Spraying layer-by-layer assembly of tannin-Fe3+ and polyethyleneimine for antibacterial coating

Abstract

Tannic acid (TA), as a natural molecule, possesses many excellent properties. It has attracted wide interest in various fields of functional coatings, food, and medicine. A simple method to prepare thick and stable TA-contained coating is required, which may promote practical applications of TA. Here, we proposed a simple and effective method of generating a stable TA-rich coating by spraying layer-by-layer technology. The coating was stabilized basing on the complexation of TA and ferric (Fe3+) ions and poly(ethyleneimine) (PEI). Because both TA and PEI have good antibacterial properties, the (TA-Fe3+/PEI) coating displayed the contact-killing against E. coli. Further, because of the reductive nature of the TA, the coating was able to incorporate nano‑silver particles by reducing silver ions. Consequently, the enhanced antibacterial property was achieved. The (TA-Fe3+/PEI) coating was then spraying coated on the nonwoven mask, showing the potential application in medical protection.