Gold nanoparticles (GNPs) have been investigated as sensitizers for radiation cancer therapy. GNPs can enter normal cells, causing cytotoxic side effects. They can be linked to an antibody that binds to a specific cancer surface protein for target delivery into cancer cells. Cell penetration peptide (CPP) can actively cross through cell membrane. Our hypothesis is that CPP paired with antibody allows efficient delivery of GNPs to cancer cells to enhance radiotherapy.