Nanoparticles in a nanochannel: Van der Waals interaction and diffusion

Kinetic processes occurring with participation of metal or oxide nanoparticles (NPs) in solution near or inside nanochannels fabricated in a membrane can be influenced by van der Waals interaction with a membrane. In addition, hydrodynamic slowdown of NP diffusion may be important under such conditions. In applications, NPs of this category can be covered by a thin protein layer referred to as protein corona, which may prevent direct contact of NPs with a membrane. In this context, an analytical expression is presented for van der Waals interaction of a spherical NP with a membrane when a NP is located near or inside a cylindrical nanochannel at the channel axis. The interaction is shown to be often appreciable (much higher than the thermal energy) and strongly dependent on the coordinate. Taking this factor and slowdown of diffusion into account, a general expression for the permeability of a channel is derived.