Preparation of water-soluble antimicrobial zein nanoparticles by a modified antisolvent approach and their characterization

We developed a simple antisolvent procedure to prepare core/shell zein/SC nanoparticles by directly pouring sodium caseinate (SC) into zein solutions. The nanoparticles are spherical in shape, possessing the re-dispersibility in de-ionized water after freeze-drying. The nanoparticles possessed strong loading capacity for thymol, and were stable over 8 months storage. Morphological attributes, antimicrobial and antioxidant properties as well as release profiles of thymol-loaded nanoparticles were investigated. Thymol loadings gave the nanoparticles antimicrobial activity against tested bacteria on agar diffusion assay as well as DPPH radical scavenging activity, in a dose-dependent manner. These nanoparticles were also effective in delaying the growth of Staphylococcus aureus in fresh M-H broth at 37 °C. Thymol loading resulted in a slight increase in particle size, and did not affect the re-dispersibility of the nanoparticles. The nanoparticle sustained the release of thymol, and the release kinetic of thymol can be described as a two-step biphasic process.