Ratiometric Fluorescent Pattern for Sensing Proteins Using Aqueous Polymer-Pyrene/γ-Cyclodextrin Inclusion Complexes

A ratiometric, versatile, and selective fluorescent pattern to sense and distinguish proteins on the basis of dissociation of aqueous polymer-pyrene/gamma-cyclodextrin (gamma-CD) inclusion complexes was developed. First, two kinds of aqueous polymer-pyrene were prepared via atom transfer radical polymerization using pyrene functionalized initiator. Then, the pyrene molecules could be accumulated into gamma-CD cavity and form polymer-pyrene/gamma-CD complexes, resulting in appearance of excimer emissions. The resultant complexes responded to proteins in two ways: nonmetalloproteins binding to polymer component triggered dissociation of the inclusion complexes, accompanied by alteration of pyrene excimer/monomer emission and ratiometric fluorescent intensity changes; the presence of metalloproteins could quench pyrene excimer/monomer emission because of energy transfer: Moreover, the fluorescent responses of the inclusion complexes to different proteins could be modulated by changing polymer type and chain length, resulting in a tunable selectivity and sensitivity. The proposed fluorescent inclusion complexes could provide a promising platform for sensing proteins.