Silver–Gold Core–Shell Nanoparticles: A Novel Contrast Agent for Tumor Computed Tomography Imaging

Abstract

The research aimed to synthesize the polyethylene glycolylated silver–gold core–shell nanoparticles (Ag@Au NPs), and to evaluate their in vitro and in vivo computed tomography (CT) contrast properties. A range of Ag@Au NPs with varying molar ratios of Ag–Au were prepared and characterized by transmission electron microscopy (TEM), Ultraviolet-Visible (UV-Vis) spectroscopy, dynamic light scattering and inductively coupled plasma mass spectrometry. Micro CT was used to evaluate the X-ray attenuation capabilities of Ag@Au NPs with different compositions. The CT imaging effects of Ag@Au NPs with high X-ray attenuation were detected in U87 glioma cells and a mouse subcutaneous glioma model. The characterization results showed that Ag@Au NPs synthesized with different molar percentages of Ag (75%, 50% and 25%) were spherical, and their mean diameters were between 12–16 nm. Ag@Au NPs with an Ag molar percentage of 50% were selected for subsequent research, because of their excellent X-ray attenuation capability, morphology and dispersibility. The attenuation coefficient of glioma cells treated with Ag@Au NPs increased in a concentration-dependent manner. The contrast of the tumor area of the mice was significantly enhanced in CT images after intratumoral injection of Ag@Au NPs. Our results suggested that Ag@Au NPs could be an excellent CT contrast agent, which provided a new thought for the development of highly efficient contrast agents for tumor CT imaging.