Robotic Micromanipulation and Mechanical Characterization of Intracellular Structures

在过去的二十年里，单细胞操作和测量取得了长足的进步。这项研究将超越最先进的水平，为细胞内的3D操作和机械测量开发一种变革性的平台技术。新的平台和技术将使亚微米磁珠（以及后来更复杂的磁性设备）在细胞内进行3D导航，以执行机械测量，这将开启细胞内物理测量和操纵的令人兴奋的新时代。 近期目标包括：目标1：建立一个新的机器人磁镊平台，用于3D细胞内导航和测量;目标2：开发新的磁力模型和力/位置控制方法，用于控制具有3D共聚焦显微镜图像反馈的亚微米磁珠;目标3：在完整细胞中的细胞核上的不同位置处进行机械测量，以量化沿着细胞核的沿着不同方向的刚度异质性。为了实现这些目标，我们将开发一种新的多极磁镊平台和技术，以操纵亚微米磁珠，并解决低带宽高分辨率视觉反馈，亚微米位置控制和皮牛顿力控制的挑战。具体来说，我们将追求3D磁镊平台的设计，建造，分析建模，数值模拟，系统测试/调试和优化。我们将建立非线性磁场模型，将驱动电流与磁场产生联系起来，并量化力的应用。还将进行磁场模拟以计算施加在亚微米磁珠上的磁力。将进行校准实验，并将在实验结果与工作空间中每个点的分析建模和有限元模拟结果之间量化位置-力误差。 将开发基于珠动力学的广义预测控制器，以将亚微米珠定位到完整细胞中的细胞核上的不同位置，从而以不同的速度使细胞核稳定。将使用力学模型分析实验数据，以生成癌细胞发育不同阶段细胞核上每个测量位置的刚度/模量/粘度图。将测量沿着细胞核的长轴和短轴的机械性质的极性、力诱导的较软轴的硬化以及癌细胞迁移行为的改变。癌细胞迁移的细胞核的机械极性的必要性将被明确证明。该研究计划将培养HQP从事NSE研究事业或满足加拿大仪器和生物技术行业的巨大需求。

The past two decades have seen strides in single-cell manipulation and measurement. This research will go beyond the state of the art to develop a transformative platform technology for 3D manipulation and mechanical measurement inside a cell. The new platform and techniques will enable 3D navigation of a sub-micron magnetic bead (and later more sophisticated magnetic devices) inside a cell to perform mechanical measurements, which will open an exciting new era of intracellular physical measurement and manipulation. The near-term objectives include: Aim 1: Establish a new robotic magnetic tweezers platform for 3D intracellular navigation and measurement; Aim 2: Develop new magnetic force models and force/position control methods for controlling a sub-micron magnetic bead with 3D confocal microscopy image feedback; Aim 3: Perform mechanical measurements at different locations on the cell nucleus in an intact cell to quantify stiffness heterogeneity along different directions of the cell nucleus. To achieve these goals, we will develop a new multi-pole magnetic tweezers platform and technologies to manipulate a sub-micron magnetic bead and tackle the challenges of low-bandwidth high-resolution visual feedback, sub-micron position control, and picoNewton force control. Specifically, we will pursue 3D magnetic tweezers platform design, construction, analytical modeling, numerical simulation, system testing/debugging, and optimization. We will establish nonlinear magnetic field models that relate driving currents to magnetic field generation and quantify force application. Magnetic field simulation will also be conducted to calculate magnetic forces exerted on the sub-micron magnetic bead. Calibration experiments will be performed and position-force errors will be quantified among experimental results and results from analytical modeling and finite element simulation for each point in the workspace. Generalized predictive controllers based on bead dynamics will be developed to position a sub-micron bead to different locations on the cell nucleus in an intact cell to indent the cell nucleus at varying speeds. Experimental data will be analyzed with mechanics models to generate a stiffness/modulus/viscosity map for each measured location on the cell nucleus at different stages of cancer cell development. Polarity of mechanical properties along the major and minor axes of the cell nucleus, force-induced stiffening of the softer axis, and alteration of the migratory behavior of cancer cells will be measured. The necessity of mechanical polarity of the cell nucleus for cancer cell migration will be unequivocally demonstrated. This research program will train HQP to pursue research careers in NSE or fulfill the great demand of Canadian instrumentation and biotech industries.