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1.	Finne Wistrand, Anna, 1976- (författare) Aliphatic poly(ester)s with thiol pendant groups 2020 Patent (populärvet., debatt m.m.)abstract The present invention relates to a novel ester monomersusceptible to ring opening polymerization where the monomer comprise a functional group that may be transformedinto thiols or S S groups which allows further functionalization . The present invention also relates to polymers andco - polymers derived from said monomer .
2.	Bartaula-Brevik, Sushma, et al. (författare) Leukocyte transmigration into tissue-engineered constructs is influenced by endothelial cells through Toll-like receptor signaling 2014 Ingår i: Stem Cell Research & Therapy. - : Springer Science and Business Media LLC. - 1757-6512. ; 5, s. 143- Tidskriftsartikel (refereegranskat)abstract Introduction: Inflammation plays a crucial role in tissue regeneration, wound healing, and the success of tissue-engineered constructs. The aim of this study was to investigate the influence of human umbilical vein endothelial cells (ECs) on leukocyte transmigration when co-cultured with primary human bone marrow-derived multipotent stromal cells (MSCs). Methods: MSCs with and without ECs were cultured in poly (L-lactide-co-1, 5-dioxepan-2-one) (poly (LLA-co-DXO)) scaffolds for 1 week in vitro in a bioreactor system, after which they were implanted subcutaneously in non-obese diabetic/severe combined immunodeficient mice. After 1 and 3 weeks, scaffolds were retrieved, and the mRNA expression of interleukin 1-beta (IL-1 beta), IL-6, IL-10, hypoxia-inducible factor 1-alpha (HIF-1 alpha), HIF-1 beta, and mammalian target of rapamycin was examined by real-time reverse transcription-polymerase chain reaction. Furthermore, immunofluorescent staining was performed for IL-1 beta, IL-6, neutrophils, and CD11b. In addition, Western blotting was done for IL-1 beta and IL-6. Leukocyte transmigration genes and genes in Toll-like receptor pathways, expressed by MSCs cultured in vitro with or without ECs, were further investigated with a microarray dataset. Results: In vitro, genes involved in leukocyte transmigration and Toll-like receptor pathways were clearly influenced by the addition of ECs. Platelet/endothelial cell adhesion molecule-1 (PECAM-1) and cadherin-5 (CDH5), both genes involved in leukocyte transmigration, were expressed significantly higher in the MSC/EC group. In vivo, the MSC/EC group showed higher mRNA expression of hypoxia-inducible factors HIF-1 alpha and HIF-1 beta. The mRNA expression of anti-inflammatory cytokine IL-10 showed no significant difference, whereas the mRNA and protein expression of pro-inflammatory cytokines IL-1 beta and IL-6 were lower in the MSC/EC group. The quantitative analysis of immunofluorescent staining revealed a significant difference in the number of neutrophils migrating into constructs, with the highest density found in the MSC/EC group. The number of macrophages positive for IL-6 and CD11b was significantly reduced in the MSC/EC group. Conclusions: The recruitment of leukocytes into tissue-engineered constructs with MSCs is strongly influenced by the addition of ECs via activation of leukocyte transmigration and Toll-like receptor pathways.
3.	Gurzawska-Comis, Katarzyna, et al. (författare) GUIDED BONE REGENERATION IN OSTEOPOROSIS BY PLANT-DERIVED NANOPARTICLES 2023 Ingår i: Tissue Engineering. Part A. - : MARY ANN LIEBERT, INC. - 1937-3341 .- 1937-335X. ; 29:11-12, s. 576-577 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Background: The repair and treatment of large bone defects in patients with compromised bone metabolism due to ageing and medical conditions such as osteoporosis present often a clinical challenge. Therefore, adjunctive methods to enhance bone healing are needed.Bone tissue engineering with application of nanotechnology allows to construct biomaterials with desired properties being osteoconductive, osteoinductive and osteogenic.Aim / Hypothesis: The aim of our study was to promote bone regeneration using functionalised scaffold with Rhamnogalacturonan-I pectins (RG-I) in vitro and in vivo using aging and osteoporotic rodent models.Material and Methods: The biomaterials were poly(l-lactide-co-ε-caprolactone) scaffolds and the RG-I was from potato. The chemical and physical properties of functionalised biomaterials with RG-I nanoparticles were characterised using confocal and atomic force microscopy. Functionalised scaffolds with RG-I (tested sample) were evaluated in vitro with human osteoblasts from osteoporotic patients and their response was tested using real-time PCR. In vivo evaluation was performed using critical-size calvaria bone defect model in ageing and osteoporotic rat models. Scaffolds were implanted randomly in the calvaria defects of aged female Wistar rats (11-12 months old) and osteoporotic female Wistar rats induced by ovariectomy. The control was scaffold without RG-I. After 2 and 8 weeks, animals were euthanised. Harvested samples were analysed for osteogenic and inflammatory markers using real-time PCR. Bone formation was evaluated radiographically and histologically. The data was analysed using one-way ANOVA.Results: The chemical and physical properties results indicated success of the functionalisation of scaffolds with RG-I. Osteoblasts response suggested osteogenic (upregulation osteopontin, osteocalcin, collagen1, bone sialoprotein) and anti-inflammatory properties (downregulation IL-1, IL-8, TNF-alpha) on the scaffold functionalised with RG-I. The in vivo results in aged and osteoporotic rat calvaria model of early (2 weeks) bone regeneration showed increase of osteogenic markers and decrease of proinflammatory markers and RANKL, compared to control. In osteoporotic rat model at week 2 and 8 and in aged rat model at week 8, the mean percentage of BV / TV (bone volume / tissue volume) in the defect with RG-I scaffold was significantly greater than the defect with control. The histological evaluation in both rat models revealed larger areas of new bone formation in RG-I scaffolds than in control.Conclusion and Clinical implications: In conclusion, the plant-derived nanoparticles significantly increased osteogenic and decreased pro-inflammatory response in vitro and in vivo. These finding may have a crucial impact on bone repair process especially in elderly and osteoporotic patients.
4.	Pedersen, Torbjorn O., et al. (författare) Endothelial microvascular networks affect gene-expression profiles and osteogenic potential of tissue-engineered constructs 2013 Ingår i: STEM CELL RES THER. - : Springer Science and Business Media LLC. - 1757-6512. ; 4, s. 52- Tidskriftsartikel (refereegranskat)abstract Introduction: A major determinant of the potential size of cell/scaffold constructs in tissue engineering is vascularization. The aims of this study were twofold: first to determine the in vitro angiogenic and osteogenic geneexpression profiles of endothelial cells (ECs) and mesenchymal stem cells (MSCs) cocultured in a dynamic 3D environment; and second, to assess differentiation and the potential for osteogenesis after in vivo implantation. Methods: MSCs and ECs were grown in dynamic culture in poly(L-lactide-co-1,5-dioxepan-2-one) (poly(LLA-co-DXO)) copolymer scaffolds for 1 week, to generate three-dimensional endothelial microvascular networks. The constructs were then implanted in vivo, in a murine model for ectopic bone formation. Expression of selected genes for angiogenesis and osteogenesis was studied after a 1-week culture in vitro. Human cell proliferation was assessed as expression of ki67, whereas a-smooth muscle actin was used to determine the perivascular differentiation of MSCs. Osteogenesis was evaluated in vivo through detection of selected markers, by using real-time RT-PCR, alkaline phosphatase (ALP), Alizarin Red, hematoxylin/eosin (HE), and Masson trichrome staining. Results: The results show that endothelial microvascular networks could be generated in a poly(LLA-co-DXO) scaffold in vitro and sustained after in vivo implantation. The addition of ECs to MSCs influenced both angiogenic and osteogenic gene-expression profiles. Furthermore, human ki67 was upregulated before and after implantation. MSCs could support functional blood vessels as perivascular cells independent of implanted ECs. In addition, the expression of ALP was upregulated in the presence of endothelial microvascular networks. Conclusions: This study demonstrates that copolymer poly(LLA-co-DXO) scaffolds can be prevascularized with ECs and MSCs. Although a local osteoinductive environment is required to achieve ectopic bone formation, seeding of MSCs with or without ECs increases the osteogenic potential of tissue-engineered constructs.
5.	Pedersen, Torbjorn O., et al. (författare) Mesenchymal stem cells induce endothelial cell quiescence and promote capillary formation 2014 Ingår i: Stem Cell Research & Therapy. - : Springer Science and Business Media LLC. - 1757-6512. ; 5, s. 23- Tidskriftsartikel (refereegranskat)abstract Introduction: Rapid establishment of functional blood vessels is a prerequisite for successful tissue engineering. During vascular development, endothelial cells (ECs) and perivascular cells assemble into a complex regulating proliferation of ECs, vessel diameter and production of extracellular matrix proteins. The aim of this study was to evaluate the ability of mesenchymal stem cells (MSCs) to establish an endothelial-perivascular complex in tissue-engineered constructs comprising ECs and MSCs. Methods: Primary human ECs and MSCs were seeded onto poly(L-lactide-co-1,5-dioxepan-2-one) (poly(LLA-co-DXO)) scaffolds and grown in dynamic culture before subcutaneous implantation in immunocompromised mice for 1 and 3 weeks. Cellular activity, angiogenic stimulation and vascular assembly in cell/scaffold constructs seeded with ECs or ECs/MSCs in a 5:1 ratio was monitored with real-time RT-PCR, ELISA and immunohistochemical microscopy analysis. Results: A quiescent phenotype of ECs was generated, by adding MSCs to the culture system. Decreased proliferation of ECs, in addition to up-regulation of selected markers for vascular maturation was demonstrated. Baseline expression of VEGFa was higher for MSCs compared with EC (P < 0.001), with subsequent up-regulated VEGFa-expression for EC/MSC constructs before (P < 0.05) and after implantation (P < 0.01). Furthermore, an inflammatory response with CD11b + cells was generated from implantation of human cells. At the end of the 3 week experimental period, a higher vascular density was shown for both cellular constructs compared with empty control scaffolds (P < 0.01), with the highest density of capillaries being generated in constructs comprising both ECs and MSCs. Conclusions: Induction of a quiescent phenotype of ECs associated with vascular maturation can be achieved by co-seeding with MSCs. Hence, MSCs can be appropriate perivascular cells for tissue-engineered constructs.
