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Covalent Surface Modification of Degradable Polymers for Increased Biocompatibility
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)Alternative title
Nano Patterened Covalent Surface Modification of Poly(ε-caprolactone) (English)
Abstract [en]

Degradable polymers have gained an increased attention in the field of biomedical applications over the past decades, for example in tissue engineering. One way of improving the biocompatibility of these polymers is by chemical surface modification, however the risk of degradation during the modification procedure is a limiting factor. In some biomedical applications, for example in nerve guides, a patterned surface is desired to improve the cell attachment and proliferation.

In this thesis a new non-destructive, single-step, and solvent free method for surface modification of degradable polymers is described. Poly(L-lactide) (PLLA) substrates have been functionalized with one of the following vinyl monomers; N-vinylpyrrolidone (VP), acrylamide (AAm), or maleic anhydride (MAH) grafts. The substrates were subjected to a vapor phase atmosphere constituted of a mixture of a vinyl monomer and a photoinitiator (benzophenone) in a closed chamber at very low pressure and under UV irradiation. Poly(ε-caprolactone) (PCL), poly(lactide-co-glycolide) (PLGA), and poly(trimethylene carbonate) (PTMC) have been surface modified with VP using the same procedure to show the versatility of the method. The wettability of all of the four substrates increased after grafting. The surface compositions were confirmed by ATR-FTIR and XPS. The VP grafted PLLA, PTMC and PLGA substrates have been shown to be good substrates for the normal human cells i.e. keratinocytes and fibroblasts, to adhere and proliferate on. The topography of substrates with well defined nano patterns was preserved during grafting, since the grafted layer is very thin. We have also shown that the method is useful for a simultaneous chemical and topographical modification of substrates by masked vapor phase grafting. The surface topography was determined with SEM and AFM.

Abstract [sv]

Intresset för användningen av nedbrytbara polymerer till biomedicinska applikationer som till exempel vävnads rekonstruktion har ökat avsevärt de senaste decennierna. Ett sätt att öka biokompatibiliteten hos dessa polymerer är genom kemisk ytmodifiering, men risken för nedbrytning under själva modifieringen är en begränsande faktor. I vissa biomedicinska applikationer, till exempel nervguider, är det önskvärt att ha en väldefinierad ytstruktur för att öka vidhäftningen och tillväxten av celler.

I den här avhandlingen presenteras en ny ickeförstörande, lösningsmedelsfri enstegsprocess för ytmodifiering av nedbrytbara polymerer. Substrat av poly(L-laktid) (PLLA) har ytfunktionaliserats med var och en av följande vinylmonomerer, N-vinylpyrrolidon (VP), akrylamid (AAm) eller maleinsyraanhydrid (MAH). Substraten har exponerats för en gasfasatmosfär av en blandning av en vinylmonomer och en fotoinitiator (bensofenon) i en tillsluten reaktor vid mycket lågt tryck och under UV-strålning. Metodens mångsidighet har även påvisats genom att ytmodifiera substrat av poly(ε-kaprolakton) (PCL), poly(laktid-co-glykolid) (PLGA) och poly(trimetylen karbonat) (PTMC) med VP. Vätbarheten ökade för alla fyra materialen efter ympning med en vinylmonomer. Ytsammansättningen fastställdes med ATR-FTIR och XPS. De VP ympade filmerna av PLLA, PLGA och PTMC visade sig vara bra substrat för mänskliga celler, i detta fall keratinocyter och fibroblaster, att vidhäfta och växa på. Yttopografin hos filmer med väldefinierade nanomönstrade ytor kunde bevaras efter ympning, tack vare att det ympade lagret är så tunt. Gasfas metoden har också visat sig användbar för att simultant ytmodifiera både kemiskt och topografiskt genom maskad gasfasympning. Yttopografin bestämdes med SEM och AFM.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , p. 59
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2005:37
Keywords [en]
Vapor phase grafting, covalent surface modification, solvent free, nano patterned topography, degradable polymers, poly(ε-caprolactone), poly(L-lactide), poly(lactide-co-glycolide), poly(trimethylene carbonate), N-vinylpyrrolidone, maleic anhydride, acrylamide
Keywords [sv]
Gasfasympning, kovalent ytmodifiering, lösningsmedelsfri, nedbrytbara polymerer, nanomönstrad topografi, poly(L-laktid), poly(ε-kaprolakton), poly(laktid-co-glykolid), poly(trimetylen karbonat), N-vinylpyrrolidon, maleinsyraanhydrid, akrylamid
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-579ISBN: 91-7178-195-1 (print)OAI: oai:DiVA.org:kth-579DiVA, id: diva2:14489
Presentation
2005-12-09, Salongen, KTHB, Osquars backe 31, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101014Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2010-12-07Bibliographically approved
List of papers
1. Single-Step Covalent Functionalization of Polylactide Surfaces
Open this publication in new window or tab >>Single-Step Covalent Functionalization of Polylactide Surfaces
2005 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, no 24, p. 8865-8871Article in journal (Refereed) Published
Abstract [en]

A single-step, nondestructive, and versatile technique for the grafting and chemical surface modification of biodegradable polymers such as polylacticle is described. The substrates are subjected to the vapor phase of any of three investigated vinyl monomers: acrylamide, maleic anhydride, and N-vinylpyrrolidone, and grafting is induced by photoinitiation of benzophenone under solvent free conditions. The modified surfaces exhibit higher wettability, and the grafting is verified by X-ray photoelectron spectroscopy, attenuated total reflection Fourier-transform IR, contact-angle measurements, and scanning electron microscopy. The graft-chain pendant groups remain functional and can subsequently be modified so that a tailor-made surface with desired properties may be achieved.

