Intracellular trafficking and therapeutic outcome of multiwalledcarbon nanotubes modified with cyclodextrins and polyethylenimine

tFunctionalized carbon nanotubes (CNTs) have been proposed in the last years as vectors for deliveryof biomolecules, proteins and DNA into various cells. In this study, a new multiwalled carbon nan-otube -cyclodextrin platform (MWCNT-CD) modified with branched polyethylenimine (PEI) and dopedwith Rhodamine (Rhod), MWCNT-CD-PEI-Rhod, was designed and investigated as drug delivery system.The drug binding abilities of MWCNT-CD-PEI-Rhod towards Cidofovir (Cid) and DNA plasmid encodingenhanced green fluorescence protein (pCMS-EGFP) were investigated by complementary spectroscopictechniques. MWCNT-CD-PEI-Rhod showed no significative cytotoxicity and an excellent ability to entrapand delivery Cid. The present study broadens the spectrum of biological evaluation by investigatingplatform-treatment induced cellular response such as antiviral activity, transfection properties, cellularuptake, internalization mechanisms and cellular localization. The mechanism of cellular uptake was elu-cidated monitoring the dependence of intracellular red fluorescence from the assembly concentration,time and presence of specific uptake inhibitors. The biological results indicated that MWCNT-CD-PEI-Rhod loaded with Cid and/or pCMS-EGFP crossed the cell membrane via clathrin-dependent pathwayand co-localized in lysosomal compartment. However, no green fluorescent protein expression of pCMS-EGFP was detected, whereas the efficient escape of Cid from lysosome and the release close to nuclearregion prompted the antiviral activity.