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Contact-active antibacterial aerogels from cellulose nanofibrils
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.ORCID iD: 0000-0001-6263-8403
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.ORCID iD: 0000-0002-7410-0333
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
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2016 (English)In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 146, p. 415-422Article in journal (Refereed) Published
Abstract [en]

The use of cellulose aerogels as antibacterial materials has been investigated by applying a contact-active layer-by-layer modification to the aerogel surface. Studying the adsorption of multilayers of polyvinylamine (PVAm) and polyacrylic acid to aerogels comprising crosslinked cellulose nanofibrils and monitoring the subsequent bacterial adhesion revealed that up to 26 mg PVAm g aerogel−1 was adsorbed without noticeably affecting the aerogel structure. The antibacterial effect was tested by measuring the reduction of viable bacteria in solution when the aerogels were present. The results show that >99.9% of the bacteria adhered to the surface of the aerogels. Microscopy further showed adherence of bacteria to the surfaces of the modified aerogels. These results indicate that it is possible to create materials with three-dimensional cellulose structures that adsorb bacteria with very high efficiency utilizing the high specific surface area of the aerogels in combination with their open structure.

Place, publisher, year, edition, pages
2016. Vol. 146, p. 415-422
Keywords [en]
Antibacterial, Cellulose nanofibrils, Aerogel, Contact active, Polymer adsorption
National Category
Paper, Pulp and Fiber Technology
Research subject
Materials Science and Engineering
Identifiers
URN: urn:nbn:se:kth:diva-185001DOI: 10.1016/j.colsurfb.2016.06.031ISI: 000382269600046PubMedID: 27391038Scopus ID: 2-s2.0-84977269377OAI: oai:DiVA.org:kth-185001DiVA, id: diva2:917790
Funder
VINNOVA
Note

QC 20160825

Available from: 2016-04-07 Created: 2016-04-07 Last updated: 2020-03-09Bibliographically approved
In thesis
1. Bacterial adhesion to polyelectrolyte modified materials based on nanocellulose
Open this publication in new window or tab >>Bacterial adhesion to polyelectrolyte modified materials based on nanocellulose
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Since the introduction of materials based on cellulose nanofibrils (CNFs), these materials have been studied extensively and are suggested to be suitable for use in, for example, hygiene and health care products. A property not very well studied but that could further increase the usability of CNF products is the possibility of controlling bacterial adhesion to the materials. Controlling and fine-tuning the bacterial adhesion makes it possible to produce contact-active antibacterial materials as well as anti-adhesive materials.

The current thesis shows how the number of bacteria adhering to CNF-based materials can be altered through the adsorption of polyelectrolyte multilayers. Polyvinylamine (PVAm) and polyacrylic acid (PAA) were adsorbed in multilayers to achieve differently charged materials. The CNF substrates consisted of both crosslinked and non-crosslinked films with different surface charges and structures as well as porous aerogels.

The results show the possibility of adsorbing PVAm/PAA to recharge the surfaces and construct multilayers. The polyelectrolyte adsorption was affected both by crosslinking and by changing the surface charge of the CNF films. Increasing the surface charge resulted in a decreased PVAm adsorption after the first polymer layer. Crosslinking the films resulted in a low initial PVAm adsorption, but as more layers were adsorbed, the PVAm adsorption increased similarly to the non-crosslinked films. The PVAm adsorption to the aerogels was lower than expected, taking into account their high surface area and surface charge, possibly due to crowding effects on the surface due to geometric limitations.

Only the CNF films with the lowest surface charge and the aerogels adsorbed high numbers of bacteria from bacterial suspensions. The bacterial adsorption to the films was affected by the surface charge, the PAA adsorption and the PVAm adsorption, with a higher net surface charge leading to higher bacterial adsorption. The aerogels efficiently removed bacteria from the bacterial suspensions by adsorbing them onto their surface, with some samples removing over 99.9 % of the bacteria. The results presented in this thesis are believed to lead to a better understanding of both polyelectrolyte adsorption on CNF materials and bacterial adhesion to CNF materials and how polyelectrolyte multilayer adsorption can alter it.

