Title

Template Mediated Nanocluster Formation

Defense Date

11-3-2004

Graduation Date

Fall 1-1-2004

Availability

Campus Only

Submission Type

dissertation

Degree Name

PhD

Department

Chemistry and Biochemistry

School

Bayer School of Natural and Environmental Sciences

Committee Chair

Mitchell E. Johnson, David W. Wright

Committee Member

Jeffry D. Madura

Keywords

Biomineralization, Cadmium Sulfide, Calcium Carbonate, Cyclic Peptide Nanotube, Group II-VI semiconductors, Informatics, Nanocluster, Nanocrystals, Phytochelatin, Quantum Dot, Spatially Addressable Combinatorial Library

Abstract

Organisms have developed processes to facilitate the formation of inorganic materials over the course of millions of years. They have evolved many different strategies for conforming readily available inorganic materials into complex function-specific biominerals with unusual chemical and mechanical properties at ambient temperatures and pressures. Advances in the understanding of biomineralization processes in a variety of organisms have revealed the critical control and design principles for the improved fabrication of synthetic materials with novel properties. Combining biomineralization processes, molecular modeling, structural biochemistry and synthetic chemistry we have developed two strategies for template mediated nanocluster formation.

Our first strategy involved the creation of a three-dimensional scaffolding architecture to create a highly functionalized surface for the nucleation of calcium minerals. Calcium mineral precipitation has been widely studied due to its importance in industrial and biomineralization applications. Based on a structural motif commonly found in calcium biominerals, the antiparallel beta-pleated sheet, the rational design and development of a hollow tube peptide architecture was created. We have used this unique multipurpose scaffold, made up of cyclic peptides with alternating D- and L- amino acids which self-assemble into nanotubes whose surface is coated with periodic functional groups, as a template for the controlled nucleation of calcite.

Our second strategy involved the use of combinatorial chemistry and material informatics to explore the important design properties of peptides capable of stabilizing and encapsulating group II-VI semiconductor nanoclusters. The synthesis of monodisperse cadmium sulfide (CdS) nanocrystals is of interest due to their unique optical and electronic properties derived from their confined size. Whereas there have been many synthetic approaches for the synthesis of CdS nanoclusters, many plants and yeasts utilize short cysteine-rich matrix peptides (phytochelatins) to synthesize CdS biogenic nanocrystals as a method of cadmium detoxification. In order to investigate what properties of the peptide are important for the controlled synthesis of CdS nanoclusters of a specific size, we have used combinatorial chemistry to create a spatially-addressable peptide library based on the cysteine-rich matrix peptides and applied a material informatics approach to analyze how the global and positional peptide properties influence the CdS nanocluster formation.

Format

PDF

Language

English

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