Abstract

Developing photoactive nanomaterials with drug-encapsulating properties is a relevant task for dual therapy applications aimed at overcoming the current limitations of conventional cancer treatments. In this work, we report the synthesis and evaluation of mesoporous black titania nanorods as novel visible-light responsive platforms for dual chemo-phototherapy. Nanorods were obtained by hydrothermal synthesis and photo-sensitized by titanium reduction via thermal decomposition of sodium borohydride at 400 degrees C under an argon atmosphere. The materials were characterized by X-ray diffraction, transmission electron microscopy, N-2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and UV-vis diffuse reflectance spectroscopy. ROS generation experiments confirmed that aqueous dispersions of black titania nanorods produce hydroxyl radicals (HO center dot) under visible light LED irradiation (150 W m(-2), 15 min). The materials exhibited moderate phototoxic activity against HeLa cells under visible light LED irradiation (150 W m(-2), 15 min) with cell viabilities similar to 70 % at dispersion concentrations of 300 mu g mL(-1), while no cytotoxic effects were observed in dark incubation conditions. Black titania nanorods efficiently encapsulated doxorubicin and released the drug in quantities suitable to exert chemotoxic effects against HeLa cells in the dark, with cell viabilities of similar to 60 % at 500 mu g mL(-1) dispersion concentrations and 24 h of incubation. Doxorubicin-loaded nanorods were evaluated in dual chemo-phototherapy experiments consisting of 12 h of dark incubation, 15 min of visible light LED irradiation, and 12 h of post-irradiation dark incubation. Our experiments showed a marked potentiation of antiproliferative effects compared with individual chemo or phototoxicity experiments, with cell viabilities similar to 30 % at dispersion concentrations of 400 mu g mL(-1). Our findings highlight the potential of black titania nanorods as intrinsically photoactive materials with drug-encapsulating properties for dual chemo-phototherapy applications.