EVALUATING GOLD NANOPARTICLES FOR ENHANCEMENT OF RADIATION AND PHOTODYNAMIC THERAPY EFFICACY IN 3D TUMOR MODELS

This study uses a 3D cell culture approach to study the impact of gold nanoparticles (GNP) uptake and localization on radiation dose enhancement, as well as on combined photodynamic (PDT)/photothermal treatment (PTT). The use of 3D cell cultures reveals that GNP resides in the extracellular matrix (ECM) for surprisingly long durations after initial delivery and prior to localization in tumor nodules, an effect which, as it will be shown here, has a big impact on the treatment outcomes for nanoparticle-aided therapy.
Here we show that heavy metal such as gold in a form of gold nanorods (GNRs) influences PDT outcome. GNRs were used to excite surface plasmon resonance (SPR) and consequently, to induce heat via PTT, which combined with PDT raises treatment response. It turned out that presence of GNRs does enhance PDT outcome, not via thermal effect, but rather because of gold photochemistry and the appearance of the heavy atom effect¹, which efficiency depends on the amount of GNRs present in the 3D cancer nodule itself.
In combined x-ray/GNP treatment, GNPs act as a source of short-range secondary radiation effects², where disproportionate accumulation of GNP in ECM significantly reduces radiation response in 3D tumor spheroids.

1. Koziar and Cowan 1977; 2. Ngwa, Kumar et al. 2014.