细胞机械特性作为一种无标签(Label-free)的生物标记,正得到越来越多的关注.然而现有进行细胞机械特性测量的方法多以手工模式进行,耗时长、效率低下,无法满足生物学统计分析对大批量样品测试的要求.针对该问题,本文在原子力显微镜(Atomic force microscopy,AFM)基础上,建立了一套高速自动化的细胞机械特性测量系统.该系统利用图像处理方法来识别细胞,利用局部扫描来实现AFM针尖和细胞相对位置的精确标定,进而不需要AFM成像就能实现细胞机械特性的连续测定,配合上程序化控制的运动载物平台,可以高速自动化完成大范围区域内细胞机械特性的批量规模化测量.实验结果表明,该系统可以使得细胞机械特性的测量效率提高27倍,从而为Label-free生物标记的批量化测试提供了技术支撑.
The invention of atomic force microscopy(AFM) has provided new technology for measuring specific molecular interaction forces.Using AFM single-molecule force spectroscopy(SMFS) techniques,CD20-Rimximab rupture forces were measured on purified CD20 proteins,Raji cells,and lymphoma patient B cells.Rimximab molecules were linked onto AFM tips using AFM probe functionalization technology,and purified CD20 proteins were attached to mica using substrate functionalization technology.Raji cells(a lymphoma cell line) or lymphoma patient cells were immobilized on a glass substrate via electrostatic adsorption and chemical fixation.The topography of the purified CD20 proteins,Raji cells,and patient lymphoma cells was visualized using AFM imaging and the differences in the rupture forces were analyzed and measured.The results showed that the rupture forces between the CD20 proteins on Raji cells and Rituximab were markedly smaller than those for purified CD20 proteins and CD20 proteins on lymphoma patient B cells.These findings provide an effective experimental method for investigating the mechanisms underlying the variable efficacy of Rituximab.
LI MiLIU LianQingXI NingWANG YueChaoDONG ZaiLiLI GuangYongXIAO XiuBinZHANG WeiJing
The observation of friction anisotropy on graphene by friction measurement at atomic scale has been reported in this paper.Atomic-scale friction measurement revealed friction anisotropy with a periodicity of 60°,which is consistent with the hexagonal periodicity of the graphene.Both experiments and theory show that the value of the friction force is related to the graphene lattice orientation,and the friction force along armchair orientation is also larger than the one along zigzag orientation.These results will play a critical role in the use of graphene to manufacture nanoscale devices.
ZHANG YuLIU LianQingXI NingWANG YueChaoDONG ZaiLiWEJINYA Uchechukwu C
