Green synthesis of copper nanoparticles and their formulation into face masks: An antibacterial study

We report the facile ultrasound-assisted synthesis of copper nanoparticles (CuNPs) using blueberries extract (Vaccinium corymbosum) under environmental conditions and their incorporation into face masks as an effective antibacterial additive. For this purpose, the hydro-alcoholic blueberry extract was combined 1:1 with a metal precursor (CuSO4). The chemical reduction process was improved by ultrasound-assisted method for 30 min, obtaining semispherical CuNPs ranging ca. 3-12 nm employing TEM analysis. Freshly synthesized CuNPs were characterized by UV-Vis spectra, demonstrating the characteristic SPR absorption band at 535 nm. XRD patterns of CuNPs powder revealed the crystalline structure FCC of CuNPs, without CuO/CuO2 species. Antibacterial activity (AA) of biosynthesized CuNPs was evaluated against two high virulence pathogens: Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, after 1 and 3 h of contact, showing a MIC of 200 mu g/ml, and a CMB of 400 mu g/ml. To validate the potential biological application of CuNPs were incorporated into PES fibers and deposited at the surface of non-woven face masks against Escherichia coli and the airborne bacteria S. aureus, demonstrating their high antibacterial capacity after 24 h. Our results represent a facile and green method to produce high amounts of antibacterial CuNPs (yield ca. 1 g/L of reaction), with potential application as an effective additive for antimicrobial coatings formulation.