Formation and Growth of Au Nanoparticles inside Live Alfalfa Plants

In modern nanotechnology one of the most exciting areas is the interaction between inorganic quantum dots and biological structures. For instance gold clusters surrounded by a shell of organic ligands covalently attach to proteins or other biological substances and can be used for labeling in structural biology. In the present report we show the possibility of using live plants for the fabrication of nanoparticles. Alfalfa plants were grown in an AuCl4 rich environment. The absorption of Au metal by the plants was confirmed by X-ray absorption studies (XAS), and transmission electron microscopy (TEM). Atomic resolution analysis confirmed the nucleation and growth of Au nanoparticles inside the plant and that the Au nanoparticles are in a crystalline state. Images also showed defects such as twins in the crystal structure, and in some cases icosahedral nanoparticles were found. X-ray EDS studies corroborated that the nanoparticles are pure gold. This is the first report on the formation of gold nanoparticles by living plants and opens up new and exciting ways to fabricate nanoparticles. It shows how it is possible to link materials science and biotechnology in the new emerging field of nanobiotechnology.