Comparison of Gold Nanospheres, Nanorods, Nanocages and Nanoflowers for Combined Photothermal-Radiotherapy of Cancer

A series of gold nanoparticles with similar sizes but different shapes was synthesized to compare their effects on combined photothermal/radiotherapy. The localized surface plasmon resonance (LSPR) wavelength of these nanoparticles is highly dependent on the geometric structure, and the nanostructure with different geometries tends to select the different endocytosis pathways in different extents. Furthermore, a high interacting surface with the exciting light facilitated the electric field entering inside the nanostructures. Gold nanoparticles are promising dual agents for combined photothermal-radiotherapy of cancer. Nevertheless, the shape effects of gold nanoparticles on photothermal conversion efficiency and radiosensitization have not been completely revealed. To address this knowledge gap, different shapes of gold nanoparticles including gold nanospheres (GNSs), gold nanorods (GNRs), gold nanocages (GNCs) and gold nanoflowers (GNFs) were synthesized. Despite being subjected to the same modification with poly (ethylene glycol) (PEG), these gold nanoparticles showed different cellular uptake efficiencies: GNFs>GNSs>GNCs>GNRs. Moreover, GNRs, GNCs and GNFs could convert near-infrared (NIR) light to heat and GNFs displayed the highest photothermal conversion efficiency, whereas GNSs showed poor photothermal effects due to the weak NIR absorption. The highest uptake efficiency as well as the best photothermal conversion ability led to GNFs to exhibit the best photothermal therapeutic effect. Furthermore, all the gold nanoparticles could be used as radiosensitizers to improve radiotherapeutic effect. Among these nanoparticles, GNFs showed the best radiation enhancement effect because of their highest uptake efficiency. Furthermore, a higher accumulation of GNFs in tumor tissues was observed than those of other shaped gold nanoparticles. Importantly, our in vitro and in vivo comparative studies revealed that GNFs possessed the strongest anticancer effect in combined photothermal-radiotherapy. Hence, compared to gold nanoparticles with other shapes, the GNFs might be more desirable dual agents for highly efficient combined photothermal-radiotherapy.

Automated summary

This study synthesized gold nanoparticles of different shapes to investigate their effects on combined photothermal/radiotherapy. Among the nanoparticles, gold nanoflowers showed the highest cellular uptake efficiency and photothermal conversion ability, leading to the strongest anticancer effect in combined treatment. This suggests that gold nanoflowers may be more desirable dual agents for highly efficient combined photothermal-radiotherapy compared to nanoparticles with other shapes.