Octa-ammonium POSS-conjugated single-walled carbon nanotubes as vehicles for targeted delivery of paclitaxel.

Background: Carbon nanotubes (CNTs) have unique physical and chemical properties. Furthermore, novel properties can be developed by attachment or encapsulation of functional groups. These unique properties facilitate the use of CNTs in drug delivery. We developed a new nanomedicine consisting of a nanocarrier, cell-targeting molecule, and chemotherapeutic drug and assessed its efficacy in vitro.

Methods: The efficacy of a single-walled carbon nanotubes (SWCNTs)-based nanoconjugate system is assessed in the targeted delivery of paclitaxel (PTX) to cancer cells. SWCNTs were oxidized and reacted with octa-ammonium polyhedral oligomeric silsesquioxanes (octa-ammonium POSS) to render them biocompatible and water dispersable. The functionalized SWCNTs were loaded with PTX, a chemotherapeutic agent toxic to cancer cells, and Tn218 antibodies for cancer cell targeting. The nanohybrid composites were characterized with transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and ultraviolet-visible-near-infrared (UV-Vis-NIR). Additionally, their cytotoxic effects on Colon cancer cell (HT-29) and Breast cancer cell (MCF-7) lines were assessed in vitro.

Results: TEM, FTIR, and UV-Vis-NIR studies confirmed side-wall functionalization of SWCNT with COOH-groups, PTX, POSS, and antibodies. Increased cell death was observed with PTX-POSS-SWCNT, PTX-POSS-Ab-SWCNT, and free PTX compared to functionalized-SWCNT (f-SWCNT), POSS-SWCNT, and cell-only controls at 48 and 72 h time intervals in both cell lines. At all time intervals, there was no significant cell death in the POSS-SWCNT samples compared to cell-only controls.

Conclusion: The PTX-based nanocomposites were shown to be as cytotoxic as free PTX. This important finding indicates successful release of PTX from the nanocomposites and further reiterates the potential of SWCNTs to deliver drugs directly to targeted cells and tissues.