Rossow, T.; Heyman, J.A.; Ehrlicher, A.J.; Langhoff, A.; Weitz, D.A.; Haag, R.; Seiffert, S.: Controlled Synthesis of Cell-Laden Microgels by Radical-Free Gelation in Droplet Microfluidics. Journal of the American Chemical Society 134 (2012), p. 4983-4989
10.1021/ja300460p

Abstract:
Micrometer-sized hydrogel particles that contain living cells can be fabricated with exquisite control through the use of dropletbased microfluidics and bioinert polymers such as polyethyleneglycol (PEG) and hyperbranched polyglycerol (hPG). However, in existing techniques, the microgel gelation is often achieved through harmful reactions with free radicals. This is detrimental for the viability of the encapsulated cells. To overcome this limitation, we present a technique that combines droplet microfluidic templating with bio-orthogonal thiol−ene click reactions to fabricate monodisperse, cell-laden microgel particles. The gelation of these microgels is achieved via the nucleophilic Michael addition of dithiolated PEG macro-cross-linkers to acrylated hPG building blocks and does not require any initiator. We systematically vary the microgel properties through the use of PEG linkers with different molecular weights along with different concentrations of macromonomers to investigate the influence of these para eters on the viability and proliferation of encapsulated yeast cells. We also demonstrate the encapsulation of mammalian cells including fibroblasts and lymphoblasts.