Cationic polyfluorenes for intracellular delivery of proteins.

Two cationic polyfluorene derivatives, quaternary amine 1 and guanidine 2 sheathed systems, were prepared as potential carriers to mediate import of proteins into cells without requiring covalent attachment to the protein. Neither polymer showed significant cytotoxicities (IC(50) 100 μM) when exposed to Clone 9 rat liver cells. Both polymers were shown to mediate import of a series of four proteins chosen because they have different pI values, sizes, and variable organic fluor attachments. Once inside the cells, the quaternary amine system 1 released more of its cargo into regions outside the lysosomes. In one exploratory experiment, pyrenebutyrate was shown to accelerate import of a protein system by polymer 1.