University of Toronto, Faculty of Applied Science & Engineering

Chemical Engineering & Applied Chemistry

Y-L. Cheng

Cheng

S.B., S.M. (MIT), Ph.D. (Stanford)

Room: WB339
Tel.: 416-978-5500/416-978-84402
Email: yuling.cheng@utoronto.ca

 

Awards

Faculty Teaching Award, 1994/95
OCUFA Teaching Award, 1994/95
Leadership in Faculty Teaching Award, Government of Ontario, 2008
Faculty Award, UTAA, 2008

Memberships

Controlled Release Society
Association for Research in Vision and Ophthamology
Canadian Society of Chemcal Engineering
American Institute of Chemical Engineering

Research Interests

Drug Delivery and Biomedical Engineering
Materials science and chemical engineering principles are applied to problems in drug delivery and biomedical engineering--both at the organ level as well as the cellular level. Emphasis is placed on ophthalmic applications.

Responsive Drug Delivery: Materials that change structurally upon exposure to external or physiologic triggers can be used to deliver drug in a programmed or responsive fashion. We are investigating several concepts for responsive membranes. We have shown that dispersed domains formed in side chain liquid crystalline polymers can be aligned electrically thus giving varying permeabilities, and that the permeability response to electric field is consistent with our theoretical predictions. We are also working on a concept that combines the responsive swelling of hydrogels with the unique transport properties of heterogeneous media to develop responsive composite membranes. As hydrogel regions dispersed in hydrophobic elastomeric polymers swell and shrink in response to external stimuli, they also become connected or disconnected, thus opening or closing permeation channels. The connectivity effect works in synergy with hydrogel hydration effects to produce very large changes in permeability.

Ophthalmic Applications: We are taking a comprehensive approach to improving effectiveness of ophthalmic therapy: Pharmacokinetics and pharmacodynamics studies are carried out to determine drug distribution characteristics, and the response of ocular tissue to various drug concentration profiles, drug delivery systems are then designed using selected vehicles to mimic optimal profiles. Projects include: cyclosporine delivery for immunosuppression after corneal transplantation, epidermal growth factor delivery for corneal wound healing, and intravitreal therapy. Recently, we started to extend our experience in corneal wound healing to the development of an artificial cornea.

Diffusion and Mass Transfer in Polymeric Systems: An understanding of diffusion and mass transfer mechanisms is important in the design and control of polymeric drug delivery systems. We have conducted theoretical and experimental studies of the mass transfer characteristics in various systems including degradable polymers, osmotically rupturing systems, and heterogeneous composites.

Selected Publications

S. Friedrich, B. A. Saville and Y-L. Cheng, Finite Element Modelling of Drug Distributions in the Vitreous Humour of the Rabbit Eye, Annals of Biomedical Engineering, 25 (1997) 303-314.

M.J. Abdekhodaie and Y-L. Cheng, Diffusional Release of a Dispersed Solute from a Polymer Matrix into Finite External Volume, Journal of Controlled Release, 43 (1997) 175-182.

H.Sheardown and Y-L. Cheng, Effect of Epidermal Growth Factor on Corneal Epithelial Cell Migration and Mitosis, Chemical Engineering Science, 115:2 (1996) 4517-4529. L-K. Chiu, W.J. Chiu, and Y-L. Cheng, Effects of Polymer Degradation on Drug Release--A Mechanistic Study Based on Changes in Morphology and Transport Properties of Degrading 50:50 Poly(DL-Lactide-co-Glycolide), International Journal of Pharmaceutics, 126 (1995) 169-178.

A. Apel, C. Oh, R. Chiu, B.A. Saville, Y-L. Cheng and D.S. Rootman, A Subconjunctival Degradable Implant for Cyclosporine Administration in Corneal Transplant Therapy, Current Eye Research, 14 (1995) 659-667.

B.G. Amsden, Y-L. Cheng, and M.F.A. Goosen, A Mechanistic Study of the Release of Osmotic Agents from Hydrophobic Polymeric Monoliths, J. Controlled Release, 30 (1994) 45-56.

Y. Ly and Y-L. Cheng, Electrically-Modulated Variable Permeability Liquid Crystalline Polymeric Membranes: Frequency Addressing Technique, J. Membrane Science, 77, (1993) 99-112.
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