6.	Percec, Virgil, et al. (författare) Ultrafast synthesis of ultrahigh molar mass polymers by metal-catalyzed living radical polymerization of acrylates, methacrylates, and vinyl chloride mediated by SET at 25 degrees C 2006 Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 128:43, s. 14156-14165 Tidskriftsartikel (refereegranskat)abstract Conventional metal-catalyzed organic radical reactions and living radical polymerizations (LRP) performed in nonpolar solvents, including atom-transfer radical polymerization (ATRP), proceed by an innersphere electron-transfer mechanism. One catalytic system frequently used in these polymerizations is based on Cu(I)X species and N-containing ligands. Here, it is reported that polar solvents such as H2O, alcohols, dipolar aprotic solvents, ethylene and propylene carbonate, and ionic liquids instantaneously disproportionate Cu(I)X into Cu(0) and Cu(II)X-2 species in the presence of a diversity of N-containing ligands. This disproportionation facilitates an ultrafast LRP in which the free radicals are generated by the nascent and extremely reactive Cu(0) atomic species, while their deactivation is mediated by the nascent Cu(II)X-2 species. Both steps proceed by a low activation energy outer-sphere single-electron-transfer (SET) mechanism. The resulting SET-LRP process is activated by a catalytic amount of the electron-donor Cu(0), Cu2Se, Cu2Te, Cu2S, or Cu2O species, not by Cu(I) X. This process provides, at room temperature and below, an ultrafast synthesis of ultrahigh molecular weight polymers from functional monomers containing electronwithdrawing groups such as acrylates, methacrylates, and vinyl chloride, initiated with alkyl halides, sulfonyl halides, and N-halides.
7.	Stjerndahl, Anna, et al. (författare) Industrial utilization of tin-initiated resorbable polymers : synthesis on a large scale with a low amount of initiator residue 2007 Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 8:3, s. 937-940 Tidskriftsartikel (refereegranskat)abstract This article presents the successful large-batch synthesis of a resorbable polymer with a minimal amount of residual tin. Ring-opening polymerization of ε-caprolactone was performed in toluene, with a tin (IV) alkoxide as the initiator. A number of parameters were varied in order to study the polymerization with respect to the purity of solvent, batch size, and the residual amount of tin in the polymers. The synthesis of ε-caprolactone in undistilled toluene with 1-di-n-butyl-1-stanna-2,5-dioxacyclopentane as the initiator was successfully performed in batches of 5, 20, and 50 g with no differences in the final conversion, molecular weight, or molecular-weight distribution. The residual amount of tin was significantly reduced from over 1000 to 23 ppm. This study examines the industrial utility of the materials regarding the size and purity of the synthesis.
8.	Stjerndahl, Anna, et al. (författare) Minimization of residual tin in the controlled Sn(II)octoate-catalyzed polymerization of ε-caprolactone 2008 Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 87A:4, s. 1086-1091 Tidskriftsartikel (refereegranskat)abstract By using less catalyst in the ring-opening polymerization of epsilon-caprolactone, a residual tin content of 5 ppm was reached without the need for additional purification. The initial amount of tin (II) 2-ethylhexanoate [Sn(Oct)(2)] was varied using catalyst:monomer ratios of 1:1000, 1:10,000, and 1:20,000. The impact on the final conversion, reaction control, average molecular weight, and polydispersity was studied. The amount of Sn(Oct)(2) could be significantly, reduced without influencing the reaction results. The residual amount of tin was reduced from 176 ppm with a catalyst:monomer ratio of 1:1000 in the polymer, to 5 ppm with the ratio 1:10,000. It was thus concluded that a catalyst:monomer ratio of 1:10,000 or lower is required to achieve a polymer with tin content Suitable for biomedical applications. The materials were also tested in a proliferation study with mesenchymal stem cells from mouse. Porous scaffolds were fabricated from the polymers, using a salt leaching technique, and the cell growth on the porous scaffolds as well as on homogeneous films was determined by light absorbance measurements. In this study, the cell proliferation results showed that cells could grow on all polymers with ail efficiency equal to or better than that on normal tissue Culture plastic.
9.	Suliman, Salwa, et al. (författare) Immune-instructive copolymer scaffolds using plant-derived nanoparticles to promote bone regeneration 2022 Ingår i: Inflammation and Regeneration. - : Springer Nature. - 1880-8190. ; 42:1 Tidskriftsartikel (refereegranskat)abstract Background Age-driven immune signals cause a state of chronic low-grade inflammation and in consequence affect bone healing and cause challenges for clinicians when repairing critical-sized bone defects in elderly patients. Methods Poly(l-lactide-co-e-caprolactone) (PLCA) scaffolds are functionalized with plant-derived nanoparticles from potato, rhamnogalacturonan-I (RG-I), to investigate their ability to modulate inflammation in vitro in neutrophils and macrophages at gene and protein levels. The scaffolds' early and late host response at gene, protein and histological levels is tested in vivo in a subcutaneous rat model and their potential to promote bone regeneration in an aged rodent was tested in a critical-sized calvaria bone defect. Significant differences were tested using one-way ANOVA, followed by a multiple-comparison Tukey's test with a p value <= 0.05 considered significant. Results Gene expressions revealed PLCA scaffold functionalized with plant-derived RG-I with a relatively higher amount of galactose than arabinose (potato dearabinated (PA)) to reduce the inflammatory state stimulated by bacterial LPS in neutrophils and macrophages in vitro. LPS-stimulated neutrophils show a significantly decreased intracellular accumulation of galectin-3 in the presence of PA functionalization compared to Control (unmodified PLCA scaffolds). The in vivo gene and protein expressions revealed comparable results to in vitro. The host response is modulated towards anti-inflammatory/ healing at early and late time points at gene and protein levels. A reduced foreign body reaction and fibrous capsule formation is observed when PLCA scaffolds functionalized with PA were implanted in vivo subcutaneously. PLCA scaffolds functionalized with PA modulated the cytokine and chemokine expressions in vivo during early and late inflammatory phases. PLCA scaffolds functionalized with PA implanted in calvaria defects of aged rats downregulating pro-inflammatory gene markers while promoting osteogenic markers after 2 weeks in vivo. Conclusion We have shown that PLCA scaffolds functionalized with plant-derived RG-I with a relatively higher amount of galactose play a role in the modulation of inflammatory responses both in vitro and in vivo subcutaneously and promote the initiation of bone formation in a critical-sized bone defect of an aged rodent. Our study addresses the increasing demand in bone tissue engineering for immunomodulatory 3D scaffolds that promote osteogenesis and modulate immune responses.
10.	Abbasi Aval, Negar, et al. (författare) An aligned fibrous and thermosensitive hyaluronic acid-puramatrix interpenetrating polymer network hydrogel with mechanical properties adjusted for neural tissue 2022 Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:4, s. 2883-2896 Tidskriftsartikel (refereegranskat)abstract Central nervous system (CNS) injuries such as stroke or trauma can lead to long-lasting disability, and there is no currently accepted treatment to regenerate functional CNS tissue after injury. Hydrogels can mimic the neural extracellular matrix by providing a suitable 3D structure and mechanical properties and have shown great promise in CNS tissue regeneration. Here we present successful synthesis of a thermosensitive hyaluronic acid-RADA 16 (Puramatrix (TM)) peptide interpenetrating network (IPN) that can be applied in situ by injection. Thermosensitive hyaluronic acid (HA) was first synthesized by combining HA with poly(N-isopropylacrylamide). Then, the Puramatrix (TM) self-assembled peptide was combined with the thermosensitive HA to produce a series of injectable thermoresponsive IPNs. The HA-Puramatrix (TM) IPNs formed hydrogels successfully at physiological temperature. Characterization by SEM, rheological measurements, enzymatic degradation and swelling tests was performed to select the IPN optimized for neurologic use. SEM images of the optimized dry IPNs demonstrated an aligned porous structure, and the rheological measurements showed that the hydrogels were elastic, with an elastic modulus of approximately 500 Pa, similar to that of brain tissue. An evaluation of the cell-material interactions also showed that the IPN had biological characteristics required for tissue engineering, strongly suggesting that the IPN hydrogel possessed properties beneficial for regeneration of brain tissue.
