聚乙二醇单分子的界面扩散:荧光关联光谱与单分子轨迹追踪测量的一致性

Interfacial diffusion of single polyethylene oxide molecules:the consistency between fluorescence correlation spectroscopy and single molecule fluorescence tracking

高分子表界面的扩散运动在决定体系流变学性质、界面化学反应速率、相分离及其动力学、生物功能与信号传导等方面发挥着关键作用,因而,有效、准确地测量表界面处单个高分子的扩散运动具有十分重要的意义.本文以荧光关联光谱、单分子荧光轨迹追踪技术为手段,以吸附于固液界面的聚乙二醇(PEO)分子为模型体系,对上述两种研究方法进行了详细的比较.结果表明,虽然两种方法原理不同,覆盖的时间窗口不同,测量空间范围不同,但是在合适的测量时间窗口内对理想界面(水/硅烷化单晶薄膜的界面)处的PEO单分子扩散运动进行测量,获得了一致的扩散系数结果,表明了两种研究方法对理想界面处单分子扩散测量的准确性与可靠性.

Due to the importance of investigation into interfacial diffusion of single polymer molecules,it is essential to conduct effective and precise measurements of interfacial diffusion.Since there have been debates on the difference between two major methods for interfacial diffusion measurement,ie.,fluorescence correlation spectroscopy and single molecule fluorescence imaging and tracking,the current study is trying to address this issue,by using these two methods to measure lateral diffusion of single molecules of polyethylene oxide(PEO)adsorbed on the interface between water and alkane silane monolayers.The results have demonstrated that due to the homogeneity of the single crystalline monolayer,the measurements on lateral diffusion of fluorescence-labeled PEO at the interface by the two methods provide the same results,despite their difference in principle,time window and length scale of measurements.The study has proved that both fluorescence correlation spectroscopy and single molecule fluorescence imaging and tracking can provide reliable measurements on interfacial diffusion of single polymer molecules on homogeneous or nearly ideal interfaces.