Abstract [sv]

Material tillverkade av cellulosa nanofibriller (CNF) öppnar upp många nya möjligheter inom bland annat hygien och sjukvårdssektorn med material som har nya eller förbättrade egenskaper. En egenskap som inte har undersökts särskilt väl, men som är viktig inom dessa tillämpningar, är hur bakterier fäster på materalets yta och hur detta kan styras. Genom att kontrollera interaktionen mellan bakterier och material är det möjligt att designa både icke adhesiva och antibakteriella material som är kontaktaktiva.

Denna avhandling beskriver hur adsorptionen av bakterier på material av CNF kan styras genom adsorption av polyelektrolyter i multilager. Polyvinylamin (PVAm) och polyakrylsyra (PAA) adsorberades i multilager till olika laddade och strukturerade material av CNF. Materialen bestod av tvärbundna och icke tvärbundna CNF-filmer med olika ytladdningar och strukturer, samt porösa aerogeler av CNF.

Resultaten visar att det är möjligt att adsorbera PVAm/PAA för att omladda ytan och bygga multilager. Polyelektrolyt-adsorptionen påverkades av både tvär bindning och ytladdningen av filmerna. Högre ytladdning ledde till en lägre PVAm adsorption. Tvärbindning av filmerna ledde till en initialt låg PVAm adsorption, dock så ökade den i de följande lagren för att bygga multilager liknande de icke tvärbundna. PVAm-adsorptionen på aerogelerna var lägre än väntat med hänseende till den höga ytarean och ytladdningen. Detta föreslås bero på geometriska begränsningar på ytan som styr PVAm adsorptionen.

Enbart CNF filmerna med lägst ytladdning och aerogelerna, adsorberade större mängder bakterier på ytan efter att de exponerats för bakterielösningar. Bakterieadsorptionen på filmerna påverkades av ytladdning och adsorptionen av både PVAm och PAA, en högre total ytladdning ledde till fler bakterier på ytorna. Aerogelerna adsorberade effektivt stora mängder bakterier, vissa av materialen minskade mängden bakterier i lösning med över 99,9 %. Resultaten från denna avhandling leder till en ökad förståelse för hur både polyelektrolyter adsorberar på CNF material och hur bakterieadhesionen kan styras för dessa material. Förhoppningarna är att dessa material kommer bättre kunna anpassas för att användning i applikationer som är känsliga för bakterier. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. p. viii, 35
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:14
Keywords
Bacterial adhesion, cellulose nanofibrils, polymer adsorption, polyvinylamine
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-184512 (URN)978-91-7595-915-3 (ISBN)
Presentation
2016-04-29, E3, Osquars backe 14, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
VINNOVA
Note

QC 20160408

Available from: 2016-04-08 Created: 2016-04-01 Last updated: 2019-12-20Bibliographically approved
2. Bio-based preparation of nanocellulose and functionalization using polyelectrolytes
Open this publication in new window or tab >>Bio-based preparation of nanocellulose and functionalization using polyelectrolytes
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [sv]

Nanocellulosa, som kan utvinnas från skogsråvara, har de senaste åren fått mycket uppmärksamhet för sina intressanta egenskaper och breda användningsområde. Studierna i denna avhandling syftar till att vidga möjligheterna att använda nanocellulosa i olika applikationer. Detta har skett genom att utveckla en ny metod för att tillverka nanocellulosa och genom att studera möjligheten att adsorbera polyelektrolyter på material av nanocellulosa för att ändra hur bakterier interagerar med dessa.

Nanocellulosan tillverkades genom att förbehandla pappersmassa med smält oxalsyra dihydrat. Reaktionsblandningen tvättades med etanol, aceton eller tetrahydrofuran innan den torkades och fibrillerades. Den resulterande nanocellulosan erhölls med högt utbyte, hade hög ytladdning (upp till 1,4 mmol g-1) och innehöll partiklar som både liknande nanofibriller och nanokristaller. Materialet visades kunna användas både för att tillverka Pickering emulsioner och tunna filmer med en styrka upp till 197 MPa, töjning upp till 5 %, E-modul upp till 10,6 GPa och syrepermeabilitet ner till 0.31 cm3 µm m‑2 dag‑kPa‑1.

