Formulation and rheological evaluation of liposomes-loaded carbopol hydrogels based on thermal waters

The aims of this study were to develop topical liposomal hydrogels based on thermal waters (TWs) acquired in the region of Biskra (Northeast Algeria) and also to investigate their rheological properties. Liposomes containing two highly mineralized thermal waters, Baraka (BTW) and Salhine (STW), were prepared by probe sonication using phosphatidylcholine (PC) and cholesterol (Chol), plain or mixed with phosphatidylglycerol (PG). Based on their lipid composition, obtained liposomes presented vesicle sizes of 60 nm, a low polydispersity index, and various negative zeta potentials. It was noted that with increasing counterions charge in TWs the zeta potential of liposomes decreased toward neutral values.Carbopol (1%, w/w) hydrogels prepared with BTW, STW, and also demineralized water (placebo hydrogel) showed a non-Newtonian behavior, pseudoplastic fluid adjusted to Carreau model. The composition of thermal waters influenced highly the rheological properties of Carbopol hydrogels. Liposomal hydrogels were prepared by dispersing liposomes in hydrogels formulated with the same encapsulated thermal water. Regardless of composition or lipid concentration of added liposomes, the viscosity and viscoelastic parameters of Carbopol hydrogels changed negligibly. Indeed, liposome composition and lipid concentration seemed to have no effect on the rheological properties of Carbopol hydrogel in the presence of an important charge of cations. Hence, hydrogels and liposomal hydrogels based on thermal waters had suitable rheological properties for topical application and delivery of minerals in the skin.