This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.We have shown the uptake of gold using live plants of alfalfa and Chilopsis linearis which results in the formation of gold nanoparticles. In addition, we have also shown the formation of gold nanoparticles on inactivated tissues of alfalfa, oat, wheat, and hops. However, more recently we have been investigating the extraction of gold nanoparticles from both the living and inactivated biological materials. We have seen some success using CTAB a quaternary ammonium ion. The extraction of gold nanoparticles is plagued by questions of nanoparticle stability and XAS provides an excellent method to follow the stability of gold nanoparticles by comparison of the XANES and EXAFS results obtained from the extraction procedures that we will be using. In addition, we have been investigating methods to increase gold uptake by live plants using gold chelating agents. Yet, the effects of these chemicals on the formation of the gold nanoparticles have not been studied in depth. We have seen from preliminary results from XAS studies the chemistry of the gold within the live plants is dependent on the chemical chelating agent used. Gold introduced in the growth media in the presence of thiocyanate resulted in the production of gold nanoparticles within the live plant. But, the use of thiourea resulted in a mixture of compounds indicating the presence of both gold-sulfur containing compounds and gold nanoparticles, this needs to be investigated further to understand the compounds coordinating the gold within the plants. In addition, we are currently testing compounds and digestion protocols for the extraction of gold nanoparticles from the living plant tissues, which XAS will be an invaluable tool for these studies. XAS will provide us with important information on the stability of gold nanoparticles during the extraction process from both live and inactivated biological tissues.
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