title: The potential use of a layer-by-layer strategy to develop LDPE antimicrobial films coated with silver nanoparticles for packaging applications.
abstract: Commercial low-density polyethylene (LDPE) films were UV/ozone treated and coated using a layer-by-layer (LbL) technique by alternating the deposition of polyethyleneimine (PEI) and poly(acrylic acid) (PAA) polymer solutions and antimicrobial silver (Ag). The effects of the initial pH of the PEI/PAA polymer solutions alternating layers (pH 10.5/4 or 9/6.5) on the antimicrobial activity of the developed LbL coatings combined with Ag against Gram-negative and Gram-positive bacteria were investigated. The results from fourier transform infrared spectroscopy and toluidine blue O assay showed that LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 10.5/4 significantly increased the presence of carboxylic acid groups and after Ag attachment the coating had higher antimicrobial activity against both Gram-negative and Gram-positive bacteria compared to the LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 9/6.5. The LDPE LbL coated films using non-modified pH PEI/PAA polymer solutions decreased the water contact-angle indicating an increased hydrophilicity of the film, also increased the tensile strength and roughness of LDPE LbL coated films compared to uncoated LbL samples. The LDPE LbL coated films attached with Ag(+) were UV/ozone treated for 20 min to oxidise Ag(+) to Ag(0). The presence of Ag(0) (Ag nanoparticles (NPs)) on the LDPE LbL coated films was confirmed by XRD, UV-vis spectrophotometer and colour changes. The overall results demonstrated that the LbL technique has the potential to be used as a coating method containing antimicrobial Ag NPs and that the manufactured films could potentially be applied as antimicrobial packaging.
authors.affiliation: Food Packaging Group, School of Food & Nutritional Sciences, University College Cork, Cork, Ireland; Department of Food Science, School of Food Science and Technology, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia.
authors.forename: Shafrina
authors.initials: S
authors.lastname: Azlin-Hasim
authors.affiliation: Food Packaging Group, School of Food & Nutritional Sciences, University College Cork, Cork, Ireland.
authors.forename: Malco C
authors.initials: MC
authors.lastname: Cruz-Romero
authors.affiliation: UCD School of Biosystems Engineering, Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Enda
authors.initials: E
authors.lastname: Cummins
authors.affiliation: Food Packaging Group, School of Food & Nutritional Sciences, University College Cork, Cork, Ireland. Electronic address: Joe.Kerry@ucc.ie.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Kerry
authors.affiliation: Department of Chemistry, University College Cork, Cork, Ireland. Electronic address: M.Morris@ucc.ie.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Morris
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D018857:Food Packaging / Q000295:instrumentation*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D020959:Polyethylene / Q000737:chemistry / Q000494:pharmacology*; D011094:Polyethyleneimine / Q000737:chemistry; D011551:Pseudomonas fluorescens / Q000187:drug effects; D012834:Silver / Q000737:chemistry / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects; D013329:Structure-Activity Relationship; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; D000900:Anti-Bacterial Agents; D012834:Silver; C006903:carbopol 940; D020959:Polyethylene; D011094:Polyethyleneimine
keywords: Antimicrobial packaging; Coating; Layer-by-layer; Low density polyethylene; Silver nanoparticles