Figure 5.

Principle of polymer-based platforms. (A) The fur shell method relies on the coupled reactions of two enzymes in which d-δ-gluconolactone is produced. The latter is a substrate in the Fenton reaction, which leads to the production of hydroxyl radicals, needed in the co-polymerization of poly(ethylene glycol)-diacrylate (PEG-diacrylate) and Polyfluor 570 [45,50]; (B) In cellular high-througput encapsulation solubilization and screening (CHESS), the polymers are assembled in a layer-by-layer manner. Each cell is subjected to the deposition of alternating layers of oppositely charged polymers [51,52]; and (C) Gel-shell beads are produced with the help of a microfluidic device. Water-in-oil droplets (indicated with a blue circle), containing agarose and a polyanion, are formed. With a decrease in temperature to 4 °C, agarose gelates within the water droplet (indicated with a brown circle). To decrease the molecular weight cut-off, the beads are de-emulsified in the presence of a polycation. Driven by the opposite charges, the polyanion and polycation form a shell bead that encloses any compounds of the reaction [48].