Encapsulation of Living Cells within Giant Phospholipid Liposomes Formed by the Inverse-Emulsion Technique

Liposomes form spontaneously by the assimilation of phospholipids, the primary component of cell membranes. Due to their unique ability to form selectively permeable bilayers in situ, they are widely used as nanocarriers for drug and small-molecule delivery. However, there is a lack of straightforward methodologies to encapsulate living microorganisms. Here we demonstrate the successful encapsulation of whole cells in phospholipid vesicles by using the inverse-emulsion technique of generating unilamellar vesicles. This method of liposome preparation allows for a facile encapsulation of large biomaterials that previously was not easily attainable. Using Escherichia coli as a model organism, we found that liposomes can protect the bacterium against external protease degradation and from harsh biological environments. Liposomes prepared by the inverse-emulsion method were also capable of encapsulating yeast and were found to be naturally susceptible to hydrolysis by enzymes such as phospholipases, thus highlighting their potential role as cell delivery carriers.