The advent of atomic force microscopy(AFM)provides a powerful tool for investigating the behaviors of single living cells under near physiological conditions.Besides acquiring the images of cellular ultra-microstructu...The advent of atomic force microscopy(AFM)provides a powerful tool for investigating the behaviors of single living cells under near physiological conditions.Besides acquiring the images of cellular ultra-microstructures with nanometer resolution,the most remarkable advances are achieved on the use of AFM indenting technique to quantify the mechanical properties of single living cells.By indenting single living cells with AFM tip,we can obtain the mechanical properties of cells and monitor their dynamic changes during the biological processes(e.g.,after the stimulation of drugs).AFM indentation-based mechanical analysis of single cells provides a novel approach to characterize the behaviors of cells from the perspective of biomechanics,considerably complementing the traditional biological experimental methods.Now,AFM indentation technique has been widely used in the life sciences,yielding a large amount of novel information that is meaningful to our understanding of the underlying mechanisms that govern the cellular biological functions.Here,based on the authors’own researches on AFM measurement of cellular mechanical properties,the principle and method of AFM indentation technique was presented,the recent progress of measuring the cellular mechanical properties using AFM was summarized,and the challenges of AFM single-cell nanomechanical analysis were discussed.展开更多
Atomic force microscopy (AFM) was used to locate CD20 molecules on the surface of lymphoma Raji cells. Rituximab (a monoclonal antibody against CD20) molecules were linked onto the AFM tip via a polyethylene glycol (P...Atomic force microscopy (AFM) was used to locate CD20 molecules on the surface of lymphoma Raji cells. Rituximab (a monoclonal antibody against CD20) molecules were linked onto the AFM tip via a polyethylene glycol (PEG) linker. Raji cells were adsorbed onto glass slides coated with poly-L-lysine. First, the CD20 distribution in a local area of the cell surface was visualized using the AFM lift scan mode. Second, 16 × 16 force curves were obtained from the same cell area to construct the CD20-rituximab binding force map. Finally, free rituximab was added to block the CD20 molecules on the cell surface and the lift phase image and CD20-rituximab force map were obtained again. The experimental results indicated that when the lift height was greater than the length of the PEG linker, no recognition sites were observed in the lift phase image. However, as the lift height decreased to the length of the PEG linker, some recognition sites were observed in the lift phase image and these sites were generally consistent with the pixels in the force map. After blocking, both the recognition sites in the lift phase image and the gray pixels in the binding force map decreased markedly. These results can improve our understanding of the distribution of protein molecules on the cell surface and facilitate further investigations into cellular functions.展开更多
细胞的力学性质与生命体的功能和健康都是息息相关的,而原子力显微镜(atomic force microscope,AFM)是研究细胞力学性质最好的仪器之一。该文较为详细叙述了AFM力曲线测量原理,以及分析AFM实验数据的常用模型。作者用该文所提到的模型...细胞的力学性质与生命体的功能和健康都是息息相关的,而原子力显微镜(atomic force microscope,AFM)是研究细胞力学性质最好的仪器之一。该文较为详细叙述了AFM力曲线测量原理,以及分析AFM实验数据的常用模型。作者用该文所提到的模型分析了肺癌细胞的弹性,结果显示在加载速率比较低的情况下,三种计算方法计算得到的结果没有显著差别,而在加载速率高于8μm/s时,结果则有显著差异。展开更多
本文结合电化学方法与原子力显微镜力曲线技术,研究了两种烷基侧链长度不同的离子液体BMITFSA和OMITFSA在Au(111)电极表面附近的层状结构的数目和耐受力对电位的依赖性,探究了烷基侧链长度变化对界面层状结构的影响.研究表明,不同烷基...本文结合电化学方法与原子力显微镜力曲线技术,研究了两种烷基侧链长度不同的离子液体BMITFSA和OMITFSA在Au(111)电极表面附近的层状结构的数目和耐受力对电位的依赖性,探究了烷基侧链长度变化对界面层状结构的影响.研究表明,不同烷基侧链长度的离子液体体系力-电位曲线形状基本相似.在零电荷电位(the potential of zero charge,PZC)附近时,力值最小,因为此时电极表面荷电量较小,层状结构不稳定;电位偏离PZC的过程中,第一层层状结构力值呈现先增大后减小的趋势.受到烷基侧链所处的不同位置影响,在PZC电位以负,短侧链离子液体的层状结构稳定性较好,而PZC电位以正,长侧链离子液体的稳定性较好.展开更多
氧化石墨烯(Graphene oxide,GO)表面具有丰富的官能团和较高的比表面积,能够作为膜材料应用于膜分离技术.然而,目前合成GO的技术很难保证其横向尺寸的均一性.此外,GO在自然水环境中分散性的稳定性受环境中pH值和离子强度的影响.本文研...氧化石墨烯(Graphene oxide,GO)表面具有丰富的官能团和较高的比表面积,能够作为膜材料应用于膜分离技术.然而,目前合成GO的技术很难保证其横向尺寸的均一性.此外,GO在自然水环境中分散性的稳定性受环境中pH值和离子强度的影响.本文研究了横向尺寸、pH值和离子强度对GO表面双电层电荷或结构组装所需的相互作用力的影响.从原位原子力显微镜(Atomic force microscope,AFM)获得的力-距离曲线(F-D)可以看出,溶液条件对DLVO力的作用.GO的双电层静电斥力随着pH值的升高而增大,这可能是由于表面官能团的电离作用增强所致.但随着离子强度的增加,双电层斥力减小,得到的数据与DLVO理论一致.通过Zeta电位和开尔文探针力显微镜(Kelvin probe force microscopy,KPFM)测量,确定了氧化石墨烯片层表面电荷的不均匀性.展开更多
