Polylysine-grafted Au nanoclusters: birth and growth of a healthy surface-plasmon-resonance-like band.

Poly(amino acid)-coated gold nanoparticles hold promise in biomedical applications, particularly because they combine the unique physicochemical properties of the gold core, excellent biocompatibility, and easy functionalization of the poly(amino acid)-capping shell. Here we report a novel method for the preparation of robust hybrid core-shell nanosystems consisting of a Au cluster and a densely grafted polylysine layer. Linear polylysine chains were grown by direct -carboxyanhydride (NCA) polymerization onto ligands capping the gold nanocluster.