title: Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma.
abstract: This work studies the surface characteristics, antimicrobial activity, and aging effect of plasma-pretreated polyamide 6,6 (PA66) fabrics coated with silver nanoparticles (AgNPs), aiming to identify the optimum size of nanosilver exhibiting antibacterial properties suitable for the manufacture of hospital textiles. The release of bactericidal Ag(+) ions from a 10, 20, 40, 60, and 100 nm AgNPs-coated PA66 surface was a function of the particles' size, number, and aging. Plasma pretreatment promoted both ionic and covalent interactions between AgNPs and the formed oxygen species on the fibers, favoring the deposition of smaller-diameter AgNPs that consequently showed better immediate and durable antimicrobial effects against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Surprisingly, after 30 days of aging, a comparable bacterial growth inhibition was achieved for all of the fibers treated with AgNPs <100 nm in size. The Ag(+) in the coatings also favored the electrostatic stabilization of the plasma-induced functional groups on the PA66 surface, thereby retarding the aging process. At the same time, the size-related ratio (Ag(+)/Ag(0)) of the AgNPs between 40 and 60 nm allowed for the controlled release of Ag(+) rather than bulk silver. Overall, the results suggest that instead of reducing the size of the AgNPs, which is associated with higher toxicity, similar long-term effects can be achieved with larger NPs (40-60 nm), even in lower concentrations. Because the antimicrobial efficiency of AgNPs larger than 30 nm is mainly ruled by the release of Ag(+) over time and not by the size and number of the AgNPs, this parameter is crucial for the development of efficient antimicrobial coatings on plasma-treated surfaces and contributes to the safety and durability of clothing used in clinical settings.
authors.affiliation: †Centro de Ciência e Tecnologia Têxtil (2C2T), Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: Andrea
authors.initials: A
authors.lastname: Zille
authors.affiliation: ‡Group of Molecular and Industrial Biotechnology, Department of Chemical Engineering, Universitat Politècnica de Catalunya, Rambla Sant Nebridi, 22, 08222 Terrassa, Spain.
authors.forename: Margarida M
authors.initials: MM
authors.lastname: Fernandes
authors.affiliation: ‡Group of Molecular and Industrial Biotechnology, Department of Chemical Engineering, Universitat Politècnica de Catalunya, Rambla Sant Nebridi, 22, 08222 Terrassa, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Francesko
authors.affiliation: ‡Group of Molecular and Industrial Biotechnology, Department of Chemical Engineering, Universitat Politècnica de Catalunya, Rambla Sant Nebridi, 22, 08222 Terrassa, Spain.
authors.forename: Tzanko
authors.initials: T
authors.lastname: Tzanov
authors.affiliation: †Centro de Ciência e Tecnologia Têxtil (2C2T), Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: Marta
authors.initials: M
authors.lastname: Fernandes
authors.affiliation: §Department of Textile Engineering, Federal University of Rio Grande do Norte, Av. Salgado Filho, 3000, Lagoa Nova, Natal, RN, 59078-970 Brazil.
authors.forename: Fernando R
authors.initials: FR
authors.lastname: Oliveira
authors.affiliation: †Centro de Ciência e Tecnologia Têxtil (2C2T), Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Almeida
authors.affiliation: †Centro de Ciência e Tecnologia Têxtil (2C2T), Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: Teresa
authors.initials: T
authors.lastname: Amorim
authors.affiliation: †Centro de Ciência e Tecnologia Têxtil (2C2T), Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: Noémia
authors.initials: N
authors.lastname: Carneiro
authors.affiliation: †Centro de Ciência e Tecnologia Têxtil (2C2T), Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: Maria F
authors.initials: MF
authors.lastname: Esteves
authors.affiliation: †Centro de Ciência e Tecnologia Têxtil (2C2T), Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
authors.forename: António P
authors.initials: AP
authors.lastname: Souto
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D053768:Metal Nanoparticles / Q000737:chemistry*; D009757:Nylons / Q000737:chemistry*; D010316:Particle Size; D058626:Plasma Gases / Q000737:chemistry; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology; D013784:Textiles; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D009757:Nylons; D058626:Plasma Gases; D012834:Silver
keywords: aging; antimicrobial effect; dielectric barrier discharge plasma; polyamide fabric; silver nanoparticles