Structurally engineered anodic alumina nanotubes as nano-carriers for delivery of anticancer therapeutics. 
Here, we report a study on the biocompatibility, cell uptake and in vitro delivery of tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) by new nano-carriers called anodic alumina nanotubes (AANTs) for potential cancer therapy.  AANTs were electrochemically engineered by a unique pulse anodization process, which enables precise control of the nanotube geometry, and used here as nano-carriers for drug delivery.  In vitro cytotoxicity and cell uptake of AANTs was assessed using MDA-MB231-TXSA human breast cancer cells and mouse RAW 264.7 macrophage cells.  AANTs exhibited excellent biocompatibility in both cell lines over a time course of five days even at a maximum concentration of AANTs of 100 μgmL(-1).  Transmission electron microscopy and fluorescence microscopy confirmed a significant uptake of AANTs by RAW 264.7 cells and breast cancer cells.  AANTs loaded with the pro-apoptotic protein Apo2L/TRAIL showed exceptional loading capacity (104 ± 14.4 μgmg(-1) of AANTs) and demonstrated significant decrease in viability of MDA-MB231-TXSA cancer cells due to apoptosis induction.  These results demonstrate that AANTs are promising nano-carriers for drug delivery applications.