Electroporation of outer membrane vesicles derived from Pseudomonas aeruginosa with gold nanoparticles

Since their discovery, extracellular vesicles have gained considerable scientific interest as a novel drug delivery system. In particular, outer membrane vesicles (OMVs) play a critical role in bacteria–bacteria communication and bacteria–host interactions by trafficking cell signalling biochemicals (i.e. DNA, RNA, proteins). Although previous studies have focused on the use of OMVs as vaccines, little work has been done on loading them with functional nanomaterials for drug delivery. We have developed a novel drug delivery system by loading OMVs with gold nanoparticles (AuNPs). AuNPs are versatile nanoparticles that have been extensively used in disease therapeutics. The particles were loaded into the vesicles via electroporation, which uses an electric pulse to create a short-lived electric field. The resulting capacitance on the membrane generates pores in the lipid bilayer of the OMVs allowing AuNPs (or any nanoparticle under 10 nm) inside the vesicles. Closure of the pores of the lipid membrane of the OMVs entraps the nanoparticles as cargo. Transmission electron microscopy was used to confirm the loading of AuNPs inside the OMVs and dynamic light scattering (DLS) and cryogenic scanning electron microscopy (cryo-SEM) verified the size and integrity of the OMVs. This is the first report to load nanoparticles into OMVs, demonstrating a potential method for drug delivery.