Silicon-based optical thin-film biosensor array for real-time measurements of biomolecular interaction

Real-time multi-channel measurements of protein-protein interaction in 1-100 mu g/ml antibody Solution samples were demonstrated using a reflectometric interference spectroscopy (RIfS) based silicon biochip. Since titanium-oxide film, whose refractive index is 2.2. was chosen for the interference layer of RIfS oil the silicon substrate, the layer interference was enhanced in aqueous solutions and the protein-protein interaction on the film could be measured as a shift in interference-peak position in the reflection spectra. To estimate the sensitivity of the sensing system using the RIfS sensor, we simulated the reflection spectra of the biochip. From these results, it was shown that a 0.01-nm shift in the interference-peak position corresponds to a binding amount of protein of approximately 10 pg/mm(2). According to this result, the sensitivity of our sensor was estimated to be in the order of 10 pg/mm(2) by comparing the simulated and experimental results.