Biochips at work: porous silicon microbiosensor for proteomic diagnostic.

The molecular interactions between the glutamine binding-protein (GlnBP) from Escherichia coli and its main ligands the L-glutamine (Gln) and the gliadin, a toxic peptide containing three Gln sequences, are detected by means of an optical biosensor based on porous silicon (PSi) technology. The binding events are optically transduced in the wavelength shifts of the porous silicon reflectivity spectrum. In the first case, the hydrophobic interaction links the GlnBP, which acts as a molecular probe for Gln, to the hydrogenated porous silicon surface area. A more stable coupling between the protein and the chip surface can be obtained by a proper functionalization process. Even if the GlnBPs are covalently bonded to the PSi, they are able to selectively recognize the gliadin in micromolar concentration.