UWinChemBiochem Seminar Series - Winter 2018
Leah Casabianca
Department of Chemistry
Clemson University, Clemson, SC
Title: “Characterization of Nanoparticle Surface Interactions Using Dissolution Dynamic Nuclear Polarization and Saturation-Transfer Difference NMR”
Web: https://chemistry.sites.clemson.edu/casabiancagroup/
Friday, Jan. 26, 2018 @ 3:00 p.m.
Room #186 Essex Hall
**Everyone Welcome**
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.
References
[1] 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.
[2] 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.
[3] 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.
