Physical stability of Pickering nanoemulsions stabilized with chitosan-octenyl succinic anhydride-modified starch polyelectrolyte complex

Abstract

This study aimed to investigate the effect of various parameters, including the molar charge ratio of chitosan-OSA-modified starch, starch-to-oil ratio, and preparation methods on the physical stability of Pickering nanoemulsions stabilized with chitosan-octenyl succinic anhydride (OSA)-modified starch polyelectrolyte complex (PEC). The nanoemulsions were prepared via ultrasonication using two different methods, namely, the PEC and layer-by-layer (LBL) methods. The investigated physical properties included appearance, droplet size, size distribution, and zeta potential of the nanoemulsions. The results indicated that at a molar charge ratio of 10:1, the nanoemulsions with chitosan-OSA-modified starch PECs had better physical stability. The droplet size, size distribution, and zeta potential were not statistically changed after 4 weeks of storage at 30 ± 2°C. At a lower chitosan-OSA-modified starch ratio, the LBL method provided better physically stable nanoemulsions than the PEC method. However, at a higher chitosan-OSA-modified starch ratio, both methods gave the nanoemulsions with comparable stability. The higher physical stability was attributable to the PEC of chitosan with OSA-modified starch at the o/w interface. In conclusion, the Pickering nanoemulsions stabilized with chitosan-OSA-modified starch PECs are a promising emulsion template for the encapsulation of lipophilic drugs.