Living Cell-Mediated Catalyst-Free Spontaneous Polymerization of Zwitterionic Methacrylates for Preparation of Probiotic-Loaded Hydrogels.

Living cell-mediated polymerization offers promising applications in biomaterials, yet its further biological utilization is hindered by the need for metal ions or radical initiators with available methods. In this study, we introduce a living cell-mediated polymerization that leverages the intrinsic metabolic activities of living cells to initiate and sustain free radical polymerization of zwitterionic methacrylates. The polymerization proceeded in the absence of transition metal catalysts, radical initiators, or light sources. The conversion of zwitterionic methacrylate strongly correlated with cellular activities and achieved a maximum conversion of 98 % within 48 hours. Living cells efflux redox power across membranes through metabolism and that terminal electron fluxes are captured by zwitterionic methacrylates pre-assembled on the living cell surface to initiate radical polymerization reactions. The polymerization caused significant changes to the cell membrane surface and synthesized hydrogels with tailored mechanical properties. The polymer hydrogel obtained via probiotic E. coli Nissle 1917 was able to release the in situ encapsulated molecules, which demonstrated living cell-mediated polymer hydrogel as a vehicle for the delivery of both cellular and molecular therapeutic agents. This research offered a green and efficient method for synthesizing bioactive materials and advancing the field of cellular therapeutics and drug delivery.