基金The project was supported by the National Natural Science Foundation of China(60904095,61175103)National High Technology Research and Development Program of China(863)(2009AA03Z316)Chinese Academy of Sciences Foreign Experts Affairs International Partnership Program for Creative Research Teams~~
基金supported by the NationalNatural Science Foundation of China(61175103,61327014)CASFEA International Partnership Program for Creative Research Teams
文摘The advent of atomic force microscopy(AFM)provides a powerful tool for investigating the behaviors of single living cells under near physiological conditions.Besides acquiring the images of cellular ultra-microstructures with nanometer resolution,the most remarkable advances are achieved on the use of AFM indenting technique to quantify the mechanical properties of single living cells.By indenting single living cells with AFM tip,we can obtain the mechanical properties of cells and monitor their dynamic changes during the biological processes(e.g.,after the stimulation of drugs).AFM indentation-based mechanical analysis of single cells provides a novel approach to characterize the behaviors of cells from the perspective of biomechanics,considerably complementing the traditional biological experimental methods.Now,AFM indentation technique has been widely used in the life sciences,yielding a large amount of novel information that is meaningful to our understanding of the underlying mechanisms that govern the cellular biological functions.Here,based on the authors’own researches on AFM measurement of cellular mechanical properties,the principle and method of AFM indentation technique was presented,the recent progress of measuring the cellular mechanical properties using AFM was summarized,and the challenges of AFM single-cell nanomechanical analysis were discussed.
基金supported by the National Natural Science Foundation of China (60904095, 61175103)the CAS FEA International Partnership Program for Creative Research Teams
文摘Atomic force microscopy (AFM) was used to locate CD20 molecules on the surface of lymphoma Raji cells. Rituximab (a monoclonal antibody against CD20) molecules were linked onto the AFM tip via a polyethylene glycol (PEG) linker. Raji cells were adsorbed onto glass slides coated with poly-L-lysine. First, the CD20 distribution in a local area of the cell surface was visualized using the AFM lift scan mode. Second, 16 × 16 force curves were obtained from the same cell area to construct the CD20-rituximab binding force map. Finally, free rituximab was added to block the CD20 molecules on the cell surface and the lift phase image and CD20-rituximab force map were obtained again. The experimental results indicated that when the lift height was greater than the length of the PEG linker, no recognition sites were observed in the lift phase image. However, as the lift height decreased to the length of the PEG linker, some recognition sites were observed in the lift phase image and these sites were generally consistent with the pixels in the force map. After blocking, both the recognition sites in the lift phase image and the gray pixels in the binding force map decreased markedly. These results can improve our understanding of the distribution of protein molecules on the cell surface and facilitate further investigations into cellular functions.
文摘细胞的力学性质与生命体的功能和健康都是息息相关的,而原子力显微镜(atomic force microscope,AFM)是研究细胞力学性质最好的仪器之一。该文较为详细叙述了AFM力曲线测量原理,以及分析AFM实验数据的常用模型。作者用该文所提到的模型分析了肺癌细胞的弹性,结果显示在加载速率比较低的情况下,三种计算方法计算得到的结果没有显著差别,而在加载速率高于8μm/s时,结果则有显著差异。
文摘本文结合电化学方法与原子力显微镜力曲线技术,研究了两种烷基侧链长度不同的离子液体BMITFSA和OMITFSA在Au(111)电极表面附近的层状结构的数目和耐受力对电位的依赖性,探究了烷基侧链长度变化对界面层状结构的影响.研究表明,不同烷基侧链长度的离子液体体系力-电位曲线形状基本相似.在零电荷电位(the potential of zero charge,PZC)附近时,力值最小,因为此时电极表面荷电量较小,层状结构不稳定;电位偏离PZC的过程中,第一层层状结构力值呈现先增大后减小的趋势.受到烷基侧链所处的不同位置影响,在PZC电位以负,短侧链离子液体的层状结构稳定性较好,而PZC电位以正,长侧链离子液体的稳定性较好.
文摘氧化石墨烯(Graphene oxide,GO)表面具有丰富的官能团和较高的比表面积,能够作为膜材料应用于膜分离技术.然而,目前合成GO的技术很难保证其横向尺寸的均一性.此外,GO在自然水环境中分散性的稳定性受环境中pH值和离子强度的影响.本文研究了横向尺寸、pH值和离子强度对GO表面双电层电荷或结构组装所需的相互作用力的影响.从原位原子力显微镜(Atomic force microscope,AFM)获得的力-距离曲线(F-D)可以看出,溶液条件对DLVO力的作用.GO的双电层静电斥力随着pH值的升高而增大,这可能是由于表面官能团的电离作用增强所致.但随着离子强度的增加,双电层斥力减小,得到的数据与DLVO理论一致.通过Zeta电位和开尔文探针力显微镜(Kelvin probe force microscopy,KPFM)测量,确定了氧化石墨烯片层表面电荷的不均匀性.
