A proper bioconjugation of molecular probes onto a transducer surface is a key point in developing new kind of biosensors. Porous Silicon (PSi) and quartz resonators (QR) are commonly used as transducers in biochemical sensors using spectroscopic reflectometry and quartz crystal microbalance (QCM). In this work, we studied bioconjugation of oligopeptides, namely Phytochelatins (PCs), which are able to bind heavy metal in aqueous solutions, both on PSi and QR surfaces: strong competition between protein-binding and protein-solubilization interactions are highlighted by both techniques.