Self-propelled Systems For Versatile Applications
Open Access
- Author:
- Yadav, Vinita
- Graduate Program:
- Chemistry
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 22, 2015
- Committee Members:
- Ayusman Sen, Dissertation Advisor/Co-Advisor
Thomas E Mallouk, Committee Member
John V Badding, Committee Member
James Hansell Adair, Committee Member - Keywords:
- Nano-motors
Micro-pumps
Drug-delivery
Crack-repair
Enzyme cascades - Abstract:
- A decade ago, the first examples of self-propelled motion at the nano and microscale by synthetic objects were discovered. This was the first step towards the design of autonomous nano and micro-machines and robots. Nature has been using nanoscale motors and pumps to power its numerous creations and this has inspired the scientific community to emulate such systems. The focus of this thesis is on colloidal systems - both biological and inorganic, whose constituents move and respond to each other and their surroundings through a specific mechanism: diffusiophoresis. This thesis begins with an introduction on diffusiophoresis - the electrolyte and non-electrolyte versions along with other competing or complementing propulsion mechanism reported for colloidal systems. The first system discussed in this thesis is an inorganic scheme that displays a one of its kind ‘on/off’ switch that controls colloidal transport. Additional built-in levels of regulation allow for both rectification and amplification of particle motion. A biological system is discussed next that utilizes the phenomenon of electrolyte diffusiophoresis to detect and repair cracks in bones. This represents one of the few viable examples of utilizing nanomotors towards a medical treatment. Repair of damaged tissues has also been expanded to curing dental ailments. Dental caries or bacterial cavities can also be detected and cured using the same underlying mechanism. This approach also offers the first explanation on why fluoride treatment works for general dental well-being. Restoration of biological cracks has also been expanded onto polymerized surfaces. The mechanism involved varies from diffusiophoresis, in that it is density driven rather than being electric field driven. Complete repair of cracked surfaces is observed in real time. Diffusiophoretic motion is then applied to polymeric systems where a fluoride ion triggered colloidal pump is designed. The pump is a versatile starting ground that is expanded into designing a bacteria scavenging material as well as systems that show first signs of memory. This thesis concludes with perhaps the most exciting chapter that brings new light to enzymatic cascades, the intricate systems that allow for the perpetuity of life on earth. Earlier work done on enzyme substrate interactions is expanded to solve the mechanistic mystery behind cascades that has eluded enzymologists and biologists for long.