Loading, release profile and accelerated stability assessment of monoterpenes-loaded solid lipid nanoparticles (SLN)

Abstract

Glycerol monostearate solid lipid nanoparticles (SLN) were produced by hot high-pressure homogenization technique to load alpha-pinene, citral, geraniol or limonene. SLN were composed of 1 wt.% monoterpene, 4 wt.% of Imwitor^® 900K as a solid lipid and 2.5 wt.% of Poloxamer188 as a surfactant. Empty SLN consisted of 5 wt.% of Imwitor^® 900K and 2.5 wt.% of Poloxamer188. The mean particles size (Z-Ave) and polydispersity index (PDI) of SLN were analyzed by dynamic light scattering (DLS), while the zeta potential (ZP) of each formulation were measured by electrophoretic light scattering. LUMiSizer^® was applied to calculate the velocity distribution in the centrifugal field and instability index. Drug release profile from SLN was analyzed using Franz cell diffusion cells assayed by UV–Vis spectrophotometry, whereas the gas chromatography technique was applied to determine the encapsulation parameters of volatile monoterpenes. The matrix state, polymorphism and phase behavior of SLN were studied by X-ray diffraction (XRD, low and wide angles) and differential scanning calorimetry (DSC). Selected monoterpenes were successfully loaded in glycerol monostearate SLN. A burst release profile within the first 15 min was observed for all formulations, being the modified release profile dependent on the type of monoterpene and on the encapsulation efficiency.

Keywords:

• Monoterpenes
• Alpha-pinene
• citral
• geraniol
• limonene
• SLN
• LUMiSizer

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors acknowledge the financial support received from Portuguese Science and Technology Foundation (FCT/MCT) and from European Funds (PRODER/COMPETE) under the project reference [M-ERA-NET/0004/2015-PAIRED and UIDB/04469/2020] (strategic fund), co-financed by FEDER, under the Partnership Agreement [PT2020].