Open Collections

Kong, Albert

University of British Columbia

This thesis explores bioadhesion at two scales. In many animals, adhesion plays a critical role to enable their traversal on inclined and inverted surfaces of varying chemistry. This is achieved through arrays of fibrils or micropillars found at the tips of these animals’ appendages. Synthetic mimics inspired by the design of these natural systems are actively developed, studied, and used in applications not limited to adhesion. A common limitation in these mimics is that adjacent micropillars tend to adhere to each other (self-adhere) by lateral van der Waals interactions, impeding on their intended function. Through mathematical modeling, our work demonstrates that slanting micropillars from their vertical arrangement permits them to be longer or more densely packed while avoiding self-adhesion. We derive a criterion to determine the critical angle above which slanting remains beneficial, providing developers of micropillar array devices with a tool to aid in their design. Our analysis further finds that the design of natural micropillar arrays in the ladybird beetle are close to optimal for packing or length, providing justification for the observed natural design. In cell biology, adhesion gives structure to organisms, enabling growth and proliferation. Furthermore, adhesion enables cells to contract against their surroundings, which has been identified as a key factor in cancer progression and metastasis. We developed an experimental platform to alter cellular concentrations of adenosine triphosphate (ATP) – the energetic currency of cells – and measure changes in their contractile response. Our work contributes to existing literature exploring nutritional approaches to cancer therapeutics but also quantifies general metabolic adaptation due to changes in nutrient levels. By processing cell images, we find that glucose deprived cells become less contractile than control cells. Through mathematical modeling, we additionally found that the glucose deprived are 36% less efficient during contraction (they perform 36% less work per ATP consumed). However, by interpolating between the response parameters of glucose deprived and control cells, we postulate that subject to low levels of glucose deprivation, cells maintain and even enhance their contractility and efficiency. Only beyond a critical level of glucose deprivation do both begin to diminish.

Text

2022-07-22

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82190

Mechanical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/