Calibration Of The Dual-trap Optical Tweezers And Force Spectroscopy Study

Human beings have never stopped the pace of biological research,from the macro aspect such as the studies of population and individual biological characteristics,to studies in single cellular and molecular level.Driven by the pursuit of a deeper understanding of the mystery of life,various tools have been developed for the study of life science.And the invention of single molecule force spectroscopy techniques has opened up new avenue for the study of biological macromolecules.Optical tweezers,as a representative of the techniques mentioned above,use the radiation pressure produced by a tightly focused continuous wave laser beam to achieve non-contact trapping and manipulation of micron-sized particles with sub-nanometer accuracy and sub-millisecond time resolution.After rapid development in recent years,optical trapping has become one of the most powerful techniques in the study of single molecular.The paper contrasts the difference between single beam optical trapping and dual-beam optical trapping.Furthermore,after the calibration of the home-built dualbeam optical trapping system,dual signal crosstalk is analyzed and several approaches are posed to eliminate the influence of crosstalk so as to improve the sensitivity and precision of the system.The main works and progresses in this paper are listed below:1.The principle of optical trapping is reviewed,then with an overview on application development status of optical tweezers at Home and Abroad.According to the comparative study of the construction of the single beam optical trap and dual-beam optical trap,the strengths of dual-beam optical trap and the interference factors induced by it are provided.2.Based on the properties of the dual-beam optical trap,possible limiting factors of system precision are studied.Then,works on correction and compensation for reducing the impact of dual signal crosstalk are done.Finally,the system is calibrated using compensation parameters.3.Microspheres,which is commonly used in biological experiments,are tested on the system in order to study their influence on trapping stiffness and determine the best experimental environment.4.Common biological samples are briefly introduced,and feasible experimental processes are established.Experiments on DsDNA and proteins are provided and their force spectroscopies are shown later so that the performance of the home-built system is verified.