C(60)-fullerene derivatives are potential building blocks in modular carrier systems for selective
tumor targeting. In [5:1]
fullerene hexakis adducts, one position can be occupied by an addressing unit (e.g.
monoclonal antibody) while the other five positions are suitable for
dendrimers or spacers loaded with several
drug moieties. This article reports intracellular uptake and
phototoxicity of three
fullerene hexakis adducts coupled with a different number of
photosensitizers: a bis(3(1),3(2)-didehydrophytochlorin)-fullerene [5:1]-hexaadduct (FHP1), a
fullerene [5:1]-hexaadduct with six
3(1),3(2)-didehydrophytochlorin groups (FHP6) and a
fullerene [6:0]-hexaadduct that carries 12
3(1),3(2)-didehydrophytochlorin units (FHP12). The most promising complex, the hexa-3(1),3(2)-didehydrophytochlorin
fullerene hexaadduct FHP6, was also compared with its
fullerene-free analogous derivative P6. It was found that the extent of intracellular uptake is influenced by both nanomolecular size and asymmetry (amphiphilicity) of the
fullerene complexes. The degree and mechanism of
phototoxicity was found to depend on intracellular concentrations and
singlet oxygen quantum yields.