Cell-laden microgel prepared using a biocompatible aqueous two-phase strategy

Abstract

Microfluidic methods are frequently used to produce cell-laden microgels for various biomedical purposes. Such microfluidic methods generally employ oil-water systems. The poor distribution of crosslinking reagents in the oil phase limits the available gelation strategies. Extracting the microgel from the oil-phase also reduces its production efficiency. In this study, an aqueous two-phase system (ATPS) involving dextran (DEX) and polyethylene glycol (PEG) was used to prepare cell-laden microgel. This avoided the problems associated with an oil phase. The microgel precursor polymers and crosslinking reagents were dispersed in the DEX and PEG phases, respectively. The ultra-low interfacial tension of the ATPS hindered droplet formation. A co-flow microfluidic device was fabricated to overcome this problem. The device incorporated a square-wave-changing injection force, to improve the efficiency of droplet formation. The microgel precursor (including alginate and carboxymethyl cellulose derivatives possessing phenolic hydroxyl moieties) could be dispersed in the DEX solution at various concentrations. Uniform droplets were formed with controllable diameters, and were sequentially converted to microgel by horseradish peroxidase-catalyzed crosslinking. Cells were dispersed in the DEX phase with the microgel precursor polymer, and retained their high viability and proliferation in the resulting microgel. The solubility of gelatin derivatives in the DEX phase was low, but was sufficient to impart cell adhesion properties on the microgel.

Methods for producing microstructured hydrogels for targeted applications in biology

“…Depending on variables such as the relative position of microchannels, the rate of injection, number of liquids used, and their viscosity, different kinds of shapes can be achieved. In addition, encapsulation of cells can be achieved by incorporating them in the desired precursor solution (usually the one that will adopt a microstructure) prior to their injection into the microfluidic channel [117,118]. More complicated microfluidic devices can be used to obtain structures such as core-shell spheres, hollow tubes, osteon-like microfibers (Fig.…”

Spherical Cellulose Micro and Nanoparticles: A Review of Recent Developments and Applications

“…The production of sphere-shaped cellulose-based microparticles can be performed by emulsification processes [ 93 , 112 , 113 , 114 , 115 ], and microfluidics technology [ 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 ], as well as other less common techniques, namely spray-assisted techniques [ 126 , 127 , 128 , 129 , 130 ], and the LbL assembly [ 131 , 132 ]. Concerning the cellulosic substrate, the majority of the studies reported the utilization of cellulose derivatives, such as CMC [ 120 , 131 ], CA [ 114 , 119 ] and EC [ 123 , 124 , 133 , 134 ], but also pristine vegetable cellulose [ 112 , 135 , 136 , 137 ], bacterial nanocellulose [ 116 , 117 , 118 ] and microcrystalline cellulose (MCC) [ 93 , 115 , 138 , 139 ]. The preference for cellulose derivatives to generate microparticles was anticipated given their solubility in water or in most common organic solvents, which translates into simpler processability.…”

Advanced biomedical applications based on emerging 3D cell culturing platforms

“…48,49 Based on this control, several microfluidic devices have been optimized to use aqueous two-phase systems to generate spheroids. [50][51][52][53] This approach is based on the use of a polymeric ATPS (DEX/PEG) to confine the cells within a nanolitre-volume aqueous drop immersed within a second, immersion aqueous phase in close proximity, and cells aggregate to spontaneously form a spheroid. The commonly used bioavailable ATPS is polyethene (PE) and dextran (DEX) due to the strong partition of cells to dextran in this system.…”

“…An ATPS consisting of DEX and PEG was reported for the preparation of a cell-laden microgel using microfluidic devices, which involved a periodically changing injection force. 50,52 The microfluidic devices will overcome the issue of low interfacial tension between the two phases. The microfluidic device chamber can pump out fluids with different injection conditions, which can control the size of droplets.…”