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  • 1.
    Ahlinder, Astrid
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Fuoco, Tiziana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Medical grade polylactide, copolyesters and polydioxanone: Rheological properties and melt stability2018In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 72, p. 214-222Article in journal (Refereed)
    Abstract [en]

    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.

  • 2.
    Fuoco, Tiziana
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Enhancing the Properties of Poly(epsilon-caprolactone) by Simple and Effective Random Copolymerization of epsilon-Caprolactone with p-Dioxanone2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 8, p. 3171-3180Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Fuoco, Tiziana
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mathisen, T.
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Minimizing the time gap between service lifetime and complete resorption of degradable melt-spun multifilament fibers2019In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 163, p. 43-51Article in journal (Refereed)
    Abstract [en]

    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.

  • 4.
    Fuoco, Tiziana
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mathisen, Torbjorn
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Poly(L-lactide) and Poly(L-lactide-co-trimethylene carbonate) Melt-Spun Fibers: Structure-Processing-Properties Relationship2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 3, p. 1346-1361Article in journal (Refereed)
    Abstract [en]

    l-Lactide/trimethylene carbonate copolymers have been produced as multifilament fibers by high-speed melt-spinning. The relationship existing between the composition, processing parameters and physical properties of the fibers has been disclosed by analyzing how the industrial process induced changes at the macromolecular level, i.e., the chain microstructure and crystallinity development. A poly(l-lactide) and three copolymers having trimethylene carbonate contents of 5, 10 and 18 mol % were synthesized with high molecular weight (M n ) up to 377 kDa and narrow dispersity. Their microstructure, crystallinity and thermal properties were dictated by the composition. The spinnability was then assessed for all the as-polymerized materials: four melt-spun multifilament fibers with increasing linear density were collected for each (co)polymer at a fixed take-up speed of 1800 m min -1 varying the mass throughput during the extrusion. A linear correlation resulted between the as-spun fiber properties and the linear density. The as-spun fibers could be further oriented, developing more crystallinity and improving their tensile properties by a second stage of hot-drawing. This ability was dependent on the composition and crystallinity achieved during the melt-spinning and the parameters selected for the hot-drawing, such as temperature, draw ratio and input speed. The crystalline structure evolved to a more stable form, and the degree of crystallinity increased from 0-52% to 25-66%. Values of tensile strength and Young's modulus up to 0.32-0.61 GPa and 4.9-8.4 GPa were respectively achieved.

  • 5.
    Fuoco, Tiziana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Aluminum Alkyl Complexes Bearing Salicylaldiminato Ligands: Versatile Initiators in the Ring-Opening Polymerization of Cyclic Esters2017In: CATALYSTS, ISSN 2073-4344, Vol. 7, no 2, article id 64Article, review/survey (Refereed)
    Abstract [en]

    Linear aliphatic polyesters are degradable thermoplastic polymers, which can be obtained by ring-opening polymerization (ROP) of cyclic esters through a coordination-insertion mechanism. Aluminum based organometallic complexes have a leading position as efficient catalysts for this polymerization process. Aluminumalkyl complexes bearing salicylaldiminato ligands, although less explored, have been shown to be efficient and versatile catalysts for the ROP of various cyclic esters. These species have the potential to function as active catalysts in the ROP because of their less coordinatively saturated nature with respect to analogous SALEN-type complexes. They have been used as efficient catalysts in the ROP of commercially available cyclic esters, such as epsilon-caprolactone, L-lactide, rac-lactide, and glycolide. Moreover, they resulted in efficient catalysts for the ROP of cyclic esters with large ring-size and for the ROP of functionalized lactide. Furthermore, they have been used in the co- and ter-polymerization of various cyclic esters affording well controlled polymerization and a plethora of microstructural architectures, ranging from random to block to multiblock.

