Engineering functional hydrogel microparticle interfaces by controlled oxygen-inhibited photopolymerization.

Functional poly(ethylene glycol) diacrylate (PEGDA) hydrogel microparticles for the detection of bioactive macromolecules were fabricated via oxygen-inhibited photopolymerization in a droplet microfluidic device. Hydrogel network functionalization and architecture were characterized using a biotin-avidin binding assay, which revealed radial network inhomogeneities dependent on exposure conditions. Empirical results were corroborated using a reaction-diffusion model, describing the effects of exposure intensity on the spatial photopolymerization kinetics and resulting polymeric mesh network. The combination of finely controlled exposure conditions and predictive simulations enables the generation of tailored particles with microengineered interfaces and gradients in crosslinking density, which dictate solute diffusivity and elasticity, augmenting the utility of this approach in engineering multifunctional, size-excluding hydrogel particles for multiplexed biomolecular sensing.