Magnetic Tweezers

这笔拨款将支持磁性镊子装置的开发，以测量细胞质和细胞外基质的局部粘弹性和结构特性。磁镊子产生已知大小和方向的磁场。磁场对注入细胞质或基质中的具有一定几何和磁性质的球形磁性颗粒施加磁力。用光学方法监测磁粒子的运动。粒子的运动轨迹被记录在计算机上。同时，粒子的运动也用标准模型来描述。通过模型轨迹与实验轨迹的匹配得到细胞质或基质的局部粘弹性参数。这些参数的知识提供了存在于细胞质（即细胞骨架）和细胞外基质中的生物大分子相互连接网络的局部结构的信息。磁镊子还将用于研究细胞内应力传播。目前，磁镊子是唯一一种能够以非破坏性的方式测量生物系统局部粘弹性的仪器。将几个磁性镊子组合在一起，可以产生类似于光镊产生的效果。后一种情况下的激光陷阱类似于前一种情况下的磁陷阱。同时，磁性镊子的开发和操作成本显著降低。

This grant will support the development of a magnetic tweezers apparatus to measure local viscoelastic and structural properties of the cell cytoplasm and the extracellular matrix. The magnetic tweezers produce a magnetic field of known magnitude and direction. The field exerts a magnetic force on spherical magnetic particles with definite geometric and magnetic properties, which are injected into the cytoplasm or matrix. The motion of the magnetic particle is monitored using optical methods. The trajectory of the particle is recorded on a computer. Simultaneously, the motion of the particle is also described in terms of standard models. The local viscoelastic parameters of the cytoplasm or matrix are obtained from the matching of the model trajectory and the experimentally obtained trajectory. The knowledge of these parameters provides information on the local structure of interconnected networks of biological macromolecules that exist in the cytoplasm (i.e. cytoskeleton) and the extracellular matrix. The magnetic tweezers will also be used to study intracellular stress propagation. At present the magnetic tweezers are the only apparatus that allows the measurement of local viscoelastic properties of biological systems in a non-destructive way. By combining several magnetic tweezers, effects similar to those produced by optical tweezers could be generated. The laser traps in the latter case are analogous to magnetic traps in the former case. At the same time, the costs associated with the development and operation of a magnetic tweezers are significantly lower.