Using Droplet Microfluidics to Encapsulate Cancer Spheroids in Hydrogel Systems

Patient-derived tumor organoids have become more relevant models for drug screening, but the limitations of conventional production techniques result in models lacking a degree of reproducibility between batches. Thus, we aim to develop a more robust system for uniform organoid formation, by leveraging droplet microfluidic (DM) technology to maneuver pre-formed cancer spheroids (cell clusters) and individually house them in nanoliter hydrogel droplets, by water-in-oil emulsion. DM chips were fabricated through replica molding using molds made by soft lithography and stereolithography, with either double flow-focusing (DFF) or T-junction geometries. The continuous phase was mineral oil with surfactant. The dispersed phase was gelatin methacrylate and spheroids. Based on criteria previously developed by the team, an optimized design has shown success in generating uniform spheroid-laden droplets without breaking the spheroids apart. Spheroids did not maintain suspension in the inlet reservoirs past 2 min due to their higher density than the buffer solution, decreasing equal distribution into the device. Instead, settled spheroids entered the DM device in groups, but the DFF design aided in alignment and eventually single encapsulation was achieved. These preliminary studies showcase the capabilities of DM for encapsulating single spheroids successfully. Further work is assessing inlet techniques for higher system effectiveness, with mindfulness of spheroid fragility and size.