Unusual enhancement of fluorescence and Raman scattering of core-shell nanostructure of polydiacetylene and Ag nanoparticle

The colorimetric and fluorescent properties of polydiacetylene (PDA) have been assessed for chemosensors and ultrafast biosensor applications. The low quantum efficiency, however, has delayed the further development of PDA based practical devices. Here, we synthesized a hybrid nanostructure of PDA with Ag nanoparticles of core. A core-shell type Ag@PDA blue phase nanoparticles showed significantly enhanced Raman scattering, whereas it dramatically decreased after the thermal treatment inducing phase transition of PDA to red. On the other hand the Ag@PDA red phase nanoparticles showed an evidently increasing fluorescence accompanying with the shortened lifetime. These unusual reinforced optical properties is attributed to the core Ag nanoparticles providing the surface selection rule and the surface enhancement effects by the localized surface plasmon. Consequently, our result demonstrates the hybrid structure of PDA with metal nanoparticles to be an alternative to overcome the limit of PDA for high performance devices.