LAUSR

Abstract Morphologically discrete nanoarchitectures, which mimic the structural complexity of biological systems, are an increasingly popular design paradigm in the development of new nanomedical technologies. Herein, engineered polymeric stomatocytes are presented as a structural and functional mimic of red blood cells (RBCs) with multifunctional therapeutic features. Stomatocytes, comprising biodegradable poly(ethylene glycol)‐block‐poly(D,L‐lactide), possess an oblate‐like morphology reminiscent of RBCs. This unique dual‐compartmentalized structure is augmented via encapsulation of multifunctional cargo (oxygen‐binding hemoglobin and the photosensitizer chlorin e6). Furthermore, stomatocytes are decorated with a cell membrane isolated from erythrocytes to ensure that the surface characteristics matched those of RBCs. In vivo biodistribution data reveal that both the uncoated and coated nano‐RBCs have long circulation times in mice, with the membrane‐coated ones outperforming the uncoated stomatoctyes. The capacity of nano‐RBCs to transport oxygen and create oxygen radicals upon exposure to light is effectively explored toward photodynamic therapy, using 2D and 3D tumor models; addressing the challenge presented by cancer‐induced hypoxia. The morphological and functional control demonstrated by this synthetic nanosystem, coupled with indications of therapeutic efficacy, constitutes a highly promising platform for future clinical application.