Sucrose ester nanodispersions: Microviscosity and viscoelastic properties

Abstract

Sucrose esters have the potential to enhance both drug solubility and drug absorption. They are therefore alternatives to the widely used glycerides in the formulation of lipid-based drug delivery systems. A simple production of aqueous nanosized drug carrier systems consisting of amphiphilic sucrose fatty acid esters using exclusively nontoxic materials has been achieved. By only using 2 wt% of the emulsifier a high viscosity of the sample could be reached. Diverse history of fabrication led to the differences in the macroviscosity of SE dispersions with equal chemical composition. Combining the well-established oscillating rheology with the electron paramagnetic resonance technique, three orders of magnitude difference in macroviscosity between the dispersions containing 2 wt% of the amphiphilic SE were obtained, whereas the viscosities at the molecular level were all close to the viscosity of water. Viscoelastic behaviour could also be shown for these systems. TEM experiments visualized coexisting irregular micelles and lamellar structures in the SE dispersions. The results are important to understand the complex LDDS based on amphiphilic SE.