title: Novel composite plastics containing silver(I) acylpyrazolonato additives display potent antimicrobial activity by contact.
abstract: New silver(I) acylpyrazolonato derivatives displaying a mononuclear, polynuclear, or ionic nature, as a function of the ancillary azole ligands used in the synthesis, have been fully characterized by thermal analysis, solution NMR spectroscopy, solid-state IR and NMR spectroscopies, and X-ray diffraction techniques. These derivatives have been embedded in polyethylene (PE) matrix, and the antimicrobial activity of the composite materials has been tested against three bacterial strains (E. coli, P. aeruginosa, and S. aureus): Most of the composites show antimicrobial action comparable to PE embedded with AgNO3 . Tests by contact and release tests for specific migration of silver from PE composites clearly indicate that, at least in the case of the PE, for composites containing polynuclear silver(I) additives, the antimicrobial action is exerted by contact, without release of silver ions. Moreover, PE composites can be re-used several times, displaying the same antimicrobial activity. Membrane permeabilization studies and induced reactive oxygen species (ROS) generation tests confirm the disorganization of bacterial cell membranes. The cytotoxic effect, evaluated in CD34(+) cells by MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazoliumbromide) and CFU (colony forming units) assays, indicates that the PE composites do not induce cytotoxicity in human cells. Studies of ecotoxicity, based on the test of Daphnia magna, confirm tolerability of the PE composites by higher organisms and exclude the release of Ag(+) ions in sufficient amounts to affect water environment.
authors.affiliation: School of Science and Technology, Chemistry Section, University of Camerino, Via S. Agostino 1, Camerino (MC) (Italy). fabio.marchetti@unicam.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Marchetti
authors.forename: Jessica
authors.initials: J
authors.lastname: Palmucci
authors.forename: Claudio
authors.initials: C
authors.lastname: Pettinari
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pettinari
authors.forename: Francesca
authors.initials: F
authors.lastname: Condello
authors.forename: Stefano
authors.initials: S
authors.lastname: Ferraro
authors.forename: Mirko
authors.initials: M
authors.lastname: Marangoni
authors.forename: Alessandra
authors.initials: A
authors.lastname: Crispini
authors.forename: Stefania
authors.initials: S
authors.lastname: Scuri
authors.forename: Iolanda
authors.initials: I
authors.lastname: Grappasonni
authors.forename: Mario
authors.initials: M
authors.lastname: Cocchioni
authors.forename: Massimo
authors.initials: M
authors.lastname: Nabissi
authors.forename: Michele R
authors.initials: MR
authors.lastname: Chierotti
authors.forename: Roberto
authors.initials: R
authors.lastname: Gobetto
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D001424:Bacterial Infections / Q000188:drug therapy*; D002460:Cell Line; D003621:Daphnia; D004926:Escherichia coli / Q000187:drug effects*; D006801:Humans; D008958:Models, Molecular; D011095:Polyethylenes / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D011720:Pyrazoles / Q000737:chemistry / Q000494:pharmacology / Q000633:toxicity; D018030:Silver Compounds / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D013211:Staphylococcus aureus / Q000187:drug effects*; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D011095:Polyethylenes; D011720:Pyrazoles; D018030:Silver Compounds
keywords: antibiotics; antiproliferation; polymers; silver; solid-state structures