11.	Ahlinder, Astrid (författare) Degradable copolymers in additive manufacturing: controlled fabrication of pliable scaffolds 2021 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Inom vävnadsregenerering är produktionen av väldefinieradematriser med en porös arkitektur av nedbrytbara polymerer av stortintresse, dessa kan nu skapas genom additiva tillverkningsprocesser. Vidadditiv tillverkning krävs ett smalt munstycke för att skapa detaljrikastrukturer och detta ställer krav på att de reologiska egenskapernaanpassat. Lägre viskositet av smältan gör de lättare att använda, men enhög molmassa krävs för tillverka matriser där de mekaniska egenskapernakan bibehållas under tiden som krävs för vävnadsregenerering. Ytterligareen utmaning uppstår när nedbrytbara polymerer används i smältbaseradadditiva tillverkningsprocesser är att termisk nedbrytning ofta reducerarmolmassan redan under produktionsfasen. För att kunna användanedbrytbara polymerer av medicinsk kvalitet i smältbaserad additivtillverkning och samtidigt minimera den termiska nedbrytningen har, idenna avhandling, reologiska fingeravtryck av nedbrytbara syntetiskapolymerer med medicinsk kvalitet använts för att bestämmaprocessparametrar. Termisk nedbrytning beroende av processparamaterar har analyserats och minimeras i två smältbaserade additivatillverkningsprocesser.En additiv tillverkningsprocess var designad där nedbrytbarapolymerer av hög molmassa kunde användas utan termisk nedbrytning närprocessparametrar hade valts utifrån polymerens egenskaper. Kunskapenom användningen av dessa polymerer inom additiv tillverkning kundeappliceras på en sampolymer som utvecklats inom forskningsgruppen förmjukvävnad, poly(ε-kaprolakton-co-p-dioxanon) för att skapa böjbaramatriser. Genom att använda reologisk analys och polymerkarakteriseringerhölls processparametrar som möjliggjorde additiv tillverkning utantermisk nedbrytning. I tillägg till val av polymer och processparametrar såkan mekaniska egenskaper också styras av den strukturella designen.Poly(ε-kaprolakton) användes som modellmaterial för att reducerastyvheten med hjälp av designen, resultatet visade att det var möjligt medmer än en faktor 10 och mjuka böjbara matriser skapades.
12.	Ahlinder, Astrid, et al. (författare) Medical grade polylactide, copolyesters and polydioxanone : Rheological properties and melt stability 2018 Ingår i: Polymer testing. - : ELSEVIER SCI LTD. - 0142-9418 .- 1873-2348. ; 72, s. 214-222 Tidskriftsartikel (refereegranskat)abstract Rheological measurements have shown that lactide-based copolymers with L-lactide content between 50 and 100 mol% with varying comonomers, as well as polydioxanone (PDX), can be used in additive manufacturing analogously to poly(L-lactide) (PLLA) if their melt behaviour are balanced. The results indicate that copolymers can be melt processed if the temperature is adjusted according to the melting point, and parameters such as the speed are tuned to conteract the elastic response. Small amplitude oscillatory shear (SAOS) rheology, thermal and chemical characterisation allowed us to map the combined effect of temperature and frequency on the behaviour of six degradable polymers and their melt stability. Values of complex viscosity and Tan delta obtained through nine time sweeps by varying temperature and frequency showed that the molecular structure and the number of methylene units influenced the results, copolymers of L-lactide with D-Lactide (PDLLA) or glycolide (PLGA) had an increased elastic response, while copolymers with trimethylene carbonate (PLATMC) or epsilon-caprolactone (PCLA) had a more viscous behaviour than PLLA, with respect to their relative melting points. PDLLA and PLGA require an increased temperature or lower speed when processed, while PLATMC and PCLA can be used at a lower temperature and/or higher speed than PLLA. PDX showed an increased viscosity compared to PLLA but a similar melt behaviour. Negligible chain degradation were observed, apart from PLGA.
13.	Ahlinder, Astrid, et al. (författare) Minimise thermo-mechanical batch variations when processing medical grade lactide based copolymers in additive manufacturing 2020 Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 181 Tidskriftsartikel (refereegranskat)abstract Additive manufacturing is suitable for producing complex geometries; however, variation in thermo-mechanical properties are observed during one batch cycle when degradable aliphatic polyesters of medical grade are used in melt extrusion-based methods. This is one important reason for why additive manufacturing has not yet been fully utilised to produce degradable medical implants. Herein, the internal variation has been minimised during one batch cycle by assessing the effect of different processing parameters when using commercially available medical grade copolymers. To minimise the molar mass, thermal and mechanical variation within one batch cycle, the rheological fingerprint of the commercially available medical grade poly(L-lactide-co-ε-caprolactone) and poly(L-lactide-co-trimethylene carbonate) has been correlated to the process parameters of the ARBURG Plastic Freeforming. An increase in the temperature up to 220°C and the associated increase in pressure are beneficial for the viscoelastic and thermally stable poly(L-lactide-co-ε-caprolactone). In contrast, a temperature below 220°C should be used for the poly(L-lactide-co-trimethylene carbonate) to reduce the variation in strain at break during one batch cycle. The residence time is decreased through the increase of the discharge parameter. An increase in temperature is however required to reduce the viscosity of the polymer and allow the pressure to stay within the machine limitations at higher discharge parameters. The results are highly relevant to the development of additive manufacturing for the production of degradable medical devices with identical properties. In fact, Food and Drug Administration guidelines for additive manufacturing of medical implants specify the need to control changes in material properties during the process.
14.	Ahlinder, Astrid, et al. (författare) Nondegradative additive manufacturing of medical grade copolyesters of high molecular weight and with varied elastic response 2020 Ingår i: Journal of Applied Polymer Science. - : WILEY. - 0021-8995 .- 1097-4628. ; 137:15 Tidskriftsartikel (refereegranskat)abstract Although additive manufacturing through melt extrusion has become increasingly popular as a route to design scaffolds with complex geometries the technique if often limited by the reduction in molecular weight and the viscoelastic response when degradable aliphatic polyesters of high molecular weight are used. Here we use a melt extruder and fused filament fabrication printer to produce a reliable nondegradative route for scaffold fabrication of medical grade copolymers of L-lactide, poly(epsilon-caprolactone-co-L-lactide), and poly(L-lactide-co-trimethylene carbonate). We show that degradation is avoided using filament extrusion and fused filament fabrication if the process parameters are deliberately chosen based upon the rheological behavior, mechanical properties, and polymer composition. Structural, mechanical, and thermal properties were assessed throughout the process to obtain comprehension of the relationship between the rheological properties and the behavior of the medical grade copolymers in the extruder and printer. Scaffolds with a controlled architecture were achieved using high-molecular-weight polyesters exhibiting a large range in the elastic response causing negligible degradation of the polymers.
15.	Albertsson, Ann-Christine, et al. (författare) Controlled synthesis of star-shaped homo- and co-polymers of aliphatic polyesters 2006 Ingår i: 7th International Biorelated Polymers Symposium. ; , s. 37-38 Konferensbidrag (refereegranskat)abstract The challenges in finding a material with the proper characteristics for a given tissue engineering application are several. One solution is improving the ability to tailor the mechanical and physical properties along with the degradation profile of aliphatic polyesters, by for example alterations in their composition and architecture. In this study, well-defined star-shaped aliphatic polyesters constituted of four arms were synthesized. As a model system, L,L-lactide and a spirocyclic tin initiator was chosen and the affect of the solvent, temperature and monomer-to-initiator ratio on the number average molecular weight, the molecular weight distribution and the conversion of the polymers was shown. Consecutively, we proved that well-defined star-shaped block copolymers composed of 1,5-dioxepan-2-one and L,L-lactide with narrow molecular weight distributions and controlled block lengths can be synthesized using this system.
16.	Albertsson, Ann-Christine, 1945-, et al. (författare) Degradable polymers with tailored properties for biomedical materials 2009 Ingår i: Abstracts of Papers of the American Chemical Society. - : American Chemical Society (ACS). - 0065-7727. ; 238 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
17.	Albertsson, Ann-Christine, 1945-, et al. (författare) Design and Syntesis of Different Types of Poly(Lactic acid) 2010 Ingår i: Poly(Lactic Acid). - Hoboken, NJ, USA : John Wiley & Sons. - 9780470293669 ; , s. 43-58 Bokkapitel (övrigt vetenskapligt/konstnärligt)
18.	Albertsson, Ann-Christine, et al. (författare) Design and synthesis of different types of poly(lactic acid)/polylactide copolymers 2022 Ingår i: Poly(lactic acid). - : Wiley. ; , s. 45-71 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract High molar mass poly(lactic acid) (PLA) is obtained by either the polycondensation of lactic acid or ring-opening polymerization (ROP) of the cyclic dimer 2,6-dimethyl-1,4-dioxane-2,5-dione, commonly referred to as dilactide or lactide (LA). This chapter describes preparation of polymers and copolymers of LAs with different structures, using polycondensation and ROP. Typical comonomers and polymers which are used for lactic acid or LA copolymerization include glycolic acid or glycolide, poly(ethylene glycol) or poly(ethylene oxide), and so on. PLAs having amino, carboxyl, or other functional groups are well reported in the literature. These functional groups can be utilized for chemical modification or as binding sites for biomolecules to impart selective binding and adhesion. PLA and its copolymers especially when used for biological applications, besides requirement of optimization of mechanical properties by engineering at the molecular level, also demands a fast degradation polymer rate.
