Chaos-Assisted Production of Micro-Architected Spheres (CAPAS).

Hydrogel droplets with inner compartments are valuable in various fields, including tissue engineering. A droplet-based biofabrication method is presented for the chaos-assisted production of architected spheres (CAPAS) for the rapid generation of multilayered hydrogel spheres (ranging from 0.6 to 3.5 mm in diameter) at high-throughput rates (up to 2000 spheres per min). This method is based on the use of chaotic advection generated by a Kenics static mixer (KSM) nozzle. The configuration of the KSM (i.e., the number of mixing elements) determines the number of compartments within the sphere. Sphere size is adjusted by flow rate, printhead outlet diameter, polymer concentration (sodium alginate or gelatin-methacryloyl (GelMA)), and crosslinking bath composition. This versatile system operates in dripping and jetting modes, preserving multilayered architecture in both modes. Proof-of-concept experiments with breast cancer (MDA-MB-231), human dermal fibroblast (HDF), and murine myoblast (C2C12) lines show over 80% cell viability immediately post-fabrication, maintained over extended culture (14 or 30 days). CAPAS is used to create a breast cancer model with cancer-tissue-like and healthy-tissue-like micro-niches to test paclitaxel doses. It is envisioned that CAPAS will enable high-throughput fabrication of hydrogel spheres for tissue engineering, chemical engineering, and material sciences applications.