Multiwalled carbon nanotubes for drug delivery: Efficiency related to length and incubation time

Batches of oxidized multiwalled carbon nanotubes differing in length were adopted to prepare two drug delivery systems (DDS) loaded with doxorubicin. The different internalization of the two batches, verified by atomic emission spectroscopy onto cell lysates, was also confirmed by the different toxicity of the same DDS loaded with doxorubicin. In vitro experiments evidenced, after 48 h of incubation, the superior efficacy of the shortest nanotubes. However, upon prolonging the incubation time up to 72 h the difference in efficiency was minimized due to the spontaneous release of doxorubicin by the non-internalized long nanotubes.