19.	Albertsson, Ann-Christine, et al. (författare) POLY 554-Controlled synthesis of star-shaped homo- and co-polymers of aliphatic polyesters 2006 Ingår i: Abstracts of Papers of the American Chemical Society. - : AMER CHEMICAL SOC. - 0065-7727. ; 232 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
20.	Alin, Jonas (författare) Microwave heating effects on degradation and migration of additives from polypropylene packaging 2011 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract The effect of different food types, polymer qualities and microwaves on the overall and specific migration during microwave heating of plastic packaging was investigated to better understand the packaging-food interactions and the effect of microwaves on food packaging. This work focuses on the migration of chemical compounds to food simulants from commercially available polypropylene packages. Packages used were made of polypropylene homopolymer (PP), co-polymer (PP-C) and random co-polymer (PP-R). Polymers matrix changes were monitored by following possible changes in crystallinity after microwave heating. Antioxidants Irgafos 168 and Irganox 1010 were present in all the three PP packages. Other volatiles, primarily degradation products of antioxidants, were also detected and identified in the unaged packages. Significant antioxidant degradation took place during microwave heating of the packages in the fatty food simulants 90/10 isooctane/ethanol and ethanol resulting in the formation and migration of degradation products while no degradation of antioxidants was detected during conventional heating of the packages in the fatty food simulants. Antioxidant Irgafos 168 and Irganox 1010 migration rates were otherwise similar during microwave heating as during conventional heating to the fatty food simulants and antioxidant diffusion coefficients were similar to earlier established values obtained during conventional heating. Antioxidant migration rates from the three polymers to fatty food simulants differed largely with respect to PP type and increased with decreasing degree of crystallinity in the materials, PP-R showing the highest migration rate. Swelling in isooctane food simulant caused the antioxidant diffusion coefficients to increase by factors of 100-1000 at 80 ºC and decreased the temperature dependence of antioxidant migration. It also increased the overall migration to above established overall migration limits during both microwave and conventional heating. Electrospray ionization mass spectrometry (ESI-MS) was shown to be a valuable new tool for additive migration analysis of compounds not detectable by HPLC or GC-MS.
21.	Arvidson, K., et al. (författare) Bone regeneration and stem cells 2011 Ingår i: Journal of Cellular and Molecular Medicine. - : Wiley-Blackwell. - 1582-1838 .- 1582-4934. ; 15:4, s. 718-746 Forskningsöversikt (refereegranskat)abstract Introduction Bone fracture healing and healing problems Biomaterial scaffolds and tissue engineering in bone formation Bone tissue engineering Biomaterial scaffolds Synthetic scaffolds Micro- and nanostructural properties of scaffolds Conclusion Mesenchymal stem cells and osteogenesis Bone tissue Origin of osteoblasts Isolation and characterization of bone marrow derived MSC In vitro differentiation of MSC into osteoblast lineage cells In vivo differentiation of MSC into bone Factors and pathways controlling osteoblast differentiation of hMSC Defining the relationship between osteoblast and adipocyte differentiation from MSC MSC and sex hormones Effect of aging on osteoblastogenesis Conclusion Embryonic, foetal and adult stem cells in osteogenesis Cell-based therapies for bone Specific features of bone cells needed to be advantageous for clinical use Development of therapeutic biological agents Clinical application concerns Conclusion Platelet-rich plasma (PRP), growth factors and osteogenesis PRP effects in vitro on the cells involved in bone repair PRP effects on osteoblasts PRP effects on osteoclasts PRP effects on endothelial cells PRP effects in vivo on experimental animals The clinical use of PRP for bone repair Non-union Distraction osteogenesis Spinal fusion Foot and ankle surgery Total knee arthroplasty Odontostomatology and maxillofacial surgery Conclusion Molecular control of osteogenesis TGF-beta signalling FGF signalling IGF signalling PDGF signalling MAPK signalling pathway Wnt signalling pathway Hedgehog signalling Notch signalling Ephrin signalling Transcription factors regulating osteoblast differentiation Conclusion Summary This invited review covers research areas of central importance for orthopaedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and foetal stem cells, effects of sex steroids on mesenchymal stem cells, use of platelet-rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed.
22.	Ayyachi, Thayanithi, et al. (författare) Defining the role of linoleic acid in acrylic bone cement 2022 Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 139:25 Tidskriftsartikel (refereegranskat)abstract Polymethylmethacrylate is clinically used as a bone cement in various orthopedic and trauma surgeries. Post the surgery, such conventional acrylic bone cement has been reported to cause adjacent vertebral fractures; modifying it by adding linoleic acid in the formulation has shown potential in averting such fractures thanks to bone-compliant mechanical properties, besides providing convenient handling properties. Although the resulting properties are attractive, the understanding of how linoleic acid imparts such advantageous properties remain unclear. Linoleic acid is typically sterilized in an autoclave before being used in the bone cement formulation; however, there are apprehensions whether the sterilization causes degradation. In this research, sterilized and unsterilized linoleic acid were evaluated alone and with different components of bone cement, such as activator, initiator, monomer, and inhibitor, and the ensuing structural changes in linoleic acid were monitored through 1H NMR and UV–Vis. The results reveal that linoleic acid degrade due to sterilization. In addition, evidence for reactions of sterilized/unsterilized linoleic acid with activator and initiator have been collected. We hypothesize that these reactions can reduce the availability of the components for the in situ polymerization of methyl methacrylate monomer and cause the improvement in handling properties and decrease in mechanical properties.
23.	Bartaula-Brevik, Sushma, et al. (författare) Angiogenic and Immunomodulatory Properties of Endothelial and Mesenchymal Stem Cells 2016 Ingår i: Tissue Engineering. Part A. - : Mary Ann Liebert. - 1937-3341 .- 1937-335X. ; 22:3-4, s. 244-252 Tidskriftsartikel (refereegranskat)abstract It has been suggested that the effect of implanted cells on the local environment is important when selecting the appropriate cell type for tissue regeneration. Our aim was to compare the local tissue response to implanted human mesenchymal stem cells (MSC) and human umbilical vein endothelial cells (EC). MSC and EC were cultured in poly(l-lactide-co-1,5-dioxepan-2-one) scaffolds for 1 week in a bioreactor system, after which they were implanted subcutaneously in NOD/SCID mice. After 3 weeks, scaffolds were retrieved, and the mRNA expression of selected genes involved in hypoxia and inflammation was examined by real-time reverse transcription polymerase chain reaction and correlated with immunofluorescent staining for corresponding proteins. The Toll-like receptor signaling pathway was examined by superarray hybridization. The expression of 53 angiogenesis-related proteins was investigated by a proteome profiler angiogenesis antibody array kit. Vascularization was quantified using immunohistochemistry for CD31. The expression of hypoxia-inducible factors and biomarkers for angiogenesis was more strongly upregulated in response to implanted EC than to MSC, suggesting a higher sensitivity to low oxygen tension among EC. Hypoxic signaling was increased after implantation of EC compared with MSC, leading to a prolonged acute inflammatory phase that promoted ingrowth of vascular cells and establishment of the circulation. Inflammatory cytokines were also differently expressed at the gene and protein levels in the two experimental groups, resulting in altered recruitment of acute and chronic inflammatory cells. The end result of these differences was increased vessel formation within the constructs in the EC group.
24.	Behroozi Kohlan, Taha, et al. (författare) Schiff base crosslinked hyaluronic acid hydrogels with tunable and cell instructive time-dependent mechanical properties 2024 Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 338 Tidskriftsartikel (refereegranskat)abstract The dynamic interplay between cells and their native extracellular matrix (ECM) influences cellular behavior, imposing a challenge in biomaterial design. Dynamic covalent hydrogels are viscoelastic and show self-healing ability, making them a potential scaffold for recapitulating native ECM properties. We aimed to implement kinetically and thermodynamically distinct crosslinkers to prepare self-healing dynamic hydrogels to explore the arising properties and their effects on cellular behavior. To do so, aldehyde-substituted hyaluronic acid (HA) was synthesized to generate imine, hydrazone, and oxime crosslinked dynamic covalent hydrogels. Differences in equilibrium constants of these bonds yielded distinct properties including stiffness, stress relaxation, and self-healing ability. The effects of degree of substitution (DS), polymer concentration, crosslinker to aldehyde ratio, and crosslinker functionality on hydrogel properties were evaluated. The self-healing ability of hydrogels was investigated on samples of the same and different crosslinkers and DS to obtain hydrogels with gradient properties. Subsequently, human dermal fibroblasts were cultured in 2D and 3D to assess the cellular response considering the dynamic properties of the hydrogels. Moreover, assessing cell spreading and morphology on hydrogels having similar modulus but different stress relaxation rates showed the effects of matrix viscoelasticity with higher cell spreading in slower relaxing hydrogels.
