Encapsulation and release of hydrophobic molecules from particles of gelled triglyceride with aminoacid-based low-molecular weight gelators

Abstract

Organogel nanoparticles of triglyceride oils were produced using an aminoacid-based low-molecular weight gelator and a polysaccharide-based stabilizer synthesized by hydrophobic modification of dextran (a non ionic bacterial polysaccharide). The hot liquid organic phase containing the organogelator was emulsified at 70°C into an aqueous solution of amphiphilic polysaccharide by application of ultrasounds. The resulting sub micrometric oil-in-water emulsion was let cooling down to room temperature leading to an aqueous suspension of gelled oil nanoparticles. The encapsulation of alkyl esters of gallic acid with various alkyl chain lengths (2, 3 and 8 carbon atoms) was carried-out by dissolving these molecules into the hot liquid oil. Octyl gallate (OG) appeared as the most suitable molecule with about 70% of the loaded drug encapsulated into the final particles. The influences of various formulation and process parameters on the final particle size distribution and the yield of encapsulation were examined. The kinetics of release of OG from gelled oil particles was monitored and it was shown that the transport at interface was limiting the rate of release of OG both for particles of gelled oil and for oil droplets without gelator. The cytotoxicity of gelator was studied with smooth muscle cells from mouse. These tests showed that it was possible to prepare formulations encapsulating enough OG and keeping the content of gelator below its limit of cytotoxicity.