UNS:Photomodulation of Forster Cycle in a Fluorescent Protein

Oklahoma State University, Stillwater OK

Investigators

Abstract

PI: Kalkan, Kaan Proposal No.: 1512157 This project seeks to develop new types of optical probes that are faster and more efficient at switching, while reducing effects of photobleaching. They will study the photophysics of energy transfer between metal nanoparticles and fluorescent proteins to develop stable photoactivatable probes for super-resolution microscopy applications. The hypothesized photoswitching is based on photocreation of the intermediate state in the Forster cycle of the FP using surface-enhanced optical pumping. This photomodulation of the Forster cycle will be verified and studied by single molecule surface-enhanced Raman scattering and micro-optical spectroscopy. This effort will develop a photoswitch using Green Fluorescent Protein (GFP) - silver NP conjugates as its prototype. The photomodulation is based upon photopopulation of the intermediate form (I-form) of GFP by excited state proton transfer that red-shifts the optical absorption from 395 to 490 nm. This spectral shift in absorption, in turn, is expected to modulate the Mie scattering of the plasmonic NP by resonant energy transfer to the FP.