Temperature triggering of kinetically trapped self-assemblies in citrem-phospholipid nanoparticles

Abstract

Lyotropic non-lamellar liquid crystalline (LLC) nanoparticles are attractive nanocarriers for drug delivery, particularly for the solubilization of poorly water-soluble drugs. Due to the reported problems of complement activation and cytotoxicity of most investigated Pluronic F127-stabilized cubosomes and hexosomes, there is an interest in introducing safe stabilizers for these LLC nanodispersions. Citrem appears to be the stabilizer of choice for the colloidal stabilization of these LLC nano-self-assemblies owing to its hemocompatiblity and poor activation of the complement system. This anionic food-grade emulsifier in combination with soy phosphatidylcholine (SPC) can be used to introduce a library of hemocompatible lamellar and non-lamellar liquid crystalline nanodispersions at different lipid compositions. We found that batch-to-batch variability in citrem composition is associated with slight alterations in the size, structural characteristics, and surface charge of the produced citrem/SPC nanoparticles. Further, we report on the temperature-triggered alterations in these nano-self-assemblies at different lipid compositions by using synchrotron small angle X-ray scattering (SAXS). The addition of citrem at different temperatures induces lamellar to non-lamellar structural transitions as evident from the appearance of inverse bicontinuous cubic Pn3m and discontinuous hexagonal (H₂) phases, respectively, upon increasing citrem concentration and varying temperature in the range of 5-59 °C. Citrem/SPC nanoparticles are attractive for use in the development of nanocarriers for drug delivery owing to their structural tunability and hemocompatiblity.

Keywords: Citrem; Cubosomes; Hexosomes; Inverse lyotropic non-lamellar liquid crystalline phases; Nanodispersion; Nanoparticle tracking analysis; Small angle X-ray scattering; Soy phosphatidylcholine.