Thread-Like Radical-Polymerization via Autonomously Propelled (TRAP) Bots.

Micromotor-mediated synthesis of thread-like hydrogel microstructures in an aqueous environment is presented. The study utilizes a catalytic micromotor assembly (owing to the presence of a Pt layer), with an on-board chemical reservoir (i.e., polymerization mixture), toward thread-like radical-polymerization via autonomously propelled bots (i.e., TRAP bots). Synergistic coupling of catalytically active Pt layer, together with radical initiators (H2 O2 and FeCl3 (III)), and PEGDA monomers preloaded into the TRAP bot, results in the polymerization of monomeric units into elongated thread-like hydrogel polymers coupled with self-propulsion. Interestingly, polymer generation via TRAP bots can also be triggered in the absence of hydrogen peroxide for cellular/biomedical application. The resulting polymeric hydrogel microstructures are able to entrap living cells (NIH 3T3 fibroblast cells), and are easily separable via a centrifugation or magnetic separation (owing to the presence of a Ni layer). The cellular biocompatibility of TRAP bots is established via a LIVE/DEAD assay and MTS cell proliferation assay (7 days observation). This is the first study demonstrating real-time in situ hydrogel polymerization via an artificial microswimmer, capable of enmeshing biotic/abiotic microobjects in its reaction environment, and lays a strong foundation for advanced applications in cell/tissue engineering, drug delivery, and cleaner technologies.