Development and Characterization of a molecualr-biomechanical sensor for the optical measurement of dynamic forces in vitro and in vivo

• Applicant: Privatdozent Dr. Frank Schleifenbaum
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; Analytical Chemistry
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 235614222

The measurement of pressures close to surfaces is of high importance in many areas in scientific research and development. To compensate for limitations of mechanical sensors, which are only capable to determine punctual forces, pressure sensitive paints (PSPs) have been developed, which base on the determination of the local oxygen partial pressure, which varies in dependence of the external air pressure. Though easy to process, PSPs suffer from the a number of disadvantages, comprising the disability to measure dynamic pressures and flows and the dependence of a calibrated oxygen-atmosphere. Moreover, they cannot be applied to fluid systems. We propose a sensor system, which optically probes the mechanical impact of surface flows and pressures with subnanotmer accuracy. To this end, the force-dependent bending of a surface-bound linker molecule composed of double stranded DNS is measured via fluorescence resonance energy transfer (FRET) between two fluorescence dyes fused to the ends of the DNS. This approach allows for the measurement of impact as well as dynamic pressures largely independent on the surrounding medium. The FRET-detection is highly robust and due to a ratiometric readout insensitive to photobleaching or local concentration inhomogeneities. Choosing a well-suited combination of fluorescence dyes, the sensor can be analyzed using commercial color-cameras. In pertinent preliminary studies we already demonstrated the functionality of our sensor approach and were able to show that the sensor works in a reversible way and can easily be adjusted in its working range. The proposed project aims to further develop and optimize the sensor to obtain higher sensitivities at lower flow rates. Moreover, the molecular-physical basics of the DNS-bending shall be analyzed and characterized. A further aspect of the project concerns the adaption of the sensor system to polymeric substrates to enable the covering of even complex surface morphologies using thin polymeric foils. In parallel, the sensor shall be modified to be composed as a Oligopeptide-system. This way, it is can be genetically coded and expressed to living organisms. By this, a local, highly sensitive sensor shall be developed, which allows for the non invasive measurement of intracellular pressures and flows.

• DFG Programme: Research Grants