Preparation of starch nanospheres through hydrophobic modification followed by initial water dialysis

Starch nanospheres smaller than 200 nm were produced from hydrophobically modified starch by using initial water dialysis method. The hydrophobic modification of starch was performed by using octenyl succinic anhydride (OSA). The resultant starch nanospheres were characterized by using Fourier transformation infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (1H NMR) spectroscopy and fluorescence spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS). Effects of degree of substitution (DS) in OSA-starch, initial water content and OSA-starch concentration on morphology and particle size of starch nanospheres were evaluated. The SEM micrographs showed that starch nanospheres with spherical shape and sharp edge can be produced at DS values ≧0.67. The particle size of starch nanospheres decreased significantly (P < 0.05) with increase in DS of OSA-starch and increase in the initial water content, whereas the particle size increased significantly (P < 0.05) with the increase in the concentration of OSA-starch. These OSA-starch nanospheres can be preferentially used to microencapsulate hydrophobic drugs.