Theranostic gold nanoparticle-assisted tumor radiosensitization and imaging

Gold nanoparticles (GNPs) have witnessed a high level of interest in radiation therapy (RT) to targetedly elevate tumor radiation dose while sparing adjacent normal tissues. Enhanced permeability and retention effect and active targeting schemes specifically increase GNP concentration in tumor masses, inducing enhanced radiation therapeutic ratio and tumor diagnosis sensitivity. Physical, chemical, and biological effects of GNPs under RT results in elevated emission of low-energy electrons, reactive oxygen species production, and DNA/mitochondrial damage, in cancer cells. GNP-based in vivo molecular imaging can be realized via various modalities such as X-ray computed tomography, magnetic resonance imaging, nuclear medicine imaging (e.g., positron emission tomography), optical molecular imaging, photoacoustic imaging, and X-ray fluorescence computed tomography. High photoelectric interaction probability of gold under X-ray excitation creates characteristic radiation, which can be used to dynamically quantify GNP biodistribution in vivo, providing valuable information for predicting treatment outcomes.