Lipid Bilayer-Modified Nanofluidic Channels of Sizes with Hundreds of Nanometers for Characterization of Confined Water and Molecular/Ion Transport

Abstract

Water inside and between cells with dimensions on the order of 101–103 nm such as synaptic clefts and mitochondria is thought to be important to biological functions, such as signal transmissions and energy production. However, the characterization of water in such spaces has been difficult owing to the small size and complexity of cellular environments. To this end, we proposed and fabricated a biomimetic nanospace exploiting nanofluidic channels with defined dimensions of hundreds of nanometers and controlled environments. A method of modifying a glass nanochannel with a unilamellar lipid bilayer was developed. We revealed that 2.1–5.6 times higher viscosity of water arises in a 200 nm sized biomimetic nanospace by interactions between water molecules and the lipid bilayer surface and significantly affects the molecular/ion transport that is required for the biological functions. The proposed method provides both a technical breakthrough and new findings to the fields of physical chemistry and biology.

Functional Reconstitution of Dopamine D2 Receptor into a Supported Model Membrane in a Nanometric Confinement

“…It has been reported that confinement in a nanometric space significantly alters the physicochemical properties of the medium. [ 11 ] The fact that the diffusivity is uniform within a single corral yet significantly varies in different positions underscores the importance of the local environment. It also suggests the possibility of regulating the diffusivity of molecules in a nanometric cleft by changing the cleft thickness.…”

Characterization of pressure-driven water flows in nanofluidic channels by mass flowmetry

“…Alternatively, the effect of loosely-structured water near the surface on the viscosity of water confined in fusedsilica nanochannel was suggested. The mass flowmetry developed in this work is available for the characterization of fluid flow in other top-down fabricated nanospaces such as graphene nanochannels 25,26 and lipid bilayer-modified nanochannels, 27 which have been developed for fundamental studies on energy harvesting and biophysics, respectively. The knowledge obtained will accelerate understanding of the properties of fluids confined in nanospaces, which is important in the field of nanofluidics and other fields such as physical chemistry and biophysics.…”

Substrate-supported Model Membrane as a Versatile Analytical/Biosensing Platform

“…42 By working with a lipid-coated glass nanochannel, Kazoe et al studied the physicochemical properties of water in confined spaces. 46 They revealed that the viscosity of water in a nanochannel with the thickness of 200 nm was 2.1 -5.6 times higher than the bulk water phase, suggesting that interactions between water molecules and a lipid bilayer surface significantly affect the molecular/ion transport. The slowed diffusion in a lipid-coated nanoscopic space also has important implications towards the behaviors of biological molecules in the cellular interior and cell-cell junction.…”