Nonviral gene delivery by tetraamino fullerene.
A fullerene derivative bearing two diamino side chains binds to a plasmid vector DNA, either 4 or 40 kbp in size, delivers it to mammalian cells on incubation, and leads to expression of the encoded gene either transiently or stably. The initial physicochemical investigations upon DNA-binding and protective properties of various fullerene compounds against nuclease led us to identify the tetraamino fullerene as an ideal candidate to probe the new concept of fullerene-mediated gene delivery to mammalian cells. Studies on transient and stable transfection of COS-1 cells using green fluorescent protein and luciferase reporter genes revealed several useful properties of the fullerene transfection as compared with the conventional lipid-based transfection method, including much higher efficiency of stable transfection and ability to transfect confluent cells. Chemical and biological studies suggested that the cell uptake of the fullerene/DNA complex takes place by an endocytosis mechanism and that the DNA internalized by endosomes is protected by the fullerene against enzymatic digestion. The stiffness of the fullerene/DNA complex may play some role in the success of the fullerene method.