LAUSR

Abstract Nano-structured lipid particles can be designed for tailored delivery of small molecules. Liquid lipid nanoparticles (LLN) stabilized by lecithin and solid lipid nanoparticles (SLN) stabilized by sodium caseinate were used to form self-assembled nano-emulsion structures (i.e., colloidosomes) via electrostatic deposition of a solid wall around a liquid reservoir. Particle size and zeta potential were measured at pH 3.5 and 7 to characterize the colloidal dispersions at selected mixing ratios (2:1 to 1:5). The partitioning, kinetic release, and reactivity of non-volatile (4-phenyl-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl nitroxide; PTMIO) and volatile (limonene) molecules were studied using electron paramagnetic resonance (EPR) spectroscopy and atmospheric pressure chemical ionization-mass spectroscopy (APcI-MS), respectively, as a function of pH-change at the 1:3 mixing ratio. Particle size (d32) of LLN (134 nm) and SLN (166 nm) remained unchanged with pH adjustment, and colloidosome particle size (450 nm) was a combination of LLN and SLN particles at pH 3.5. The presence of the solid wall significantly reduced the diffusion rate (ca. 80 %) of PTMIO from the LLN core protecting the compound. APcI-MS measurements showed similar behavior for limonene release to air. These systems can be used for controlled delivery of various active compounds in food and pharmaceutical formulations.