Genom att adsorbera polyvinylamin och polyakrylsyra på material av nanocellulosa visades det vara möjligt att påverka mängden bakterier som fäster till materialet. Substraten bestod både av kompakta filmer och porösa aerogeler. Genom att variera ytladdningen på materialen, ytans struktur och antalet adsorberade lager av polymererna var det möjligt att tillverka material med både hög och låg bakterieadhesion. Detta gör det möjligt att anpassa material för användning antingen som kontaktaktivt- eller icke-adhesivt antibakteriellt material. Båda dessa kan vara miljövänliga alternativ till dagens antibakteriella material.

Nanocellulosa är ett material som inom snar framtid sannolikt kommer användas inom en mängd olika applikationer. För att öka mängden applikationer där nanocellulosa tillför ett stort värde är det nödvändigt att utveckla alternativa tillverkningsmetoder till dagens välkända, exempelvis, genom att använda den beskrivna oxaleringen som förbehandling. Förmågan att styra bakterieadhesionen på material av nanocellulosa ger därtill möjlighet att hitta nya användningsområden inom t.ex. hälso- och sjukvårdsbranschen.

Abstract [en]

Nanocellulose is a material which can be extracted from wood, and in recent years it has received great attention for its interesting properties and wide range of possible applications. With the aim of further expanding the applications of nanocellulose, this work has studied a new way to produce nanocellulose as well as the possibility of using polyelectrolyte adsorption to alter the interaction with bacteria of materials made from nanocellulose.

Nanocellulose was produced by a novel concurrent esterification and hydrolysis of wood pulp in molten oxalic acid dihydrate. The resulting mixture was washed using ethanol, acetone or tetrahydrofuran before the cellulose oxalate was dried and fibrillated. The nanocellulose obtained with a high yield had a high surface charge (up to 1.4 mmol g-1) and contained particles with a morphology similar to both cellulose nanocrystals and cellulose nanofibrils. The material was used to prepare both Pickering emulsions and thin films with a strength of up to 197 MPa, a strain at break of up to 5 %, a modulus of up to 10.6 GPa and an oxygen permeability as low as 0.31 cm3 µm m-2 day-1 kPa-1.

Polyelectrolyte adsorption of polyvinylamine and polyacrylic acid was used to modify materials made from nanocellulose. Materials in the form of films and aerogels were used as substrates. By altering the surface charge of the material, the surface structure and the number of layers of polyvinylamine/polyacrylic acid adsorbed, it was possible to prepare materials with both high and low bacterial adhesion. By changing the material properties it is possible to tailor materials with either contact-active or non-adhesive antibacterial properties, both of which are sustainable alternatives to the currently used antibacterial materials.

Nanocellulose is a material which in the near future will probably be used in many applications. In order to improve the suitability of nanocellulose in certain applications it will be necessary to use production methods which differ from the existing methods, for example by using oxalation as a pre-treatment. By modifying the bacterial adhesion to materials prepared from nanocellulose, new medical and health applications emerge.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 67
Series
TRITA-CBH-FOU ; 2019:36
Keywords
cellulose nanofibrils, cellulose nanocrystals, oxalic acid, polyvinylamine, layer by layer, cellulose oxalate, antibacterial, Cellulosa nanofibriller, cellulosa nanokristaller, oxalsyra, polyvinylamin, lager på lager, cellulosa oxalat, antibakteriell
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-252580 (URN)978-91-7873-245-6 (ISBN)
Public defence
2019-08-30, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 2019-06-05

Available from: 2019-06-05 Created: 2019-06-02 Last updated: 2019-06-05Bibliographically approved

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Publisher's full textPubMedScopushttp://www.sciencedirect.com/science/article/pii/S0927776516304611

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Henschen, JonatanIllergård, JosefinLarsson, Per A.Wågberg, Lars

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