title: Microscopic Movement of Slow-Diffusing Nanoparticles in Cylindrical Nanopores Studied with Three-Dimensional Tracking.
abstract: To study slow mass transport in confined environments, we developed a three-dimensional (3D) single-particle localization technique to track their microscopic movements in cylindrical nanopores. Under two model conditions, particles are retained much longer inside the pores: (1) increased solvent viscosity, which slows down the particle throughout the whole pore, and (2) increased pore wall affinity, which slows down the particle only at the wall. In viscous solvents, the particle steps decrease proportionally to the increment of the viscosity, leading to macroscopically slow diffusion. As a contrast, the particles in sticky pores are microscopically active by showing limited reduction of step sizes. A restricted diffusion mode, possibly caused by the heterogeneous environment in sticky pores, is the main reason for macroscopically slow diffusion. This study shows that it is possible to differentiate slow diffusion in confined environments caused by different mechanisms.
authors.affiliation: Chemistry Department, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Luyang
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Chemistry Department, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Yaning
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: Chemistry Department, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Chemistry Department, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Nathalia
authors.initials: N
authors.lastname: Ortiz
authors.affiliation: Chemistry Department, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Fang
authors.initials: F
authors.lastname: Chen
authors.affiliation: Chemistry Department, North Carolina State University , Raleigh, North Carolina 27695, United States.
authors.forename: Gufeng
authors.initials: G
authors.lastname: Wang