Photophysics of fluorescent silver nanoclusters

• Main Author: Patel, Sandeep A.
• Published: Georgia Institute of Technology 2009
• Subjects: Nanoparticle; Bio-labling; Fluorescence modulation; Charge transfer; Two-photon absorption; Silver; Nanocluster; Fluorescence; Single molecule; Nanostructured materials; Metal clusters; Photochemistry; Fluorimetry
• Online Access: http://hdl.handle.net/1853/28110

Fluorescence imaging has been increasingly relied upon as the method of choice for many biological and medical applications. As demands for more sensitive and higher resolution imaging are ever-increasing, it is critical that photostable, and robust fluorophores capable of delivering high emission rates are available. Fluorescent silver nanoclusters offer an attractive compromise between the photostability and brightness of quantum dots and the compact versatility of organic chromophores. They have been shown to be superior in many roles, including as single molecule fluorophores and bulk multiphoton biological staining agents. The two-photon absorption cross sections are several orders of magnitude larger than commercially-available dyes, and they have demonstrated superior photostability under high intensity irradiation. In addition to the endogenous effects of the cluster, its small size of only a few atoms renders it highly susceptible to surface and environmental effects, which manifests, for example, in the observed photoinduced charge transfer between the silver cluster and oligonucleotide. This state has been shown to be highly advantageous in imaging applications, as control of this state enables better control over the time-averaged emission rate of the molecule. The mechanism of charge transfer, and the possible means by which this state can be controlled will be also be investigated in this work.