InP/ZnS Luminescent Quantum Dots for Bioimaging with Improved Cellular Targeting Capabilities

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Quantum dots are extremely small nanocrystals of semiconductors that are 100,000 times smaller than a grain of salt and contain just a few thousand atoms. When exposed to light, quantum dots luminesce, and the color of their emitted light depends on their size. It is these unique optical properties that make quantum dots useful in applications ranging from cell phones to light emitting diodes (LEDs). Quantum dots have also attracted the attention of the biotechnology community due to their potential use in bioimaging and biosensing applications. However, most quantum dots contain heavy metals like cadmium and lead that are toxic to living cells and their surfaces quickly become coated with proteins and lipids that degrade their stability. With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Zeev Rosenzweig in the Department of Chemistry and Biochemistry at the University of Maryland Baltimore County (UMBC) is developing non-toxic quantum dots from indium phosphide. Working with his students and collaborator Dr. Karen Leinkamp at Albert-Ludwigs Universitat in Germany, Professor Rosenzweig is modifying the surface of the quantum dots with novel polymers that inhibit the formation of protein corona on their surface, allowing them to maintain their bright luminescence and stability in biological solutions. Their discoveries could have broad implications for using semiconductor quantum dots in biological applications. The project provides interdisciplinary research training opportunities for graduate and undergraduate students involved. Professor Rosenzweig and his team are also actively engaged in outreach to nearby high schools to introduce students to concepts in nanoscience and nanotechnology, including their impact on human health and the environment.Highly emitting quantum dots (QDs) are currently limited in their chemical stability in complex biological media, and in their cellular targeting efficiency due to protein corona formation. The project is addressing these limitations, enabling the use of InPZn/ZnS QDs as non-toxic bioimaging probes. The goals of the project are realized through the following specific aims: Aim 1) Modifying the surface of InPZn/ZnS QD with oxonorbornene-based polymers that allow systematic functionalization of the polymer side chains to inhibit corona formation. Aim 2) Development and use of a high-resolution fluorescence microscopy system, typically used in single molecule fluorescence studies, to follow in real time the process of protein corona formation on InPZn/ZnS QDs without photodegradation, or the need for large quantities of nanoparticles. Aim 3) Demonstrate that the surface modification of InPZn/ZnS QDs with oxonorbornene polymers results in protein corona formation inhibition, and increased macrophage targeting efficiency. The project provides interdisciplinary research training opportunities for graduate and undergraduate students. It also enhances the recruitment of students from underrepresented groups to scientific research in nanomaterials chemistry through partnership with the national Interdisciplinary Consortium for Research and Educational Access in Science and Engineering (INCREASE).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.