Please join the Institute for Polymer Research (IPR) on Tuesday, February 5, 2019 for a guest lecture by Professor Mitchell Winnik, University Professor of Chemistry at University of Toronto, speaking on Biomedical Applications of Metal-chelating Polymers and Lanthanide Nanoparticles.
One of the goals of modern bioanalytical chemistry is the simultaneous (multiplexed) detection of multiple biomarkers in individual cells. A biomarker can be broadly defined as a characteristic protein, gene or small molecule that can be objectively measured and evaluated as an indicator of normal biological or pathogenic processes. The classical approach to high throughput biomarker detection employs flow cytometry, in which antibodies (Abs) are labelled with fluorescent dyes. Here spectral overlap limits the number of dyes that can be detected simultaneously and restricts the number of biomarkers per cell that can be detected.
Mass cytometry (MC) is a much newer technique in which various Abs are labelled with different heavy metal isotopes. Cells are injected into the plasma torch of an inductively coupled plasma mass spectrometer with time of flight detection. Here signal intensity increases linearly with the number of copies of an isotope carried by each Ab.
Professor Winnik's research group's contribution to this technique is the synthesis of metal-chelating polymers (MCPs) with 20 to 50 chelators for carrying a metal ion and functionality at one end for covalent attachment to the Ab. In this way, each Ab can carry up to 200 copies of an isotope and, with these reagents, detection and quantification at high throughput of 40 to 45 biomarkers per cell is now routine.
There is a need to increase the sensitivity of MC by one to two orders of magnitude to detect as few as 100 molecules per cell. To address this problem, heavy metal nanoparticles, such as 12 nm NaHoF4 NPs, that contain on the order of 15000 Ho atoms are synthesized. The two main challenges are passivating the NP surface to prevent non-specific interactions with cells and introducing functionality for attachment of Abs.
Professor Winnik's research group is also part of a team led by R. M. Reilly in the University of Toronto's Faculty of Pharmacy to develop MCPs as radioimmunotherapeutic agents for imaging tumors and treating pancreatic cancer. MCPs are attached to therapeutic antibodies or antibody fragments. The conjugates are labelled with 111In for µSPECT imaging or 64Cu for PET imaging. Electrons emitted by the radiometals enhance the cytotoxicity of the antibodies. 111In undergoes Auger decay, emitting electrons that are highly destructive to cells but travel only short distances (up to 1 µm). For effective use in therapy, polymer conjugates that target tumor cells and are transported to the cell nucleus to ensure localized destruction of nuclear DNA must be developed. For studies in animal models and for eventual clinical applications, the polymers must be designed to maximize blood circulation time and minimize uptake in the body by healthy tissues like the liver and spleen.
In his talk, Professor Winnik will summarize his group's progress in meeting these challenging goals.
Mitch Winnik is Professor of Chemistry at the University of Toronto, specializing in fundamental and applied aspects of polymer science. His research group provided new scientific knowledge that helped the coatings industry develop the environmentally friendly paints that are now sold commercially.
In parallel, Professor Winnik collaborated with Ian Manners to pioneer the study of crystallization-driven self-assembly of block copolymer micelles in solution. In 2005, he joined a team of scientists who were developing mass cytometry for rapid multiparameter cell-by-cell analysis of biomarker expression. He and his students created polymer reagents for this technique.
More recently, he has become involved in a collaboration to develop metal-chelating polymers into targeted reagents for radioimmunotherapy treatment of breast cancer and pancreatic cancer.
He is an ISI “Most cited author” in chemistry, with 730+ publications and 20,000+ citations. His contributions have been recognized by an Alexander von Humboldt Senior Scientist Award (Germany); the 2013 national award in Applied Polymer Science of the American Chemical Society; the 2004 CIC Medal and the 2011 LeSueur Memorial Award, Society of the Chemical Industry, Canada. He is a Fellow of the Royal Society of Canada, and in 1998 he was named University Professor, the University of Toronto’s highest recognition for scholarly achievement.
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