Porous silicon (PSi) is interesting optical transducer in biosensors development. PSi can interact with biological and chemical species which penetrate inside the pores after a proper functionalization with specific bioprobes, producing a selective optical readout. In this work, we reported a functionalization approach to develop optical biosensors for heavy metal detection. Oligopeptides, namely Phytochelatins, were selected as bioprobes due to their ability to chelate heavy metal ions. Spectroscopic reflectometry and Fourier transform infrared spectroscopy were used as characterization techniques. Data show successful and repeatable functionalization process. These results are very good starting step in development of heavy metal ions optical biosensors.