TY - JOUR A1 - Razzaq, Muhammad Yasar A1 - Behl, Marc A1 - Lendlein, Andreas T1 - Thermally-induced actuation of magnetic nanocomposites based on Oligo(ω-pentadecalactone) and covalently integrated magnetic nanoparticles JF - MRS advances: a journal of the Materials Research Society (MRS) N2 - The incorporation of inorganic particles in a polymer matrix has been established as a method to adjust the mechanical performance of composite materials. We report on the influence of covalent integration of magnetic nanoparticles (MNP) on the actuation behavior and mechanical performance of hybrid nanocomposite (H-NC) based shape-memory polymer actuators (SMPA). The H-NC were synthesized by reacting two types of oligo(ω-pentadecalactone) (OPDL) based precursors with terminal hydroxy groups, a three arm OPDL (3 AOPDL, Mn = 6000 g mol•1−1 ) and an OPDL (Mn =3300 g • mol−1 ) coated magnetite nanoparticle (Ø = 10 ± 2 nm), with a diisocyanate. These H-NC were compared to the homopolymer network regarding the actuation performance, contractual stress (σcontr) as well as thermal and mechanical properties. The melting range of the OPDL crystals (ΔTm,OPDL) was shifted in homo polymer networks from 36 ºC − 76 ºC to 41ºC − 81 °C for H-NC with 9 wt% of MNP content. The actuators were explored by variation of separating temperature (Tsep), which splits the OPDL crystalline domain into actuating and geometry determining segments. Tsep was varied in the melting range of the nanocomposites and the actuation capability and contractual stress (σcontr) of the nanocomposite actuators could be adjusted. The reversible strain (εrev) was decreased from 11 ± 0.3% for homo polymer network to 3.2±0.3% for H-NC9 with 9 wt% of MNP indicating a restraining effect of the MNP on chain mobility. The results show that the performance of H-NCs in terms of thermal and elastic properties can be tailored by MNP content, however for higher reversible actuation, lower MNP contents are preferable. Y1 - 2018 U6 - https://doi.org/10.1557/adv.2018.613 SN - 2059-8521 VL - 3 IS - 63 SP - 3783 EP - 3791 PB - Cambridge University Press CY - New York ER - TY - JOUR A1 - Nie, Yan A1 - Wang, Weiwei A1 - Xu, Xun A1 - Ma, Nan A1 - Lendlein, Andreas T1 - The response of human induced pluripotent stem cells to cyclic temperature changes explored by BIO-AFM JF - MRS advances : a journal of the Materials Research Society (MRS) N2 - Human induced pluripotent stem cells (hiPSCs) are highly sensitive to extrinsic physical and biochemical signals from their extracellular microenvironments. In this study, we analyzed the effect of cyclic temperature changes on hiPSCs behaviors, especially by means of scanning force microscopy (BIO-AFM). The alternation in cellular mechanics, as well as the secretion and pattern of deposition of extracellular matrix (ECM) protein in hiPSCs were evaluated. The arrangement of the actin cytoskeleton changed with the variation of the temperature. The rearranged cytoskeleton architecture led to the subsequent changes in cell mechanics (Young's modulus of hiPSCs). With the exposure to the cyclic cold stimuli, an increase in the average surface roughness (Ra) and roughness mean square (RMS) was detected. This observation might be at least in part due to the upregulated secretion of Laminin alpha 5 during repeated temporary cooling. The expression of pluripotent markers, NANOG and SOX2, was not impaired in hiPSCs, when exposed to the cyclic cold stimuli for 24 h. Our findings provide an insight into the effect of temperature on the hiPSC behaviors, which may contribute to a better understanding of the application of locally controlled therapeutic hypothermia. Y1 - 2021 U6 - https://doi.org/10.1557/s43580-021-00110-4 SN - 2059-8521 VL - 6 IS - 31 SP - 745 EP - 749 PB - Springer CY - Cham ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Kratz, Karl A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - The relevance of hydrophobic segments in multiblock copolyesterurethanes for their enzymatic degradation at the air-water interface JF - Polymer : the international journal for the science and technology of polymers N2 - The interplay of an enzyme with a multiblock copolymer PDLCL containing two segments of different hydrophilicity and degradability is explored in thin films at the air-water interface. The enzymatic degradation was studied in homogenous Langmuir monolayers, which are formed when containing more than 40 wt% oligo(epsilon-caprolactone) (OCL). Enzymatic degradation rates were significantly reduced with increasing content of hydrophobic oligo(omega-pentadecalactone) (OPDL). The apparent deceleration of the enzymatic process is caused by smaller portion of water-soluble degradation fragments formed from degradable OCL fragments. Beside the film degradation, a second competing process occurs after adding lipase from Pseudomonas cepacia into the subphase, namely the enrichment of the lipase molecules in the polymeric monolayer. The incorporation of the lipase into the Langmuir film is experimentally revealed by concurrent surface area enlargement and by Brewster angle microscopy (BAM). Aside from the ability to provide information about the degradation behavior of polymers, the Langmuir monolayer degradation (LMD) approach enables to investigate polymer-enzyme interactions for non-degradable polymers. (C) 2016 Elsevier Ltd. All rights reserved. KW - