DNA is a versatile biomaterial with well-defined mechanical and biochemical properties. It has been broadly adopted to synthesize tension sensors that calibrate and visualize cellular forces at the cell-matrix interface. Here we showed that DNA-based tension sensors are vulnerable to deoxyribonucleases (DNases) which cells may express on cell membrane or secret to the culture environment. These DNases can damage the sensors, lower signal-to-noise ratio or even produce false signal in cellular force imaging. To address this issue, we tested peptide nucleic acid (PNA), chemically modified RNA and their hybrids with DNA as alternative biomaterials for constructing tension sensors. Four duplexes: double-stranded DNA (dsDNA), PNA/DNA, dsRNA (modified RNA) and PNA/RNA, were tested and evaluated in terms of DNase resistance, cellular force imaging ability and material robustness. The results showed that all PNA/DNA, dsRNA and PNA/RNA exhibited strong resistance to both soluble DNase I and membrane-bound DNase on cells. However, PNA/RNA-based tension sensor had low signal-to-noise ratio in cellular force imaging, and dsRNA-based tension sensor exhibited strong non-specific signal unrelated to cellular forces. Only PNA/DNA-based tension sensor reported cellular forces with highest signal-to-noise ratio and specificity. Collectively, we confirmed that PNA/DNA hybrid is an accessible material for the synthesis of DNase-resistant tension sensor that retains the force-reporting capability and remains stable in DNase-expressing cells. This new class of tension sensors will broaden the application of tension sensors in the study of cell mechanobiology.

中文翻译：

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基于肽核酸的张力传感器，具有强大的DNase抗性，可用于细胞力成像。

DNA是一种具有明确的机械和生化特性的通用生物材料。它已被广泛用于合成张力传感器，该传感器可校准和可视化细胞-基质界面处的细胞力。在这里，我们证明了基于DNA的张力传感器容易受到脱氧核糖核酸酶（DNase）的破坏，脱氧核糖核酸酶可能会在细胞膜上表达或者是培养环境的秘密。这些DNase会损坏传感器，降低信噪比，甚至在细胞力成像中产生错误信号。为了解决这个问题，我们测试了肽核酸（PNA），化学修饰的RNA及其与DNA的杂合体作为构建张力传感器的替代生物材料。测试了四个双链体：双链DNA（dsDNA），PNA / DNA，dsRNA（修饰的RNA）和PNA / RNA，并根据DNase抗性进行了评估，细胞力成像能力和材料坚固性。结果显示，所有PNA / DNA，dsRNA和PNA / RNA均对细胞上的可溶性DNase I和膜结合型DNase均表现出较强的抗性。但是，基于PNA / RNA的张力传感器在细胞力成像中信噪比低，而基于dsRNA的张力传感器表现出与细胞力无关的强非特异性信号。只有基于PNA / DNA的张力传感器报告的细胞力具有最高的信噪比和特异性。总的来说，我们确认PNA / DNA杂合体是用于合成DNase抗性张力传感器的一种易于获得的材料，该传感器保留了力报告功能，并在表达DNase的细胞中保持稳定。这种新型的张力传感器将拓宽张力传感器在细胞力学生物学研究中的应用。