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Development of Indirect Competitive Immuno-Assay Method Using SPR Detection for Rapid and Highly Sensitive Measurement of Salivary Cortisol Levels.

Tahara Y, Huang Z, Kiritoshi T, Onodera T, Toko K - Front Bioeng Biotechnol (2014)

Bottom Line: The surface of an Au chip was modified with PEG6-COOH aromatic dialkanethiol self-assembled monolayers and hydrocortisone 3-(O-carboxymethyl) oxime (hydrocortisone 3-CMO) as a cortisol analog.A detection limit of 38 ppt range with a measurement range of 10 ppt-100 ppb was accomplished without the incubation of a mixing solution consisting of standard cortisol and an anti-cortisol antibody, and the time for quantification of cortisol concentration was 8 min from the sample injection.It was found that the results obtained by the cortisol immuno-assay had a good correlation with those obtained by ELISA assay (R = 0.96).

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Information Science and Electrical Engineering, Kyushu University , Fukuoka , Japan.

ABSTRACT
The monitoring of salivary cortisol as a key biomarker of an individual's stress response has been increasingly focused on. This paper describes the development of a novel cortisol immuno-assay method based on an indirect competitive method using a commercially available surface plasmon resonance instrument. The surface of an Au chip was modified with PEG6-COOH aromatic dialkanethiol self-assembled monolayers and hydrocortisone 3-(O-carboxymethyl) oxime (hydrocortisone 3-CMO) as a cortisol analog. A detection limit of 38 ppt range with a measurement range of 10 ppt-100 ppb was accomplished without the incubation of a mixing solution consisting of standard cortisol and an anti-cortisol antibody, and the time for quantification of cortisol concentration was 8 min from the sample injection. We experimentally compared our immuno-assay with a commercialized salivary cortisol enzyme-linked immunosorbent assay (ELISA) kit using human saliva samples. It was found that the results obtained by the cortisol immuno-assay had a good correlation with those obtained by ELISA assay (R = 0.96). Our findings indicate the potential utility of the cortisol immuno-assay for measurements of human salivary cortisol levels.

No MeSH data available.


Calibration curve of the cortisol biosensor with or without incubation before injection of cortisol standard cortisol and cortisol antibody.  ; without incubation,  ; 2 h incubation.
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Figure 3: Calibration curve of the cortisol biosensor with or without incubation before injection of cortisol standard cortisol and cortisol antibody.  ; without incubation,  ; 2 h incubation.

Mentions: Before injection onto the sensor surface, each mixture of the antibody and cortisol solutions was incubated for 2 h. A mixture solution containing 600 ppb antibody and the each standard cortisol solution was applied for 5 min after incubation for 2 h or without incubation before injection. Figure 3 shows the obtained calibration curves. Even without incubation, a calibration curve similar to that for the case of 2 h incubation was obtained. The detection limits of the calibration curves in the case of 2 h incubation and no incubation were 72.8 and 38.0 ppt, respectively. Alderling et al. reported that the cortisol level in human saliva ranges from approximately 2–20 nM (0.7–7.1 ppb) with circadian variation. Thus, this cortisol immuno-assay method does not need sample incubation, antibody, and cortisol solution, before sample injection to monitor human cortisol levels. Here, Δθ1 for cortisol quantification was determined approximately 8 min after sample injection and rapid compared with other reports. Moreover, it can be used to analyze the cortisol concentrations in blood plasma and urine, which are approximately 10 times higher than that in saliva, upon controlling the sensitivity.


Development of Indirect Competitive Immuno-Assay Method Using SPR Detection for Rapid and Highly Sensitive Measurement of Salivary Cortisol Levels.

Tahara Y, Huang Z, Kiritoshi T, Onodera T, Toko K - Front Bioeng Biotechnol (2014)

Calibration curve of the cortisol biosensor with or without incubation before injection of cortisol standard cortisol and cortisol antibody.  ; without incubation,  ; 2 h incubation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126460&req=5

Figure 3: Calibration curve of the cortisol biosensor with or without incubation before injection of cortisol standard cortisol and cortisol antibody.  ; without incubation,  ; 2 h incubation.
Mentions: Before injection onto the sensor surface, each mixture of the antibody and cortisol solutions was incubated for 2 h. A mixture solution containing 600 ppb antibody and the each standard cortisol solution was applied for 5 min after incubation for 2 h or without incubation before injection. Figure 3 shows the obtained calibration curves. Even without incubation, a calibration curve similar to that for the case of 2 h incubation was obtained. The detection limits of the calibration curves in the case of 2 h incubation and no incubation were 72.8 and 38.0 ppt, respectively. Alderling et al. reported that the cortisol level in human saliva ranges from approximately 2–20 nM (0.7–7.1 ppb) with circadian variation. Thus, this cortisol immuno-assay method does not need sample incubation, antibody, and cortisol solution, before sample injection to monitor human cortisol levels. Here, Δθ1 for cortisol quantification was determined approximately 8 min after sample injection and rapid compared with other reports. Moreover, it can be used to analyze the cortisol concentrations in blood plasma and urine, which are approximately 10 times higher than that in saliva, upon controlling the sensitivity.

Bottom Line: The surface of an Au chip was modified with PEG6-COOH aromatic dialkanethiol self-assembled monolayers and hydrocortisone 3-(O-carboxymethyl) oxime (hydrocortisone 3-CMO) as a cortisol analog.A detection limit of 38 ppt range with a measurement range of 10 ppt-100 ppb was accomplished without the incubation of a mixing solution consisting of standard cortisol and an anti-cortisol antibody, and the time for quantification of cortisol concentration was 8 min from the sample injection.It was found that the results obtained by the cortisol immuno-assay had a good correlation with those obtained by ELISA assay (R = 0.96).

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Information Science and Electrical Engineering, Kyushu University , Fukuoka , Japan.

ABSTRACT
The monitoring of salivary cortisol as a key biomarker of an individual's stress response has been increasingly focused on. This paper describes the development of a novel cortisol immuno-assay method based on an indirect competitive method using a commercially available surface plasmon resonance instrument. The surface of an Au chip was modified with PEG6-COOH aromatic dialkanethiol self-assembled monolayers and hydrocortisone 3-(O-carboxymethyl) oxime (hydrocortisone 3-CMO) as a cortisol analog. A detection limit of 38 ppt range with a measurement range of 10 ppt-100 ppb was accomplished without the incubation of a mixing solution consisting of standard cortisol and an anti-cortisol antibody, and the time for quantification of cortisol concentration was 8 min from the sample injection. We experimentally compared our immuno-assay with a commercialized salivary cortisol enzyme-linked immunosorbent assay (ELISA) kit using human saliva samples. It was found that the results obtained by the cortisol immuno-assay had a good correlation with those obtained by ELISA assay (R = 0.96). Our findings indicate the potential utility of the cortisol immuno-assay for measurements of human salivary cortisol levels.

No MeSH data available.