Application of 300× enhanced fluorescence on a plasmonic chip modified with a bispecific antibody to a sensitive immunosensor

Keiko Tawa, Mitsuo Umetsu, Hikaru Nakazawa, Takamitsu Hattori, Izumi Kumagai

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)8628-8632
Number of pages5
JournalACS applied materials & interfaces
Issue number17
Publication statusPublished - 2013 Sept 11


  • bispecific antibody
  • enhanced fluorescence
  • grating
  • immunosensor
  • plasmonic chip
  • zinc oxide


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