Another notable finding in the new study is that the mice survived for longer when the immunostimulant cyclophosphamide was administered at a low dose two days before the near-infrared irradiation. This was possible even though the mouse breast tumour studied is poorly immunogenic.

The researchers targeted the nanotubes to the tumour vessels by conjugating them to the protein annexin V, which is known to bind strongly to anionic phospholipids. Annexin V binds to phospholipids expressed externally on the tumour vasculature and on tumour cells, but not to normal vasculature. The nanotube-annexin V conjugate is designed to bind rapidly to the tumour vasculature once it is injected into the bloodstream.

The annexin V used was produced by recombinant DNA technology and purified. The nanotube-annexin V conjugate was shown to absorb the same amount of light as non-conjugated nanotubes. The team used vascular cells grown in the lab to mimic the tumour vasculature, and found that a significant number of these cells died when bound with nanotube-annexin V conjugate and treated with near-infrared irradiation at a wavelength of 980 nm. The SWNTs used were produced by the CoMoCAT® process.

The researchers believe that this treatment combined with other immunostimulants, such as cytotoxic T lymphocyte antigen-4, might allow the mice to survive for even longer periods of time and perhaps cure some cancers, either alone or in combination with cyclophosphamide. They also reckon that this therapy would be useful for treating surface cancers like melanoma and bladder cancer.

More information can be found in the journal Nanotechnology 24 375104.

Further reading

Photothermal effect of gold nanorod cluster disinfects biofilm (Jul 2013)
Formulating dual-function nanoparticles for photodynamic and photothermal cancer therapy (Jan 2012)
Cooking cancer cells from the inside out (Mar 2011)
Golden nanotubes show super contrast (Sep 2009)