Unique optical properties of metal nanoparticles (Au, Ag) provide a wide range of opportunities to the development of optical nanosensors. Indeed, Au and Ag nanoparticles have a sharp characteristic absorption (Local Surface Plasmon Resonance- LSPR) bands at 520 nm and 400 nm in the visible region, respectively. This property allows the use of such nanoparticles in various optical applications. This study presents label-free optical method to study biomolecular interactions of Cancer Antigen CA 125 in real time at the glass and gold metallic substrate. This method relies on the change in the absorbance spectrum of a self assembled monolayer of Au/Ag nanoparticles on glass or gold metal surface as a function of biomolecular binding to the surface of the immobilized Au nanoparticles. Using this approach, we demonstrate a label-free optical nanosensor to qualify as well as quantify biomolecular interactions in real time on a surface in a commercially available UV-visible spectrophotometer and Surface Enhanced Raman Spectroscopy techniques. In order to enhance sensitivity of biomolecular binding, size, type and density of metal nanoparticle are examined. During the surface preparation process the surfaces are characterized by using surface examination techniques such as X-Ray Photoelectron Spectroscopy (XPS), Fourier Transform IR Spectroscopy (FT-IRS) to have broader structural information. Additionally, distribution of the nanoparticles on the surfaces is monitored by Scanning Electron Microscopy (SEM). Finally, bioconjugation is monitored by Confocal Raman Microscopy and Circular Dichroism (CD) Spectroscopy.Experimental details and results will be presented and discussed.

Colormetric LSPR nanosensor for detecting cancer antigen CA 125

248th National Meeting (2014)

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