(6i) Engineering Visible-Light Organic Photocatalysis for Polymers in Biomaterials, Biosensing, and Photomedicine

Visible-light organic photocatalysis is one of the most promising methods to synthesize and modify polymers of medical and biomedical relevance. These reactions permit spatiotemporal control at biologically benign irradiation levels with low-cost biocompatible organic photocatalysts. However, we have poor control of these reactions. This stems from the general lack of knowledge of the complex reaction mechanisms around proteins. Therefore, discovery of the right photocatalyst for every biomedical application has advanced slowly through trial-and-error. Molecular engineering of photocatalysts promises to accelerate the implementation and expand the utility of visible-light photocatalysis in biomedicine. My goal is to promote specific reaction pathways that yield desired outcomes, e.g. radical initiation, polymer/protein grafting, reversible crosslinking, or protein crosslinking, by engineering organic photocatalysts.

I have discovered that the photocatalysis of methylene blue mimics photosynthesis in that it involves a 2e^-/H⁺ photocatalytic cycle, as opposed to the concerted e^-/H⁺ transfer that is generally assumed for photoinduced electron transfer reactions. This allows synthesis of centimeter thick optically absorptive polymers for dental and orthopedic restorative medicine. Then, I investigated the photocatalysis of Eosin to initiate radical polymerization of hydrogels against a thousand times excess oxygen around proteins, useful for biosensing in medical diagnostics. The next step is elucidating the mechanism for the crosslinking of collagen proteins with Rose Bengal useful for surgical wounds closure, corneal sealing, nerve, tendon and vessel repair, and cartilage regeneration. Applying chemical engineering principles to photochemical reactions will allow me to design photocatalysts that crosslink collagen fibers with minimal tissue inflammation.

Teaching Interests:

A startled classroom of junior and senior Chemical Engineering students looked at me as I opened a lecture with a simulation of the explosion of a chemical reactor. As TA of the Reaction Engineering and Chemical Kinetics course at the University of Colorado I wanted to do something different to get students out of our classical equation-heavy class routine. I selected the best video I could find on Runaway Reactions to engage students in the topic of incorporating heat considerations into reactor design. Office Hours were well spent observing their progress and discussing specific questions in small groups. Most questions were directly related to problem sets and midterms, but some served as discussion points to chat about chemical kinetics, numerical methods, and reaction mechanisms. I saw our students making their schematics and postulating new questions as the learning process sparked their curiosity. I believe this classical learning/teaching interaction is invaluable to stimulate active learning. I enjoyed designing online assessments to assess studentsâ?? knowledge, critical thinking, and inventiveness as TA of the Statistics for Engineering course at the University of Colorado. A combination of Backwards Design and Constructive Alignment will allow me to create an engaging environment where my students achieve the intended learning outcomes. I work to engage all students in their own learning experience. I observed this first hand in the students I mentored as the founding president of the AIChE student Chapter at my undergraduate University. All this coalesced in my Teaching Philosophy developed during the Kaufman Teaching Certificate Program at MIT.