Protein-Assisted Supramolecular Control over Fluorescence Resonance Energy Transfer in Aqueous Medium

Abstract

The supramolecular approach has been exploited to modulate the fluorescence resonance energy transfer between an oligofluorene fluorophore and an ionic styryl dye with the assistance of a protein (bovine serum albumin) in aqueous medium. Self-assembled nanoparticles of oligofluorene with a negatively charged surface have functioned as the energy donor, and the positively charged styryl dye acts as the energy acceptor. The hydrophobic pockets in the secondary structure of the added protein enabled complimentary supramolecular interactions in the ternary complex. Moreover, it provided a rigid, nonpolar microenvironment to the dyes, thereby reducing the charge-transfer phenomenon in the dye and favored emission from the locally excited states. As a result, modulation of the energy transfer was observed, yielding significant tuning in emission wavelengths (or color) of the donor-acceptor complex.