This work was financially supported by the Biotechnology and
Biological Sciences Research Council, the Cancer and Polio
Research Fund, the Human Frontiers Science Programme, and
the North West Cancer Research Fund. We would like to
acknowledge the supply of gold nanoparticles from BBInternational,
and we thank A. G. Kanaras, I. E. Sendroju, and S. Romero
for the supply of experimental data which helped to confirm the
equations presented in this paper.