25.	Danmark, Staffan, et al. (författare) Osteogenic Differentiation by Rat Bone Marrow Stromal Cells on Customized Biodegradable Polymer Scaffolds 2010 Ingår i: Journal of bioactive and compatible polymers (Print). - : SAGE Publications. - 0883-9115 .- 1530-8030. ; 25:2, s. 207-223 Tidskriftsartikel (refereegranskat)abstract In this report, poly(L-lactide-co-epsilon-caprolactone), poly(LLA-co-CL) and poly(L-lactide-co-1,5-dioxepan-2-one), poly(LLA-co-DXO) were evaluated and compared for potential use in bone tissue engineering constructs together with bone marrow stromal cells (BMSC). The copolymers were tailored to reduce the level of harmful tin residuals in the scaffolding. BMSC isolated from Sprague-Dawley rats were seeded onto the scaffolds and cultured in vitro for up to 21 days. Cell spreading and proliferation was analyzed after 72 h by scanning electron microscopy and thiazolyl blue tetrazolium bromide (MTT) conversion assay. Osteogenic differentiation of BMSC was evaluated by real-time PCR after 14 and 21 days of culture. Hydrophilicity was significantly different between poly(LLA-co-CL) and poly(LLA-co-DXO) with the latter being more hydrophilic. After 72 h, both scaffolds supported increased cell proliferation and the mRNA expression of osteocalcin and osteopontin was significantly increased after 21 days. Further investigation of these constructs, with lower levels of tin residuals, are being pursued.
26.	Dånmark, Staffan, et al. (författare) Development of a novel microfluidic device for long-term in situ monitoring of live cells in 3-dimensional matrices 2012 Ingår i: Biomedical microdevices (Print). - : Springer Science and Business Media LLC. - 1387-2176 .- 1572-8781. ; 14:5, s. 885-893 Tidskriftsartikel (refereegranskat)abstract Using the latest innovations in microfabrication technology, 3-dimensional microfluidic cell culture systems have been developed as an attractive alternative to traditional 2-dimensional culturing systems as a model for long-term microscale cell-based research. Most microfluidic systems are based on the embedding of cells in hydrogels. However, physiologically realistic conditions based on hydrogels are difficult to obtain and the systems are often too complicated. We have developed a microfluidic cell culture device that incorporates a biodegradable rigid 3D polymer scaffold using standard soft lithography methods. The device permits repeated high-resolution fluorescent imaging of live cell populations within the matrix over a 4 week period. It was also possible to track cell development at the same spatial location throughout this time. In addition, human primary periodontal ligament cells were induced to produce quantifiable calcium deposits within the system. This simple and versatile device should be readily applicable for cell-based studies that require long-term culture and high-resolution bioimaging.
27.	Dånmark, Staffan, et al. (författare) Development of Novel Microfluidic Device for Long-Term in situ Monitoring of Live Cells in 3-dimensional Matrices Annan publikation (övrigt vetenskapligt/konstnärligt)
28.	Dånmark, Staffan, et al. (författare) Enhanced Osteoconductivity of Degradable co-Polyester Scaffolds through Covalent Immobilization of BMP-2 Annan publikation (övrigt vetenskapligt/konstnärligt)
29.	Dånmark, Staffan, et al. (författare) In vitro and in vivo degradation profile of aliphatic polyesters subjected to electron beam sterilization 2011 Ingår i: ACTA BIOMATERIALIA. - : Elsevier BV. - 1742-7061. ; 7:5, s. 2035-2046 Tidskriftsartikel (refereegranskat)abstract Degradation characteristics in response to electron beam sterilization of designed and biodegradable aliphatic polyester scaffolds are relevant for clinically successful synthetic graft tissue regeneration Scaffold degradation in vitro and in vivo were documented and correlated to the macroscopic structure and chemical design of the original polymer The materials tested were of inherently diverse hydrophobicity and crystallinity poly(L-lactide) (poly(LLA)) and random copolymers from L-lactide and epsilon-caprolactone or 1.5-dioxepan-2-one, fabricated into porous and non-porous scaffolds After sterilization, the samples underwent hydrolysis in vitro for up to a year In vivo, scaffolds were surgically implanted into rat calvarial defects and retrieved for analysis after 28 and 91 days In vitro, poly(L-lactide-co-1, 5-dioxepan-2-one) (poly(LLA-co-DXO)) samples degraded most rapidly during hydrolysis, due to the pronounced chain-shortening reaction caused by the sterilization. This was indicated by the rapid decrease in both mass and molecular weight of poly(LLA-co-DXO). Poly(L-lactide-co-epsilon-caprolactone) (poly(LLA-co-CL)) samples were also strongly affected by sterilization, but mass loss was more gradual; molecular weight decreased rapidly during hydrolysis Least affected by sterilization were the poly(LLA) samples, which subsequently showed low mass loss rate and molecular weight decrease during hydrolysis. Mechanical stability varied greatly. poly(LLA-co-CL) withstood mechanical testing for up to 182 days, while poly(LLA) and poly(LLA-co-DXO) samples quickly became too brittle Poly(LLA-co-DXO) samples unexpectedly degraded more rapidly in vitro than in vivo. After sterilization by electron beam irradiation, the three biodegradable polymers present widely diverse degradation profiles, both in vitro and in vivo. Each exhibits the potential to be tailored to meet diverse clinical tissue engineering requirements
30.	Dånmark, Staffan, et al. (författare) Integrin-mediated adhesion of human mesenchymal stem cells to extracellular matrix proteins adsorbed to polymer surfaces 2012 Ingår i: Biomedical Materials. - : IOP Publishing. - 1748-6041 .- 1748-605X. ; 7:3, s. 035011- Tidskriftsartikel (refereegranskat)abstract In vitro, degradable aliphatic polyesters are widely used as cell carriers for bone tissue engineering, despite their lack of biological cues. Their biological active surface is rather determined by an adsorbed layer of proteins from the surrounding media. Initial cell fate, including adhesion and proliferation, which are key properties for efficient cell carriers, is determined by the adsorbed layer of proteins. Herein we have investigated the ability of human bone marrow derived stem cells (hBMSC) to adhere to extracellular matrix (ECM) proteins, including fibronectin and vitronectin which are present in plasma and serum. hBMSC expressed integrins for collagens, laminins, fibronectin and vitronectin. Accordingly, hBMSC strongly adhered to these purified ECM proteins by using the corresponding integrins. Although purified fibronectin and vitronectin adsorbed to aliphatic polyesters to a lower extent than to cell culture polystyrene, these low levels were sufficient to mediate adhesion of hBMSC. It was found that plasma- and serum-coated polystyrene adsorbed significant levels of both fibronectin and vitronectin, and fibronectin was identified as the major adhesive component of plasma for hBMSC; however, aliphatic polyesters adsorbed minimal levels of fibronectin under similar conditions resulting in impaired cell adhesion. Altogether, the results suggest that the efficiency of aliphatic polyesters cell carriers could be improved by increasing their ability to adsorb fibronectin.
31.	Dånmark, Staffan (författare) Polyester scaffold: Material design and cell-protein-material interaction 2011 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Tissue engineering has emerged as a valid approach for the regeneration and restoration of bone defects. The concept of bone tissue engineering includes degradable scaffolds, osteogenic cells and osteoinductive growth factors either alone or in any combination of these three. The scaffold bulk material and its design, in particular, are essential for reaching clinically relevant treatments. It is essential that the scaffold is biocompatible and acts as a temporary extra-cellular matrix with a porous 3-dimensional structure, supporting adhesion, proliferation and differentiation of osteogenic cells. Yet another criterion of the scaffold is that is must have sufficient mechanical stability to maintain structural integrity and protect the cells with a gradual transfer of mechanical load to the developing tissue. At the same time, the scaffolds needs to be bioresorbable with a controllable degradation rate depending on its application and the rate of tissue regrowth. In this thesis, aliphatic polyester scaffolds have been modified and shown to be suitable for bone tissue engineering applications. In addition, a new microfluidic device for live imaging of cell behavior within porous 3-dimensional scaffolds has been developed. Highly porous and degradable aliphatic polyester scaffolds with varying pore sizes and interconnected pores were fabricated. The polyesters assayed were random co-polyesters poly(L-lactide-co-ε-caprolactone) [poly(LLA-co-CL)] and poly(L-lactide-co-1,5-dioxepan-2-one) [poly(LLA-co-DXO] and the homopolymer poly(L-lactide) [poly(LLA)]. The inherently different polymers yielded scaffolds with a wide range of properties with respect to surface chemistry, thermal properties, mechanical stability and degradation rate. The polyester scaffolds were shown to support the increased proliferation of bone marrow-derived stromal cells (BMSC) as well as enhanced osteogenic differentiation, with increased levels of osteocalcin gene expression, which emphasized their potential to act as cells carriers in bone tissue engineering. The potential of poly(LLA-co-CL) scaffolds and common biomedical polyesters in bone tissue engineering was further enhanced by surface functionalization. This involved two different methods of immobilization of bone morphogenetic protein-2 (BMP-2), a potent bone-growth-inducing factor, to the assayed polyesters. The first method used BMP-2 immobilized to heparin functionalized polyesters, while the second method covalently bonded BMP-2 to grafted linker groups on polyesters. Both immobilization techniques retain the bioactivity of BMP-2, and growth-factor-modified polyesters showed an increasing expression of osteogenic genes and production of osteocalcin in osteoblasts-like cells as well as increased proliferation in the mouse cell line, C3H10T1/2. The rate of degradation of electron-beam-sterilized polyester scaffolds and the subsequent loss of mechanical stability were strongly dependent on the chemical, physical and macroscopic architecture of the samples. The degradation rate and loss of mechanical integrity were much greater in porous scaffolds with hydrophilic co-monomers. By incorporating hydrophobic co-monomers with a limited ability to crystalize instead of hydrophilic co-monomers, the mechanical stability was retained for a longer time during the degradation process. The polyester supported spreading and flattened the morphology of both BMSC and osteoblast-like cells. The early cell adhesion to synthetic surfaces is mainly governed by the proteins adsorbed from its surrounding fluids. Early adhesion of BMSC to blood-plasma-coated polyesters was limited, despite the ability of the polyesters to adsorb adhesive proteins and expression of appropriate integrins on BMSC. However, adhesion to a purified adhesive matrix protein on the polyesters did occur, suggesting that pretreatment of polyester scaffolds with adhesive proteins or peptides is a feasible way to enhance the efficiency of cell loading into polyester scaffolds. Polyester scaffolds were combined with microfluidics and soft lithography to develop a new method for high-resolution imaging of live cells within porous scaffolds. The microfluidic device was used to frequently follow live cell proliferation and differentiation on the same spatial location within 3-dimansional porous scaffolds over a period of more than four weeks. This device is attractive for the evaluation of cells and materials intended for tissue engineering. We conclude that degradable aliphatic co-polyester scaffolds carefully designed with respect to macroscopic structure, bulk material and surface chemistry are able to meet the specific requirements of various bone tissue engineering applications. In addition, microfluidic devices permit reoccurring high resolution imaging of live cells within porous scaffolds and have a potential as a method of evaluating tissue engineering constructs.
