Contents:
Research Projects
 

Flocculation to enhance microfiltration

Tangential flow microfiltration is used in the manufacture of biopharmaceutical products to separate the cells and cell debris from the growth medium. However, the filtrate flux is often compromised by fouling of the membrane particularly by the smaller cell debris. The filterability of biological feeds may be improved by adding synthetic flocculating agents prior to microfiltration. These synthetic polymers contain multiple charged groups along a macromolecular backbone. The charged groups can reduce the electrostatic repulsion between particles. In addition, since these polymers contain multiple adsorption sites, they can form bridges between particles. Our aim is to maximize the filtrate flux and determine optimum operating conditions.
 

Virus clearance by flocculation during bioreactor harvesting

Biotechnological manufacturing processes use carefully cultured cell lines and animal-derived cell culture media in the manufacture of products such as drugs. The cells are merely mini-reactors where the drugs are made. Contamination of the final product by viruses associated with the cells and cell culture media is a serious concern. Hence there is a tremendous need to validate adequate virus clearance during the manufacture of biopharmaceutical products. Like the previous research project, synthetic polymeric flocculating agents are added to the bioreactor prior to bioreactor harvesting. Any viruses present in the cell broth are trapped in the flocculated biomass. Centrifugation, sedimentation or microfiltration of the biomass (bioreactor harvesting) then results in significant virus clearance in the supernatant or filtrate which contains the desired product. The aim of this work is to maximize the level of virus clearance.

 
Particle fractionation by inertial lift forces

As the demand for highly purified blood products such as leukodepleted red blood cells and platelets increases more efficient separation techniques are required. When a dilute suspension of non-settling particles flows through a tube, the particles flow radically in the flow field and congregate in an annular region of the tube located between the centreline and the wall. Thus particles originally near the wall move inwards away from the wall. In blood vessels, it is observed that red blood cells and platelets separate into distinct annular zones, platelets being closer to the walls of the blood vessel. This natural tendency of particles of different sizes to separate during laminar flow suggests a way to fractionate cells.
 

Optimizing the design of blood oxygenators

Extracorporeal blood oxygenators are designed to replace pulmonary function during cardiac surgery requiring cardiopulmonary bypass. In 1995, 800,000 cardiac procedures requiring blood oxygenators were performed throughout the world. The majority of the blood oxygenators used today contain microporous hydrophobic membranes. Since the membranes are hydrophobic the pores are gas filled. Blood flows on one side of the membrane while air or oxygen flows on the other side. Oxygen diffuses through the membrane pores and into the blood while carbon dioxide diffuses in the opposite direction. The objective of this study is to design more efficient or optimized blood oxygenators. There is tremendous clinical and commercial interest in developing better designs which maximize the gas transfer per priming volume of the device and minimize the shear stress on the blood. Increasing the rate of gas transfer will reduce the membrane surface area required and thus lower the cost of the device.

  


Courses 

Undergraduate

 
CB 331 Momentum transfer and mechanical separations

This course is designed to introduce students to the fundamental principles underlying the behaviour of fluids. Topics such as dimensional analysis and scale up, fluid properties, fluid statics, pipe flow, flow measurement and control, pumps and compressors, flow in porous media and fluidization and sedimentation are covered.

CB 333 Momentum and heat transfer laboratory

This laboratory course is designed to reinforce knowledge gained in CB 331 (see above) and CB 332 (Heat transfer and thermal systems). Students work in groups of 4 to 6. All students will conduct 5 of the following experiments:

CB 443 Mass transfer and separation laboratory

This laboratory course is designed to reinforce knowledge gained in CB 341 (Equilibrium staged separations) and CB 442 (Rate controlled separations). Students work in groups of 4 to 6. All students will conduct 5 of the following experiments:
 

Graduate

CB 723 Bioseparation processes

This course introduces students to the separation and purification operations used in the downstream processing of biochemicals such as biopharmaceuticals. Unit operations such as microfiltration, chromatography, ultrafiltration, crystallization and drying will be studied. The course includes a number of demonstrations.

  


Selected Publications
  Patents