Confinement Effects on Polymer Dynamics: Thermo-Responsive Behaviours of Hydroxypropyl Cellulose Polymers in Phospholipid-Coated Droplets (Water-in-Oil Emulsion)

Abstract

Abstract:In order to construct the artificial cells and to understand the physicochemical properties of living cells, it is important to clarify the cell-sized confinement effect on the behaviours of bio-inspired polymers. We report the dynamic behaviours of aqueous hydroxypropyl cellulose (HPC) solution coated with phospholipids in oil (water-in-oil droplets, W/O droplets), accompanied by an increase in the temperature. We directly observed the beginning of phase separation of HPC solution using a fluorescence microscope and confirmed the dependence of such phenomena on droplet size. The results indicate that the start time of phase separation is decreased with an increase in droplet size. The experimental results suggest that the confinement situation accelerates the phase separation of aqueous HPC solutions.

Versatility of Reverse Micelles: From Biomimetic Models to Nano (Bio)Sensor Design

“…The effects of droplet size and temperature on the dynamic behaviors of an aqueous solution of hydroxypropyl cellulose (HPC) coated with phospholipids in oil (water-in-oil droplets) were studied by Yoshida et al [157]. The beginning of phase separation of the HPC solution, one of the most representative biocompatible polymers, with its main component (multi-sugar chain) being found in living cells, was observed by the authors, who demonstrated that the start time of phase separation is decreased with the increase in droplet size [157].…”

“…The effects of droplet size and temperature on the dynamic behaviors of an aqueous solution of hydroxypropyl cellulose (HPC) coated with phospholipids in oil (water-in-oil droplets) were studied by Yoshida et al [157]. The beginning of phase separation of the HPC solution, one of the most representative biocompatible polymers, with its main component (multi-sugar chain) being found in living cells, was observed by the authors, who demonstrated that the start time of phase separation is decreased with the increase in droplet size [157]. This study of cell-size confinement effects on the dynamic behaviors of biocompatible polymers highlighted the importance of droplet size and of the lower critical solution temperature for the dynamic phase behavior, not only for artificial cell construction, but also for understanding the physicochemical properties of living cells [157].…”

Acetonitrile-Induced Destabilization in Liposomes

“…Artificial model systems of biological membranes, such as liposomes and water-in-oil (W/O) droplets, are quite beneficial for studies of the dynamic behaviors of biological membranes owing to the fact that liposomes and W/O droplets can be easily prepared and possess a simple membrane structure [4][5][6]. Using such liposomes, it was shown that the surfactants, such as Triton X-100 and ethanol, with amphiphilic properties have an ability to invade the lipid bilayers and to form lipid/surfactant mixed micelles, which consequently induce destabilization and destroy the lipid bilayer structure [7].…”

Aggregation of Water Molecules to Phospholipid Head Groups Accompanied with Separation into Water‐ and Polysaccharide‐Rich Phases in Water‐in‐Oil Emulsions

“…Our previous study revealed that the start time of the phase separation into HPCÀ and water-rich phases is strongly correlated with droplet size. [35] In that case, the concentration of HPC in the droplets was 40 wt%, and we focused on the droplet size dependency. Further experiments are required for a better understanding of dynamic behaviours of confined aqueous HPC solutions and the effect of lipid head groups located in droplet/oil interfaces.…”

“…The experimental setup is the same as in our previous study. [35] Figure 2 shows typical time-dependent fluorescence microscopic images of aqueous HPC droplets without and with lipid coating. The green fluorescent dye is calcein, which dissolves in water.…”