Fig. 2

Hydrogel particle synthesis and tunable swelling with DNA hairpin fuel and terminators. a Hydrogel particles are prepared by pipetting droplets of pre-polymer acrylamide-DNA crosslinker solution into mineral oil and polymerizing the droplets with UV light. Rhodamine-B is incorporated into the acrylamide backbone to allow fluorescence imaging of particles (see Methods). b The changes in area of the 2D projection of particles without locks over time for different fractions of hairpin monomers that are terminating hairpins. Each solid curve represents 1 particle (2%, 25%, 50%) or the average of measurements of 2 particles (5%, 10%); dotted lines are the individual replicates of each average. The edges of particles expanded with 2% terminator monomer were unable to be discerned from the surrounding solution after 90 h. Hairpin fuel with 10% terminator was chosen for further hydrogel swelling experiments because particles with 2% and 5% terminator expanded to a diameter larger than the microscope’s field of view. Image intensities are scaled based on each image’s minimum and maximum intensity. Scale bars: 500 µm