32.	Fagerland, Jenny, et al. (författare) Mapping the synthesis and the impact of low molecular weight PLGA-g-PEG on sol-gel properties to design hierarchical porous scaffolds 2013 Ingår i: Journal of polymer research. - : Springer Science and Business Media LLC. - 1022-9760 .- 1572-8935. ; 21:1, s. 337- Tidskriftsartikel (refereegranskat)abstract Bone morphogenetic protein 2 (BMP-2)-functionalized poly(l-lactide-co-epsilon-caprolactone) (PLCL) porous scaffolds have shown promising results in bone tissue regeneration studies. It is believed that even better results are achieved by hierarchical porous scaffolds and a designed sequential release of growth factors. We therefore synthesized (l-lactide-co-glycolide)-g-poly(ethylene glycol) (PLGA-g-PEG) oligomers which could be injected into PLCL porous scaffolds. They were synthesized by ring-opening polymerization and carefully characterized by nuclear magnetic resonance spectroscopy (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The sol-gel transition temperature, pH, and functional life were determined and correlated with the molecular structure of PLGA-g-PEG. We found that low molecular weight PLGA-g-PEG was obtained and poly(l-lactide-co-glycolide-co-poly(ethylene glycol) methyl ether) (PLGA-MPEG) appeared to contribute to gelation. It was possible to design a system that formed a hydrogel within 1 min at 37 A degrees C with a pH between 6 and 7 and with a functional life of around 1 month. These low molecular weight thermosensitive PLGA-g-PEG oligomers, which can be injected into PLCL scaffolds, appear promising for bone tissue engineering applications.
33.	Fagerland, Jenny, et al. (författare) Modulating the thermal properties of poly(hydroxybutyrate) by the copolymerization of rac-beta-butyrolactone with lactide 2016 Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 40:9, s. 7671-7679 Tidskriftsartikel (refereegranskat)abstract Biobased poly(hydroxybutyrate) is produced by microorganisms under controlled conditions. It is a linear, high molecular weight, fully isotactic and highly crystalline polymer. However, it has poor mechanical and thermal properties. We have modulated the thermal properties of this material by ring-opening co-polymerization of rac-beta-butyrolactone (BL) with lactide (LA) in the presence of salan-based yttrium and aluminum catalysts. The prepared poly(hydroxybutyrate-co-lactide) copolymers were characterized by proton and carbon nuclear magnetic resonance (H-1 and C-13 NMR), size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) analyses. The salan-yttrium compound was a more effective catalyst compared to the aluminum compound, affording high molecular weight copolymers with higher monomer conversion and a monomodal distribution of the molecular weights. The kinetic experiments showed a higher rate of polymerization for the LA with respect to the BL. The copolymers were amorphous and DSC showed unique transition temperatures for all of the samples. The formation of a gradient copolymer is proposed.
34.	Fagerland, Jenny, et al. (författare) Short One-Pot Chemo-Enzymatic Synthesis of L-Lysine and L-Alanine Diblock Co-Oligopeptides 2014 Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 15:3, s. 735-743 Tidskriftsartikel (refereegranskat)abstract Amphiphilic diblock co-oligopeptides are interesting and functional macromolecular materials for biomedical applications because of their self-assembling properties. Here, we developed a synthesis method for diblock co-oligopeptides by using chemo-enzymatic polymerization, which was a relatively short (30 min) and efficient reaction (over 40% yield). Block and random oligo(L-lysine-co-L-alanine) [oligo(Lys-co-Ala)] were synthesized using activated papain as enzymatic catalyst. The reaction time was optimized according to kinetic studies of oligo(L-alanine) and oligo(L-lysine). Using H-1 NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we confirmed that diblock and random co-oligopeptides were synthesized. Optical microscopy further revealed differences in the crystalline morphology between random and block co-oligopeptides. Plate-like, hexagonal, and hollow crystals were formed due to the strong impact of the monomer distribution and pH of the solution. The different crystalline structures open up interesting possibilities to form materials for both tissue engineering and controlled drug/gene delivery systems.
35.	Fagerland, Jenny, et al. (författare) Short one-pot chemo-enzymatic synthesis of L-lysine and L-alanine diblock copolypeptides Annan publikation (övrigt vetenskapligt/konstnärligt)
36.	Fagerland, Jenny, 1985- (författare) Synthesis and Characterization of Self-Assembling Low Molecular Weight Copolymers for Bioengineering Applications 2013 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract The constant need for improved biomedical materials and the interest in producing materials with similar properties to the extracellular matrix in different tissues has resulted in increasing interest in research on hydrogels. Over the last decade self-assembling copolymers have been of particular interest since they form hydrogels in response to external stimuli such as temperature. In this thesis, two self-assembling low molecular weight copolymers; poly(L-lactide-co-glycolide) grafted with poly(ethylene glycol) methyl ether (PLGA-g-MPEG) and poly(L-lysine-co-L-alanine) (poly(Lys-co-Ala)) were synthesized for possible bioengineering applications. Their chemical structure and composition was analysed by nuclear magnetic resonance spectroscopy (NMR) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The results showed that low molecular weight PLGA-g-MPEG and poly(Lys-co-Ala) were successfully obtained.PLGA-g-MPEG hydrogels were formed at 37°C, within 1 minute, at a pH between 6-7 and had a functional life of one month. The block cooligopeptides of L-lysine and L-alanine formed cubic, hexagonal and hollow crystals in low pH and irregularly shaped crystals in at pH 7, while plate-like crystals were formed at both pH 3 and 7 form the random cooligopeptides. Evaluation of the properties of the low molecular weight copolymers, such as pH, functional life and crystalline morphology, revealed that the chemical composition and solvent composition strongly affects their self-assembling properties.These synthesized low molecular weight copolymers showed promise results for use as material in biomedical applications. Areas of potential use for these materials include bioengineered hierarchical scaffold material facilitating sequential release of growth factors, for example in bone tissue engineering, and as materials for encapsulated drug delivery.
37.	Fagerland, Jenny, 1985- (författare) Synthesis of degradable aliphatic polyesters: strategies to tailor the polymer microstructure 2018 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Key factors for successful tissue engineering are the synthesis and design of the scaffold materials. Aliphatic polyesters have been studied and often used as scaffold materials for tissue engineering. However, their lack of biological cues and degradation under high-temperature processing (e.g., 3D printing) are a limitation. In this thesis, different synthesis strategies are presented which has the potential to improve the performance of aliphatic polyesters as scaffolds for tissue regeneration.To stimulate interactions between exogenous materials and the surrounding tissue, two different strategies were applied. Either, by designing a two component system in which the different degradation profiles of the polymers allow for sequential release of growth factors. Or, by peptide functionalization of an aliphatic polyester chain using template-assisted chemo-enzymatic synthesis. The results from the studies were successful. A hierarchical system was obtained in which the poly(L-lactide-co-glycolide)-graft-poly(ethylene glycol) methyl ether (PLGA-g-MPEG), hydroxyapatite solution formed a gel around and within the pores of the poly(L-lactide-co-ε-caprolactone) scaffold at 37 ºC, within 1 min, that was stable for 3 weeks. The peptide functionalization was also successful where an aliphatic polyester of L-lactide was functionalized with different oligopeptides using a grafter (ethyl hept-6-enoylalaninate) and chemo-enzymatic synthesis.The thermal properties of poly(L-lactide-co-hydroxybutyrate) were tailored (by modification of the microstructure) to potentially improve the processability of the aliphatic polyester. The results showed that the yttrium salan catalyst was the most successful, yielding high molecular weight copolymers in shorter time. They also showed that the Tg could be tailored by varying the amount of rac-β-butyrolactone in the copolymer to better suit thermal processing techniques, such as 3D printing.
