Capacitance Measurements of Antibody-Antigen Interactions in a Flow System
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- 作者：Christine Berggren and Gillis Johansson
- 刊名：Analytical Chemistry
- 出版年：1997
- 出版时间：September 15, 1997
- 年：1997
- 卷：69
- 期：18
- 页码：3651 - 3657
- 全文大小：7644K
- 年卷期：v.69,no.18(September 15, 1997)
- ISSN：1520-6882
文摘
Capacitive immunosensors were made by coupling monoclonal antibodies to thioctic acid, which had self-assembled on a gold electrode. Surface areas that werenotcovered were plugged with 1-dodecanethiol to make thelayer dense and insulating. Cyclic voltammetry showedthat the hexacyanoferrate redox reactions were blockedby this procedure. The capacitance of the electrodewasevaluated from the current transients obtained when apotentiostatic step was applied. The immunosensor wasplaced in a flow system, and a capacitance decrease couldbe observed after injection of an unlabeled antigen. Itwaslinear over almost three decades when plotted vs thelogarithm of the antigen concentration. Humanchorionicgonadotropin hormone could be determined in the range1 pg/mL-1 ng/mL, with a detection limit of 0.5 pg/mL(15 10-15 M). A similar response wasobtained withimmobilized F(ab')2 fragments. No cross-reactivitywasobserved with the thyrotropic hormone, which has onechain in common with gonadotropin. Monoclonal antibodies toward interleukin-2 immobilized on the immunosensor gave also a response over 1 pg/mL-1 ng/mL,with a detection limit of 1 pg/mL. An immunosensorwithmonoclonal antibodies toward human albumin gave acalibration curve with lower slope than the other proteinsbut still with a detection limit of 1 pg/mL.