Biosensors fabricated on the nanoscale offer exciting new avenues in the quest for better understanding and characterization of biological systems. Porous silicon is an ideal nanostructured material for the construction of optical transducer matrices because it is easily functionalized with biomolecular probes and displays strong optical interferences. Here, we show that certain transition metal complexes, including nickel(II)cyclam, are able to induce corrosion in porous silicon films rapidly, generating a strong optical interferometric signal that originates from the porous layer. We subsequently exploit this effect to design a transducer for ligand-receptor recognition. With a nickel(II)cyclam derivative as a catalytic label, DNA- and avidin-binding events are detected by time-lapse interferometric reflectance spectroscopy in a fast, simple, and inexpensive fashion.