Co-Encapsulation of Curcumin and Diosmetin in Nanoparticles Formed by Plant-Food-Protein Interaction Using a pH-Driven Method.

ABSTRACT

In this work, a pH-driven method was used to prepare zein-soy protein isolate (SPI) composite nanoparticles (NPs). The mass ratio of SPI to zein influenced the Z-average size (Z-ave). Once the zeta potential stabilized, SPI was completely coated on the periphery of the zein NPs. The optimal mass ratio of zeinSPI was found to be 23. After determining the structure using TEM, curcumin (Cur) and/or diosmetin (Dio) were loaded into zein-SPI NPs for co-encapsulation or individual delivery. The co-encapsulation of Cur and Dio altered their protein conformations, and both Cur and Dio transformed from a crystalline structure to an amorphous form. The protein conformation change increased the number of binding sites between Dio and zein NPs. As a result, the encapsulation efficiency (EE%) of Dio improved from 43.07% to 73.41%, and thereby increased the loading efficiency (LE%) of zein-SPI NPs to 16.54%. Compared to Dio-loaded zein-SPI NPs, Cur/Dio-loaded zein-SPI NPs improved the storage stability of Dio from 61.96% to 82.41% within four weeks. The extended release of bioactive substances in the intestine during simulated gastrointestinal digestion improved the bioavailability. When exposed to a concentration of 0-800 µg/mL blank-loaded zein-SPI NPs, the viability of HepG2 and LO-2 cells was more than 90%, as shown in MTT assay tests. The zein-SPI NPs are non-toxic, biocompatible, and have potential applications in the food industry.