Hybrid Au-SiO2 Core-Satellite Colloids as Switchable SERS Tags

Gold-silica self-assembled nanostructures are reported as multiplex surface enhanced Raman scattering (SERS) tags forbionnaging applications. These hybrid colloidal partides were 'obtained by heteroassembly of Au-SiO2 Janus particles with smaller Au spheres, atid, two Raman-active molecules that can, be independently imaged by varying the wavelength Of the excitation laser. The Janus strugure of Au-SiO2 not only directs the assembly, but also provides physical separation of the Ramat tags and colloidal stability thereby facilitating complete silica encapsulation. The bioimaging capabilities of this system are demonstrated through SERS Mapping of individual cells.