A programmable oral bacterial hydrogel for controllable production and release of nanovaccine for tumor immunotherapy.

Oral protein vaccines are mainly used to prevent the infection of intestinal pathogens in clinic due to their high safety and strong compliance. However, it is necessary to design the efficient delivery systems to overcome the harsh gastrointestinal environment in the application process. Here we established a programmable oral bacterial hydrogel system for spatiotemporally controllable production and release of nanovaccines. The system was divided into three parts: (1) Engineered bacteria were encapsulated in chitosan-sodium alginate microcapsules, which offered protection against the extreme acid conditions in the stomach. (2) Microcapsules were dissolved, and then engineered bacteria were released and colonized in the intestine. (3) The release of nanovaccines was controlled periodically by a synchronous lysis genetic circuit for tumor immunotherapy. Compared to control groups, tumor volume of subcutaneous tumor-bearing mice treated with bacterial microgels releasing optimized nanovaccine was almost inhibited by 75% and T cell response was activated at least 2-fold. We believe that this programmable bacterial hydrogel will offer a promising way for the application of oral nanovaccines.