However, it is notable that after sonication zeta potential was higher than that of before the treatment.
Starch bears negative surface charge because the hydroxyl groups tend to ionize in water and which may be effected by the sonication process (Liu, Wu, Chen, & Chang, 2009). Meanwhile, loading with curcumin significantly changed the size distribution and zeta potential. Size of cur@star increased from 182 nm to 255 nm when curcumin loading amount varied from 1 wt% to 5 wt %. PDI values were lower than 0.2, indicating the size of cur@star nanocomposite follows homogeneous distribution pattern. Zeta potential values were also higher than that of pure starch.