In this work, the surface of nanostructured fluorine-doped ZnO (nZnO· F) is functionalized with protein A (PrA), and used as a model biomolecule. The chemical procedure is characterized by several analytical techniques such as Fourier Transform Infrared Spectroscopy, water contact angle analysis, and fluorescence microscopy. The surface modification of nZnO· F by binding increasing concentrations of PrA is also investigated by two label-free optical techniques, ie, the spectroscopic reflectometry and the steady-state photoluminescence. The results are compared with those obtained using undoped nZnO substrates in order to highlight the better performances of nZnO· F due to the fluorine doping. The results of this study pave the way for the design and realization of a ZnO-based nanostructured platform for label-free optical sensing. View Full-Text