Self-assembled rosette nanotubes for incorporating hydrophobic drugs in physiological environments.

Rosette nanotubes (RNTs) are novel, biomimetic, injectable, self-assembled nanomaterials. In previous studies, materials coated with RNTs have significantly increased cell growth (eg, osteoblasts, chondrocytes, and endothelial cells) due to the favorable cellular environment created by RNTs. It has also been suggested that the tubular RNT structures formed by base stacking and hydrophobic interactions can be used for drug delivery, and this possibility has not been studied to date. Here we investigated methods to load and deliver tamoxifen (TAM, a hydrophobic anticancer drug) using two different types of RNTs: single- base RNTs and twin-base RNTs. Drug-loaded RNTs were characterized by nuclear magnetic resonance spectroscopy, diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY NMR), and ultraviolet-visible (UV-Vis) spectroscopy at different ratios of twin-base RNTs to TAM. The results demonstrated successful incorporation of hydrophobic TAM into RNTs. Importantly, because of the hydrophilicity of the outer surface of the RNTs, TAM-loaded RNTs were dissolved in water, and thus have great potential to deliver hydrophobic drugs in various physiological environments. The results also showed that twin-base RNTs further improved TAM loading. Therefore, this study demonstrated that hydrophobic pharmaceutical agents (such as TAM), once considered hard to deliver, can be easily incorporated into RNTs for anticancer treatment purposes.