Enhancement of stability and controlled drug release of lipid nanoparticles by modified solvent-evaporation method

Abstract

The purpose of this study was to improve the physicochemical properties of solid lipid nanoparticles (SLNs) by modified solvent-evaporation methods. Stearylamine, Tween 80, egg phosphatidylcholine, and docetaxel were used to prepare SLNs. In the conventional method, the lipid is heated to 5–10°C above its melting point; however, the samples prepared using the modified method were heated to twice the lipid melting point. The particle size, polydispersity index (PdI), and zeta potentials were measured to compare the physicochemical characteristics of SLNs prepared using the conventional and modified methods. The morphologies of the SLNs were observed using scanning electron microscopy (SEM) and the crystal forms confirmed using DSC thermograms. The aqueous stability of the SLNs was evaluated by examining changes in mean particle size and polydispersity during storage at 4°C. An in vitro drug release test was conducted to study the release patterns of each SLN formulation. mSLN particles were smaller and more uniform than those of cSLNs in dynamic light-scattering (DLS) and SEM measurements. The particle size and PdI were 321±15.5nm, 0.208±0.0208 for mSLNs and 403.2±24.7nm, 0.486±0.0138 for cSLNs, respectively. The zeta potentials of mSLNs and cSLNs were +26.2±2.01 and +24.1±0.83, respectively. Docetaxel was incorporated in both SLNs with about 80% encapsulation efficiency. Mean particle diameters and PdI of mSLNs were maintained throughout the observation period. However, in cSLNs, extensive particle growth and gelation were observed when the cSLNs were stored at 4°C. The in vitro drug release test showed that mSLNs had a more sustained release pattern. In conclusion, the stability and controlled drug release of SLNs can be enhanced by fabrication using modified solvent-evaporation methods.