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The Antibacterial Effect of Contact-Active Multilayers: A Mechanistic Approach
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.ORCID iD: 0000-0003-1812-7336
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0001-8622-0386
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
(English)Manuscript (preprint) (Other academic)
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-90749OAI: oai:DiVA.org:kth-90749DiVA: diva2:506363
Note
QS 2012Available from: 2012-02-28 Created: 2012-02-28 Last updated: 2012-02-28Bibliographically approved
In thesis
1. The creation of antibacterial fibres through physical adsorption of polyelectrolytes
Open this publication in new window or tab >>The creation of antibacterial fibres through physical adsorption of polyelectrolytes
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Contact-active antibacterial surfaces with irreversibly attached antibacterial com-pounds are a sustainable alternative to traditional biocides. No chemicals are released into nature and the antibacterial mechanism reduces the risk of the evolution of re-sistant bacteria. However, the preparation of such surfaces is far from sustainable, as organic solvents and harsh reaction conditions commonly are required. An alter-native option is to use polyelectrolyte multilayers (PEM), based on physical ad-sorption, which can be performed in water-based solutions at room temperature. Although contact-active antibacterial PEMs have been reported previously, this is the first study of renewable cellulosic wood fibres.

The build-up of cationic polymer polyvinylamine (PVAm) and anionic polyacrylic acid (PAA) multilayers on model surfaces was studied to optimise adsorption. The amount of adsorbed polyelectrolytes was continuously growing with increasing number of layers, but remained dense and flat as the number of layers increased. The largest adsorption was obtained at a high salt concentration, which shielded the repulsion between the polymers.

Model surfaces were also used to evaluate the influence of the polymer and number of layers on the antibacterial properties. Multilayers on model surfaces showed a low bacteriostatic effect, with up to approximately 40 % inhibition for 3 layers of un-modified PVAm/PAA. In contrast, when the same multilayers were applied on cel-lulosic fibres, bacterial-growth inhibition of > 99.9% was obtained. Hydrophobically modified PVAm did not yield better results, despite being superior in solution. An increase in fibre charge by fibre oxidation led to the largest amount of adsorbed pol-ymer and the best antibacterial properties, an effect that lasted for weeks. Electron microscopy study of bacteria on the fibres showed that the bacteria interacted more on a highly charged surface and that the morphology of the bacterial cell could be affected. The effect was suggested to be due to electrostatic interaction with the pos-itively charged modified fibres. The promising results offer the possibilities of a new generation of antibacterial surfaces based on a renewable resource.

Abstract [sv]

Antibakteriella kontaktaktiva ytor som har ett antibakteriellt ämne permanent fäst på ytan är ett miljövänligt och säkrare alternativ till traditionell biocidanvändning. Inget utsläpp av giftiga ämnen sker från ytorna och detta tillsammans med den anti-bakteriella mekanismen minskar risken för att bakterierna utvecklar resistens. Till-verkningsprocessen i sig har dock hittills varit allt annat än miljövänlig, då den ke-miska modifieringen kräver organiska lösningsmedel och har reaktioner som kräver speciella villkor, t ex höga temperaturer. En alternativ ytmodifiering är att använda sig av fysikalisk adsorption av polyelektrolyter i multiskikt, eftersom detta kan göras i vat-tenlösningar och i rumstemperatur. Det här arbetet är det första som beskriver kon-takt-aktiva multilager på förnyelsebara svedbaserade cellulosafiber.

Som ett första steg gjordes en adsorptionsstudie på modellytor för att optimera ad-sorptionen av katjonisk polyvinylamin (PVAm) och anjonisk polyakrylsyra (PAA). Med ökande antal lager ökade totala mängden adsorberad polymer samtidigt som multilagerna förblev platta och täta. Den högsta adsorptionen skedde vid en hög salt-halt som minimerade den elektrostatiska repulsionen mellan polymerkedjorna.

Modellytor användes även för att studera hur de antibakteriella egenskaperna påver-kades av polymermodifiering och av antal lager. På dessa ytor uppmättes en låg bakte-riostatisk effekt med upp till 40 % inhibering av bakterietillväxten för tre lager av PVAm./PAA När däremot samma multilager fanns på cellulosafiber ökade in-hiberingen till uppemot 99.9 %. Hydrofobmodifiering av PVAm påverkade inte det antibakteriella resultatet när de var i multilager, trots bevisad ökad verkan i lösning. Genom att via oxidering öka fiberladdningen kunde mängden adsorberad polymer yt-terligare öka och resulterade i en förbättrad antibakteriell verkan som höll i sig i flera veckor. Elektronmikroskopi av bakterier på fiber visade en ökad interaktion med hög-laddade ytor och att bakteriernas cellmorfologi kan påverkas av ytorna.Den observerade antibakteriella effekten föreslås vara en följd av elektrostatisk inter-aktion mellan de negativt laddade bakterierna och positivt laddade modifierade fibrena. Resultaten är lovande och banar väg för nya kontakt-aktiva antibakteriella material.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 58 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2012:11
Keyword
antibacterial, polyelectrolyte multilayers, polyvinylamine, contact-active antibacterial surfaces
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-90731 (URN)978-91-7501-274-2 (ISBN)
Public defence
2012-03-16, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
Biointeractive fibres with antibacterial properties
Available from: 2012-02-28 Created: 2012-02-28 Last updated: 2013-02-25Bibliographically approved

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Illergård, JosefinWågberg, Lars

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