Real time secondary antibody detection by means of silicon-based multilayers sustaining Bloch surface waves

We report on time resolved sensing experiments demonstrating the direct, label-free and specific binding of an Antibody/Anti-antibody system probed by means of Bloch surface waves on silicon-based one-dimensional photonic crystals. The selectivity of the device is verified by monitoring the adsorption of Anti Mouse IgG (non-specific target) and Anti Rabbit IgG (specific target) on rabbit IgG receptors previously transferred by micro contact printing on the surface of 1DPC devices. The limits of the sensitivity are explored by varying the concentration of the tested solutions. Based on a modified ELISA assay, we performed a quantitative estimation of the number of detected antibodies adsorbed at the probed surface in both the non-specific and specific case (∼104 and ∼108, respectively), as associated to measured spectral shifts in the sensorgram.