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Controllable degradation product migration from biomedical polyester-ethers
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The use of degradable biomedical materials has during the past decades indeed modernized medical science, finding applications in e.g. tissue engineering and drug delivery. The key question is to adapt the material with respect to mechanical properties, surface characteristics and degradation profile to suit the specific application. Degradation products are generally considered non-toxic and they are excreted from the human body. However, large amounts of hydroxy acids may induce a pH decrease and a subsequent inflammatory response at the implantation site.

In this study, macromolecular design and a combination of cross-linking and adjusted hydrophilicity are utilized as tools to control and tailor degradation rate and subsequent release of degradation products from biomedical polyester-ethers. A series of different homo- and copolymers of -caprolactone (CL) and 1,5-dioxepan-2-one (DXO) were synthesized and their hydrolytic degradation was monitored in phosphate buffer solution at pH 7.4 and 37 °C for up to 546 days. The various materials comprised linear DXO/CL triblock and multiblock copolymers, PCL linear homopolymer and porous structure, and random cross-linked homo- and copolymers of CL/DXO using 2,2’-bis-(ε-caprolactone-4-yl) propane (BCP) as a cross-linking agent.

The results showed that macromolecular engineering and controlled hydrophilicity of cross-linked networks were useful implements for customizing the release rate of acidic degradation products in order to prevent the formation of local acidic environments and thereby reduce the risk of inflammatory responses in the body.

Place, publisher, year, edition, pages
Stockholm: KTH , 2007. , 39 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2007:23
Keyword [en]
degradation products, ε-caprolactone, 1, 5-dioxepan-2-one, 6-hydroxyhexanoic acid, 3-(2-hydroxyethoxy)propanoic acid, cross-linking, inflammatory response
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-4366ISBN: 978-91-7178-653-1 (print)OAI: oai:DiVA.org:kth-4366DiVA: diva2:11968
Presentation
2007-05-24, E3, KTH, Osquars backe 14, Stockholm, 09:00
Opponent
Supervisors
Note
QC 20101109Available from: 2007-05-10 Created: 2007-05-10 Last updated: 2010-11-09Bibliographically approved
List of papers
1. Degradation profile of poly(epsilon-caprolactone) - the influence of macroscopic and macromolecular biomaterial design
Open this publication in new window or tab >>Degradation profile of poly(epsilon-caprolactone) - the influence of macroscopic and macromolecular biomaterial design
2007 (English)In: Journal of macromolecular science. Pure and applied chemistry (Print), ISSN 1060-1325, E-ISSN 1520-5738, Vol. 44, no 7-9, 1041-1046 p.Article in journal (Refereed) Published
Abstract [en]

Macroscopic and macromolecular material design and their influence on hydrolysis mechanism of poly(epsilon-caprolactone) (PCL) was evaluated. Homogoenous discs of linear PCL, porous scaffolds of linear PCL and crosslinked PCL networks were subjected to hydrolytic degradation for up to 364 days in 37 degrees C and pH 7.4 phosphate buffer solution. After different hydrolysis times, mass loss and changes in molecular weight and thermal properties were determined in parallel to extraction and analysis of the formed degradation products. Size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and gas chromatography-mass spectrometry (GC-MS) were used for the analyses. The results clearly demonstrated different degradation profiles and susceptibilities towards hydrolysis depending on the macroscopic and macromolecular biomaterial design.

Keyword
degradation, hydrolysis, poly(epsilon-caprolactone), macromolecular design, film-blown poly(epsilon-caprolactone), in-vitro degradation, epsilon-caprolactone, aliphatic polyesters, scaffolds, 1, 5-dioxepan-2-one, polycaprolactone, biodegradation, copolymers, products
National Category
Polymer Chemistry Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-16756 (URN)10.1080/10601320701424487 (DOI)000247724400050 ()2-s2.0-34250875108 (Scopus ID)
Note

QC 20100525

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
2. Tuning the release rate of acidic degradation products through macromolecular design of caprolactone-based copolymers
Open this publication in new window or tab >>Tuning the release rate of acidic degradation products through macromolecular design of caprolactone-based copolymers
2007 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 19, 6308-6312 p.Article in journal (Refereed) Published
Abstract [en]

Macromolecular engineering is presented as a tool to control the degradation rate and release rate of acidic degradation products from biomedical polyester ethers. Three different caprolactone/1,5-dioxepan-2-one (CL/DXO) copolymers were synthesized: DXO/CL/DXO triblock, CL/DXO multiblock, and random cross-linked CL/DXO copolymer. The relation of CL and DXO units in all three copolymers was 60/40 mol %. The polymer discs were immersed in phosphate buffer solution at pH 7.4 and 37 degrees C for up to 364 days. After different time periods degradation products were extracted from the buffer solution and analyzed. In addition mass loss, water absorption, molecular weight changes, and changes in thermal properties were determined. The results show that the release rate of acidic degradation products, a possible cause of acidic microclimates and inflammatory responses, is controllable through macromolecular design, i.e., different distribution of the weak linkages in the copolymers.

Keyword
epsilon-caprolactone, aliphatic polyesters, hydrolytic degradation, l-lactide, 1, 5-dioxepan-2-one, polymers, implants, polymerization, glycolide, blends
National Category
Polymer Chemistry Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-16623 (URN)10.1021/ja0702871 (DOI)000246415100047 ()2-s2.0-34249041978 (Scopus ID)
Note

QC 20150720

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
3. Controllable Degradation Product Migration from Cross-Linked Biomedical Polyester-Ethers through Predetermined Alterations in Copolymer Composition
Open this publication in new window or tab >>Controllable Degradation Product Migration from Cross-Linked Biomedical Polyester-Ethers through Predetermined Alterations in Copolymer Composition
2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 6, 2025-2032 p.Article in journal (Refereed) Published
Abstract [en]

Uniformly degrading biomaterials with adjustable degradation product migration rates were customized by combining the advantages of cross-linked poly(epsilon-caprolactone) with the hydrophilic character of poly(1,5-dioxepan-2-one). Hydrolytic degradation of these random cross-linked networks using 2,2'-bis-(epsilon-caprolactone-4-yl) propane (BCP) as the cross-linking agent was studied for up to 546 days in phosphate buffer solution at pH 7.4 and 37 degrees C. The hydrophilicity of the materials was altered by varying the copolymer compositions. After different hydrolysis times the materials were characterized, and the degradation products were extracted from the buffer solution and analyzed. Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, scanning electron microscopy, and gas chromatography-mass spectrometry were used to observe the changes taking place during the hydrolysis. From the results it was concluded that degradation profiles and migration of degradation products are controllable by tailoring the hydrophilicity of cross-linked polyester-ether networks.

Keyword
Biomaterials; Crosslinking; Degradation; Ethers; Hydrolysis; Hydrophilicity; Polyesters; Hydrolytic degradation; Product migration
National Category
Polymer Chemistry Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-8054 (URN)10.1021/bm070292x (DOI)000247107900035 ()2-s2.0-34347335743 (Scopus ID)
Note

QC 20100812

Available from: 2008-03-03 Created: 2008-03-03 Last updated: 2017-12-14Bibliographically approved

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