Chemistry Seminar: Dr. Jie Li

The Department of Chemistry in the College of Arts and Sciences is pleased to welcome Dr. Jie Li, a Postdoctoral Associate at MIT.

The seminar will be held on Zoom. Please email chemistry@syr.edu for Zoom info.

Title: Applications of Biomaterials in Combating Human Disease

Abstract

Humankinds have been using materials in medical devices to repair the body since antiquity. With the development of technology, the synthetic materials have replaced naturally derived materials with better performance and increased functionality, which led to a pronounced increase in the efficacy of biomaterials. Biomaterials made today are playing a greater role in medicine through biologically inspired design and incorporation of dynamic behavior. In this talk, I will discuss the application of enzyme-instructed self-assembly (EISA) to generate intracellular supramolecular assemblies that drastically boost the activity of cisplatin against drug-resistant ovarian cancer cells. We design small peptide precursors that could self-assemble into nanofibers in response to carboxylesterase (CES) in cancer cells, by cleaving the pre-installed ester bond. The precursors at low concentrations are innocuous to cancer cells, but they could significantly boost the anti-cancer efficacy of cisplatin without increasing the systemic toxicity when they are applied to drug resistant ovarian cancer cells in the combination therapy.

My focus will then shift to another application of self-assemblies. Usually, isolated peptides are unable to maintain the original secondary structures without the restrictions from the protein. We are able to restore the secondary structure of the isolated peptides that were part of a β-sheet motif of a protein by connecting an aromatic motif to the C-terminal of the two pentapeptides. By using aromatic-aromatic interactions to mimic the conformational restriction in a protein, our work illustrates a bioinspired way to generate peptide nanofibers with predefined secondary structures.

Finally, I will discuss the design and development of a biosensing technology based on Janus emulsions for the detection of Listeria Monocytogenes, which is a genus of gram-positive bacteria and is responsible for listeriosis, a potentially lethal disease. Janus emulsion is composed of an equal amount of hydrocarbon and fluorocarbon and we install the Listeria antibody to the surface of Janus emulsions’ hydrocarbon phase by a click reaction. We dissolve a blocking dye and an emissive dye into the two phases of the Janus emulsions separately. When there are Listeria existed in the solution, the strong binding between Listeria and the Listeria antibody located at the hydrocarbon surface of the emulsions results in the tilting of the Janus structure from its equilibrium position to produce emission signals. This sensing method shows very high sensitivity and could be extended to create a new class of biosensors by the utilization of corresponding stable and selective antibodies.