Living plastics from plasticizer-assisted thermal molding of silk protein

The pursuit of materials, particularly plastics, with a minimal ecological footprint throughout their circular lifecycle, is crucial for advancing sustainable materials development. Living materials composed of embedded yet active organisms can leverage endogenous biotic resources to achieve functional materials that align with sustainability goals. However, current living material systems face challenges such as weak mechanical properties, limited environmental adaptability, and restricted cellular functionality. In this study, we propose an approach to sustainable living materials by incorporating active organisms into silk-based plastics through a plasticizer-assisted thermal molding process. We investigate the mechanism of structure formation in these materials, correlating manufacturing performance to the resulting secondary structure. These silk-based plastics provide a protective matrix for probiotics, ensuring their survival through the harsh gastrointestinal tract and enhancing intestinal delivery. Similarly, soil rhizobacteria encapsulated within the plastics exhibit long-term protease activity, accelerating plastic degradation upon soil exposure. This work demonstrates the potential of sustainable plastics as a form of living materials, where active organisms are processed, entrapped, retain metabolic functions, and are protected in harsh environments. Living materials align with sustainability goals, but usually face challenges such as limited environmental adaptability and restricted cellular functionality. Here, the authors report a sustainable plasticizer-assisted thermoplastic molding process to develop silk protein-based living plastics with dense structures, functioning as protective matrices for encapsulated microorganisms.