Surface Plasmon Resonance and Surface Plasmon Field-Enhanced Fluorescence Spectroscopy for Sensitive Detection of Tumor Markers
Surface plasmon resonance (SPR), which provides real-time, in situ analysis of dynamic surface events, is a valuable tool for studying interactions between biomolecules. In the clinical diagnosis of tumor markers in human blood, SPR is applied to detect the formation of a sandwich-type immune complex composed of a primary antibody immobilized on a sensor surface, the tumor marker, and a secondary antibody. However, the SPR signal is quite low due to the minute amounts (ng-pg/mL) of most tumor markers in blood. We have shown that the SPR signal can be amplified by applying an antibody against the secondary antibody or streptavidin-conjugated nanobeads that specifically accumulate on the secondary antibody. Another method employed for highly sensitive detection is the surface plasmon field-enhanced fluorescence spectroscopy-based immunoassay, which utilizes the enhanced electric field intensity at a metal/water interface to excite a fluorophore. Fluorescence intensity attributed to binding of a fluorophore-labeled secondary antibody is increased due to the enhanced field in the SPR condition and can be monitored in real time.
KeywordsSurface plasmon resonance Immunosensing Tumor marker Signal amplification Polyclonal antibody Surface plasmon field-enhanced fluorescence spectroscopy.
- 2.Raether, H. (1988) Surface Plasmons on Smooth and Rough Surfaces and on Gratings. Springer, BerlinGoogle Scholar
- 3.Besselink, G. A. J., Kooyman, R. P. H., van Os, P. J. H. J., Engbers, G. H. M., and Schas- foorta, R. B. M. (2004) Signal amplification on planar and gel-type sensor surfaces in surface plasmon resonance-based detection of prostate-specific antigen. Anal. Biochem. 333, 165–173CrossRefPubMedGoogle Scholar
- 8.Hirata, I., Morimoto, Y., Murakami, Y., Iwata, H., Kitano, E., Kitamura, H., and Ikada, Y. (2000) Study of complement activation on well-defined surfaces using surface plasmon resonance. Colloid Surf. B 18, 285–292Google Scholar