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Roxanne Chu

Biomineralization of CuInS2 and CuInS2/ZnS Quantum Dots Using CSE

Department: Chemical and Biomolecular Engineering
Advisor: Bryan Berger and Steve McIntosh

Quantum dots are semiconductors nanocrystals that have unique optical properties that differ from their bulk counterparts. These optical properties can be tuned by controlling the size, shape, and material of the nanocrystals. Quantum dots have a wide range of applications such as in solar cells, bioimaging, and electronics. Traditionally, quantum dot synthesis is performed at high temperatures in organic solvents, leading to a high cost of production. Consequently, biological routes have been studied as an inexpensive and environmentally friendly method for synthesis.

Cystathione γ-lyase (CSE), an enzyme isolated from a biologically engineered strain of Stenotrophomonas maltophilia, was found to be capable of metal sulfide nanoparticle synthesis. This work demonstrates copper indium sulfide (CIS) quantum dots synthesized by incubating cysteine, indium, and copper with CSE. The luminescence of CIS was shown to increase by subsequent growth of a zinc sulfide shell. The most common quantum dots studied to date are cadmium and lead chalcogenides. However, CIS is of interest because it is less toxic than its heavy-metal counter parts. This property makes it a more suitable choice for biological applications of quantum dots, specifically bioimaging. The CIS/ZnS core-shell nanocrystals have also been conjugated to Leukemia cells as fluorescent markers, demonstrating their potential application in bioimaging.

About Roxanne Chu:
Roxanne Chu is a senior at Lehigh University graduating in May 2017 with a B.S. in Chemical Engineering. She has worked under Dr. Steve McIntosh and Dr. Bryan Berger for two years focusing on the biosynthesis of various metallic chalcogenide quantum dots. After graduation, she plans on pursuing a career in the chemical engineering industry.