Photofullerenes and Nanotechnology - PowerPoint PPT Presentation

Title: Photofullerenes and Nanotechnology


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Photofullerenes and Nanotechnology
Elizabeth Han Dr. Kenneth Pritzker Pathology and
Laboratory Medicine Mount Sinai Hospital
Jan. 13th, 2009 U of T Nano Research Talks
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Nanotechnology in Biomedicine Developing tools
that can work at the molecular level for
clinical applications
(A) Metal and Metal Oxide-based Nanotechnology
( Submicron micelle particle )
Au
TiO2
( Nanoparticle )
(B) Carbon-based Nanotechnology
( C60 Cage and Fullerenes )
( Carbon Nanotube )
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Photodynamic Therapy (PDT)

• Light source
• Target tissue
• Photosensitizer (PS)
• Molecular oxygen

Use of visible and near-infrared light with a
photosensitizer to treat disease
Tumour
Excitation of PS generation of reactive oxygen
Credit Castano et al. Nature Reviews Cancer 6,
535545 (July 2006) doi10.1038/nrc1894
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PDT in Cancer Treatment

• Tumour cells take up nanoparticles more readily
• Minimally invasive
• Effects less damage to surrounding healthy cells

PDT for cancer of the esophagus
Credit Mayo Clinic - http//www.mayoclinic.com/he
alth/photodynamic-therapy/MM00719
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Photosensitizers for PDT
Design Criteria

• Chemically pure and of known composition
• Localize to the target tissue
• Absorb strongly at a specific wavelength
• high extinction coefficient
• Efficiently generate reactive oxygen
• high quantum yield

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Fullerenes Kroto, Curl, Smalley (1985)
1996 Nobel Prize in Chemistry
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C60 - Buckminsterfullerene
1996 Nobel Prize in Chemistry
R. Buckminster Fuller
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Photofullerenes

• Geometry gives many unique properties
• non-linear optics (NLO)
• more efficient generation of singlet oxygen

lt
lt
lt
C60
Prozac
Peptide a-Helix
DNA
C60 Cage diameter 1 nm
Functionalized Hydrophobic, Hydrophilic, or
Amphiphilic Derivatives
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Photofullerenes

• Geometry gives many unique properties
• non-linear optics (NLO)
• multi-photon absorption (MPA)
• longer wavelengths
• improved penetration, less dangerous

One-photon absorption
Two-photon absorption
Credit http//www.umich.edu/protein/NSOM/image/f
ig7.gif
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Design of Fullerene PS

• Challenge low solubility in physiological media,
• functionalization

n 1
n 2
C60(gtDPAF-C9)n series of fullerene derivatives
Credit Elim et al., J. Mater. Chem., 2007, 17,
18261838
n 4
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Behaviour of Fullerene PS

• Challenge effects of intermolecular
  interactions, concentration, on molecular
  packing, MPA

Recent study C60(gtDPAF-C9)n series
Decreasing aggregation, increasing 2PA

• Decreased size
• Decreased conc.

• Increased size
• Increased conc.

(Vincent Lau, 2008)
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Control of Fullerene PS
Further work

• Optimize MPA
• Optimize delivery concentration
• Test in physiological media
• Study metabolism and degradation in the body
• possible harmful effects
• Develop delivery molecules/systems

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Control of Fullerene PS

• Challenge study reactive oxygen species
  quenching

Comparison of quenching of beta-carotene and
emerald green
Emerald Green (EF)
Credit Chiang et al., J. AM. CHEM. SOC. 2005,
127, 26-27

• Beta-carotene (BC)
• many conj. double bonds
• known anti-oxidant

Credit R. Edge et aL /Jountal of PhotochemistLv
and Photobiology B Biology 41 (1"97) 189--200
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Control of Fullerene PS
Further Work

• Elucidate properties and mechanisms of quenching
• Design better quenchers or generators of singlet
  oxygen
• Develop tools for decreasing harmful effects of
  radiation
• sunscreen

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Summary Fullerene Nanotechnology

• Stable
• Form complex derivatives with designed
  properties
• Specific excitation behaviour
• Efficiently generate reactive oxygen species
• Many potential applications
• PDT, antimicrobial treatments, biosensors

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Pritzker Lab Pathology and Laboratory
Medicine Mount Sinai Hospital
Acknowledgements Dr. Kenneth Pritzker, PI,
MSH Dr. Long Chiang, UML Vincent Lau Advanced
Imaging Lab staff, MSH
Contact elizabeth.han_at_utoronto.ca