應用磁光鉗於癌細胞機械性質之研究

Abstract

分析細胞內部的力學特性將有助於了解細胞本身的性質；如近幾年研究發現細胞外型影響細胞存活率之高低，以及受感染之細胞其機械性質明顯不同等等，因此探討控制細胞外型與遷徙的細胞骨架(Cytoskeleton)其與周圍胞器之間的力學特性等，為相當值得研究之課題。為了探討細胞內部的力學特性，精密的細胞操作儀器是必需的。例如原子力顯微鏡適合細胞機械性質的局部量測、光鉗適合DNA和RNA之研究以及磁鉗將磁顆粒與生醫結合應用。本研究以可控制磁顆粒的磁鉗並結合光鉗作為探討細胞力學特性之生物操控儀器。 為從事本論文探討，實驗研究首先著手架設整合磁鉗與光鉗於奈(微)米級的磁顆粒和癌細胞的操控，並將其應用於探討細胞之機械性質。藉由量測細胞力學特性所得之數據，再代入等效的數學模型(modified Voigt model)，並進一步利用curve fitting method將細胞的黏彈性行為數據化成彈性係數和黏滯係數。藉由探究不同細胞的機械性質，將有助於瞭解細胞於不同力學情況與生化環境下的反應機制。 本研究所使用的細胞為人體的腎臟癌細胞(human renal cancer cell, 786-0)並利用其吞噬的特性將磁顆粒引入細胞內。再施予一交變的磁場，磁力大小為95 pN，進而藉由分析磁顆粒的位移反應而得到癌細胞的黏滯係數為介於8.3 Pa×s至39.3 Pa×s，而彈性係數則是3.7 Pa至11 Pa。另外，從實驗結果也顯示接近細胞膜之區域，其彈性係數高於細胞質的五倍，但黏滯係數則低兩倍之多。因而磁光鉗為一套十分具有發展潛力之系統且利用本系統將可有效率的量測與分析細胞之機械性質，此更可應用於日後探討細胞之力學行為並發展於生物醫學的領域。

Studying the intracellular interaction force is helpful for understanding the characteristics of cells. In recent years, it was found that cell shape plays an important role of controlling cell life and death. Therefore, the mechanical force comes from the interaction of cytoskeleton, which controls cell shape and cell motility, is worthy studying. In order to study the interaction within cells, nano(micro)-manipulation for cells is required. For example, AFM is used to analyze local mechanical properties of cells. In this thesis, we start from constructing and integrate magnetic tweezers with optical tweezers for manipulate small magnetic particles and specific cells. To explore the mechanism underlying for the mechanical properties of different compartments of cell, the mechanical equivalent models were applied to quantify the viscoelastic behavior of cells such as viscosity, elasticity and relaxation time. Depending on discussing these mechanical properties of different compartments of cell, it will help us to understand the difference of cell organelles in different conditions. In this thesis, human renal cancer cells were used to be examined and measured locally the mechanical properties of them by applying alternative magnetic field with 95 pN magnetic force. By analyzing the experimental data in terms of modified Voigt model, the cytoplasmic viscosity of the cancer cell is from 8.3 Pa×s to 39.3 Pa×s and the elasticity is from 3.7 Pa to 11 Pa. It was also found that the elasticity of the compartment close to cell membrane is 6-fold stiffer than the one of cytoplasm but viscosity of it is 2-fold less than the one of cytoplasm. In the end, magneto-optical tweezers is a potential technique for bioresearch and we can measure and analyze the mechanical properties of cells efficiently by using this system which can study the dynamic behavior of cells and provide novel information on biomedicine.