Highly efficient loading of amorphous paclitaxel in mesoporous hematite nanorods and their in vitro antitumor activity.

Porous hematite nanorods (PHNRs) are potential candidates as drug delivery carriers because of their pores which are available for the encapsulation of drugs and genes, large surface area for loading biomacromolecules, biocompatibility, storage stability and inexpensive large-scale preparation. We report a facile synthesis of PHNRs loaded with a poorly water-soluble drug, paclitaxel (PTX). PHNRs were used as templates for the precipitation of PTX in a dimethyl sulfoxide (DMSO)-water mixture. The precipitation of amorphous PTX in the pores of PHNRs was characterized by nitrogen adsorption-desorption analysis, differential thermal analysis (DTA) and fourier transform infrared spectroscopy (FT-IR). Thermogravimetric analysis (TGA) and ultraviolet-visible (UV-vis) measurements determined that the loading of paclitaxel in PHNRs was high (17.6 wt%) and that the loading efficiency was up to 96%. We further studied the effect of free PTX or PTX-loaded PHNRs on the growth inhibition of HeLa cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and live/dead staining. PTX-loaded PHNRs showed significant cytotoxicity to HeLa cells. However, the ability of PTX-loaded PHNRs to inhibit cell growth was slightly lower or similar to that of free PTX after 48 h incubation. Confocal laser scanning microscopy (CLSM) and flow cytometric analysis suggested that HeLa cell death induced by free PTX or PTX-loaded PHNRs occurred via apoptosis, which was detected by Annexin V antibody and propidium iodide staining.