A high-throughput method to quantify the structural properties of individual cell-sized liposomes by flow cytometry

We describe a new high-throughput method to quantify the structural properties of individual cell-sized liposomes. We labeled an internal aqueous solution of liposomes with a green fluorescent protein (GFP) and the membrane with a fatty acid conjugated with a red fluorescent probe. The internal aqueous volume and lipid membrane volume of each liposome was measured, and double-labeled liposomes were analyzed by flow cytometry, a useful tool that enables us to estimate the internal aqueous and lipid membrane volumes of individual cell-sized liposomes independently of shape and structure. This method shows promise in opening the way to understanding the characteristics of biochemical reactions occurring within a liposome, to optimizing the preparation method of liposomes, and to overcoming many of the difficulties in realizing an artificial cell.