pH-Degradable antioxidant nanoparticles based on hydrogen-bonded tannic acid assembly

Abstract

Hydrogen-bonded polyphenol-based assemblies have attracted increasing interest for biomedical applications. Polyphenolic drug-loaded films can be coated on various devices with different shapes and sizes. Here, we report a novel versatile pH-responsive system based on hydrogen-bonded poly(ethylene glycol) (PEG)/tannin acid (TA) coatings on zein/TA colloidal nanoparticles (zein/TA/PEG NPs). Hydrogen bonding was considered to be the driving force for the coating buildup between PEG and TA, which was confirmed by Fourier transform infrared (FTIR) spectra. Because of the reversible/dynamic nature of hydrogen bonding, the release profile of TA was directed by pH value, temperature, ionic strength and TA concentration. The release rate of TA increased with increasing pH and temperature, but decreased with increasing ionic strength. This new drug delivery vehicle could also be used to load hydrophobic and unstable molecules through interacting with zein by hydrophobic interaction to achieve efficient protection. We demonstrated that the hydrophobic molecular nutrient, VD3, can be successfully loaded into zein/TA/PEG NPs with high encapsulation efficiency. Photostability against UV light was significantly improved after encapsulation. The encapsulated VD3 could be regulated not only by the pH of the solutions but also by TA concentration.