  • 6.
    Fuoco, Tiziana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Department of Science and Technology, University of Sannio, via dei Mulini 59/A, 82100 Benevento, Italy.
    Wistrand, Anna Finne
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Redox-Responsive Disulfide Cross-Linked PLA-PEG Nanoparticles2017In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 50, no 18, p. 7052-7061Article in journal (Refereed)
    Abstract [en]

    We have developed a strategy for the preparation of redox-responsive PEG PLA-based nanoparticles containing disulfide bonds that can be disassembled in the presence of cellular concentrations of glutathione. Functionalized poly-(lactide)s were prepared by ring-opening copolymerization of L-lactide and 3-methyl-6-(tritylthiomethyl)-1,4-dioxane-2,5-dione, a monomer bearing a pendant trityl-thiol group, followed by the postpolymerization modification of trityl-thiol into pyridyl disulfide groups. Polymeric networks composed of PLA and PEG blocks linked by disulfide bonds were prepared by a disulfide exchange reaction between the functionalized PLAs and telechelic PEG having thiol groups at both ends, HS-PEG-SH, in DMF. When dialyzed against water, they assembled into dispersible nanoparticles, with a flowerlike structure having a hydrophobic core and a hydrophilic shell, with sizes in the range 167-300 nm that are suitable for drug delivery. The effects of the number of functional groups, molecular weight, and concentration on the nanoparticle size were evaluated. The stability of the nanoparticles after dilution and the redox-responsive behavior in the presence of different concentrations of glutathione were assessed. The hydrophobic molecule Nile red could be encapsulated in the nanoparticles and then released in the presence of glutathione at cellular concentration.

  • 7.
    Munir, Arooj
    et al.
    Univ Bergen, Ctr Clin Dent Res, Dept Clin Dent, Fac Med, N-5009 Bergen, Norway..
    Doskeland, Anne
    Univ Bergen, Dept Biomed, Bergen, Norway..
    Avery, Steven J.
    Cardiff Univ, Dept Oral & Biomed Sci, Sch Dent, Cardiff, S Glam, Wales.;CITER, Cardiff, S Glam, Wales..
    Fuoco, Tiziana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mohamed-Ahmed, Samih
    Univ Bergen, Ctr Clin Dent Res, Dept Clin Dent, Fac Med, N-5009 Bergen, Norway..
    Lygre, Henning
    Univ Bergen, Ctr Clin Dent Res, Dept Clin Dent, Fac Med, N-5009 Bergen, Norway..
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH Royal Inst Technol, sDept Fibre & Polymer Technol, Stockholm, Sweden..
    Sloan, Alastair J.
    Cardiff Univ, Dept Oral & Biomed Sci, Sch Dent, Cardiff, S Glam, Wales.;CITER, Cardiff, S Glam, Wales..
    Waddington, Rachel J.
    Cardiff Univ, Dept Oral & Biomed Sci, Sch Dent, Cardiff, S Glam, Wales.;CITER, Cardiff, S Glam, Wales..
    Mustafa, Kamal
    Univ Bergen, Ctr Clin Dent Res, Dept Clin Dent, Fac Med, N-5009 Bergen, Norway..
    Suliman, Salwa
    Univ Bergen, Ctr Clin Dent Res, Dept Clin Dent, Fac Med, N-5009 Bergen, Norway..
    Efficacy of copolymer scaffolds delivering human demineralised dentine matrix for bone regeneration2019In: Journal of Tissue Engineering, ISSN 2041-7314, E-ISSN 2041-7314, Vol. 10, article id 2041731419852703Article in journal (Refereed)
    Abstract [en]

    Poly(L-lactide-co-epsilon-caprolactone) scaffolds were functionalised by 10 or 20 mu g/mL of human demineralised dentine matrix. Release kinetics up to 21 days and their osteogenic potential on human bone marrow stromal cells after 7 and 21 days were studied. A total of 390 proteins were identified by mass spectrometry. Bone regeneration proteins showed initial burst of release. Human bone marrow stromal cells were cultured on scaffolds physisorbed with 20 mu g/mL and cultured in basal medium (DDM group) or physisorbed and cultured in osteogenic medium or cultured on non-functionalised scaffolds in osteogenic medium. The human bone marrow stromal cells proliferated less in demineralised dentine matrix group and activated ERK/1/2 after both time points. Cells on DDM group showed highest expression of IL-6 and IL-8 at 7 days and expressed higher collagen type 1 alpha 2, SPP1 and bone morphogenetic protein-2 until 21 days. Extracellular protein revealed higher collagen type 1 and bone morphogenetic protein-2 at 21 days in demineralised dentine matrix group. Cells on DDM group showed signs of mineralisation. The functionalised scaffolds were able to stimulate osteogenic differentiation of human bone marrow stromal cells.

