Self-assembly of zein microspheres with controllable particle size and narrow distribution using a novel built-in ultrasonic dialysis process

Abstract Zein microspheres with controllable particle size and narrow size distribution were self-assembled using a novel built-in ultrasonic dialysis process (BUDP). The effects of different variables on the microstructures of obtained zein particles were investigated using an OA 16 (4 5 ) orthogonal experimental design. The results showed that zein particles prepared by the BUDP possessed a spherical morphology with mean particle size ( Dp 50 ) from 431.2 ± 69.6 nm to 2335 ± 406.1 nm under different process parameters. Zein microspheres prepared at optimized conditions presented much smaller particle size and narrower size distribution ( Dp 50  = 398.2 ± 41.3 nm) than those obtained without ultrasound ( Dp 50  = 1776 ± 1181.1 nm). FT-IR, 1 H NMR, XRD, TG and DSC characterization results showed that the chemical structure, crystal structure and thermal behavior of the zein microspheres obtained by BUDP were similar with raw zein and that prepared without ultrasound. The ultrasound power and zein concentration were the most important process parameters affecting particle formation. The formation mechanisms of zein microspheres and the influence mechanisms of the operating parameters were discussed in detail. Also, a semi-empirical model was developed for predicting particle size. Furthermore, curcumin was encapsulated into zein microspheres using BUDP, and curcumin-loaded zein microspheres sustained curcumin release rate successfully in vitro.