Preferential magnetic targeting of carbon nanotubes to cancer sites: noninvasive tracking using MRI in a murine breast cancer model

Aim: This study evaluated the improvement in magnetic targeting of single-walled carbon nanotubes (SWCNTs) in a 4T1-induced breast cancer murine model and compared their enhanced delivery with active targeted SWCNTs conjugated with a specific antibody for prospective applications as drug-delivery nanocarriers. Materials & methods: Polyvinylpyrrolidone SWCNTs, loaded with iron oxide nanoparticles to improve their magnetic resonance detection and magnet attraction using an optimized flexible magnet positioned over the tumor site were developed. They were equally conjugated with Endoglin/CD105 antibody for SWCNTs active targeting. A noninvasive MRI protocol was then optimized to allow in vivo imaging of tumor site, sensitive detection of SWCNTs and apparent diffusion coefficient measurements. Special focus was devoted to evaluate the biocompatibility of the used SWCNTs. Results: Iron-tagged SWCNTs exhibited very high magnetic resonance r2* relaxivities allowing their sensitive detection using noninvasive MRI and enhanced targeting using the magnet. Biocompatibility evaluations confirmed their safety for animal administration. Both T2* and apparent diffusion coefficient measurements confirmed their enhanced magnetic targeting starting from 2 h postinjection while a lower, but statistically significant enhanced targeting of antibody-conjugated active targeting was observed starting from 24 h postinjection of iron-tagged SWCNT + CD105 samples. Conclusion: These results demonstrate the efficiency of magnetic targeting to specifically deliver higher load of iron-tagged SWCNTs as novel nanocarriers for cancer theranostics and allow their sensitive detection using noninvasive MRI.