Reversible Protein Detection Method Based on Self-Assembled Monolayers Using Ellipsometry

We propose a simple, and selective optical method for biological detection, using reflection or absorption of light upon transmission through a homogeneous/inhomogeneous thin film surface. In this experimental study, a wavelength band is sought as an optical signature to identify biological sample immobilized on an ultrathin film. We have used variable angle spectroscopic ellipsometry, a technique generally used in the semiconductor industry, to identify proteins. For immobilizing the proteins, 1-octadecanethiol (C-18) coated to gold (Au) substrate has been used because of its low surface energy. In order to characterize 1-octadecanethiol and evaluate its re-usability, fourier transform infrared spectroscopy (FTIR) was employed. Experimental results illustrate that proteins are sensitive to optical investigation in visible and near infrared region of the electromagnetic spectrum.