Dissertation/Thesis Abstract

The Road to Colloidal Self-Replication
by Wu, Kun-Ta, Ph.D., New York University, 2014, 360; 3614913
Abstract (Summary)

Self-replication exists everywhere in nature from bacteria to human beings. Several generations of scientists have worked on self-replication in nature. However, a more challenging breakthrough is to self-replicate through lifeless matter, such as colloids. To accomplish this paradigm shift, technically, we need to investigate thermodynamics, kinetics, multi-functionality, mobility, and the formation of specific covalent bonds of DNA-coated colloids. These are the essential studies for realizing colloidal self-replication.

We present and experimentally test a mean field thermodynamic model for DNA-functionalized colloidal aggregation and find excellent agreement when accounting for the binding configurations between a pair of particles and adding an additional entropic term due to restricted configurations for DNA bound to both surfaces. We study the kinetics of aggregation as a function of DNA coverage and salt concentration over the range: 4 minutes - 79 hours. The fundamental factor is an intrinsic hybridization time for a pair of complementary DNA in solution retarded by Coulomb repulsion, and the entropic search for inter-particle binding configurations. We investigate the flexibility of the DNA colloid system for colloidal architecture by evaluating theoretically and experimentally the number of specific associations each of our colloids can have with its neighbors. In theory, we find that our particles can recognize up to 76 different particles due to intrinsic properties of DNA hybridization and sequence combination while in experiment we confine that up to 40 different particles can be bound. A practical limit is ∼100. To demonstrate the utility of our "polygamous particles," we synthesize a dual-phase material, which by control process forms either gels or liquids at the same temperature.

"Sticky" particles typically have low mobility. We demonstrate a novel solution to this problem by combining depletion and DNA interactions, and we successfully synthesize crystals and designed hexagon clusters. Finally, we use cinnamate-modified DNA to control formation of specific covalent bonds and develop a new DNA photolithography. We functionalize a patterned area on a gold surface by a controlled UV light pattern.

Indexing (document details)
Advisor: Chaikin, Paul M.
Commitee: Grosberg, Alexander Y., MacFadyen, Andrew I., Pine, David J., Seeman, Nadrian C.
School: New York University
Department: Physics
School Location: United States -- New York
Source: DAI-B 75/07(E), Dissertation Abstracts International
Subjects: Polymer chemistry, Condensed matter physics, Materials science
Keywords: Colloids, Cross-linking, DNA, Kinetics, Self-assembly, Thermodynamics
Publication Number: 3614913
ISBN: 9781303806100
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