Comparative effect of gold nanorods and nanocages for prostate tumor hyperthermia

Gold nanoparticles have been investigated as photothermal agents, drug delivery carriers, diagnostics, and theranostics. As long-term accumulation of nanoparticles in nontarget tissues is a growing concern, it is vital to establish biodistribution profiles, tumor uptake, and tissue residence times for each nano-based system. This study aimed to investigate the prostate tumor uptake, photothermal therapy mediated macromolecular delivery, acute and chronic biodistribution profiles, and organ residence time differences between two nanoparticles, i.e., gold nanocages and gold nanorods. These particles have tunable surface plasmon resonances in the near infrared, but dissimilar shapes. Gold nanocages and nanorods had very different light to heat transduction efficiencies, with gold nanocages requiring 18.4 times fewer particles and approximately half the gold mass of gold nanorods to achieve the same heating profile given a constant laser intensity. It was also observed that while the photothermal macromolecular delivery enhancements were similar for the two systems when dosed by optical density, the tumoral uptake and biodistribution profiles for each of these shapes differed, with the nanocages residing in the liver, kidneys and spleen for less time than the nanorods. Additionally, it was observed that the nanocages were excreted from the body at a higher percentage of injected dose than the nanorods at both the 7 and 28 day time points. These findings have implications for the use of these constructs in diagnostic and therapeutic applications.