCR with the six primer sets showed specificity for the pathogenic viruses. The detection limit of the developed multiplex RT-PCR, as evaluated using serially diluted viral RNAs, was comparable to that of one-step single RT-PCR. Moreover, this multiplex RT-PCR was evaluated using food samples such as water, oysters, lettuce, and vegetable product. These food samples were artificially spiked with the four kinds of viruses in diverse combinations, and the spiked viruses in all food samples were detected successfully.

• Journal of Applied Biological Chemistry
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• v.48 no.1
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• pp.16-25
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• 2005

To develop an enzyme-linked immunosorbent assay (ELISA) for the detection of the residues of the acaricide fenazaquin, five haptens were synthesized and assessed. A competitive indirect format was used with polyclonal antibodies. Under an optimized condition using the selected rabbit C antiserum, an $IC_{50}$ of $96.97\;ng{\cdot}ml^{-1}$, the detection range of $14.9{\sim}631\;ng{\cdot}ml^{-1}$, and the lowest detection limit of $8\;ng{\cdot}ml^{-1}$ were obtained. Some structurally related compounds of practical use showed low crossreactivities to the antibody. Highest cross-reactivity observed with hapten IV indicates that the antiserum C recognizes very well quinazoline ring, 4-tert-butylphenyl, and an adequate length of spacer arm. The length of spacer arm affected recognition of quinazoline ring and 4-tert-butylphenyl moieties. When applied to apple and pear, recoveries were within acceptable ranges of $93.18{\sim}104.77%$ (n = 4) and $79.40{\sim}111.95%$ (n = 4), respectively.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1569-1571
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• 2002

The determination of DNA hybridization can apply the molecular biology research, clinic diagnostics, bioengineering, environment monitoring, food science and other application area. So, The determination of hybridization is very important for the improvement of DNA detection system. In this study, we report the characterization of the DNA hybridization by the electricalchemical methods. A new electrochemical biosensor is described for voltammetric detection of gene sequence related to probe oligonucleotide of bacterium Escherichia coli O157:H7. The biosensor involves the immobilization of a 18-mer probe oligonucleotide, which is complemetary to a specific gene sequence related to Escherichia coli O157:H7 on a gold electrode through specific adsorption. The probe oligonucleotide was used to determine the amount of target oligonucleotide in solution using mitoxantrone(MTX) as the electrochemical indicators. The cathodic peak currents $(I_{peak})$ of MTX were linearly related to the concentration of the target oligonucleotide sequence in the range $1[{\mu}M]{\sim}0.1[nM]$. The detection limit of this approach was 0.01[nM]. In addition, these indicators were capable of selectivity discriminating against various mismatching condition.

• Food Science and Biotechnology
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• v.15 no.4
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• pp.625-630
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• 2006

Polymerase chain reaction (PCR) method was developed for the specific detection of insect-resistant rice containing cry1Ac gene derived from Bacillus thuringiensis (Bt). Primers were designed from the 35S promoter, NOS terminator, cry1Ac gene, and sucrose phosphate synthase (SPS) for general screening of Bt rice. By sequencing the PCR products from the two putative kinds of Bt rice, we designed a specific primer from the junction region between the cry1Ac gene and the NOS terminator that had been inserted into Bt rice. The construct-specific primer was employed to amplify a 147 bp product in the two lines of Bt rice. No amplified products were observed from the other Bt crops with various Bt genes introduced. In qualitative PCR analysis, the limit of detection was 0.005 ng from genomic DNA of Bt rice. In addition, PCR analysis was performed on 64 kinds of rice presently available in the Korean market, and no Bt rice was detected. This method presented in this paper can be used as a highly sensitive and specific detection method of Bt rice.

• Journal of Microbiology and Biotechnology
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• v.29 no.10
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• pp.1543-1552
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• 2019

Salmonella is a common zoonotic and foodborne pathogen that causes high morbidity and mortality in developing countries. In this study, we established and validated a polymerase spiral reaction (PSR) assay which targeted the conserved invasion gene (invA) of Salmonella by SYBR Green I indicator methods. Subsequently, assays for determination of the optimal conditions for optimal specificity and sensitivity of PSR were performed. We performed comprehensive evaluations using loop-mediated isothermal amplification (LAMP) and real-time PCR. A total number of 532 samples of daily food were analyzed by PSR. Twenty-seven bacterial strains were tested in the specificity assay, from which positive results were obtained only for 14-Salmonella strains. However, none of the 13 non-Salmonella strains was amplified. Similarly with LAMP and real-time PCR, the detection limit of the PSR assay was 50 CFU/ml. The PSR method was also successfully applied to evaluate the contamination with Salmonella in 532 samples of daily food, corroborating traditional culture method data. The novel PSR method is simple, sensitive, and rapid and provides new insights into the prevention and detection of foodborne diseases.