Keywords
Biodegradation; Chemical modification; Contact angle; Fourier transform infrared spectroscopy; Grafting (chemical); Monomers; Scanning electron microscopy; Substrates; Surface treatment; X ray photoelectron spectroscopy; Biodegradable polymers; Polylactide; Vapor phase; Vinyl monomers; Acrylamide; Benzophenones; Gases; Maleic Anhydrides; Photochemistry; Polyesters; Pyrrolidinones; Spectroscopy, Fourier Transform Infrared; Surface Properties; Ultraviolet Rays
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8971 (URN)10.1021/ja052073u (DOI)000229981200047 ()15954795 (PubMedID)2-s2.0-20944443598 (Scopus ID)
Note
QC 20100804Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2017-12-14Bibliographically approved
2. Surface Functionalization of Degradable Polymers by Covalent Grafting
Open this publication in new window or tab >>Surface Functionalization of Degradable Polymers by Covalent Grafting
2006 (English)In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 27, no 9, p. 1788-1796Article in journal (Refereed) Published
Abstract [en]

With a new non-destructive and solvent-free photografting technique, N-vinylpyrrolidone was covalently grafted onto the surfaces of degradable polymers; poly(L-lactide), poly(L-caprolactone), poly(lactide-co-glycolide),. and poly(trimethylene carbonate). The modified surfaces were characterized by XPS, ATR-FTIR, SEM.. and cell growth tests. The wettability was markedly improved, as static contact angles changed from about 80 degrees for the pristine substrates to around 30 degrees after 30 min of grafting. Well-defined surface topographies, such as micro-patterns, are preserved in the process since the graft layers are thin. The biological response, measured as cytotoxicity, showed that the modified films provide good substrates, comparable with optimized cell culture plastics, for the adhesion and proliferation of normal human keratinocytes and skin fibroblasts.

Keywords
Covalent; Degradable; N-vinyl pyrrolidone; Solvent free; Surface modification; Vapor-phase grafting; Adhesion; Cell culture; Degradation; Substrates; Surface treatment; 1 vinyl 2 pyrrolidinone; carbonic acid derivative; polycaprolactone; polyglactin; polylactide; polymer; polytrimethylene carbonate; solvent; unclassified drug; article; biocompatibility; cell adhesion; cell assay; cell culture; cell growth; cell proliferation; controlled study; covalent bond; cytotoxicity; drug degradation; drug structure; film; human; human cell; infrared spectroscopy; keratinocyte; light; normal human; priority journal; scanning electron microscopy; skin fibroblast; surface property; time; Biocompatible Materials; Biodegradation, Environmental; Cell Adhesion; Cell Proliferation; Cells, Cultured; Dioxanes; Fibroblasts; Humans; Photochemistry; Polyesters; Polyglactin 910; Polymers; Pyrrolidinones; Skin; Surface Properties; Ultraviolet Rays
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8972 (URN)10.1016/j.biomaterials.2005.10.010 (DOI)000234962500014 ()16257444 (PubMedID)2-s2.0-28744453384 (Scopus ID)
Note
QC 20100804. Uppdaterad från In press till Published 20100804.Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2017-12-14Bibliographically approved
3. Nano Patterened Covalent Surface Modification of Poly(ε-caprolactone)
Open this publication in new window or tab >>Nano Patterened Covalent Surface Modification of Poly(ε-caprolactone)
2005 (English)In: Israel Journal of Chemistry, ISSN 0021-2148, Vol. 45, no 4, p. 429-435Article in journal (Refereed) Published
Abstract [en]

Using our new vapor-phase grafting technique, we have simultaneously chemically and physically modified the surface of poly(e-caprolactone) (PCL) films. The substrates were covered with nano patterned silicone rubber stamps and subjected to UV irradiation in the presence of the solvent-free vapor phase of either N-vinyl pyrrolidone or maleic anhydride, and a photoinitiator, under reduced pressure. The treated films display a surface pattern of grafted channels of 450-nm width, as confirmed by AFM and SEM. The grafting was further verified with ATR-FTIR, and contact angle measurements show an increased wettability of the surfaces.

Keywords
POLYMER SURFACES, BIOMATERIALS, CELLS; FILM, FUNCTIONALIZATION, OXYGEN, LLDPE
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-8973 (URN)10.1560/BY1J-CGHN-7MF4-QX85 (DOI)000233570300006 ()2-s2.0-27844477377 (Scopus ID)
Note
QC 20101207Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2017-12-14Bibliographically approved

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