• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.70-74
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• 2003

The heterogeneous bioluminescence immunoassay for digoxin was developed using photoprotein, native aequorin as a label and the site-directed immobilization technique based on avidin/biotin interaction. Aequorin is a bioluminescence protein, originally isolated from the jellyfish Aequoria Victoria and an attractive label in analytical applications because of sensitive detection due to virtually no background bioluminescent signal. Digoxin is a cardioactive drug, and its therapeutic level in serum is at low concentration with very narrow therapeutic index. The aequorin-digoxigenin conjugates were synthesized by the N-hydroxysuccinimide ester method and characterized in terms of bioluminescent residual activity. The resulting dose-response curve shows that the detection limit is $1.0\;{\times}\;10^{-10}\;M$ and a dynamic range is three orders of magnitude, which was obtained by $1.0\;{times}\;10^{-10}\;M$ conjugate and 0.9 μg/mL anti-digoxin antibody. Three structurally similar molecules to digoxin were examined for their cross-reactivity. None of these three compounds showed any crossreactivity with digoxin antibody employed in this study. Standard amounts of digoxin corresponding to the therapeutic range were spiked into the each serum solution. Study of the serum matrix effect indicated that correlation coefficient shows good agreement between luminescence light intensity between in buffer and in serum.

• Analytical Science and Technology
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• v.23 no.1
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• pp.60-67
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• 2010

A sensitive competitive heterogeneous bioluminescence immunoassay for serotonin was developed using photoprotein, aequorin as a label for the first time with the optimal assay conditions; especially, serotoninavidin conjugate was prepared by Mannich reaction and the synthetic process of serotonin-avidin conjugate was optimized by controlling the initial molar ratios of serotonin, formaldehyde and avidin (1:12,000:25). The developed bioluminescence immunoassay for serotonin showed good sensitivity (LOD of 0.68 ng/mL) with wide area of dynamic range ($5.0{\times}10^{-10}\;M\sim5.0{\times}10^{-7}\;M$). (cf. the range for serotonin in human blood serum is $151{\pm}45\;ng$/mL). In addition, cross-reactivity studies demonstrated that 5-methoxytryptamine showed some cross-reactivity (28.0%), whereas 3-methylindole, melatonin and 5-hydroxylindole-3-acetic acid showed no crossreactivity, and good recoveries were obtained in serum. Thus, this developed method provides a good tool to monitor serotonin in serum.

• Bulletin of the Korean Chemical Society
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• v.27 no.3
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• pp.407-412
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• 2006

Bioluminescence single-site immunometric assay for methamphetamine (MA) using the native aequorin, a photoprotein, as a signal generator was developed for the first time. MA is a potent sympathomimetic amine with stimulant effects on the central nervous system. MA abuse induces hallucinations and, thus, may cause a serious social problem. The single-site immunometric MA assay was optimized and its dose-response behavior was examined. The dose-response curve shows that the detection limit is 1.1 ${\times}$ $10^{-10}$ M and a dynamic range is four orders of magnitude with 15 $\mu$g/mL BSA-MA conjugate and 1.0 ${\times}$ $10^{-8}$ M anti-MA antibody-biotin conjugate. In order to evaluate this assay, the structurally similar compounds, amphetamine, ephedrine, norephedrine, benzphetamine and N-4-(aminobutyl)methamphetamine were examined for their crossreactivity. None of these five compounds showed any cross-reactivity. Additionally, an artificial urine solution spiked with MA was analyzed by the MA assay, and the result of the analysis demonstrated the usefulness of the present assay for the determination of MA in urine.