A polyethylenimine (PEI) self-assembled monolayer (SAM) is prepared, capable of complexing silver and copper cations and of anchoring silver nanoparticles, exerting antibacterial activity against Escherichia coli and Staphylococcus aureus. Functionalized glassy surfaces have been fully characterized through spectroscopic techniques (UV-Vis spectroscopy, spectroscopic ellipsometry), atomic force microscopy imaging and quantitative Ag and Cu analysis (ICP optical emission spectroscopy).