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    Item type:Publication,
    Copper-Modified Cellulose Paper: A Comparative Study of How Antimicrobial Activity Is Affected by Particle Size and Testing Standards
    (MDPI AG, 2025-01-08)
    Sara Ramírez
    ;
    Fabian Zúñiga
    ;
    Alejandra Amenábar
    ;
    ;
    Viviana Benavides
    This study aims to provide evidence that when testing cellulose paper modified with copper particles (CuPs), the particle size and the analysis method influence the antimicrobial activity observed by this material. Commercial CuPs of nanometric size (2.7 nm, CuNPs) and micrometric size (2.5 µm, CuMPs) were used to modify cellulose paper sheets. CuPs were incorporated during the pulp disintegration phase (stage 1) of the sheet formation process, according to the ISO 5269-1:2005 standard. Modified paper sheets retained 16% and 14% of CuNPs and CuMPs, respectively. Additionally, CuPs were distributed randomly on the fiber surfaces, often forming aggregates. Finally, the antimicrobial activity of the modified paper sheets was evaluated using ISO 20645:2004 and ISO 20743:2013. The results showed that the antimicrobial activity assessed using each standard method is conditioned by the mechanism of action of the CuPs and, therefore, by their size. It was concluded that ISO 20645:2004 is suitable for evaluating the antibacterial effect of paper/CuNPs, as nanoparticles diffuse from the paper and are released into the culture medium. In contrast, ISO 20743:2013 can be used for both CuNP- and CuMP-based paper, as it evaluates the antibacterial effect based on the direct interaction between the copper particle and the bacteria.
    Scopus© Citations 2  14
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    Item type:Publication,
    Fast and easy synthesis of silver, copper, and bimetallic nanoparticles on cellulose paper assisted by ultrasound
    (2023)
    Rodrigo Araya-Hermosilla
    ;
    ;
    César Zúñiga Loyola
    ;
    Sara Ramírez
    ;
    Sebastián Salazar
    Scopus© Citations 11  5
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    Item type:Publication,
    Oxide copper nanoparticles stabilized by acrylonitrile and methyl methacrylate polar monomers through a ligand exchange reaction
    (2021)
    Bárbara Rodríguez
    ;
    Sara Ramírez
    ;
    Pablo Gutiérrez
    ;
    ;
    Isaac Díaz-Aburto
    <jats:title>Abstract</jats:title> <jats:p>This research reports the synthesis of copper oxide nanoparticles (CuONP) functionalized by the polar monomers acrylonitrile (ACN) and methyl methacrylate (MMA). The synthesis was achieved by a practical exchange ligand reaction from CuONP previously stabilized by hexadecyltrimethylammonium bromide (CTAB). The replacement of CTAB by ACN or MMA produced the functionalized nanoparticles CuONP-ACN and CuONP-MMA, respectively. The functionalized nanoparticles were characterized by ultraviolet-visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (SEM), dynamic light scattering (DLS), Zeta potential, x-ray diffraction (XRD), high-resolution-transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED) analysis. Changes in surface plasmon resonance (SPR) band and the functional group bands observed in UV–vis and FTIR spectra confirmed the efficient replacement of CTAB by polar monomers. Moreover, CuONP-ACN and CuONP-MMA showed a negative surface charge with spherical morphology. X-ray diffraction (XRD) analysis showed that a monoclinic CuO crystal system was formed.</jats:p>
      3Scopus© Citations 6