Gold nanoparticles measured in tumour tissue

The amount of gold nanoparticles that reach tumour tissue following injection in readiness for photothermal ablation treatment can be measured by EDXRF, taking just 12 hours compared with several days by other methods.

For inoperable tumours, an experimental course of treatment that is currently being trialled in animals and humans involves the use of gold nanoparticles attached to tumour-specific antibodies. After they bind to the tumour, they are irradiated with near-IR light, which penetrates deep into the tissue to heat the particles which then destroy the tumour. One of the key problems is gauging how much gold reaches the tumour.

Scientists at Louisiana Tech University in the US are testing the ability of energy dispersive X-ray fluorescence (EDXRF) to achieve this, as they explained in Analytical Methods. In tests on mice, they found that biopsies can be analysed within 12 hours with a detection limit of 1.4 ppm. This might seem to be a long time but the current methods in use, inductively coupled plasma mass spectrometry and instrumental neutron activation analysis, can take up to several days to carry out.

The research group use EDXRF routinely in their lab for animal research but more work is required before it can be extended to humans. When validated it will help to improve the treatment of patients with inoperable tumours, providing more rapid feedback on the uptake of the gold nanoparticles and the chances of success.