  • 8.
    Sorrentino, Andrea
    et al.
    Natl Res Council Italy, IPCB, I-23900 Lecce, Italy..
    Gorrasi, Giuliana
    Univ Salerno, Dipartimento Ingn Ind, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy..
    Bugatti, Valeria
    Univ Salerno, Dipartimento Ingn Ind, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy..
    Fuoco, Tiziana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Univ Salerno, Dipartimento Chim & Biol A Zambelli, Via Giovanni Paolo II 132, I-84084 Fisciano, SA, Italy.;KTH Royal Inst Technol, Dept Fibre & Polymer Technol, S-11428 Stockholm, Sweden..
    Pappalardo, Daniela
    Univ Sannio, Dipartimento Sci & Tecnol, Via Mulini, I-82100 Benevento, Italy..
    Polyethylene-like macrolactone-based polyesters: Rheological, thermal and barrier properties2018In: Materials Today Communications, ISSN 2352-4928, Vol. 17, p. 380-390Article in journal (Refereed)
    Abstract [en]

    Linear aliphatic poly(ester)s are receiving increasing interest due to their properties comparable to that of common polyethylene. In this work, unsaturated macrolactone omega-6-hexadecenlactone (6HDL) is used for the preparation of long-methylene chain aliphatic polyesters by metal-catalyzed ring-opening polymerization (ROP). Block and random copolymer of e-caprolactone (CL) are then synthetized. The microstructures of these polyesters are characterized by H-1 and C-13 NMR. Their rheological, thermal and barrier properties are evaluated and discussed. For comparison purposes, the properties of the relative homopolymers are also determined. Results show that the properties of these polymers differ depending on the main chain structure. In particular, the viscoelastic behavior of the copolymer sample shows an order-disorder transition in the temperature range of 75-85 degrees C. Thermogravimetric analysis and barrier properties show that the copolymers have a resistance to the diffusion of gases and vapors intermediate between that of the parent homopolymers.

  • 9.
    Yassin, Mohammed A.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Fuoco, Tiziana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Mohamed-Ahmed, Samih
    Dept Clin Dent, Arstadveien 19, N-5009 Bergen, Norway..
    Mustafa, Kamal
    Dept Clin Dent, Arstadveien 19, N-5009 Bergen, Norway..
    Finne Wistrand, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    3D and Porous RGDC-Functionalized Polyester-Based Scaffolds as a Niche to Induce Osteogenic Differentiation of Human Bone Marrow Stem Cells2019In: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 19, no 6, article id 1900049Article in journal (Refereed)
    Abstract [en]

    Polyester-based scaffolds covalently functionalized with arginine-glycine-aspartic acid-cysteine (RGDC) peptide sequences support the proliferation and osteogenic differentiation of stem cells. The aim is to create an optimized 3D niche to sustain human bone marrow stem cell (hBMSC) viability and osteogenic commitment, without reliance on differentiation media. Scaffolds consisting of poly(lactide-co-trimethylene carbonate), poly(LA-co-TMC), and functionalized poly(lactide) copolymers with pendant thiol groups are prepared by salt-leaching technique. The availability of functional groups on scaffold surfaces allows for an easy and straightforward method to covalently attach RGDC peptide motifs without affecting the polymerization degree. The strategy enables the chemical binding of bioactive motifs on the surfaces of 3D scaffolds and avoids conventional methods that require harsh conditions. Gene and protein levels and mineral deposition indicate the osteogenic commitment of hBMSC cultured on the RGDC functionalized surfaces. The osteogenic commitment of hBMSC is enhanced on functionalized surfaces compared with nonfunctionalized surfaces and without supplementing media with osteogenic factors. Poly(LA-co-TMC) scaffolds have potential as scaffolds for osteoblast culture and bone grafts. Furthermore, these results contribute to the development of biomimetic materials and allow a deeper comprehension of the importance of RGD peptides on stem cell transition toward osteoblastic lineage.

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