Facile Preparation of Fluorescent Nanoparticles with Tunable Exciplex Emission and Their Application to Targeted Cellular Imaging

Fluorescent nanoparticles with a tunable emission show a good potential for usage in biological imaging. Exciplex emission usually appears with a large red shift from the normal emission peak. The integration of exciplex emission into nanoparticles offers a rational strategy to designing fluorescent nanoparticles with a tunable emission. In this work, we doped electron acceptors into the electron donor poly(N-vinylcarbazole) (PVK) to develop novel fluorescent nanoparticles with a conveniently modulated PVK emission. Through careful design of the molecular structures of the electron acceptors, we demonstrated that controlled donor-acceptor spatial stacking and electron transitions could regulate the exciplex emission of the PVK/ acceptor nanoparticles. Thus, the structurally controlled exciplex formation allowed for the preparation of multicolored fluorescent nanoparticles. Moreover, further modifications with the cyclic peptide RGD showed little disruption to the structure of the PVK/acceptor nanoparticles and the corresponding exciplex emission. Hence, the nanoparticles showed the ability to be used for targeted cellular imaging. On the basis of the RGD-integrin alpha(nu)beta(3) (ligand-receptor) interaction, the nanoparticles were effectively endocytosed by target cancer cells. We anticipate that this research could provide a new strategy for the fabrication of fluorescent nanoparticles with a tunable emission, leading to useful materials for fluorescent imaging.