Fig. 1.

Schematic drawing showing the concept of the genetically encoded targeted drug delivery system this study aimed to develop. The genetically engineered antibody mimetic protein DARPin9.29 (orange) is fused to the capsid protein of the T. maritima encapsulin (purple) and loaded with the cytotoxic protein miniSOG (not shown). This drug delivery system binds specifically to breast cancer cells on the HER2 receptor (brown) and upon uptake and illumination releases reactive oxygen species (ROS, yellow) which trigger apoptosis of the targeted cell.