Single-particle ICP-MS characterization of magnetoliposomes: toward measurement of the number distribution of encapsulated magnetic nanoparticles

Abstract

Magnetoliposomes (MLs) are very pertinent candidates for biomedical applications. They can be used as drug delivery vectors and magnetic resonance imaging (MRI) contrast agents. Their characterization in terms of size and size distribution by dynamic light scattering (DLS), surface charge by electrophoretic light scattering, and morphology by (cryo)-transmission electron microscopy (TEM) is well documented in the literature. However, no study on the distribution of the number of encapsulated magnetic nanoparticles (NPs) per ML has been reported thus far, despite its importance in the design of efficient MLs for targeted applications. The work presented herein reveals that this information could be obtained by employing a relatively innovative technique, i.e. single-particle inductively coupled plasma-mass spectrometry (spICP-MS). This required the development of an orderly calculation methodology and a mathematical treatment of raw data detailed herein, and validated on four different concentrations of MLs. The results for the number of encapsulated magnetic NPs per ML show satisfactory agreement among the concentrations, confirming the suitability of this technique for characterization of MLs.