Abstract: Being a negatively charged polymer with four heterocyclic bases, DNA is quite versatile in interacting with metal ions and metal containing nanoparticles. We are interested in understanding the interface between DNA and inorganic surfaces and the effect of metal ions. This talk will include four related examples. 1) In vitro selection of RNA-cleaving DNAzymes in the presence of lanthanide ions has been carried out, yielding highly selective new enzymes that works only with trivalent lanthanides. With phosphorothioate modification, the activity is shifted from lanthanides to thiophilic metal ions. Related biosensor applications for heavy metal detection will be discussed. 2) DNA can be adsorbed by a number of metal oxide nanoparticles via the phosphate backbone. This conjugate was used for detecting hydrogen peroxide and arsenate ions. Related reaction mechanisms have also been explored. 3 and 4) Finally, we present our work on the adsorption of DNA by gold nanoparticles and DNA-templated fluorescent gold nanoclusters. In these cases, DNA bases play a critical role in binding the soft gold species.  

Short bio: Dr. Juewen Liu received his B.Sc. in Chemistry from the University of Science and Technology of China (USTC) in 2000, and his Ph.D. in Chemistry with Professor Yi Lu at the University of Illinois Urbana-Champaign in 2005. After being a Postdoctoral Fellow at the University of New Mexico and Sandia National Labs under the direction of Professor C. Jeffrey Brinker, he joined the Department of Chemistry of the University of Waterloo in 2009, and he is currently an Associate Professor. He is also affiliated with the Waterloo Institute for Nanotechnology (WIN). He received the Early Researcher Award (2011) from the Ontario Ministry of Research and Innovation (MRI) and the Fred Beamish Award (2014) from the Analytical Division of the Canadian Society for Chemistry (CSC). He has published >120 peer-reviewed papers, receiving over 6000 citations. His group is interested in biointerface chemistry involving phospholipids, nucleic acids, and various nanoparticles; bioanalytical chemistry using DNAzymes and aptamers as probes, and targeted drug delivery.