• Current Applied Physics
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• v.18 no.11
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• pp.1255-1260
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• 2018

In this work, a green and simple one-pot route was developed for the synthesis of highly fluorescent aminofunctionalized graphene quantum dots (a-GQDs) via hydrothermal process without any further modification or surface passivation. We synthesized the a-GQDs using glucose as the carbon source and ammonium as a functionalizing agent without the use of a strong acid, oxidant, or other toxic chemical reagent. The as-obtained aGQDs have a uniform size of 3-4 nm, high contents of amino groups, and show a bright green emission with high quantum yield of 32.8%. Furthermore, the a-GQDs show effective fluorescence quenching for $Cu^{2+}$ ions which can serve as effective fluorescent probe for the detection of $Cu^{2+}$. The fluorescent probe using the obtained aGQDs exhibits high sensitivity and selectivity toward $Cu^{2+}$ with the limit of detection as low as 5.6 nM. The mechanism of the $Cu^{2+}$ induced fluorescence quenching of a-GQDs can be attributed to the electron transfer by the formation of metal complex between $Cu^{2+}$ and the amino groups on the surface of a-GQDs. These results suggest great potential for the simple and green synthesis of functionalized GQDs and a practical sensing platform for $Cu^{2+}$ detection in environmental and biological applications.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1464-1469
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• 2009

To achieve more accurate and rapid detection of macrolide-lincosamide-streptogramin B resistance genes, erm(A), erm(B), and erm(C), we developed a TaqMan probe-based real-time PCR (Q-PCR) method and compared it with conventional PCR (C-PCR), which is the most widely using erm gene identification method. The detection limit of Q-PCR was 5 fg of genomic DNA or 5-8 CFU of bacterial cells of Staphylococcus aureus. The utilization of Q-PCR might shorten the time to erm detection from 3-4 h to about 50 min. These data indicated that Q-PCR assay appears to be not only highly sensitive and specific, but also the most rapid diagnostic method. Therefore, the appropriate application of the Q-PCR assay will permit rapid and accurate identification of erm genes from clinical and other samples.

• YAKHAK HOEJI
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• v.34 no.3
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• pp.215-218
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• 1990

An ion chromatographic method based on indirect photometric detection of UV transparent anions was developed. Separation of anion was accomplished on strong anion exchange column (Waters SAX) using UV detector at 254 nm. Among examined UV-active additives (Dns-H, Dns-glu, Dnsser, Dns-val), Dns-glu showed the highest sensitivity. Studies on the effects of the pH and ionic strength of eluent revealed that the increase of pH and ionic strength of the eluent decreased capacity factor. The best eluent for the separation of acetate, fluoride, chloride, nitrate and bromide was $1\;{\times}\;10^{-4}M$ Dns-glu in 5 mM phosphate buffer (pH 6.30). The detection limit of chloride ion was 2.1 ng in this condition.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1705-1707
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• 2005

This paper proposes a novel active frequency drift(AFD) method for the islanding prevention of grid-connected photovoltaic inverter. To detect the islanding phenomenon of grid-connected photovoltaic(PV) inverters concerning about the safety hazards and the damage to other electric equipments, many kinds of anti-islanding methods have been presented. Among them, AFD method using chopping fraction(cf) enables the islanding detection to drift up(or down) the frequency of the voltage during the islanding situation. However, the performance of the conventional AFD methods, which have a certain value of cf only, is inefficient and difficult to design the appropriate cf value analytically to meet the limit of harmonics. In this paper, the periodic chopping fraction based on an AFD method is proposed. This proposed method shows the analytical design value of cf to meet the test procedure of IEEE Std. 929-2000 with the power quality and islanding detection time. To verify the validation of the proposed method, the islanding test results are presented. It is confirmed that the proposed method has not only less harmonic distortion but also good performance of islanding detection compare with the conventional AFD method.