Optical Chopsticks for Multidimensional Cellular Mechanics Study

皮：刘，宇翔提案编号：1403257机构：伍斯特理工学院标题：多维细胞力学研究的光学筷子机械力在细胞形态、运动、增殖和生理中起着重要作用。尽管它们很重要，但目前关于机械力对细胞生物学作用的了解仍然有限，特别是对于三维(3D)环境中的细胞，与二维(2D)基质上的细胞相比，它们的行为非常不同。其中一个原因是缺乏合适的技术和工具来非侵入性地施加特征良好的力并精确地测量3D环境中细胞的机械响应。拟议的研究旨在开发和使用一种名为光学筷子的新工具。这将使在非线性、非均匀的3D环境中同时进行力施加和细胞响应测量，打破现有技术的限制。开发的光学筷子将是便携式的，易于使用，并由广泛的商业化光纤组件支持。这一研究成果不仅将对细胞生物物理学、机械生物学和生物光子学等多个领域产生重大影响，而且将进一步阐明其病理机制和诊断方法。该研究项目将为从高中到研究生的广泛受众提供跨学科的培训和教育。细胞力学已经用不同的方法进行了定量研究，包括基于荧光成像的牵引力显微镜、原子力显微镜(AFM)和光学镊子。然而，到目前为止，还没有显示出在3D环境中同时应用和测量3D力的工作，因为3D环境更接近体内环境。原子力显微镜受到侧向力测量分辨率的限制，而传统的光钳由于工作距离有限，不适合对3D矩阵中的单元进行测量。提出的光学筷子是基于光纤镊子，可以创建3D光学陷阱，用于非接触力的施加和测量。只要介质是透明的，光纤镊子就可以到达介质中的任何地方，这对于嵌入3D矩阵的细胞的力测量尤其重要。此外，将实施光纤调制和检测系统，以便于对3D矩阵单元上的所需波形进行光学力的动态控制。有了这些能力，光学筷子将与荧光成像技术相结合，用于时空表征2D衬底上细胞骨架中的力传播。更重要的是，光学筷子将被用来精确测量非线性非均匀3D矩阵中的胞力。同时，对细胞施加方向和大小可控的三维力，研究细胞在外界机械刺激下的迁移。提出了四个具体目标。1)发展光开关。2)实现了光学筷子，模拟了光学力的产生。3)在二维衬底上进行细胞力学研究。4)在三维矩阵中进行细胞力学研究。这项研究的结果有望对包括细胞生物物理学、机械生物学和生物光子学在内的多个领域产生重大影响，并进一步阐明病理机制和诊断。

PI: Liu, Yuxiang Proposal Number: 1403257Institution: Worcester Polytechnic InstituteTitle: Optical Chopsticks for Multidimensional Cellular Mechanics StudyMechanical forces play an important role in cell morphology, motility, proliferation, and physiology. Despite their importance, the current knowledge on the role of mechanical forces on cell biology is still limited, especially for cells in a three-dimensional (3D) environment, which behave very differently compared with those on two-dimensional (2D) substrates. One of the reasons is lack of suitable techniques and tools to non-invasively apply well characterized forces to and precisely measure mechanical response from cells in 3D environments. The proposed studies aim to develop and use a novel tool entitled ?optical chopsticks,? which would enable simultaneous force application and cell response measurements in a nonlinear heterogeneous 3D environment, breaking the limitation of existing techniques. The developed optical chopsticks will be portable, easy to work with, and supported by a broad spectrum of commercialized fiber optic components. The outcome of this research will not only have a significant impact to multiple areas such as cellular biophysics, mechanobiology, and biophotonics, but also shed further light on pathological mechanisms and diagnosis. The research project will provide interdisciplinary training and education for a broad audience of students ranging from high school to graduate school.Cell mechanics have been quantitatively investigated with different methods, including fluorescence imaging-based traction force microscopy, atomic force microscopy (AFM), and optical tweezers. However, no work has been shown so far to both apply and measure 3D forces in a 3D environment, which is much closer to the in vivo environment. AFM is limited by the resolution of lateral force measurements, while conventional optical tweezers are not suitable for measurements on cells in a 3D matrix due to limited working distances. The proposed optical chopsticks are based on fiber optical tweezers that can create 3D optical traps for non-contact force exertion and measurements. Fiber optical tweezers can reach anywhere inside the medium as long as the medium is transparent, which is especially important for force measurements on cells embedded in a 3D matrix. Moreover, a fiber optic modulation and detection system will be implemented to facilitate dynamic control of optical forces with desired waveforms on cells in a 3D matrix. With these capabilities, optical chopsticks will be integrated with fluorescence imaging techniques for spatiotemporal characterization of force propagation in cytoskeletons of cells on 2D substrates. More importantly, optical chopsticks will be used to precisely measure cell forces in a nonlinear heterogeneous 3D matrix. In the meantime, 3D forces with controllable directions and magnitudes will be applied to cells to study cell migration under external mechanical stimuli. Four specific aims are proposed. 1) To develop the optical chopstics. 2) To implement the optical chopsticks and model the optical force generation. 3) To perform cell mechanics studies on 2D substrates. 4) To perform cell mechanics studies in 3D matrices. The outcome of this research is expected to have a significant impact on multiple areas, including cellular biophysics, mechanobiology, and biophotonics, and also shed further light on pathological mechanisms and diagnosis.