Presentation on theme: "PEGylated Gold Nanoparticles Conjugated to Monoclonal F19 Antibodies as Targeted Labeling Agents for Human Pancreatic Carcinoma Tissue February 26, 2009."— Presentation transcript:
PEGylated Gold Nanoparticles Conjugated to Monoclonal F19 Antibodies as Targeted Labeling Agents for Human Pancreatic Carcinoma Tissue February 26, 2009 Gary Craig Department of Chemical and Biological Engineering University of Maine
Sections of Talk 1. Pancreatic Cancer 2. Noble Metal Nanoparticles 3. Functionalization and Bio- Linking 4. Tissue Studies 5. Conclusions 6. Future Directions
Application to Pancreatic Cancer Detection Early diagnosis – whole animal imaging (x-ray tomography) Help the surgeon identify cancer margins during surgery. Pancreatic Cancer produces low density tumor masses: Not visible early by screening methods (CT scanning) During surgical removal, the tumor margins are difficult to find.
Histology of Pancreatic Adenocarcinoma (Standard Diagnostic Method) Healthy Pancreatic Tissue Standard Histology StainLabeled for Cancer Stroma
Histology of Pancreatic Adenocarcinoma Pancreatic Cancer Tissue Standard Histology StainCancer Stroma Labeled
Interconnected Themes of Interest in our Lab Observation of (Bio)- Chemical processes at the single-molecule level in heterogeneous systems Nanoprobe Photophysics – Understanding Chemical and Physical characteristics Developing nanoprobes for imaging at the single molecule level (Engineering and synthesis) Development of imaging tools for single molecule detection Sample Driven Design Constraints: Question (material or animal system) Geometry Chemical/Physical Environment Time scale Measurement (1) (2) (3) (Tissue)
Design Requirements 1. Small, shape and size tunable 2. Non-toxic 3. Biocompatible (stable, non-aggregating). 4. Long-circulating in blood – not rapidly removed by the body 5. Target Specific (sticks only to cancer) 6. Significant improvement in image contrast 7. Cost effective (health care $$$) We are Engineers
Metal salts are brought to boil in aqueous solution (HAuCl 4.H 2 O for gold) A reducing agent is added (sodium citrate) and reaction proceeds for 2 minutes Excess reducing agent electro-statically stabilizes against aggregation 100 o C Stirring Size depends on the molar ratio of metal ion and reducing agent time Au 0 Metallic Nanoparticles – Batch Synthesis Rod shaped particles formed via surfactant templating (CTAB, TOAB) Au 3+ Ostwald Ripening Reducing Stable Colloid
Metallic Nanoparticles Size and geometry tunable (2.5 – 65 nm) Very expensive to buy (spheres), relatively cheap and easy to make Gold (spheres) Gold (Rods) Photo-physics??
Particle Stability Ideally particles should not agglomerate Typical gold synthesis produces a stable colloid, but not stable enough to be used in vivo Changes in temperature, pH, concentration will cause agglomeration
Elastic Scattering (Rayleigh) – energy of the photon is unchanged A light induced oscillation of conduction electrons gives rise to a peak in the absorption curve (Plasmon Resonance). Small particles scatter shorter wavelengths, Larger particles scatter longer wavelengths Part I. Simple Light Scattering
Metal Nanoparticle Light Scattering small large mixed 50 mm Mixed Sample Spectra Darkfield Scattering Image 100ms integration Full Color Scattering Spectra
Surface Modification Covalently bonding a polymer to the surface of the particle sterically prevents agglomeration Thiol linked polyethylene glycol (PEG) is convenient for gold particles Provides point of attachment of targeting molecule Polyethylene Glycol Dithiol (Wolfgang Eck)
Antibodies Proteins produced by the immune system Used to target foreign material such as bacteria or viruses Convenient targeting mechanism
Monoclonal Antibody F19 Developed at the Ludwig Institute for Cancer Research Specific to FAP α (expressed in stroma) Coupled to PEG via NHS/EDC chemistry Purified by Size Exclusion Chromatography
Y The PEG coating enhances particle biocompatibility and eliminates agglomeration (Electro-static and Steric). Antibodies can be attached via the terminal carboxy groups using standard NHS/EDC coupling chemistry. F-19 antibody coupled via the carboxy moiety (Ludwig Institute) – Binds to glycoproteins on stromal cell surface Design Approach mAb F19 functionalized gold nanoparticles for visualization of pancreatic cancer stromal cells Y Y Y Y Y Y Y Y
PEG Dithiol Synthesis Synthesizing our own allows us to control length and functionality
Gold Nanoparticles Narrow size distribution Broad size distribution (40 mm images)
The antibody-functionalized gold nanoparticles can be fractionated according to size and antibody content by size exclusion chromatography (SEC). They can be prepared free from any non-bound antibody and are fully stable over a period of at least several weeks. SEC Column Fractions
Fraction 3 Fraction 8 Fraction 13 TEM images of SEC fractions.
NIH 3T3 Cells Labeled with WGA conjugated Gold Nanoparticles
Cancer 40x + Au-PEG - ControlCancer 40x + Au-IgG Control 35 mm A B
Comparison of stained vs Au-mABF19 lableled 35 mm Histological Staining Labeling with F19 Conjugate A.B.
Cell / Ex Vivo labeling - Preliminary < 5 mm pancreatic tissue sections Optimization of nanoparticle geometry for optical contrast Reproducibility Lots of tissue studies Nanotoxicity (John Wise – USM) Immunohistochemically Stained F-19 Nanoparticle Labeled Negative control
Immunoelectron Microscopy Gold Scatters Electrons! Labeling with Conjugates Fixation and Embedding Viewed by TEM Labeling or Tissue Expression?
Conclusions: Gold nanoconjugates have great potential in cancer diagnosis and treatment due to their optical contrast Pegylated gold is extremely stable MAB-F19 based conjugates show promise but more characterization is necessary.
Future Directions Hard to get F19 Problems with animal model – Different antibody? Other contrast mechanisms -CT Contrast
References W J Rettig, P Garin-Chesa, H R Beresford, H F Oettgen, M R Melamed, and L J Old. Cell-surface glycoproteins of human sarcomas: differential expression in normal and malignant tissues and cultured cells. Proc Natl Acad Sci U S A. 1988 May; 85(9): 3110–3114. W. Eck, G. Craig, A. Sigdel, G. Ritter, L. Old, L. Tang, M. Brennan, P. Allen and M. Mason, PEGylated Gold Nanoparticles Conjugated to Monoclonal F19 Antibodies as Targeted Labeling Agents for Human Pancreatic Carcinoma Tissue. ACS Nano, 2(11):2263-72, November 2008. G.D. Kymionus, M.M. Konstadoulakis, E. Leandros, A. Manouras, A. Apostolou, D. Alexiou, S. Katsaragakis and G. ANDROULAKIS. J.R. Effect of Curative versus palliative surgical treatment for stage III pancreatic cancer patients. Coll.Surg.Edinb., 44, August 1999, 231-5.
The Mason Group Collaborators William DeSisto Sam Hess David Neivandt Peter Allen Wolfgang Eck Gary Craig Matt King Ray Kennard Ed Allgeyer David Paul Sara Sterling Ben Freedman Sushil Kadka Aruna Sigdel Mike Browne Adam Pongan Eric Young Jennifer Brown Eben Estell Maria Collins Thank You! Support: NSF, Memorial Sloan Kettering Cancer Center
Excessive intake of Silver colloids (Argyria) Questions?