Gold Coated Nanoparticles Functionalized by Photochemical Immobilization Technique for Immunosensing

Gold nanoparticles (AuNP)s play a fundamental role in biosensing in view of their various applications, each of them exploiting one or more properties of such a system. In any case, to make AuNPs effective as biosensing tools, it is necessary to provide them with high specificity by means of processes able to achieve an efficient gold surface functionalization with antibodies. This issue can be easily addressed by the so-called Photochemical Immobilization Technique (PIT). Herein, we report PIT-functionalized AuNPs applied as ballast for improving the sensitivity of quartz-crystal microbalances, but also as optical transducers (colorimetric biosensor) in which the key role is played by the plasmonic properties of nanostructured gold. Eventually, the role of gold is highlighted in its combination with magnetic nanoparticles, a physical system in which the magnetic behaviour of the core is joined to the optical properties of the surface.