Energy transfer plays a significant role in numerous chemical, physical, and biological processes. While the use of fluorescent proteins in Forster resonance energy transfer (FRET) studies of biomolecules is common, energy transfer between fluorescent proteins and inorganic nanoparticles has not been explored in detail. In this study, energy transfer from fluorescent phycobiliproteins to noble metal nanoparticles was analyzed. Solutions of B-phycoerythrin (B-PE) were mixed with colloidal Au and Ag nanoparticles and were characterized by steady-state and time-resolved fluorescence spectroscopy to determine the magnitude and mechanism of the energy transfer. It was found that the protein fluorescence was quenched after the addition of metal nanoparticles. Electron microscopy and absorption spectroscopy confirmed that B-PE was adsorbed onto the nanoparticles, creating a favorable geometry for quenching. Time-resolved fluorescence spectroscopy showed that B-PE fluorescence lifetimes decreased from 2.2 ns to 0.5 and 0.6 ns upon adsorption onto Au and Ag nanoparticles, respectively, corresponding to energy transfer efficiencies of >70%. Our results, which include lifetimes, efficiencies, and energy transfer distances, show that energy was transferred via the surface energy transfer (SET) mechanism, rather than FRET.
Saraswat, Suraj; Desireddy, Anil; Zheng, Desheng; Guo, Lijun; Lu, H. Peter; Bigioni, Terry P.; and Isailovic, Dragan, "Energy Transfer From Fluorescent Proteins To Metal Nanoparticles" (2011). Chemistry Faculty Publications. 156.
Journal Of Physical Chemistry C