Dynamic Fluorescent Nanoparticle Assemblies for Biosensing Applications
G. Daniel Lilly and Nicholas A. Kotov. Chemical Engineering, University of Michigan, 2300 Hayward, HH Dow Building #3074, Ann Arbor, MI 49109
The conjugation of nanomaterials to one another to create unique superstructures allows novel coupling of the electronic and optical properties of the constituent materials. This paper focuses on the unique optical properties of assemblies formed by the conjugation of Au nanoparticles (NPs) and core/shell CdSe/ZnS NPs using polyethylene glycol (PEG). Similar assemblies have been formed with Au NPs and CdTe NPs whose quantum yield is temperature dependant; however, the diameter of CdTe cannot be tuned such that its PL covers all visible wavelengths, and CdTe NPs experience contact quenching when many NPs are bound together, thus limiting their potential applications. The PL of CdSe can be tuned to any visible wavelength by changing the diameter of the NP; moreover, when a shell with a larger bandgap than CdSe is applied to a CdSe core (ZnS, ZnSe, or CdS), contact quenching can be prevented and the quantum yield further enhanced. These core shell materials are also more photochemically stable and more resistant to photobleaching than traditional NPs.