Key features of Solid Lipid Nanoparticles prepared with nanoclay and spring water ingredients with demonstrated wound healing activity: a pilot study

Solid Lipid Nanoparticles (SLN) emerged in the late 20^th century as versatile nanoparticle drug delivery systems. Since then, SLNs have demonstrated to be useful for the encapsulation of a great number of actives. In particular, the role of SLN in wound healing is pretty recent, since the major part of scientific literature on this field is concentrated during 2019 and 2020 (keywords “solid lipid nanoparticle” and “wound healing”; Boolean operator “and”; databases: Web of Sciences, Science Direct and Pubmed) [1–7].

In this pilot study we propose the formulation of a semisolid system formed by SLN embedded in an inorganic hydrogel with demonstrated wound healing activity [8]. The aim is to assess the main properties and stability of SLN embedded in a wound healing hydrogel. The hot emulsification method was used to prepare the SLN. Spring water (ALI) and ultrapurified water (milliQ^®) were used as aqueous medium. Then, the clay mineral (PS9) was added and homogenized by means of an Ultraturrax^®. Granulometry, pH, rheology and TEM microscopy were used to characterize the formulations.

Granulometry showed that the use of natural spring water does not affect the SLN’s particle size. The presence of the PS9 moved the granulometry towards higher sizes and maintained stable for three months. TEM results confirm the granulometry previously reported, some coalescence of SLN found in the samples with PS9. The pH of all the samples was around 6-8 and stable for 3 months. Regarding the rheology, it was revealed that the composition of the aqueous medium significantly influenced the viscosity and time-dependent properties.

In conclusion, the proposed SLN formulations would be very versatile for the treatment of skin diseases, especially for wound healing, due to the possibility to load different actives inside the SLN together with the already demonstrated wound healing activity of the inorganic hydrogel.