A role for gold in cancer treatment?
During the course of their treatment, around half of cancer patients receive some type of radiation therapy. This therapy is widely used to target tumours and modern techniques aim to avoid dose to healthy tissue as much as possible. However, toxicity developing within healthy tissue is still a problem and, as a result, scientists are looking for new techniques that can make cancer cells more sensitive to radiation.
In recent years, scientists have been investigating the use of heavy-element contrast agents. These agents significantly increase the dose deposited in their vicinity due to their high energy absorption coefficients. While there are many potential heavy-atom contrast agents that could work as radio-sensitisers, gold nanoparticles (GNPs) are of particular interest due to the combination of gold’s high atomic number and their apparent bio-compatibility.
The sensitising properties of GNPs have been verified experimentally, however there is a discrepancy between experimental results and theoretical predictions. This discrepancy suggests that the sensitising effect does not solely depend on gold’s superior absorption of energetic photons.
Researchers from Northern Ireland, France the UK and Canada have recently published the results of two independent experiments carried out at different synchrotrons, Diamond and the European Synchrotron Radiation Facility (ESRF) in Grenoble, together with supporting experiments using a tuneable broadband Therapax X-ray source.
Fred Currell, from the School of Mathematics and Physics at Queen’s University in Belfast, explains.
“We’ve mapped out the energy dependence of the radio-sensitising effects of GNPs on plasmid DNA suspended in water and the results depart significantly from theoretical predictions in two ways. Firstly, the sensitisation is much larger than would be predicted and, secondly, it does not vary with energy as would be predicted from energy absorption coefficients. While these results still leave us with the mystery of how to accurately predict the effects of GNP-enhanced therapies, the fact that two groups working independently came to the same conclusions means we can trust the data. The next stage for us will be to design further experiments to improve our understanding of the processes involved. Ultimately we believe this work will help in the development of future therapeutics and look forward to gaining a better insight into GNPs and the role they can potentially play in cancer treatment.”
Fred Currell, Queen’s University, Belfast
Fred Currell, Queen’s University, Belfast
Energy Dependence of Gold Nanoparticle Radio-Sensitisation in Plasmid DNA, Stephen J. McMahon, Wendy B. Hyland, Emilie Brun, Karl T. Butterworth, Jonathan A. Coulter, Thierry Douki, David G. Hirst, Suneil Jain, Anthony P. Kavanagh, Zeljka Krpetic, Marcus H. Mendenhall, Mark F. Muir, Kevin M. Prise, Herwig Requardt, Léon Sanche, Giuseppe Schettino, Fred J. Currell, and Cécile Sicard-Roselli Journal of Physical Chemistry. C (2011) DOI: 10.1021/jp206854s