38.	Fagerland, Jenny, 1985-, et al. (författare) Template-assisted enzymatic synthesis of oligopeptides from a polylactide chain 2017 Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 18:12, s. 4271-4280 Tidskriftsartikel (refereegranskat)abstract Peptides are often attached to polymer materials, as bioactive components, for the control of interactions between the material and its surrounding proteins and cells. However, synthesizing peptides and attaching them to polymers can be challenging and laborious. Herein, we describe the grafting of oligopeptides to an aliphatic polyester, using a one-step chemo-enzymatic synthesis with papain as the biocatalySt. To enable enzyme-mediated functionalization of the polyester, ethyl hept-6-enoylalaninate (grafter) was synthesized and attached to polylactide chains using thiol-ene click reactions. The oligopeptides were grafted onto the polylactide chains using two different synthetic routes: the grafting from strategy, in which the grafter was attached to the polyester prior to oligopeptide synthesis, or the grafting to strategy, in which oligopeptides were synthesized on the grafter first, then attached to the polymer chain. The final products were analyzed and their structures were confirmed using nuclear magnetic resonance (NMR). The peptide attachment was evaluated using size exclusion chromatography (SEC), contact angle measurement and energy-dispersive X-ray spectroscopy scanning electron microscopy (EDS-SEM). Furthermore, the mechanistic aspects of the synthesis of the oligopeptides on the grafter were studied using molecular dynamics (MD) simulations. The simulation revealed that hydrogen bonding (between the P1 amide nitrogen of the grafter backbone and the carbonyl oxygen of D158 in the papain) maintain the grafter in a productive conformation to stabilize the transition state of nitrogen inversion, a key step of the biocatalytic mechanism. Apart from being biologically relevant, both experimental and computational results suggest that the designed grafter is a good template for initiating chemo-enzymatic synthesis. The results also showed that the grafting to strategy was more successful compared to the grafting from strategy. Overall, a successful synthesis of predefined peptide functionalized polylactide was prepared, where the oligopeptides were grafted in an easy, time efficient, and environmentally friendly way.
39.	Fall, Andreas (författare) Cellulose nanofibril materials with controlled structure : the influence of colloidal interactions 2011 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Nanoparticles are very interesting components. Due to their very large specific surface area they possess properties in between molecules and macroscopic materials. In addition, a material built up of hierarchically assembled nanoparticles could obtain unique properties, not possessed by the nanoparticles themself. A very interesting group of nanoparticles is the cellulose nanofibrils. The fibrils are found in various renewable resources such as wood, bacteria and tunicates. In this work fibrils extracted from wood is studied. In wood the fibrils are the smallest fibrous component with the approximate dimensions; 4 nm in width and length in the micrometer range, providing a high aspect ratio. In addition, they have a crystallinity above 60% and, hence, a high stiffness. These fibrils are hierarchically ordered in the wood fiber to give it its unique combination of flexibility and strength. The properties of the fibrils make them very suitable to be used as reinforcement elements in composites and, due to their ability to closely pack, to make films with excellent gas barrier properties. The key aspect to design materials, efficiently utilizing the properties of the individual fibrils, is to control the arrangement of the fibrils in the final material. In order to do so, the interactions between fibrils have to be well characterized and controlled. In this thesis the interaction between fibrils in aqueous dispersions is studied, where the main interactions are attractive van der Waals forces and repulsive electrostatic forces. The electrostatic forces arise from carboxyl groups at the fibrils surface, which either are due to hemicelluloses at the fibrils surfaces or chemically introduced to the cellulose chain. This force is sensitive to the chemical environment. It decreases if the pH is reduced or if the salt concentration is increased. If it is strongly reduced the system aggregates. In dilute dispersions aggregation causes formation of multiple clusters, whereas in semi-dilute dispersions (above the overlap concentration) a volume filling network, i.e. a gel, is formed. The tendency of aggregation, i.e. the colloidal stability, can be predicted by using the DLVO theory. In this thesis DLVO predictions are compared to aggregation measurements conducted with dynamic light scattering. Good agreement between experiments and the designed theoretical model was found by including specific interactions between added counter-ions and the carboxyl groups of the fibrils in the model. Thus, the surface charge is both reduced by protonation and by specific interactions. This emphasizes a much larger effect of the counter-ions on the stability then generally thought. Hence, this work significantly improves the understanding of the interfibril interactions in aqueous media. As mentioned above, the fibrils can be physically cross-linked to form a gel. The gelation is an instant process, occurring at pH or salt levels causing the interfibril repulsion to decrease close to zero. If a well dispersed stationary dispersion is gelled, the homogenous and random distribution of the fibrils is preserved in the gel. These gels can be used as templates to produce composites by allowing monomers or polymers to enter the network by diffusion. In an effort to mimic processes occurring in the tree, producing materials with fibrils aligned in a preferred direction, the ability to form gels with controlled fibril orientation were studied. Such networks were successfully produced by applying strain to the system prior or past gelation. Orientation prior gelation was obtained by subjecting the dispersion to elongational flow and freezing the orientation by “turning off” the electrostatic repulsion. Orienting the fibrils after gelation was achieved by applying shear strain. Due to the physical nature of the crosslinks, rotation in the fibril-fibril joints can occur, enabling the fibrils to align in the shear direction. This alignment significantly increased the stiffness of the gels in the shear direction.
40.	Finne Wistrand, Anna, et al. (författare) Degradable polymers : Design, synthesis and testing 2003 Ingår i: Macromolecular Symposia. - : Wiley. - 1022-1360 .- 1521-3900. ; 195, s. 241-246 Tidskriftsartikel (refereegranskat)abstract The object for our research is to mimic Nature's perfectly designed resorbable materials to obtain important materials, which are biocompatible and degradable. We have therefore synthesized different architectures and copolymers of aliphatic polyesters with ring-opening polymerization. The first studies of these materials properties show that properties like hydrophilicity and tensile properties can be controlled.
41.	Finne Wistrand, Anna, et al. (författare) Polylactide : 2011 Ingår i: Handbook of Engineering and Speciality Thermoplastics. - Hoboken, NJ, USA : John Wiley & Sons. - 9780470639269 - 9781118104729 ; , s. 349-376 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract The production of durable functional products without using petroleumbased raw materials is a focus of much academic research today but it is also prioritized by many industries. Many questions still remain concerning the use, production and properties of bio-based and/or degradable polymers and whether or not they are more environmentally friendly than oil-based products. Polylactide is a bio-based compostable thermoplastic that is considered as one of the most promising materials for replacement of traditional volume plastics. The properties of polylactide can be tuned to resemble polystyrene, poly(ethylene terephthalate) or polyolefins by controlling the stereochemistry by copolymerization or blending. This chapter reviews the life-cycle of polylactide based materials as well as the properties and applications. The recent trends in the area are also discussed.
42.	Finne Wistrand, Anna, et al. (författare) Resorbable Scaffolds from Three Different Techniques : Electrospun Fabrics, Salt-Leaching Porous Films, and Smooth Flat Surfaces 2008 Ingår i: Macromolecular Bioscience. - : Wiley. - 1616-5187 .- 1616-5195. ; 8:10, s. 951-959 Tidskriftsartikel (refereegranskat)abstract Nanofibrous scaffolds of poly[(L-lactide)-co-(1,5-dioxepan-2-one)] generated by electrospinning have been compared with porous films obtained by solvent cast/salt leaching and homogeneous films. A comparison between the fibrous materials and the homogeneous solvent-cast films revelead that the surface of the nanofibers was more hydrophobic and that the nanofibers were degraded more rapidly in the presence of proteinase. It was obvious that the strain-to-break was reduced by the nanofiber formation, it decreased from 370% to 130% independent of fiber diameter. These values were however considerably higher than the strain-to-break of the solvent-cast/salt leaching scaffold. In addition, the nanofibrous material accelerated the adhesion and growth of the mesenchymal stem cell compared to the smooth material.
43.	Finne Wistrand, Anna, et al. (författare) The use of polymer design in resorbable colloids 2006 Ingår i: Annual review of materials research (Print). - : Annual Reviews. - 1531-7331 .- 1545-4118. ; 36, s. 369-395 Forskningsöversikt (refereegranskat)abstract During the past decade, researchers in the field of polymer chemistry have developed a wide range of very powerful procedures for constructing ever-more-sophisticated polymers. These methods subsequently have been used in suitable systems to solve specific medical problems. This is complicated, and many key factors such as mechanical properties, biocompatibility, biodegradation, stability, and degradation profile must be considered. Colloid particle systems can be used to solve many biomedical- and pharmaceutical-related problems, and it is expected that nanotechnology can be used to develop these materials, devices, and systems even further. For example, an injectible scaffold system with a defined release and degradation profile has huge potential for the repair and regeneration of damaged tissues. This short, nonexhaustive review presents examples of polymer architecture in resorbable particles that have been compared and tested in biomedical applications. We also discuss the design of polymers for core-shell structures.
