One- vs two-step preparation of antimicrobial coatings composed of laser ablated copper nanoparticles and poly-lactic acid

Abstract

Copper-containing nanomaterials have been developed as antimicrobial additives for food packaging applications. These nano-antimicrobials are composed of copper nanoparticles (CuNPs) embedded in poly-lactic acid (PLA), which has been selected as a biodegradable polymer matrix. Copper nanostructures have been synthesized by laser ablation following two different protocols: (I) one-pot synthesis in presence of PLA and (II) in absence of polymer matrix. In the latter route, the as prepared CuNPs suspension has been subsequently mixed to a PLA solution. The resulting dispersions have been directly drop-cast on several substrates. Nanoantimicrobials have been characterized by UV-Vis and x-ray photoelectron spectroscopies, and transmission electron microscopy. The kinetics of copper release in aqueous solution from antimicrobial nanomaterials have been studied by means of Electro-Thermal Atomic Absorption Spectroscopy. Finally, preliminary biological tests have been performed on Pseudomonas species by JIS methods (Japanese Industrial Standard, JIS Z 2801:2000).