Engineered Therapeutic Nanoparticles as Catalytic Antioxidants

1
Engineered Therapeutic Nanoparticles as
Catalytic Antioxidants (NSF-NIRT, CBET 0708172)
Artem Masunov1A, William Self1B, James McGinnis2
and Sudipta Seal1C
Ajay Karakoti1C
Nanoscience and Technology CentreA, Centre for
Biomedical and Biomolecular SciencesB, Advanced
Materials Processing and Analysis CenterC,
University of Oklahoma Health Sciences Centre,
Dean A. McGee Eye Institute, Oklahoma City,
Oklahoma2, University of Central Florida,
Orlando, Florida1
Theoretical Modeling (Density Functional Theory)
Understanding Origin of Reactivity and Role of
Surfaces
Nanomedicine Trials Cytotoxicity, Viability
and Enzyme Expression
Rare Earth Nano oxides as Nanomedicine

• 13-14 million cases of loss of vision due to
  retinal diseases
• Rare earth oxide nanomaterials can prevent
  retinal degeneration
• Nano cerium oxide with its multiple valence
  oxidation states can treat diseases caused by the
  reactive oxygen intermediates (ROI)

• Calculations are performed with Gaussian 2003
  code (CRENBL basis/ECP, BMK exchange-correlation
  DFT)
• The 7 atoms of ceria (yellow) found on 111
  surface, surrounded by 14 oxygen atoms (red).
• The rest of the 2000 nanoparticle atoms are
  represented by point charges
• Nearest Ce neighbors are represented by
  pseudopotentials
• All surface atoms and point charges are kept
  frozen

Human Corneal Epithelial Cell Viability Analysis
Without CeO2
With CeO2
Photoreceptor cells
Rods and cones cells
Bipolar cell layer
Synaptic connections
Objectives of Current Research
Nuclei of ganglion cells

1. Engineering of surface active nano cerium oxide
   in various media
2. Accurate theoretical description of cerium mixed
   valence states (3 and 4) and vacancy
   interaction with ROI
3. Evaluation and confirmation of theoretical
   prediction with redox chemistry using
   spectrophotometric assays
4. In vivo studies to validate the therapeutic
   effects of nanoceria based on rat photoreceptor
   cells
5. Utilize nanotechnology as a tool for better
   advancement of science, technology, healthcare
   and education
6. Education and outreach of nanotechnology

