3D Force Microscopy for Microheology & Active Transport

描述(由申请人提供)： 生物介质的流变性，包括细胞质、细胞外基质和生物凝胶，如粘液，在理解细胞内运输、病原体清除、药物输送等方面的重要性正在被认识到。相应地，由分子马达和细丝聚合驱动的生物环境中的力被理解为对于理解细胞分裂和运动、囊泡在细胞内的运输以及纤毛的敲打是必不可少的，这些都是细菌运动和粘液流体动力学的负责。我们建议将磁珠操作发展成一种新的微观技术，用于研究生物系统中的力和流变学。有三个趋势使现在成为取得快速进展的好时机。首先，磁分离技术的日益发展导致了各种大小和功能的磁性颗粒的可用，并将微型制造的磁极系统结合到硅晶片上。其次，虽然微珠流变学是一项有几十年历史的技术，但在应用亚微米尺寸的微珠测量生物凝胶的复杂粘弹性模量方面取得了新的进展，包括布朗运动和两粒子关联函数的分析。第三个发展是在用户界面领域。先进的实时三维可视化，结合触觉(触敏)控制和力探头的显示，已经在原子力显微镜中得到了应用。我们建议将这三项发展纳入这样一个系统：a)使用微型制造的磁极几何结构对悬浮在生物介质中的磁珠施加力，这将允许b)同时使用h数值孔径光学技术进行纳米级粒子跟踪和3D共焦显微镜，以及c)高级用户界面，以立即了解复杂的数据集和仪器控制。该系统的最后一个功能，即用户界面和仪器控制，将几乎完全由现有的NCRR赠款提供支持。

DESCRIPTION (provided by applicant): The importance of the rheological properties of biological media, including the cytoplasm, the extracellular matrix and biological gels such as mucus is being appreciated in understanding intracellular transport, pathogen clearance, drug delivery, to name a few. Correspondingly, forces in biological contexts, as driven by molecular motors and filament polymerization, is understood as essential for the understanding of cell division and motility, intracellular trafficking of vesicles, and the beating of cilia that are responsible for bacterial locomotion and mucus hydrodynamics. We propose to develop magnetic bead manipulation into a new microscopic technology for studying forces and rheology in biological systems. There are three trends that make now the opportune time to make rapid progress. First, there has been a growing development of magnetic separation technology that has led to the availability of a wide range of magnetic particles, in size and functionality, and the incorporation of micro-fabricated magnetic pole systems onto silicon wafers. Second, while bead rheology is a decades old technology, there have been recent developments in the application of submicron-sized beads for measuring the complex viscoelastic moduli of biological gels, including the analysis of Brownian motion and two-particle correlation functions. The third development has been in the area of user interfaces. The application of advanced 3D visualization in real time, combined with haptic (touch-sensitive) control and display of force probes has been demonstrated in atomic force microscopy. We propose to bring these three developments into a system that a) applies forces to magnetic beads suspended inside biological media using micro-fabricated pole geometries that will allow b) the simultaneous use of h numerical aperture optics for nanometer scale particle tracking and 3D confocal microscopy, and c) advanced user interfaces for the immediate understanding of complex data sets and control of the instrument. The last feature of the system, the user interface and instrument control, will be supported almost entirely from an existing NCRR grant.