title: Immunosensor with fluid control mechanism for salivary cortisol analysis.
abstract: The purpose of this research is to demonstrate a new design for a cortisol immunosensor for the noninvasive and quantitative analysis of salivary cortisol. We propose a cortisol immunosensor with a fluid control mechanism which has both a vertical flow and a lateral flow. The detected current resulting from a competitive reaction between the sample cortisol and a glucose oxidase (GOD)-labeled cortisol conjugate was found to be inversely related to the concentration of cortisol in the sample solution. A calibration curve using the relative detected current showed a R(2)=0.98 and CV=14% for a range of standard cortisol solutions corresponding to the concentrations of native salivary cortisol (0.1-10 ng/ml). The measurement could be accomplished within 35 min and the cortisol immunosensor could be reused. These results show promise for realizing an on-site and easy-to-use biosensor for cortisol. Used for evaluation of human salivary cortisol levels, the cortisol immunosensor measurement corresponded closely with commercially available ELISA method (R(2)=0.92). Our results indicate the promise of the new cortisol immunosensor for noninvasive, point of care measurement of human salivary cortisol levels.
authors.affiliation: Biomedical Engineering & Robotics Laboratory, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551, Japan. masakiy@iwate-u.ac.jp
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Yohei
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Shohei
authors.initials: S
authors.lastname: Sasaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kadoma
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Imai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Niwa
authors.forename: Vivek
authors.initials: V
authors.lastname: Shetty
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017743:Equipment Reuse; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007118:Immunoassay / Q000295:instrumentation*; D044085:Microfluidics / Q000295:instrumentation*; D019095:Point-of-Care Systems; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D012680:Sensitivity and Specificity
chemical_list: D006854:Hydrocortisone