Heterogeneous Nanostructures Cause Anomalous Diffusion in Lipid Monolayers

Abstract

The diffusion and mobility in biomembranes are crucial for various cell functions; however, the mechanisms involved in such processes remain ambiguous due to the complex membrane structures. Herein, we investigate how the heterogeneous nanostructures cause anomalous diffusion in dipalmitoylphosphatidylcholine (DPPC) monolayers. By identifying the existence of condensed nanodomains and clarifying their impact, our findings renew the understanding of the hydrodynamic description and the statistical feature of the diffusion in the monolayers. We find a universal characteristic of the multistage mean square displacement (MSD) with an intermediate crossover, signifying two membrane viscosities at different scales: the short-time scale describes the local fluidity and is independent of the nominal DPPC density, and the long-time scale represents the global continuous phase taking into account nanodomains and increases with DPPC density. The constant short-time viscosity reflects a dynamic equilibrium between the continuous fluid phase and the condensed nanodomains in the molecular scale. Notably, we observe an “anomalous yet Brownian” phenomenon exhibiting an unusual double-peaked displacement probability distribution (DPD), which is attributed to the net dipolar repulsive force from the heterogeneous nanodomains around the microdomains. The findings provide physical insights into the transport of membrane inclusions that underpin various biological functions and drug deliveries.

Chemistry of Materials Nanoarchitectonics for Two-Dimensional Films: Langmuir–Blodgett, Layer-by-Layer Assembly, and Newcomers

“…For example, Hu and co-workers have examined how heterogeneous nanostructures in monolayers at the air−water interface of dipalmitoylphosphatidylcholine (DPPC), a typical phospholipid, cause anomalous diffusion. 90 The findings provide physical insights into the anomalous diffusion of membrane inclusions and improve our understanding of various biological phenomena, including drug delivery functions. Li, Zhang, and co-workers used LB technology to fabricate a poly(vinylidene fluoride) film surface with wide bandgap Ca 2 Nb 3 O 10 nanosheets on the surface of poly(vinylidene fluoride) films using the LB technique.…”

“…It is certainly a technology that contributes to diverse fields. For example, Hu and co-workers have examined how heterogeneous nanostructures in monolayers at the air–water interface of dipalmitoyl­phosphatidyl­choline (DPPC), a typical phospholipid, cause anomalous diffusion . The findings provide physical insights into the anomalous diffusion of membrane inclusions and improve our understanding of various biological phenomena, including drug delivery functions.…”

A comparison of lipid diffusive dynamics in monolayers and bilayers in the context of interleaflet coupling

“…simple models that mimic each leaflet of a bilayer 100,101 . Previous works have reported Dm values for monolayers with few specific lipid compositions 43,44,[102][103][104] , however, systematic studies of Dm values as a function of sn-1 and sn-2 acyl chain structure are limited 102 . Here, monolayers were prepared with the same set of lipids as for GUV samples, using a previously described setup 42,43 .…”

Anomalous Transport of Small Polarons Arises from Transient Lattice Relaxation or Immovable Boundaries

“…Anomalous transport is an important feature across many important processes ranging from biomolecular flow in cells, , to nanoparticle coordination, diffusion of gas through porous materials, and even penetrant transport in glassy polymers . The ubiquity of this phenomenon has ignited an intense focus on uncovering the sources and time scales of anomalous transport. − Theory and experiment indicate that it requires at least one of the following conditions: heterogeneous environments, mixed motion with both diffusion and trapping or binding, or the presence of memory effects . A complicating factor that can obfuscate the physical origin of anomalous transport, and even preclude its observation in small polaron-forming materials, is the reliance on perturbative hopping rates , that truncate the tunneling and interference effects present in a full quantum dynamical treatment.…”