Solid lipid nanoparticles (SLN (TM)) based on binary mixtures of liquid and solid lipids: a H-1-NMR study

SLN with improved payloads and enhanced storage stability were investigated . Based on the experiences with solid lipid nanoparticles, a new type of so lid lipid nanoparticle has been developed by incorporating triglyceride con taining oils in the solid shell of the particle. The structure and mixing b ehaviour of these particles was characterised by DSC and H-1-NMR. DSC yield s information on the melting and crystallisation behaviour of the solid and liquid constituents of the particles. NMR is especially suited for the cha racterisation of the liquid oil domains inside the SLN. In this study a med ium chain triglyceride oil was successfully incorporated in a matrix of a s olid long chain glyceride (glycery behenate). The resulting particles were solid but the oil inside the particle remained in a liquid state. The relat ion between oil supplementation and melting point depression of glyceryl be henate proved to be linear. Mobility of the oil molecules inside the partic les was considerably reduced compared to the emulsified oil. Moreover, two different chemical shifts for each of the lipid signals were observed indic ating two different chemical environments. The experimental data is in line with a model describing uniform distribution of the oil molecules in the g lyceryl behenate for low oil loads. However, at higher oil loads our data i ndicate the formation of oil clusters within the solid nanoparticle. (C) 20 00 Elsevier Science B.V. All rights reserved.