Antimicrobial efficacy of curcumin nanoparticles against Listeria monocytogenes is mediated by surface charge

Curcumin, a hydrophobic phenolic compound isolated from tumeric (Curcuma longa), has gained a great attention due to its health benefits and antimicrobial effects. In this study, curcumin nanoparticles (CNPs) were formulated via acusto-plastic deformation technique, with three differently surface-charged surfactants-sodium dodecylsulfate, Tween 20 and cetrimonium bromide (CTAB). The fabricated CNPs were evaluated for their antimicrobial activity against Listeria monocytogenes, one of the most severe foodborne pathogens. Our results demonstrated that the CNPs formulated with positively charged surfactant (CTAB) exhibited the highest antimicrobial activity against L. monocytogenes, indicating that there is a strong relationship between surface charge and antimicrobial activity of curcumin. The enhanced antimicrobial action of CNPs-CTAB was concluded to be due to the increased cell-antimicrobial interaction, which resulted from the opposing electrical charges between CNPs-CTAB and L. monocytogenes cells, as well as increased antimicrobial penetration endowed by the small size. Practical applications: In this study, we showed that surface charge as well as the small size of curcumin nanoparticles play a key role in enhancing cell-antimicrobial interaction and antimicrobial efficacy. The fabricated CNP-CTAB showed the best antimicrobial activity against Listeria monocytogenes. A size reduction to nano-scale is a recently developed strategy used to improve drug/food delivery and matching the public demand for effective and safe antimicrobial formulations for control of foodborne pathogens.