| 1. |
- Finne Wistrand, Anna, 1976-
(author)
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Aliphatic poly(ester)s with thiol pendant groups
- 2020
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Patent (pop. science, debate, etc.)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 .
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| 2. |
- Gurzawska-Comis, Katarzyna, et al.
(author)
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GUIDED BONE REGENERATION IN OSTEOPOROSIS BY PLANT-DERIVED NANOPARTICLES
- 2023
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In: Tissue Engineering. Part A. - : MARY ANN LIEBERT, INC. - 1937-3341 .- 1937-335X. ; 29:11-12, s. 576-577
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Journal article (other academic/artistic)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.
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| 3. |
- Suliman, Salwa, et al.
(author)
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Immune-instructive copolymer scaffolds using plant-derived nanoparticles to promote bone regeneration
- 2022
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In: Inflammation and Regeneration. - : Springer Nature. - 1880-8190. ; 42:1
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Journal article (peer-reviewed)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.
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| 4. |
- Abbasi Aval, Negar, et al.
(author)
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An aligned fibrous and thermosensitive hyaluronic acid-puramatrix interpenetrating polymer network hydrogel with mechanical properties adjusted for neural tissue
- 2022
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In: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:4, s. 2883-2896
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Journal article (peer-reviewed)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.
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| 5. |
- Ahlinder, Astrid
(author)
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Degradable copolymers in additive manufacturing: controlled fabrication of pliable scaffolds
- 2021
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Doctoral thesis (other academic/artistic)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.
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| 6. |
- Ahlinder, Astrid, et al.
(author)
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Minimise thermo-mechanical batch variations when processing medical grade lactide based copolymers in additive manufacturing
- 2020
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In: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 181
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Journal article (peer-reviewed)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.
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| 7. |
- Ahlinder, Astrid, et al.
(author)
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Nondegradative additive manufacturing of medical grade copolyesters of high molecular weight and with varied elastic response
- 2020
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In: Journal of Applied Polymer Science. - : WILEY. - 0021-8995 .- 1097-4628. ; 137:15
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Journal article (peer-reviewed)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.
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| 8. |
- Albertsson, Ann-Christine, et al.
(author)
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Design and synthesis of different types of poly(lactic acid)/polylactide copolymers
- 2022
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In: Poly(lactic acid). - : Wiley. ; , s. 45-71
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Book chapter (other academic/artistic)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.
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| 9. |
- Ayyachi, Thayanithi, et al.
(author)
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Defining the role of linoleic acid in acrylic bone cement
- 2022
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In: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 139:25
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Journal article (peer-reviewed)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.
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| 10. |
- Behroozi Kohlan, Taha, et al.
(author)
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Schiff base crosslinked hyaluronic acid hydrogels with tunable and cell instructive time-dependent mechanical properties
- 2024
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In: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 338
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Journal article (peer-reviewed)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.
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