Chen-Sheng Yeh from National Cheng Kung University, Tainan, and colleagues have coated infectious E-coli bacteria in a gold nanoshell, making biocompatible nanocomposites in which, they say, the E-coli bacteria are alive, but non-toxic to mammalian cells. 

Yeh explains that the combination of biological microorganisms with the optical properties of gold nanoparticles 'transforms the microorganisms into a weapon for anti-cancer therapy.' The biocompatible nanocomposites exhibit near infra-red absorption, which means they can be irradiated when in tissue and used for phototherapy, where generated heat is used to kill cells. The scientists have shown that the E-coli bacteria coated in gold can target certain cancer cells. This is done by combining them with the antibodies to anti-epidermal growth factor receptors, which are over-expressed by the cancer cells. 

Yeh plans to do further studies to investigate why the E. coli bacteria lost infectious ability after being coated in gold: 'Even though the bacteria@Au composites in this report showed a good biocompatibility, infectious bacteria still possess pathogenic characteristics intrinsically, and more cytotoxicity studies for designing such nano-bio-composites are required.' 

Rachel Cooper