Size of single-wall carbon nanotube affects the folate receptor-mediated cancer cell targeting

Advances in nanobiotechnology and targeting strategy could improve the delivery of therapeutic molecules into cancer cells, leading to improved treatment efficiency with minimal side effects on normal cells. To design an efficient nanocarrier, consideration of parameters that facilitate direct drug delivery into the target cells is important. We studied the effect of single-wall carbon nanotubes (SWNTs) size on their cell internalization level via the folate receptor-mediated pathway through folic acid targeting. Folate-SWNTs were covalently synthesized and characterized. Folate-SWNTs ≤ 450 nm had lower cell internalization level than folate-SWNTs >450 nm with a P value of ≤0.01. This indicated that using folate-SWNT with an average length of ≤450 nm was not suitable for receptor-mediated cancer cell targeting. Receptor-mediated uptake of folate-SWNTs is dependent on the nanoparticle length. However, sub-450 nm SWNTs could serve as a vehicle to transfer nucleic acids into the cells due to direct cell penetrance based on their needle-like structure. We find that SWNTs larger than 450 nm were suitable to target the cells through receptors. These results might provide a promising approach for designing more effective targeted delivery systems based on SWNTs.