Membrane Sensors by DNA Nanotech

Representing the boundary of the cell, the cell membrane is the compartment where sensing and cellular response are first elicited. In addition, the membrane is instrumental for communication channels including electrical potentials for neuronal functions.

Based on the previous DFG-funded project “Optical Voltage Sensing Nano-Devices using DNA Self-Assembly”, in which a new concept for optical voltage sensing of membrane potentials was elaborated, we now aim at establishing a whole new family of non-genetically encoded membrane sensors using DNA nanotechnology. DNA nanotechnology can fundamentally overcome the problems of small molecular sensors that have to combine a multitude of properties into fairly small molecular components. In contrast, the modular design enabled by DNA nanotech offers the unique advantages that central functions such as the sensing unit design, the transduction process, as well as required side-functionalities including membrane targeting and biocompatibility can be optimized separately. In addition, different sensing modalities can benefit from synergy effects by using common modules or can even be integrated into a single device.
In previous work, we established assays for DNA origami synthesis and functionalization for membrane targeting and equipped the DNA origamis with a sensing unit for membrane potentials. These ratiometric sensors work by Förster Resonance Energy Transfer (FRET) between a fluorescent dye on the DNA origami and a charged but hydrophobic fluorescent dye placed at the end of a lipophilic flexible element that dips into the membrane and whose position depends on the membrane potential. So far, the voltage sensing nanodevices have been demonstrated in proof-of-principle experiments in model systems such as large unilamellar vesicles with chemically controlled electrical potentials.
Within the SFB, we plan to extend the concept to further develop the voltage-sensing nanodevices especially with respect to contrast and sensitivity of voltage sensing. We will incorporate alternative transducing mechanisms based on environmentally sensitive dyes and optimize the flexible element for better and longer membrane embedding. In addition, we will expand the approach to living cells including genetically modified HEK cells and neurons. Furthermore, we will generalize the concept of DNA nanotech membrane sensing and develop DNA origami membrane curvature sensors and membrane tension sensors. Especially, membrane curvature sensors could be integrated with further functionalities including force sensing, and drug release could be coupled to curvature sensing for theranostic approaches. Within the SFB, the project aims for synergies and cooperation with A02, A06, A11, and B11.