An effective polydopamine coating to improve stability and bioactivity of carvacrol-loaded zein nanoparticles

Abstract

In this study, a simple and facile method was used to fabricate carvacrol-loaded zein nanoparticles (CLZNPs), and CLZNPs were coated with different concentrations (0.25, 0.5 and 1 mg mL−1) of polydopamine (PDA) to fabricate CLZPNPs. Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses showed that CLNPs and CLZPNPs possessed spherical shapes with smooth surfaces in the sizes of 562 and 725 nm and were highly stable possessing high encapsulation efficiency (81.3%). The antioxidant activity of CLZPNPs (ranging from 70.97% to 89.84%) was higher than that (51.42%) of CLZNPs. PDA had a significant effect to increase the antioxidant activity of the CLZNPs. The thermal stability of the particles was influenced by a temperature change from 30 °C to 70 °C. While 1 CLZPNP sample possessed the highest retention rate of carvacrol, the uncoated CLZNPs had the lowest retention value at all temperatures. The antibacterial effect of CLZNPs could be remarkably increased by their coating with PDA at different concentrations (0.25, 0.5 and 1 mg mL−1), reaching the level of 100% inhibition of Salmonella typhimurium, Pseudomonas aeruginosa and Staphylococcus aureus. As a result, coating the carvacrol-loaded nanoparticles (CLZNPs) with PDA enabled us to fabricate highly stable CLZPNPs possessing improved stability and bioactivity. The results of this study suggest that the fabricated nanoformulation would find an application in food packaging technology to increase the storage stability of the products and control various foodborne bacterial pathogens.