Gang Zhen - joint CMIC-WEISS seminar series

Dr Gang Zheng, Associate Research Director of the Princess Margaret Cancer Center, University of Toronto

Title: Porphysome Nanotechnology: Explore New Frontiers of Cancer Imaging and Therapy

Abstract:

Porphyrins are aromatic, organic, light-absorbing molecules that occur abundantly in nature, especially in the form of molecular self-assemblies. By conjugating porphyrins to lipids, we formed porphysomes, self-assembled liposome-like nanoparticles with intrinsic multimodal photonic properties. High-density porphyrin packing in the nanoparticle bilayer enables light absorption and conversion to heat with extremely high efficiency, making porphysomes ideal candidates for photothermal therapy and photoacoustic imaging. Upon nanostructure dissociation during cell uptake, the fluorescence and photodynamic activity of the porphyrin monomers is restored. In addition, metal ions can be directly incorporated into the porphyrin building blocks, thus unlocking porphysome’s potential for PET, MRI and radiotherapy. Beyond porphysomes, we developed porphyrin lipoproteins, porphyrin microbubbles, porphyrin nanodroplets, porphyrin-gold nanoparticles, and metal-chelating nanotexaphyrins, thus expanding the purview of porphyrin nanomedicine. By mimicking the light harvesting systems found in photosynthetic bacteria, we created supramolecular assemblies of highly ordered porphyrin aggregates possessing stimuli-responsive photonic properties. Such properties are also responsible for our discovery of the ultrasound-induced microbubbles-to-nanoparticle conversion phenomenon, which opens the door to EPR-independent nanomedicine delivery. We have validated porphysome’s utilities in different tumour types/models and animal species. The effort of moving porphysomes towards first-in-human is well on its way. The simple yet intrinsic multimodal nature of porphysome nanotechnology popularize the one-for-all nanomedicine design and confers high clinical translation potential.

Biosketch:

Dr. Gang Zheng is a Professor of Medical Biophysics and Canada Research Chair in Cancer Nanomedicine at the University of Toronto. He is also the Associate Research Director of the Princess Margaret Cancer Center. Dr. Zheng received his B.Sc. in Chemistry from the Hangzhou University (now Zhejiang University) in 1988 and Ph.D. in Medicinal Chemistry from the SUNY Buffalo in 1999. Following a postdoctoral training in photodynamic therapy at the Roswell Park Cancer Institute, he joined the University of Pennsylvania in 2001 as an Assistant Professor of Radiology and moved to Canada in 2006. His lab is most well-known for the development of activatable photosensitizers for photodynamic therapy and the discovery of porphysome nanotechnology in cancer imaging and therapy. Dr. Zheng is a Fellow of the American Institute of Medical and Biological Engineering and an Associate Editor for the Bioconjugate Chemistry.