Effects of gold core size on regulating the performance of doxorubicin-conjugated gold nanoparticles

Studies on the influence of one critical parameter (e.g., size), targeting a specific disease, while keeping other factors unchanged, are important for improving understanding and application of the molecular design of biomedical nanomaterials. In this study, we used doxorubicin (Dox)-conjugated gold nanoparticles (GNPs) to investigate the effects of the size of the gold core (10, 20, or 60 nm) on the performance of their conjugates. We found that all three conjugates differed slightly in their physicochemical properties, facilitating a direct and accurate assessment of the size effects of GNP-Dox conjugates on their in vitro and in vivo performance. The cytological properties (the cell penetration rate and efficiency, as well as the cytotoxicity) and antitumor performance (the intratumoral penetration, treatment efficacy, and biodistribution) were highly correlated to the size of the inorganic core. Among all test groups, although the conjugate with a 60-nm gold core had the highest drug loading and release efficiency, the conjugate with a 10-nm gold core displayed the best antitumor efficacy toward the liver cancer models. This was because it showed the deepest tumor permeability and the highest tumor cell-killing ability of Dox transported by the relatively small GNPs. This study provides important evidence for better understanding the effect of size on in vitro and in vivo properties of potential therapeutic nanosystems and their structure design.