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 (CuSO 4 ). 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/CuO 2 species.Antibacterial activity (AA) of biosynthesized CuNPs was evaluated against two high virulence pathogens: Gram-positive Staphylococcus aureus and Gramnegative Pseudomonas aeruginosa, after 1 and 3 h of contact, showing a MIC of 200 μg/ml, and a CMB of 400 μg/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.
Porous materials are of great importance because of their multiple applications in pharmacy, catalysis, and biomedicine among others. Ice segregation induced self-assembly (ISISA) is a cryogenic technique that uses the ice as a template that forms upon immersion of a polymer solution into liquid nitrogen to obtain highly porous materials. Some highlights of this technique are its versatility, simplicity, and control over the final structure of the produced material; besides, no organic solvents are used during the process, and the material can be used without the need of further cleaning. In this contribution, the elaboration of scaffolds using a poly(ethylene glycol) aqueous solutions by an ice-template process has been studied from experimental and theoretical viewpoints. The experimental study of the process parameters, such as immersion velocity and a prescribed freezing front on the morphology, was carried out. Simulations were performed to understand the ISISA process by calculating temperature profiles and pore size as a function of time. The most important result of this study was the effect of freezing rate on pore size. The technique was optimized such that a recipe is proposed to form materials with 1−100 μm pore sizes.
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