Gold nanoparticle-induced sonosensitization enhances the antitumor activity of ultrasound in colon tumor-bearing mice

Introduction: Light-driven cancer therapy strategies (e.g. photodynamic therapy and photothermal therapy) have undergone remarkable progress in recent years, but they still suffer from a serious drawback of limited penetration depth of light in tissue. As a non-invasive and non- ionizing radiation, ultrasound can be focused remotely, transferring acoustic energy deep in the body, thereby addressing the penetration depth barrier of light. In cancer therapy, the effectiveness of ultrasound can be enhanced by utilizing nanomaterials that exhibit sonosensitizing properties called as nanosonosensitizers. The gold nanoparticle (AuNP) has been recently presented as a potent nanosonosensitizer with the potential to simultaneously enhance both the thermal and mechanical interactions of ultrasound with the tissue of the human body. Accordingly, this paper attempts to evaluate the in vivo antitumor efficiency of ultrasound in combination with AuNP. Materials and Methods: BALB/c mice bearing CT26 colorectal tumor model were intraperitoneally injected with AuNPs and then subjected to ultrasound irradiation (1 MHz; 2 W/cm2; 10 min) for three sessions. Results: The tumors were thoroughly eradicated and the mice appeared healthy over 21 days of study span without the evidence of relapse. Furthermore, [18F] FDG (2-deoxy-2-[18F] fluoro-D- glucose)-positron emission tomography (PET) imaging was performed and the radiomic features from different feature categorizes were extracted to quantify the tumors' phenotype. The animals treated with AuNP+ultrasound exhibited an obvious decline in tumor metabolic parameters such as standard uptake value (SUV), total lesion glycolysis (TLG), and metabolic tumor volume (MTV) compared to other treatment groups. Conclusion: These findings strictly propose AuNP as a potent sonosensitizing agent with the potential to use the thermal and mechanical effects of ultrasound so as to cause damage to the focused tumor site, resulting in a strong antitumor efficacy.