ABSTRACT
The short working distance of microscope objectives has severely restricted the application of optical micromanipulation techniques at larger depths. We show the first use of fiber-optic tweezers toward controlled guidance of neuronal growth cones and stretching of neurons. Further, by mode locking, the fiber-optic tweezers beam was converted to fiber-optic scissors, enabling dissection of neuronal processes and thus allowing study of the subsequent response of neurons to localized injury. At high average powers, lysis of a three-dimensionally trapped cell was accomplished.
Subject(s)
Cell Separation/instrumentation , Laser Therapy/instrumentation , Micromanipulation/instrumentation , Microsurgery/instrumentation , Optical Tweezers , Animals , CHO Cells , Cell Separation/methods , Computer-Aided Design , Cricetinae , Cricetulus , Equipment Design , Equipment Failure Analysis , Micromanipulation/methods , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
There has been considerable current interest in the rotational behavior of red blood cells (RBCs) in optical tweezers. However, the mechanism of rotation in polarized tweezers is still not well understood and conflicts exist in the understanding of this phenomenon. Therefore, we reexamined the underlying phenomenon by use of confocal fluorescence microscopy in combination with optical tweezers. Under different osmolarities of the buffer, the three-dimensionally reconstructed images showed that the trapped RBC maintains its shape and is oriented in the vertical direction. Using dual optical tweezers, the RBC could also be oriented three-dimensionally in a controlled manner. The mechanism of orientation and alignment of RBCs with the polarization of the tweezers' beam was attributed to its form-birefringence rather than optical birefringence.
Subject(s)
Erythrocytes/cytology , Optical Tweezers , Birefringence , Cell Shape , Humans , Imaging, Three-Dimensional , Microscopy, Confocal , Microscopy, Fluorescence , RotationABSTRACT
It has recently been shown that a red blood cell (RBC) can be used as optically driven motor. The mechanism for rotation is however not fully understood. While the dependence on osmolarity of the buffer led us to conclude that the osmolarity dependent changes in shape of the cell are responsible for the observed rotation, role of ion gradients and folding of RBC to a rod shape has been invoked by Dharmadhikari et al to explain their observations. In this paper we report results of studies undertaken to understand the dynamics of a RBC when it is optically tweezed. The results obtained support our earlier conjecture that osmolarity dependent changes in shape of the cell are responsible for the observed rotation.
