AstraZeneca’s (NYSE: AZN) oncology unit in Waltham is reportedly working with a Maryland company, CytImmune, to develop a method of delivering cancer drugs using gold nanoparticles. The Boston Globe reports (subscription) that the tiny pieces of gold, so small that 5,000 can fit in a hair’s breadth, can easily carry other molecules like cancer drugs, and are believed to be safe for use in the human body.