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Kim M.I.,KAIST | Yu B.J.,MD Science Inc. | Woo M.-A.,KAIST | Cho D.,LabGenomics Co. | And 4 more authors.
Analytical Chemistry | Year: 2010

We describe a novel multiplex "amino acid array" for simultaneously quantifying different amino acids based on the rapid growth of amino acid auxotrophic E. coli. First, we constructed genetically engineered amino acid auxotrophs of E. coli containing a bioluminescence reporter gene, yielding concomitant luminescence as a response to cell growth, and then immobilized the reporter cells within individual agarose of respective wells in a 96-well plate serving as a mimic of a biochip. Using the amino acid array, we were able to determine quantitatively the concentrations of 16 amino acids in biological fluid by simply measuring bioluminescent signals from the immobilized cells within 4 h without pre- and post-treatment. The clinical utility of this method was verified by quantifying different amino acids in dried blood spot specimens from clinical samples for the diagnosis of metabolic diseases of newborn babies. This method serves as a convenient route to the rapid and simultaneous analysis of multiple amino acids from complex biological fluids and represents a new analytical paradigm that can replace conventional, yet laborious methods currently in use. © 2010 American Chemical Society. Source

Jung Y.L.,KAIST | Jung C.,KAIST | Parab H.,KAIST | Cho D.-Y.,LabGenomics Co. | Park H.G.,KAIST
ChemBioChem | Year: 2011

Red gold/blue gold: A highly convenient colorimetric method for the identification of single-nucleotide polymorphism was developed by utilizing gold nanoparticles and an allele-specific polymerase chain reaction. Its diagnostic capability was successfully demonstrated by correctly identifying various mutations in the BRCA1 gene. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Shin S.,KAIST | Won B.Y.,KAIST | Jung C.,KAIST | Shin S.C.,KAIST | And 3 more authors.
Chemical Communications | Year: 2011

Utilizing a peptide nucleic acid (PNA)-modified electrode and a single-stranded DNA specific endonuclease, a novel electrochemical method to identify DNA mutations has been developed and represents a totally new strategy for the electrochemical diagnosis of human genetic mutations. © 2011 The Royal Society of Chemistry. Source

Woo M.-A.,KAIST | Woo M.-A.,Korea Food Research Institute | Park J.H.,KAIST | Cho D.,LabGenomics Co. | And 3 more authors.
Analytical Chemistry | Year: 2016

We developed a whole-cell surface plasmon resonance (SPR) sensor based on a leucine auxotroph of Escherichia coli displaying a gold-binding protein (GBP) in response to cell growth and applied this sensor to the diagnosis of maple syrup urine disease, which is represented by the elevated leucine level in blood. The leucine auxotroph was genetically engineered to grow displaying GBP in a proportion to the concentration of target amino acid leucine. The GBP expressed on the surface of the auxotrophs directly bound to the golden surface of an SPR chip without the need for any additional treatment or reagents, which consequently produced SPR signals used to determine leucine levels in a test sample. Gold nanoparticles (GNPs) were further applied to the SPR system, which significantly enhanced the signal intensity up to 10-fold by specifically binding to GBP expressed on the cell surface. Finally, the diagnostic utility of our system was demonstrated by its employment in reliably determining different statuses of maple syrup urine disease based on a known cutoff level of leucine. This new approach based on an amino acid-auxotrophic E. coli strain expressing a GBP that binds to an SPR sensor holds great promise for detection of other metabolic diseases of newborn babies including homocystinuria and phenylketonuria, which are also associated with abnormal levels of amino acids. © 2016 American Chemical Society. Source

Woo M.-A.,KAIST | Kim M.I.,KAIST | Yu B.J.,MD Science Inc. | Cho D.,LabGenomics Co. | And 5 more authors.
Analytical Chemistry | Year: 2011

A cell-based quantitative assay system for Hcy has been developed by utilizing two Escherichia coli auxotrophs that grow in the presence of methionine (Met) and either homocysteine (Hcy) or Met, respectively. A bioluminescent reporter gene, which produces luminescence as cells grow, was inserted into the auxotrophs, so that cell growth can be readily determined. When the relative luminescence unit (RLU) values from the two auxotrophs immobilized within agarose gels arrayed on a well plate were measured, the amount of Hcy was quantitatively determined on the basis of differences between two RLU values corresponding to cell growth of two auxotrophs with excellent levels of precision and reproducibility. Finally, the diagnostic utility of this assay system was verified by its employment in reliably determining different stages of hyperhomocysteinemia in human plasma samples providing CVs of within and between assays that are less than 2.9% and 7.1%, respectively, and recovery rates of within and between assays that are in the range of 99.1-103.5% and 97.5-105.5%, respectively. In contrast to existing conventional methods, the new system developed in this effort is simple, rapid, and cost-effective. As a result, it has great potential to serve as a viable alternative for Hcy quantification in the diagnosis of hyperhomocysteinemia. © 2011 American Chemical Society. Source

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