Sparse bottlebrush poly (OEGMA-stat-MMA) copolymers for 3D printing and multicellular spheroids harvesting

Tissue engineering demands biomaterials that integrate tunable mechanical properties, cytocompatibility, and simple processability. Here, we report the synthesis and characterization of a new class of sparse bottlebrush thermoplastic elastomers— poly(oligo(ethylene glycol) methyl methacrylate-stat-methyl methacrylate) (poly(OEGMA-stat-MMA)) copolymers—prepared via atom transfer radical polymerization (ATRP). By incorporating oligo(ethylene glycol) side chains, the materials with strain-hardening behavior and high elasticity, and Young’s moduli ranging from 3 to 750 MPa were achieved, mimicking tensile properties of native tissues. These copolymers demonstrate excellent melt processability, enabling extrusion-based 3D printing at temperatures starting from 80 °C and with high shape fidelity. The temperature dependent contact angle measurements showed thermoresponsive behavior. The 3T3 fibroblast tissue cultured on copolymers grew in the form of 3D spheres that were able to detach from surface upon cooling. Such materials performance of thermoplastic elastomer has not been reported so far. The results showed a new pathway for preparation of substrates for tissue harvesting. Tissue engineering requires cytocompatible biomaterials with tunable mechanical properties and simple processing. Here, the authors report thermoresponsive, 3D-printable bottlebrush thermoplastic elastomers with tissue-like mechanics and potential for tissue harvesting.