Using Phytoglycogen Nanoparticles to Improve the Water Solubility of Bioactive Compounds

Phytoglycogen (PG) is a naturally occurring, dendrimeric polysaccharide produced as compact nanoparticles in the kernels of sweet corn. PG nanoparticles are soft, porous, digestible and nontoxic, which makes them ideally suited for applications in human health and nutrition. Many bioactive compounds suffer from poor water solubility, and enhancement of their bioavailability is a major challenge for industry. We have explored improving the solubility of the insoluble carotenoid astaxanthin (ASX) through association with PG as a gateway to enhanced bioavailability. We have developed a technique that incorporates roto-evaporation and freeze-drying to create a dehydrated ASX-PG powder that is readily dispersed in water and creates stable dispersions of ASX-PG at concentrations that exceed the solubility limit of ASX in water by many orders of magnitude. We use ultraviolet-visible (UV-Vis) spectroscopy to characterize the aggregation state of the ASX-PG dispersions, and surface plasmon resonance imaging (SPRi) to quantify the degree of binding between ASX-PG and a PG-functionalized SPR sensor surface. Our results demonstrate that PG is an effective solubilizing agent for ASX.