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外泌体在细胞生理病理活动过程中起着重要的调控作用,研究外泌体的行为特性对于揭示生命活动及疾病发生发展的内在机理具有重要的基础意义.然而由于缺乏合适的观测手段及方法,目前对于活体状态下外泌体结构及特性的认知仍然很不足.原子力显微镜(AFM)的发明为研究溶液环境下天然状态生物样本提供了强大的技术工具,已成为生物学重要研究手段.本文利用AFM对单个活体状态外泌体的纳米结构及机械特性进行了研究.通过多聚赖氨酸静电吸附作用将从淋巴瘤患者骨髓中分离的外泌体吸附至基底,在溶液环境下实现了对单个活体状态外泌体的高质量AFM形貌成像并通过与空气中成像结果进行对比揭示了空气干燥处理对外泌体形貌的影响.在此基础上,分别利用AFM压痕试验和多参数成像技术实现了对单个活体状态外泌体机械特性的定量测量和可视化表征.最后基于所建立的方法技术揭示了化学处理后外泌体结构和机械特性的动态变化.研究结果为研究纳米尺度下活体状态外泌体的结构及特性,以更好理解天然状态外泌体的生理行为提供了新的方法和思路,对于外泌体研究具有潜在积极的意义.“,”Exosomes play an important role in the fulfillment of cellular physiological activities and are strongly involved in the pathological processes of numerous diseases.Investigating the behaviors of exosomes is therefore of critical significance for revealing the underlying mechanisms guiding life mysteries and diseases.Nevertheless,due to the lack of adequate tools,the detailed structures and mechanics of living exosomes in their native states are still not fully understood.In this work,atomic force microscopy(AFM),a powerful multifunctional tool for characterizing native biological samples without pretreatments under aqueous conditions,was utilized to probe the nanostructures and mechanics of single living exosomes prepared from clinical cancer patients.Firstly,by attaching exosomes isolated from the bone marrow of lymphoma patients onto the substrates with electrostatic adsorption,single living exosomes were clearly visualized by AFM in situ imaging in liquids.The morphological differences of exosomes in liquids and in air were revealed.Secondly,the mechanical properties of single living exosomes were quantitatively and visually studied by AFM indentation assays and AFM multiparametric imaging,respectively.Finally,structural and mechanical changes of exosomes after the treatment of chemical fixation were revealed by AFM.The research benefits investigating the structures and properties of living exosomes at the nanoscale for comprehensively understanding the behaviors of exosomes,which will have potential impacts on the studies of exosomes.