Potential of ultrafine gold nanoparticles (AuNPs) as radio-contrast agent for early cancer detection.

e15062 Background: Gold nanoparticles have been employed in cancer imaging and treatment, offering advantages over iodine-based contrast agents, such as higher atomic number, electron density, X-ray absorption, and superior contrast enhancement at low doses, with reduced bone interference. Methods: Citrate-capped AuNPs (5 nm) were synthesized using hydrogen tetrachloroaurate (III) hydrate. In vitro toxicity tests, including cell viability, oxidative stress, and immuno-hemocompatibility assays, were conducted on HepG2 and HEK cell lines. In vivo toxicity studies covering biokinetics, histopathology, hematology, and biochemistry were performed on albino mice. The property of AuNPs as X-ray/CT contrast agents was first investigated in vitro and compared with iopromide contrast agent as a control. Micro-CT imaging of AuNPs in vitro was demonstrated using 2.5% agar gel at concentrations ranging from 0.8 to 20 mg/mL. In vivo X-ray attenuation of AuNPs was evaluated in an Ehrlich ascites tumor (EAT)-bearing Swiss albino mouse model. AuNPs at a concentration of 5 mg/mL were injected intravenously in tumored mice via tail vein and compared with iodine-based X-ray contrast agents in control animals. Results: AuNPs of sized 5±1 nm were fabricated and characterized by UV-visible spectroscopy, DLS, and TEM microscopy. In-vitro and in-vivo toxicity studies ensured the compatibility of AuNPs for systemic administration. No significant toxicity was produced by AuNPs in the biological environment. The reconstructed CT images of injected AuNPs showed X-ray attenuation at 4.0 mg/mL as compared to control iopromide, which showed at 20.0 mg/mL. 5 mg/mL of AuNPs were injected in the tumored mice model, and microCT images were taken after 2 min, 5 min, and 10 min of administration. The images showed marked enhancement of organs and tumor area after 2 min of AuNPs injection as compared to control animals. Conclusions: In-vitro and in-vivo toxicity tests indicated the 5 nm-sized AuNPs were compatible for systemic administration. In-vitro micro-CT imaging demonstrated significant X-ray attenuation at lower doses. At this dose, in vivo micro-CT imaging revealed marked enhancement in tumor regions and other organs. AuNPs show great potential for further research and development as significant radioenhancers for early cancer diagnosis.