Fig. 1.

State-of-art plasmonic and photonic platforms for high-sensitivity label-free biosensing. For each platform, namely SPR⁵⁴, LSPR⁵⁵, interferometer^56,57, ring resonator⁵⁸, photonic crystal⁵⁹, optical fiber⁶⁰, the best-performing biosensor exploiting nanostructured materials is indicated with an asterisk, when available. Porous silicon (PSi) nanostructured biosensors performed less well than the other platforms to date, at least in terms of sensitivity and, in turn, limit of detection (LoD). The LbL biofunctionalization of nanostructured materials proposed in this work allows the gap between PSi optical biosensors and other optical biosensing platforms to be filled, thus pushing PSi biosensors to minimum detectable analyte concentrations comparable to those of the best-performing label-free biosensing platforms