Resistive Pulse Sensing of Phytoglycogen Nanoparticle Translocation: Examining Structure and Brownian motion

Dendrimers are an important platform for a variety of applications such as cosmetics, lubricants, and drug delivery. Understanding the relationship between structure, mobility, and mechanical properties is crucial for designing new systems for these applications. In particular, examining the transport of nanoparticles (NPs) through nanopores and nanochannels by translocation may enable high-throughput analysis of these properties. These measurements track ionic current through the nanochannel, which is blocked when a particle occludes the channel. Here, we studied experimentally the translocation of phytoglycogen NPs through single solid-state SiN_x nanochannels with diameters between 40 and 100 nm, and lengths of 100 nm. Using Poisson-Nernst-Planck calculations, we quantitatively predicted the magnitude of the current blockade of phytogylcogen NPs by including a “hardness parameter” term to describe the degree to which the NPs occlude the nanochannel, and found good agreement with neutron scattering measurements. The NPs diffused through the nanochannels under pure three-dimensional Brownian motion, and diffusion coefficients were measured in quantitative agreement with dynamic light scattering.