Molecular fluorescent reporters for force and smart surfaces for sensing cell-surface interaction

Abstract

Molecular sensors are powerful because they make it possible to adapt the measurement to the sample instead of a sample to an instrument. Many reporter are available for measuring the chemical properties of a sample, but no purpose-built molecular sensors exist to report a sample's mechanical properties. To address recent interest in the mechanical coordinate of molecular interactions, we developed a prototype molecular sensor, calibrated its force-fluorescence relationship, and adapted the sensor to a cell adhesion assay. This thesis focuses on the considerations for combining force measurement with the environmental and distance sensitivity offered by fluorescence to measure cell-surface adhesion. We showed that DNA can be used as a scaffold to build a sensor molecule, that fluorescence can be used as a reporter of a threshold force, and that introducing cells to the sensor molecules changes the fluorescence properties. Because Cy3 experiences an enhanced intensity sensitivity when conjugated to DNA, the reporter's FRET signal was occluded and we instead activated the sensor complex as a novel, all-fluorescent means of reporting cell-surface proximity. This method for reporting cell-surface separation is significant because it simplifies measurements in thicker and more complex materials interesting to cell-substrate interaction studies.