Bacterial outer membrane vesicles and their functionalization as vehicles for bioimaging, diagnosis and therapy

Abstract

Bacterial outer membrane vesicles (OMVs) are spherical nanostructures spontaneously released from Gram-negative bacteria. Natural OMVs that are abundant in lipopolysaccharides, phospholipids, proteins, and nucleic acids have diverse biological functions including extracellular communication, transferring contents to host cells, and modulating immune responses, which are involved in multiple processes in human health. In addition to their native characteristics, functionalization of OMVs has sparked substantial biomedical applications due to their advantages of nanoscale size and the ability to carry a broad variety of payloads. In this review, we summarize the bioactivities of OMVs, including biogenesis, immunogenicity, and interactions with host cells, followed by a discussion on the strategies of utilizing functionalized OMVs as delivery vehicles for bioimaging, diagnosis, and therapy. Particularly, the applications of engineered OMVs as therapeutics to treat inflammatory bowel diseases and several types of cancer and also as vaccines to prevent infections have been elaborated. We also highlight the challenges and future perspectives of using OMVs for different biomedical applications. This work would inspire new thoughts on the development of innovative OMV-based biomedical nanomaterials through synthetic bioengineering and physicochemical modification.