Encapsulation Efficiency Measured On Single Small Unilamellar Vesicles

摘要

During the past two decades liposomes have been studied intensively for their use as biocompatible drug delivery systems (DDS) and transfection agents. One of the critical parameters that have to be optimized in the development of a delivery system is the encapsulation efficiency (EE, ratio of encapsulant concentration inside the delivery vehicle over the loading solution). So far EE has been regarded as a bulk property and was measured as the average of all DDS particles in a solution. Recent technical advances however allowed the monitoring of single particles and are beginning to provide unique information on heterogeneous properties that were otherwise lost due to ensemble averaging. Here we focus on measuring the EE of single vesicles with sizes below the optical resolution. The measurements revealed an intrinsic in-trasample EE variability that may be a property of other delivery formulations as well.