UWinChemBiochem Seminar Series - Winter 2018
Department of Chemistry
Clemson University, Clemson, SC
Title: “Characterization of Nanoparticle Surface Interactions Using Dissolution Dynamic Nuclear Polarization and Saturation-Transfer Difference NMR”
Friday, Jan. 26, 2018 @ 3:00 p.m.
Room #186 Essex Hall
Characterization of Nanoparticle Surface Interactions Using Dissolution Dynamic Nuclear Polarization and Saturation-Transfer Difference NMR
Leah B. Casabianca, Department of Chemistry, Clemson University
Nanotechnology is becoming increasingly prevalent in our everyday lives. Nanoparticles that are used as lubricants, in drug delivery, and as antibacterial agents are finding their way into the body and into the environment, where they interact with biological macromolecules such as proteins. Understanding the nature of the interactions between nanoparticles and adsorbed molecules is therefore increasingly relevant in fields such as drug delivery, nanoparticle catalysis, and nanoparticle toxicity. In this talk, I will discuss several recent studies in my lab that are aimed at developing Nuclear Magnetic Resonance (NMR) techniques for studying noncovalent nanoparticle surface interactions.
NMR is an incredibly powerful characterization technique, capable of providing atomic-level structural as well as dynamic information. However, NMR is not ideally suited for surface studies due to the inherent low sensitivity of this technique. One way of improving the sensitivity of NMR is Dynamic Nuclear Polarization (DNP). DNP relies on the transfer of polarization from a nearby unpaired electron to nuclei of interest in NMR. My group has recently1 developed HighlY-effective Polymer/Radical Beads (HYPR-Beads), which are organic nanoparticles that have been doped with radicals for use as DNP polarization agents. Using HYPR-beads, we were able to hyperpolarize nuclei in small molecules that are located near the beads in an aqueous environment.
We are also using Saturation Transfer Difference (STD)-NMR Spectroscopy to identify small molecules that interact noncovalently with the surface of functionalized organic nanoparticles in solution.2,3 STD-NMR was originally developed to identify small-molecule ligands that bind to a particular protein receptor. Since this technique does not require the receptor to be seen by solution-state NMR, there is no upper limit to the size of the receptor that can be studied. This makes the STD-NMR technique an ideal one to study small molecules adsorbed on the surface of nanoparticles. We have used STD-NMR to determine the binding constant between small molecules and solvent water on the surface of nanoparticles,2 and to determine the binding epitopes of a fluorescent dye associating with the nanoparticle surface.3 This work has future applications in determining the structure of proteins adsorbed on the surface of nanoparticles, and in the development of dual-use imaging contrast agents.
 Y. Zhang, P. J. Baker, L. B. Casabianca, “BDPA-Doped Polystyrene Beads as Polarization Agents for DNP-NMR.” J. Phys. Chem. B 2016, 120, 18-24.
 Y. Zhang, H. Xu, A. M. Parsons, L. B. Casabianca, “Examining Binding to Nanoparticle Surfaces Using Saturation Transfer Difference (STD)-NMR Spectroscopy.” J. Phys. Chem. C 2017, 121, 24678-24686.
 Y. Zhang, H. Xu, L. B. Casabianca, “Interaction Between Cyanine Dye IR-783 and Polystyrene Nanoparticles in Solution.” submitted.
Bio: Dr. Casabianca received a B. S. degree in chemistry from Rice University in 2002 where she did undergraduate research with Prof. Seiichi P.T. Matsuda. She completed her Ph. D. in the lab of Prof. Angel C. de Dios at Georgetown University in 2008. Her thesis work involved using solution-state NMR and chemical shift calculations to understand the mechanism of action of anti-malarial drugs. She then did a postdoctoral fellowship (2008-2010) with Prof. Yoshitaka Ishii at the University of Illinois at Chicago working on structural characterization of graphite oxide. Her second postdoctoral fellowship was in the group of Prof. Lucio Frydman at the Weizmann Institute (2010-2013) where she worked on dynamic nuclear polarization of diamond samples. She joined the faculty at Clemson University in 2014.