Biological Synthesis of Copper/copper Oxide Nanoparticles

Metal nanoparticles have gained significant interest in the past decade because of their unique physio-chemical properties which has a potential to be used in a wide range of applications. Recent efforts have gained success in synthesising nanoparticles with excellent shape and size control; however they are largely restricted to chemical methods. There is an increasing focus on eco-friendly ‘green’ routes for the production of metal nanoparticles, e.g. using biological entities. Morganella sp., a known silver resistant bacterium, was recently reported by our group to produce anisotropic silver nanoparticles by controlling the bacterial growth kinetics. Interestingly, due to structural similarity between silver and copper ions, bacteria that are silver resistant might also be able to uptake copper ions which can then be reduced to synthesize copper nanoparticles. Although similarities in the resistance machinery for silver and copper have been established, their role in synthesizing copper nanoparticles is not well understood. In an effort to synthesize copper nanoparticles via a green biological route, we herein demonstrate for the first time that exposing silver resistant bacteria Morganella sp. to Cu ions can enable aqueous phase synthesis of Cu nanoparticles. The results obtained were characterized using a wide range of techniques such as TEM, HR-TEM, UV-vis spectroscopy and XPS.