Secondary Ion Mass Spectrometry of Macromolecules Loading in Individual Polyelectrolyte Multilayer Microcapsules

Abstract

The control over the amount of a payload in polyelectrolyte multilayer microcapsules is of particular importance for several applications, such as transportation and delivery of drugs, enzymes, and other (bio)active materials. In this work, secondary ion mass spectrometry is applied to measure the content of peroxidase in individual capsules. The distribution of a payload among the capsules in a batch is analyzed for different loading routines. Absorption in porous CaCO3 demonstrates lower enzyme content with a standard deviation of 40 % on average. pH-Controlled post-loading gives two to three times higher content and a standard deviation of 20–25 %. The decrease of pH upon post-loading increases the encapsulation efficiency.