44.	Finne Wistrand, Anna, et al. (författare) Tuned mechanical properties achieved by varying polymer structure : Knowledge that generates new materials for tissue engineering 2007 Ingår i: Chinese Journal of Polymer Science. - 0256-7679 .- 1439-6203. ; 25:2, s. 113-118 Tidskriftsartikel (refereegranskat)abstract By changing both the monomer composition and the polymer structure, we have varied the mechanical properties of resorbable polymers. The polymers were synthesized by ring-opening polymerization using L-lactide (LLA), epsilon-caprolactone (epsilon CL), trimethylene carbonate (TMC) and 1,5-dioxepan-2-one (DXO) as monomers. Well-defined triblock copolymers, microblock copolymers and networks have been evaluated, and comparisons between them show that it is possible to tune the mechanical properties. Triblock copolymers with an amorphous middle block of poly(1,5-dioxepan-2-one) (PDXO) and semi-crystalline end-blocks of poly(epsilon-caprolactone) (PCL) were stronger and had a higher strain at break than triblock copolymers with poly(L-lactide) (PLLA) as end-blocks. Polymers with both DXO and TMC in the amorphous middle-block and PLLA as end-blocks showed a lower stress at break, but the material gained elasticity, a property which is very valuable in tissue engineering. Mechanical properties of networks, synthesized by a novel method, containing PDXO and PCL are also presented. Although it is difficult to compare them with the uncross-linked polymers, this is an additional way to modify and widen the properties.
45.	Fuoco, Tiziana, et al. (författare) A Route to Aliphatic Poly(ester)s with Thiol Pendant Groups : From Monomer Design to Editable Porous Scaffolds 2016 Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 17:4, s. 1383-1394 Tidskriftsartikel (refereegranskat)abstract Biodegradable aliphatic polyesters such as poly(lactide) and poly(ϵ-caprolactone), largely used in tissue engineering applications, lack suitable functional groups and biological cues to enable interactions with cells. Because of the ubiquity of thiol groups in the biological environment and the pliability of thiol chemistry, we aimed to design and synthesize poly(ester) chains bearing pendant thiol-protected groups. To achieve this, 3-methyl-6-(tritylthiomethyl)-1,4-dioxane-2,5-dione, a lactide-type monomer possessing a pendant thiol-protected group, was synthesized. This molecule, when used as a monomer in controlled ring-opening polymerization in combination with lactide and ϵ-caprolactone, appeared to be a convenient "building block" for the preparation of functionalized aliphatic copolyesters, which were easily modified further. A polymeric sample bearing pyridyl disulfide groups, able to bind a cysteine-containing peptide, was efficiently obtained from a two-step modification reaction. Porous scaffolds were then prepared by blending this latter copolymer sample with poly(l-lactide-co-ϵ-caprolactone) followed by salt leaching. A further disulfide exchange reaction performed in aqueous medium formed porous scaffolds with covalently linked arginine-glycine-aspartic acid sequences. The scaffolds were characterized by thermal and mechanical tests, and scanning electron microscopy surface images revealed a highly porous morphology. Moreover, a cytotoxicity test indicated good cell viability.
46.	Fuoco, Tiziana, PhD, 1986-, et al. (författare) Capturing the Real-Time Hydrolytic Degradation of a Library of Biomedical Polymers by Combining Traditional Assessment and Electrochemical Sensors 2021 Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 22:2, s. 949-960 Tidskriftsartikel (refereegranskat)abstract We have developed an innovative methodology to overcome the lack of techniques for real-time assessment of degradable biomedical polymers at physiological conditions. The methodology was established by combining polymer characterization techniques with electrochemical sensors. The in vitro hydrolytic degradation of a series of aliphatic polyesters was evaluated by following the molar mass decrease and the mass loss at different incubation times while tracing pH and L-lactate released into the incubation media with customized miniaturized electrochemical sensors. The combination of different analytical approaches provided new insights into the mechanistic and kinetics aspects of the degradation of these biomedical materials. Although molar mass had to reach threshold values for soluble oligomers to be formed and specimens' resorption to occur, the pH variation and L-lactate concentration were direct evidence of the resorption of the polymers and indicative of the extent of chain scission. Linear models were found for pH and released L-lactate as a function of mass loss for the Llactide-based copolymers. The methodology should enable the sequential screening of degradable polymers at physiological conditions and has potential to be used for preclinical material's evaluation aiming at reducing animal tests.
47.	Fuoco, Tiziana, PhD, 1986-, et al. (författare) Enhancing the Properties of Poly(epsilon-caprolactone) by Simple and Effective Random Copolymerization of epsilon-Caprolactone with p-Dioxanone 2019 Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 20:8, s. 3171-3180 Tidskriftsartikel (refereegranskat)abstract We have developed a straightforward strategy to obtain semicrystalline and random copolymers of epsilon-caprolactone (CL) and p-dioxanone (DX) with thermal stabilities similar to poly(epsilon-caprolactone), PCL, but with a faster- hydrolytic degradation rate-CL/DX-copolymers-are promising inks when printing scaffolds aimed for tissue engineering. Such copolymers behave similar to PCL and resorb faster. The copolymers were synthesized by bulk ring-opening copolymerization, achieving a high yield; a molecular weight, M-n, of 57-176 kg mol(-1); and an inherent viscosity of 1.7-1.9 dL g(-1). The copolymer microstructure consisted of long CL blocks that are separated by isolated DX units. The block length and the melting point were a linear function of the DX content. The copolymers crystallize as an orthorhombic lattice that is typical for PCL, and they formed more elastic, softer, and less hydrophobic films with faster degradation rates than PCL. Relatively high thermal degradation temperatures (above 250 C), similar to PCL, were estimated by thermogravimetric analysis, and copolymer filaments for three-dimensional printing and scaffolds were produced without thermal degradation.
48.	Fuoco, Tiziana, PhD, 1986-, et al. (författare) Hydrogel Polyester Scaffolds via Direct-Ink-Writing of Ad Hoc Designed Photocurable Macromonomer 2022 Ingår i: Polymers. - : MDPI. - 2073-4360. ; 14:4 Tidskriftsartikel (refereegranskat)abstract Synthetic, degradable macromonomers have been developed to serve as ink for 3D printing technologies based on direct-ink-writing. The macromonomers are purposely designed to be cross-linkable under the radical mechanism, to impart hydrophilicity to the final material, and to have rheological properties matching the printer's requirements. The suitable viscosity enables the ink to be printed at room temperature, in absence of organic solvents, and to be cross-linked to manufacture soft 3D scaffolds that show no indirect cytotoxicity and have a hydration capacity of up to 100% their mass and a compressive modulus in the range of 0.4-2 MPa.
49.	Fuoco, Tiziana, PhD, 1986-, et al. (författare) Minimizing the time gap between service lifetime and complete resorption of degradable melt-spun multifilament fibers 2019 Ingår i: Polymer degradation and stability. - : Elsevier. - 0141-3910 .- 1873-2321. ; 163, s. 43-51 Tidskriftsartikel (refereegranskat)abstract We have succeeded to modulated the degradation rate of poly(L-lactide) (PLLA) melt-spun multifilament fibers to extend the service lifetime and increase the resorption rate by using random copolymers of L-lactide and trimethylene carbonate (TMC). The presence of TMC units enabled an overall longer service lifetime but faster degradation kinetics than PLLA. By increasing the amount of TMC up to 18 mol%, multifilament fibers characterized by a homogenous degradation profile could be achieved. Such composition allowed, once the mechanical integrity was lost, a much longer retention of mechanical integrity and a faster rate of mass loss than samples containing less TMC. The degradation profile of multifilament fibers consisting of (co)polymers containing 0, 5, 10 and 18 mol% of TMC has been identified during 45 weeks in vitro hydrolysis following the molecular weight decrease, mass loss and changes in microstructure, crystallinity and mechanical properties. The fibers degraded by a two-step, autocatalyzed bulk hydrolysis mechanism. A high rate of molecular weight decrease and negligible mass loss, with a consequent drop of the mechanical properties, was observed in the early stage of degradation for fibers having TMC content up to 10 mol%. The later stage of degradation was, for these samples, characterized by a slight increase in the mass loss and a negligible molecular weight decrease. Fibers prepared with the 18 mol% TMC copolymer showed instead a more homogenous molecular weight decrease ensuring mechanical integrity for longer time and faster mass loss during the later stage of degradation.
50.	Fuoco, Tiziana, PhD, 1986-, et al. (författare) Multipurpose Degradable Physical Adhesive Based on Poly(d,l-lactide-co-trimethylene Carbonate) 2020 Ingår i: Macromolecular Chemistry and Physics. - : Wiley. - 1022-1352 .- 1521-3935. ; 221:10 Tidskriftsartikel (refereegranskat)abstract Solutions of amorphous poly(d,l-lactide-co-trimethylene carbonate)s (PDLTMCs) in ethyl acetate work as solvent-based physical adhesives through diffusion mechanisms for a variety of aliphatic polyester-based adherents. The random PDLTMCs with a trimethylene carbonate content of 11, 16, and 20 mol% are synthesized in bulk, achieving high molecular weight, M-n, up to 128 kg mol(-1) and dispersity around 1.7. The PDLTMCs are amorphous and have a glass transition temperature in the range 34.7 to 43.6 degrees C and in agreement with the theoretical values calculated using the Fox equation. The mechanical and surface properties of the PDLTMCs are tested preparing solvent cast films, which are soft and tough and, although they have a higher contact angle than the parent homopolymer, they show higher water uptake capacity. The potential application as adhesives of the synthesized PDLTMCs is evaluated by preparing a 20 wt% solution in ethyl acetate and testing them by adhering films with different compositions as well as constructs having different geometries and surface roughness. The results demonstrate that the adhesion strength is higher on adherent films having similar chemical compositions as the adhesives and on surfaces having similar compositions to each other but different roughness. The similar chemical nature of the adhesive and adherent probably favors the diffusion mechanism through which adhesion takes place.

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