Monodisperse polyethylene glycol diacrylate hydrogel microsphere formation by oxygen-controlled photopolymerization in a microfluidic device

Abstract

PEG-based hydrogels have become widely used as drug delivery and tissue scaffolding materials. Common among PEG hydrogel-forming polymers are photopolymerizable acrylates such as polyethylene glycol diacrylate (PEGDA). Microfluidics and microfabrication technologies have recently enabled the miniaturization of PEGDA structures, thus enabling many possible applications for nano- and micro- structured hydrogels. The presence of oxygen, however, dramatically inhibits the photopolymerization of PEGDA, which in turn frustrates hydrogel formation in environments of persistently high oxygen concentration. Using PEGDA that has been emulsified in fluorocarbon oil via microfluidic flow focusing within polydimethylsiloxane (PDMS) devices, we show that polymerization is completely inhibited below critical droplet diameters. By developing an integrated model incorporating reaction kinetics and oxygen diffusion, we demonstrate that the critical droplet diameter is largely determined by the oxygen transport rate, which is dictated by the oxygen saturation concentration of the continuous oil phase. To overcome this fundamental limitation, we present a nitrogen micro-jacketed microfluidic device to reduce oxygen within the droplet, enabling the continuous on-chip photopolymerization of microscale PEGDA particles.

Spatially and temporally controlled hydrogels for tissue engineering

“…Microfluidic platforms have been used to microfabricate hydrogel spheres with well-defined diameters, architectures, and chemical compositions [60–64], as well as fibers of a particular architecture including hollow fibers and gradients within hydrogels [65]. Numerous studies have demonstrated the generation of cell-laden hydrogel microparticles using microfluidic devices[64].…”

UV-Cured Poly(Ethylene Glycol) Diacrylate/Carbon Nanostructure Thin Films. Preparation, Characterization, and Electrical Properties

“…It is an acrylate-based monomer and thus radical chain-growth polymerization was preferred as more suitable and common in photo-curable procedures. [19,20] Moreover, free radicals can be also added on the double bond of a graphene or CNT surface, enhancing the connectivity between carbon nanofiller and polymer matrix [21,22]. Fabbri et al have shown that PEGDA can be combined successfully with GO to form transparent and conductive coatings by photopolymerization [20].…”

A micrometer head integrated microfluidic device for facile droplet size control and automatic measurement of a droplet size

“…The micro‐droplet can be regarded as an independent micro‐reactor and can be produced in a high‐throughput manner, rendering it an attractive tool for a variety of research fields . They include not only the biochemical applications such as a single‐cell analysis , an enzyme assay , and a PCR reaction but also the chemical synthesis for inorganic nanoparticles , organic nanoparticles , polymer microparticles , and colloidal microparticles . The micro‐droplet technology has demonstrated its ability to produce homogeneous ones with a predictable size in a modest fashion .…”