Application of 300× enhanced fluorescence on a plasmonic chip modified with a bispecific antibody to a sensitive immunosensor.
The grating substrate covered with a metal layer, a plasmonic chip, and a bispecific antibody can play a key role in the sensitive detection of a marker protein with an immunosensor, because of the provision of an enhanced fluorescence signal and the preparation of a sensor surface densely modified with capture antibody, respectively. In this study, one of the tumor markers, a soluble epidermal growth factor receptor (sEGFR), was selected as the target to be detected. The ZnO- and silver-coated plasmonic chip with precise regularity and the appropriate duty ratio in the periodic structure further enhanced the fluorescence intensity. As for sensor surface modification with capture antibody, a bispecific antibody (anti-sEGFR and anti-ZnO antibody), the concentrated bispecific antibody solution was found to nonlinearly form a surface densely immobilized with antibody, because the binding process of a bispecific antibody to the ZnO surface can be a competitive process with adsorption of phosphate. As a result, the interface on the plasmonic chip provided a 300× enhanced fluorescence signal compared with that on a ZnO-coated glass slide, and therefore sEGFR was found to be quantitatively detected in a wide concentration range from 10 nM to 700 fM on our plasmonic surface.
Health Research Institute, AIST , Ikeda, Osaka 563-8577, Japan.
Keiko
K
Tawa
Mitsuo
M
Umetsu
Hikaru
H
Nakazawa
Takamitsu
T
Hattori
Izumi
I
Kumagai
D000906:Antibodies / Q000276:immunology*; D002232:Carbocyanines / Q000737:chemistry; D066246:ErbB Receptors / Q000276:immunology; D005456:Fluorescent Dyes / Q000737:chemistry*; D007118:Immunoassay; D046210:Microfluidic Analytical Techniques; D012834:Silver / Q000737:chemistry; D020349:Surface Plasmon Resonance; D015034:Zinc Oxide / Q000737:chemistry
D000906:Antibodies; D002232:Carbocyanines; D005456:Fluorescent Dyes; C085321:cyanine dye 5; D012834:Silver; D066246:ErbB Receptors; D015034:Zinc Oxide