Denise Williams-Harris


Chemistry and Biochemistry

Area of Doctoral Study: Chemistry

Undergraduate Institute: University of New Haven

Research Advisor: Zeev Rosenzweig, Ph.D

Description of Research

My research focuses on the synthesis and characterization of luminescent ZnSe/ZnS quantum dots, a new type of luminescent nanoscale material. The objective of her study is to replace toxic cadmium-containing nanomaterials, like CdSe/ZnS quantum dots, with alternative materials that will retain the high functionality of cadmium-containing quantum dots in a wide range of applications while reducing the impact of these luminescent nanomaterials on human health and the environment.  My research is currently a part of a larger project which is carried out by the NSF Center of Sustainable Nanotechnology (CSN), a consortium of 15 research laboratories in academic institutions and government laboratories including the Rosenzweig laboratory at UMBC. The goal of CSN is to realize molecular level understanding of the interactions between synthetic nanomaterials and biological systems, in order to develop new design principles for the synthesis of next generation nanomaterials.

My immediate objective is to synthesize and compare the chemical and optical properties of ZnSe/ZnS quantum dots with the properties of currently used CdSe/ZnS quantum dots. ZnSe/ZnS quantum dots present an attractive alternative because they are cadmium-free, made from earth abundant elements, and similarly to CdSe/ZnS quantum dots, they exhibit particle size dependent emission tunability.  Their synthesis is similar to the synthesis of CdSe/ZnS quantum dots, but their photophysical properties need to be improved through modification of different synthesis techniques and conditions in order to quantum dots with comparable quality to CdSe/ZnS quantum dots. As it is anticipated that ZnSe/ZnS quantum dots will replace CdSe/ZnS quantum dots in some applications, the next objective will be to study the environmental impact these quantum dots might have. Interactions with biological systems and organisms- such as nematodes, daphnia, shewanella, and zebrafish- are being planned in collaboration with other research laboratories at the NSF CSN.