DNA-based force sensor with colorimetric detection | Molecular Force Balance

许多大分子在活细胞内发生的构象变化对其生物学功能至关重要。在这样的运动中，分子施加并经历拉伸和压缩力。我们提出了利用分子力传感器在皮牛顿尺度上测量力的新概念。这些传感器克服了现有力谱技术的局限性，这些技术需要通过长连接器将分子与宏观设备（如珠子或尖端）进行侵入式连接。为此，DNA折纸和DNA张拉完整性的强大概念将与建立和新颖的单分子荧光技术相结合。纳米级力传感器将利用单链DNA （ssDNA）的熵力行为。传感器将由刚性DNA折纸元素组成，这些元素可以相互转移。移位的程度将通过光学检测。因此，光稳定的荧光团及其对应的猝灭剂将附着在DNA折纸结构的指定位置。我们提出了纳米级倾斜天平和弹簧天平的概念。前者将使我们能够在比较分析中测量配体相互作用，后者将提供感测力的模拟读出机制：类似于滑动卡尺的功能，不同颜色的荧光团与其猝灭剂之间的距离变化将导致被检测荧光光谱的颜色变化，从而允许非侵入性地读出力传感器的状态。对于未来，我们设想在活细胞和材料中的非侵入性力测量以及感知分子相互作用的新方法。

The conformational changes that many macromolecules undergo inside living cells are crucial for their biological functions. During such motions, the molecules exert and experience stretching and com-pressing forces. We propose new concepts for the measurements of forces on the piconewton scale using molecular force sensors. These sensors overcome the limitations of available force spectrosco-py techniques that require an invasive connection of the molecules with macroscopic devices such as beads or tips via long linkers. For this purpose, the powerful concepts of DNA Origami and DNA Tensegrity will be combined with established and novel single-molecule fluorescence techniques. The endeavored nanoscopic force sensors will employ the entropic force behavior of single-stranded DNA (ssDNA). The sensors will be composed of rigid DNA origami elements, which can be translocated with respect to each other. The degree of translocation will be detected optically. Therefore, photostable fluorophores and their corresponding quenchers will be attached to the DNA origami structure at designated positions. We propose concepts for nanoscopic tilting balances and spring balances. The former will enable us to measure ligand interactions in comparative assays, the latter will provide an analog readout mechanism of the sensed force: In analogy to the function of a sliding caliper, changes in distance between fluorophores of varying colors and their quenchers will lead to chromatic changes in the detected fluorescence spectrum allowing non-invasive readout of the force sensor’s state. For the future, we envision non-invasive force measurements in living cells and materials as well as new approaches to sense molecular interactions.