TY - JOUR A1 - Neffe, Axel T. A1 - Zhang, Quanchao A1 - Hommes-Schattmann, Paul J. A1 - Lendlein, Andreas T1 - Ethylene oxide sterilization of electrospun poly(L-lactide)/poly(D-lactide) core/shell nanofibers JF - MRS advances N2 - The application of polymers in medicine requires sterilization while retaining material structure and properties. This demands detailed analysis, which we show exemplarily for the sterilization of PLLA/PDLA core-shell nanofibers with ethylene oxide (EtO). The electrospun patch was exposed to EtO gas (6 vol% in CO2, 1.7 bar) for 3 h at 45 degrees C and 75% rel. humidity, followed by degassing under pressure/vacuum cycles for 12 h. GC-MS analysis showed that no residual EtO was retained. Fiber diameters (similar to 520 +/- 130 nm) of the patches remained constant as observed by electron microscopy. Young's modulus slightly increased and the elongation at break slightly decreased, determined at 37 degrees C. No changes were detected in H-1-NMR spectra, in molar mass distribution (GPC) or in crystallinity measured for annealed samples with comparable thermal history (Wide Angle X-Ray Scattering). Altogether, EtO emerged as suitable sterilization method for polylactide nanofibers with core-shell morphology. Y1 - 2021 U6 - https://doi.org/10.1557/s43580-021-00058-5 SN - 2059-8521 VL - 6 IS - 33 SP - 786 EP - 789 PB - Springer CY - Cham ER - TY - JOUR A1 - Lützow, Karola A1 - Hommes-Schattmann, Paul J. A1 - Neffe, Axel T. A1 - Ahmad, Bilal A1 - Williams, Gareth R. A1 - Lendlein, Andreas T1 - Perfluorophenyl azide functionalization of electrospun poly(para-dioxanone) JF - Polymers for advanced technologies N2 - Strategies to surface-functionalize scaffolds by covalent binding of biologically active compounds are of fundamental interest to control the interactions between scaffolds and biomolecules or cells. Poly(para-dioxanone) (PPDO) is a clinically established polymer that has shown potential as temporary implant, eg, for the reconstruction of the inferior vena cava, as a nonwoven fiber mesh. However, PPDO lacks suitable chemical groups for covalent functionalization. Furthermore, PPDO is highly sensitive to hydrolysis, reflected by short in vivo half-life times and degradation during storage. Establishing a method for covalent functionalization without degradation of this hydrolyzable polymer is therefore important to enable the surface tailoring for tissue engineering applications. It was hypothesized that treatment of PPDO with an N-hydroxysuccinimide ester group bearing perfluorophenyl azide (PFPA) under UV irradiation would allow efficient surface functionalization of the scaffold. X-ray photoelectron spectroscopy and attenuated total reflectance Fourier-transformed infrared spectroscopy investigation revealed the successful binding, while a gel permeation chromatography study showed that degradation did not occur under these conditions. Coupling of a rhodamine dye to the N-hydroxysuccinimide esters on the surface of a PFPA-functionalized scaffold via its amine linker showed a homogenous staining of the PPDO in laser confocal microscopy. The PFPA method is therefore applicable even to the surface functionalization of hydrolytically labile polymers, and it was demonstrated that PFPA chemistry may serve as a versatile tool for the (bio-)functionalization of PPDO scaffolds. KW - biological applications of polymers KW - fibers KW - functionalization of polymers KW - microstructure Y1 - 2018 U6 - https://doi.org/10.1002/pat.4331 SN - 1042-7147 SN - 1099-1581 VL - 30 IS - 5 SP - 1165 EP - 1172 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Izraylit, Victor A1 - Hommes-Schattmann, Paul J. A1 - Neffe, Axel T. A1 - Gould, Oliver E. C. A1 - Lendlein, Andreas T1 - Polyester urethane functionalizable through maleimide side-chains and cross-linkable by polylactide stereocomplexes JF - European polymer journal N2 - Sustainable multifunctional alternatives to fossil-derived materials, which can be functionalized and are degradable, can be envisioned by combining naturally derived starting materials with an established polymer design concept. Modularity and chemical flexibility of polyester urethanes (PEU) enable the combination of segments bearing functionalizable moieties and the tailoring of the mechanical and thermal properties. In this work, a PEU multiblock structure was synthesized from naturally derived L-lysine diisocyanate ethyl ester (LDI), poly(L-lactide) diol (PLLA) and N-(2,3-dihydroxypropyl)-maleimide (MID) in a one-step reaction. A maleimide side-chain (MID) provided a reactive site for the catalyst-free coupling of thiols shown for L-cysteine with a yield of 94%. Physical cross-links were generated by blending the PEU with poly(D-lactide) (PDLA), upon which the PLLA segments of the PEU and the PDLA formed stereocomplexes. Stereocomplexation occurred spontaneously during solution casting and was investigated with WAXS and