Analysis of the differences in self-assembly behaviour, molecular structure and drug delivery performance between α and β-Zein

The past decade has witnessed rapid development in zein-based drug delivery systems. However, the lack of a deep understanding of self-assembly and co-self-assembly between drug and zein has limited its application. In this work, alpha and beta-zein, the main ingredients of zein, were separated and the different self-assembly behaviour was investigated, respectively. In ethanol solution, alpha-zein shows uncontrollable self-assembly and explosive nucleation. The nano-mechanical properties investigated by AFM show that alpha-zein nanoparticles self-assembled in the ethanol possessed a higher adhesion force (99.45 +/- 6.90 nN), which explains its uncontrollable self assembly. After loading with paclitaxel (PTX), Young's modulus of alpha-zein had significantly reduced from 525.57 +/- 53.82-95.35 +/- 20.98 MPa, which implies that the PTX-alpha-zein nanoparticle has a loose structure. The interaction between drug and carrier was studied using a fluorescence quenching experiment, and the mathematical model was established. The result shows that the main driving force for interaction between PTX and alpha-zein is the hydrophobic force, while interaction between PTX and beta-zein is hydrogen bonding and Van der Waals forces. The negative Delta G value indicates that the binging between PTX and alpha-zein or beta-zein is a spontaneous process although the nature of the interaction is somewhat different. An in vitro cytotoxicity study shows that the different self-assembly behaviour resulted in different cell viability. Finally, a possible self-assembly mechanism of alpha and beta-zein was proposed. It is anticipated that a fundamental understanding of self-assembly between drug and alpha or beta-zein will provide an important foundation for its application in biological and material fields.

Automated summary

This study separated the main components of zein, alpha-zein and beta-zein, and investigated their different self-assembly behaviors. The driving force between PTX and alpha-zein was found to be hydrophobic force, while the interaction between PTX and beta-zein involved hydrogen bonding and Van der Waals forces.