Research Seminar:Dr. Ajay Karakoti" Ligand Mediated Reversal of the Oxidation State Dependent ROS Scavenging Activity of Cerium Oxide Nanoparticles"
Abstract: Cerium oxide nanoparticles (CNPs) are regarded as universal inorganic antioxidant capable of scavenging multiple reactive oxygen species (ROS) such as superoxide, peroxide, nitric oxide etc. This nanozyme like activity of cerium oxide has been employed in realizing multiple
applications such as treatment of tumours and cancers, radiation protection and development of oxygen sensors. The oxidation state of cerium in CNPs play an important role in determining which ROS species can be scavenged. It has been established that partially reduced CNPs with higher Ce3+/Ce4+ ratio can scavenge superoxide and nitric oxide while stoichiometric CNPs with predominant Ce4+ can scavenge peroxide species. Our research shows that the fundamental redox behavior of CNPs can be modified with selected ligands. Modification of stoichiometric CNPs with triethyl
phosphate (TEP) increases its ability to scavenge superoxide species while leaving the properties of partially reduced ceria unaltered. On the other hand tris(trimethoxyphenyl) phosphine (TTMPP) imparts peroxide scavenging ability to partially reduced CNPs and does not alter the peroxide
scavenging activity of stoichiometric ceria. Thus we conclude that the TEP and TTMPP ligands with their differences in sigma donor and pi acceptor properties can tune the ROS scavenging properties of CNPs independent of the oxidation state of cerium.
[This work was presented at the 256th ACS National Meetingand Exposition, Aug 19-23, 2018 Boston, MA, USA] About the Speaker: Ajay Karakoti is an Associate Professor at School of Engineering and Applied Science and at School of Arts and Sciences, Ahmedabad University. His main research interests are synthesis and application of novel materials in addressing problems in biology and engineering.