HO2 H-CeO2 ? H2O2 CeO2
Human Corneal Epithelial Cell Cytotoxicity
Analysis
Surface with single oxygen vacancy do not react
with nanoceria
Superoxide radical abstracts hydrogen atom from
protonated ceria (no vacancy) surface
Controlled Engineering Synthesis, Handling and
Storage of Nanomaterials
VEGF expression in VLDLr-/- mice (Retina) with or
without intravitreous CeO2 injection (1ul,
1mmol)
Biocompatibility of Nanoceria Targeting Drug
Delivery
VEGF expression is inhibited No toxicity reported
H2O2 CeO2(2 vacancies) ? H2-CeO2(no vacancies)
Hydrogen peroxide reacts with a double vacancy on
the surface the H2O2 splits into 2 OH fragments,
each fills in one of the vacancies on the surface.
Role of Vacancy and Redox State Experimental
Verification using SOD and Catalase Mimetic
Activity
Education Outreach and Dissemination Training
and Learning
Nanoceria Demonstrates Catalase Mimetic Properties
Personal Training Post Doc - Dr. Talgat
Inerbaev (UCF), Dr. S. Babu (UCF), Dr. X. Yu
(OU), Dr. X. Zhou (OU), L. Wong (Instructor), S.
Sezate (Technician) Graduate Students Ms.
Shruba Gangopadhayay (F), A. Karakoti (M), A.
Kumar (M), A. Vincent (M), E.. Heckert
(M)Undergraduates Mr. Andrew Teblum (UG),
Jessica King (F), Jarrod Spring (NARCH Program),
REUs B. Wasserman, D. Patel, and Brandon Hey
(BRIN Program), High School Mr. Ivan Schoop
(HS)Course Development Introduction of
nanomedicine lecture in EGN 3365 Intro to Mat
Eng.Publications6 peer reviewed journals, REU
student 1) Chen J, Patil S, Seal S, McGinnis JF.
Nanoceria particles prevent ROI-induced
blindness. Adv Exp Med Biol, 613, 53-59, 2008. 2)
D. Sayle, S. Seal, Z. Wang, B. Mangil, D. Price,
A. Karakoti, S. Kuchibatla, Q. Hao, G. Moebus, X.
Xu, and T. X. T. Sayle, Mapping Nanostructure A
Systematic Enumeration of Nanomaterials by
Assembling Nanobuilding Blocks at
Crystallographic Positions, ACS NANO, 2(6),
1237-51, 2008. 3) A. Karakoti, S. Kuchibatla, D.
Baer, S. Thevuthasan, D. C. Sayle and S. Seal,
Self assembled nanostructures using ice molds,
SMALL, 4(8), 1210-16, 2008. 4) S. Babu, A.
Shulte, and S. Seal, Defects and symmetry
influence on visible emission of Eu-doped
nanoceria, Applied Physics Letters, 92, 123112-4,
2008. Also appear in Virtual Journal of
Nanoscience and Nanotechnology, Vol 17, 15,
April 2008. 5) E. Heckert, J. Spence, A.
Karakoti, S. Seal and W. Self, The role of
cerium redox state in the catalytic reaction of
superoxide with nanoceria, Biomaterials, 29,
2705-2709, 2008. 6) Invited A. Karakoti, S. Seal
et al Overview-Nanoceria as antioxidants
Synthesis and Biomedical Applications, JOM
33-37, 2008. Invited talks 5, and Conference
presentations 10Patents accepted 1 (7,347,987 )
and 2 pendingCollaboration with EMSL- PNNLHigh
School Outreach Using Boing Boing Bionic Cat
model in collaboration with Prof L. Hench to
introduce nanotechnology and medicine to school
kidsMajor awards Dr. S. Seal Fellow of
American Soc Materials, Royal Academy of Eng
Dist. Prof Fellow Imperial College of
ScienceTech and Medicine, UK, PhD Student A.
Karakoti Top Level AVS Graduate Student Award
(Dorothy Hoffman Scholarship)Research Highlight
in Nature Nanotech 2008.
Microemulsion in Toluene
Wet chemical - Dextran
Wet chemical - PEG

• Nanoceria catalytically reacts with hydrogen
  peroxide
• Rate depends on concentration of nanoceria and
  H2O2

• Highly dispersed nanoparticles synthesized in
  biocompatible mediums such as poly(ethylene)
  glycol and dextran
• Tools for target specific delivery of
  nanomedicine and crossing cell membranes

Long Term Stability and Storage of Nanoparticles
Rate of removal of hydrogen peroxide Higher
3/4 ratio

• Nanoceria can be stored at room temperature and
  ambient lab conditions
• Samples stable and potent for more than 3 years
  and still active
• Storage at freezing temperature lead to
  self-assembled nanorods

10 ?M ceria 50 ?M ceria 100 ?M ceria
0.5 mM H2O2 0.35 1.09 1.61
1 mM H2O2 0.32 1.16 2.05
5 mM H2O2 0.85 1.94 2.57
10 mM H2O2 0.93 2.27 2.71
Green manufacturing of nanorods
1 day
21 days

• Catalase mimetic activity shows strong
  dependence on 3/4 concentration
• Two preparations of nanoceria tested/compared
• Sample A Higher 3/4 ratio, Sample B Higher
  4/3 ratio
• Sample B shows higher catalase activity as
  opposed to SOD mimetic activity (described
  recently in two published papers)
• Amplex Red assay was used to verify the
  spectrophotometric assay
• Catalase activity is dependent on Ce4
  concentration
• Ceria surface can be tuned for varying
  activities, role of each in vivo still not fully
  understood

time (sec)
Theoretical analysis by MD simulation shows good
agreement

• Long term storage in ice lead to self assembled
  polycrystalline nanorods
• Natural phenomenon solute rejection and capillary
  action
• Controlling parameters such as freezing rate and
  aging could be the next big leap to simple and
  green manufacturing of nanostructures