DSC. Stereocomplex crystallites were observed in the blends, while isotactic PLA crystallization was not observed. The presented material platform with tailorable mechanical properties by blending is of specific interest for engineering biointerfaces of implants or carrier systems for bioactive molecules. KW - Functionalization KW - Polylactide stereocomplex KW - Biomolecules coupling Y1 - 2020 U6 - https://doi.org/10.1016/j.eurpolymj.2020.109916 SN - 0014-3057 SN - 1873-1945 VL - 137 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Hommes-Schattmann, Paul J. A1 - Neffe, Axel T. A1 - Ahmad, Bilal A1 - Williams, Gareth R. A1 - Vanneaux, Valerie A1 - Menasche, Philippe A1 - Kalfa, David A1 - Lendlein, Andreas T1 - RGD constructs with physical anchor groups as polymer co-electrospinnable cell adhesives JF - Polymers for advanced technologies N2 - The tissue integration of synthetic polymers can be promoted by displaying RGD peptides at the biointerface with the objective of enhancing colonization of the material by endogenous cells. A firm but flexible attachment of the peptide to the polymer matrix, still allowing interaction with receptors, is therefore of interest. Here, the covalent coupling of flexible physical anchor groups, allowing for temporary immobilization on polymeric surfaces via hydrophobic or dipole-dipole interactions, to a RGD peptide was investigated. For this purpose, a stearate or an oligo(ethylene glycol) (OEG) was attached to GRGDS in 51-69% yield. The obtained RGD linker constructs were characterized by NMR, IR and MALDI-ToF mass spectrometry, revealing that the commercially available OEG and stearate linkers are in fact mixtures of similar compounds. The RGD linker constructs were co-electrospun with poly(p-dioxanone) (PPDO). After electrospinning, nitrogen could be detected on the surface of the PPDO fibers by X-ray photoelectron spectroscopy. The nitrogen content exceeded the calculated value for the homogeneous material mixture suggesting a pronounced presentation of the peptide on the fiber surface. Increasing amounts of RGD linker constructs in the electrospinning solution did not lead to a detection of an increased amount of peptide on the scaffold surface, suggesting inhomogeneous distribution of the peptide on the PPDO fiber surface. Human adipose-derived stem cells cultured on the patches showed similar viability as when cultured on PPDO containing pristine RGD. The fully characterized RGD linker constructs could serve as valuable tools for the further development of tissue-integrating polymeric scaffolds. Copyright (c) 2016 John Wiley & Sons, Ltd. KW - electrospinning KW - RGD peptides KW - cell adhesion KW - biofunctionalization Y1 - 2017 U6 - https://doi.org/10.1002/pat.3963 SN - 1042-7147 SN - 1099-1581 VL - 28 SP - 1312 EP - 1317 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Neffe, Axel T. A1 - Izraylit, Victor A1 - Hommes-Schattmann, Paul J. A1 - Lendlein, Andreas T1 - Soft, formstable (Co)polyester blend elastomers JF - Nanomaterials : open access journal N2 - High crystallization rate and thermomechanical stability make polylactide stereocomplexes effective nanosized physical netpoints. Here, we address the need for soft, form-stable degradable elastomers for medical applications by designing such blends from (co)polyesters, whose mechanical properties are ruled by their nanodimensional architecture and which are applied as single components in implants. By careful controlling of the copolymer composition and sequence structure of poly[(L-lactide)-co-(epsilon-caprolactone)], it is possible to prepare hyperelastic polymer blends formed through stereocomplexation by adding poly(D-lactide) (PDLA). Low glass transition temperature T-g <= 0 degrees C of the mixed amorphous phase contributes to the low Young's modulus E. The formation of stereocomplexes is shown in DSC by melting transitions T-m > 190 degrees C and in WAXS by distinct scattering maxima at 2 theta = 12 degrees and 21 degrees. Tensile testing demonstrated that the blends are soft (E = 12-80 MPa) and show an excellent hyperelastic recovery R-rec = 66-85% while having high elongation at break epsilon(b) up to >1000%. These properties of the blends are attained only when the copolymer has 56-62 wt% lactide content, a weight average molar mass >140 kg center dot mol(-1), and number average lactide sequence length >= 4.8, while the blend is formed with a content of 5-10 wt% of PDLA. The devised strategy to identify a suitable copolymer for stereocomplexation and blend formation is transferable to further polymer systems and will support the development of thermoplastic elastomers suitable for medical applications. KW - thermoplastic elastomer KW - biomaterial KW - stereocomplexes KW - mechanical KW - properties KW - form stability KW - crystallinity Y1 - 2021 U6 - https://doi.org/10.3390/nano11061472 SN - 2079-4991 VL - 11 IS - 6 PB - MDPI CY - Basel ER -