A Novel Single-Step Fabrication Technique to Create Heterogeneous Poly(ethylene glycol) Hydrogel Microstructures Containing Multiple Phenotypes of Mammalian Cells

Abstract

In this study, a novel method for the one-step fabrication of stacked hydrogel microstructures using a microfluidic mold is presented. The fabrication of these structures takes advantage of the laminar flow regime in microfluidic devices, limiting the mixing of polymer precursor solutions. To create multilayered hydrogel structures, microfluidic devices were rotated 90 degrees from the traditional xy axes and sealed with a cover slip. Two discreet fluidic regions form in the channels, resulting in the multilayered hydrogel upon UV polymerization. Multilayered patterned poly(ethylene glycol) hydrogel arrays (60 mum tall, 250 mum wide) containing fluorescent dyes, fluorescein isothiocyanate, and tetramethylrhodamine isothiocyanate were created for imaging purposes. Additionally, this method was used to generate hydrogel layers containing murine fibroblasts and macrophages. The cell adhesion promoter, RGD, was added to hydrogel precursor solution to enhance fibroblast cell spreading within the hydrogel matrix in one layer, but not the other. We were able to successfully generate patterns of hydrogels containing multiple phenotypes by using this technique.

Microfluidic patterning of alginate hydrogels

“…Burdick et al 27 and Zaari et al 28 produced a hydrogel with continuous distribution of embedded particles or molecules using a microfluidic gradient generator and photopolymerization. Other authors described the formation of vertically stacked layers by polymerizing parallel laminar flows 29 or by repeatedly filling a microchannel with a hydrogel that shrinks on solidification. 30 Here we present methods which enable the micropatterning of particles in a thin bar of alginate gel on a microfluidic chip.…”

Encapsulation of Biological Agents in Hydrogels for Therapeutic Applications

“…The fact that hydrogels can be made under mild conditions of temperature and pH make them ideal not only for the encapsulation of the fragile living systems and biomolecules involved, but also permit their formation in situ for minimally invasive applications. Given that other molecules, such as adhesive [24,63,64,67,69,70,71,72,73,74,75,96,106,125,143,255,256,257,258,259] and/or degradation [64,73,76,97,98,99,106,109] sequences, and signaling molecules, such as growth factors [4,68,91,107,130,131,133,134,135,136,137,138,139,140,141,144,148,150,151,152,248,255,260,261,262,263,264,265], can be incorporated into these systems, offers the possibility not only to deliver cells, but also to modulate their function according to the required response. These are just some of the most salient characteristics of hydrogels that makes them useful in medical applications.…”

Microfluidic-Based Synthesis of Hydrogel Particles for Cell Microencapsulation and Cell-Based Drug Delivery

“…Chemical and physical cues, such as degradable linkages and cell adhesion groups, can also be incorporated to mimic critical aspects of the natural hydrogel matrix [72,73]. Most importantly, PEG hydrogels can be processed using photolithographic or microfluidic approaches [74,75], which enable the gradient patterning of gel properties and facilitates the fabrication of microarchitectures that can potentially mimic the key aspects of tissue architecture.…”