Mechanofluorescent Surfaces for Investigating Microscopic Contact Forces at Aqueous Interfaces

• Applicant: Quinn Alexander Besford, Ph.D.
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; Physical Chemistry of Solids and Surfaces, Material Characterisation ; Polymer Materials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 496201730

This project aims to develop new cutting-edge pressure sensing surfaces that can directly resolve contact forces in aqueous environments. Contact forces between solid bodies, and at fluid-solid interfaces, are omnipresent in physical and biological systems, and play vital roles in adhesion, cell growth, and vascular flow. Current methods for quantifying surface contact forces have several limitations in terms of spatial resolution, dimensionality and force sensitivity. To overcome these challenges, mechanofluorescent polymer brush surfaces will be developed to directly quantify high-resolution contact forces, with variable directionality (pushing or pulling). This will be realised by exploiting the dependency of fluorescent lifetimes of fluorophores on fluorophore-fluorophore proximity within polymer brush layers. This is hypothesised to be dependent on the polymer brush conformation, which can be changed by contact mechanical force (by fluid or contacting solid). This hypothesis will be investigated in 5 consecutive work packages: (1) synthesis of complex co-polymers that contain specific fluorophores; (2) assembly of polymer brushes and validation of fluorescent properties against polymer conformation; (3) validation of fluorescent properties by molecular dynamics simulations; 4) integrating atomic force microscopy to fluorescence lifetime imaging to directly probe force vs. fluorescence relations; 5) incorporate polymer brushes within microfluidic chanels in order to quantify internal fluid pressure in complex architectures. These data are expected to provide new information on the physics of contact forces in real-time, towards the nanoscale, which can reveal new understanding into force generation and propagation against aqueous interfaces. It is anticipated that such new insight will aid comprehension of contact forces in biological systems.

• DFG Programme: Research Grants