Cancer-killers on nanotubes
doi:10.1038/nindia.2011.148 Published online 19 October 2011
Researchers have designed a new drug-delivery vehicle by attaching a respiratory protein to titanium-dioxide-based nanotubes. The resulting nanobioconjugates can be used to target and image specific cancer cells.
Titanium-dioxide-based nanotubes have demonstrated significant potential as non-toxic sensors and photocatalysts. The researchers enhanced their biocompatibility by attaching cytochrome c, a respiratory protein, to hollow multiwalled hydrogen titanate nanotubes with inner and outer diameters of 4–5 nm and 9–10 nm, respectively. Cytochrome c exhibits a strong positive charge on its surface, which facilitates binding to the negatively charged surfaces of nanotubes. This protein is also known to trigger the programmed death of cells that activate caspases, a class of enzymes.
The researchers carried out spectroscopic and electrochemical studies of the nanobioconjugates. The results showed that strong electrostatic attraction between the nanotubes and cytochrome c caused a structural change in the protein, thus tailoring its anticancer activity. The binding of titanate to cytochrome c is reversible but strong, which allows the protein to be released at the surface of a cell.
This study will help scientists design a way of transporting cytochrome c to specific cancer cells and thus initiate the death of malignant cells. "Other molecules such as anticancer peptides can be attached to such nanobioconjugates for therapeutic and diagnostic purposes," says lead researcher Shyamalava Mazumdar.
The authors of this work are from: Department of Chemical Sciences and Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai, India.