Upcoming Talks and Events

Talks (Internal)

Feb
11
Tue
Chris Contag-Biomedical Engineering Invited Seminar @ Medical Sciences Building Room MS3154
Feb 11 @ 12:00 pm – 1:00 pm
Abstract: TBA
Feb
13
Thu
Defining Delivery Pathways of Nanoparticles | Wilson Poon, University of Toronto |PhD Defense @ Medical Sciences Building Room MSB3153
Feb 13 @ 1:00 pm – 4:00 pm

Speaker: Wilson Poon

Institution: University of Toronto

Abstract: 

The goal of nanomedicine is to use nanoparticles to carry drugs to specific target site in the body. For
cancer nanomedicine, a recent meta-analysis showed that only 0.7% of the injected nanoparticles reach
the tumour. To address this delivery inefficiency, it is important to examine each biological barrier to
determine its impact on delivery. In this thesis, first the body was modelled as a series of barriers that
nanoparticles need to overcome successively in order to access the target site. The model shows that
the number and strength of barriers limits what is available to be delivered. The macrophages of the
liver can sequester up to 99% of the injected nanoparticles, and thus are the biggest barrier for targeted
delivery. Next, clodronate-liposomes were used to remove the liver macrophages and showed that both
nanoparticle tumour delivery and hepatobiliary elimination can be improved. Specifically, nanoparticle
tumour delivery can be increased up to 50× and hepatobiliary elimination up to 10×. Removal of the
liver macrophages then allowed the exploration of other secondary barriers to delivery such as tumour
pathophysiology and the liver sinusoidal endothelium. Together, these studies define concepts and
strategies that can improve nanoparticle delivery and reduce unwanted bioaccumulation to pave the
way for their clinical translation and regulatory approval.

Mar
10
Tue
Lance Davidson- Biomedical Engineering Invited Seminar @ Bahen Centre for Information Technology Room BA1190
Mar 10 @ 12:00 pm – 1:00 pm

Abstract: TBA

Apr
14
Tue
Mikhail Shapiro- Biomedical Engineering Invited Seminar @ Sandford Fleming Building Room SF1101
Apr 14 @ 12:00 pm – 1:00 pm

Abstract:

Talking to Cells: Biomolecular Engineering for Non-Invasive Imaging and Control of Cellular Function

The study of biological function in intact organisms and the development of targeted cellular therapeutics necessitate methods to image and control cellular function in vivo. Technologies such as fluorescent proteins and optogenetics serve this purpose in small, translucent specimens, but are limited by the poor penetration of light into deeper tissues. In contrast, most non-invasive techniques such as ultrasound and magnetic resonance imaging – while based on energy forms that penetrate tissue effectively – are not effectively coupled to cellular function. Our work attempts to bridge this gap by engineering biomolecules with the appropriate physical properties to interact with magnetic fields and sound waves. In this talk, I will describe our recent development of biomolecular reporters and actuators for ultrasound and magnetic resonance imaging. The reporters are based on a unique class of gas-filled protein nanostructures from buoyant photosynthetic microbes. These proteins produce nonlinear scattering of sound waves, enabling their detection with ultrasound, and perturb magnetic fields, allowing their detection with MRI. I will describe our recent progress in understanding the biophysical and acoustic properties of these biomolecules, engineering their mechanics and targeting at the genetic level, developing methods to enhance their detection in vivo and expressing them heterologously as reporter genes. Our actuators are based on temperature-dependent transcriptional repressors, which provide switch-like control of bacterial gene expression in response to small changes in temperature. We have genetically tuned these repressors to activate at thresholds within the biomedically relevant range of 32ºC to 46ºC, and constructed genetic logic circuits to connect thermal signals to various cellular functions. This allows us to use focused ultrasound to remote-control engineered bacterial cells in vivo. In addition, we have used ultrasound in combination with viral vectors and engineered receptors to provide spatially and cell-type specific non-invasive control over neural activity.

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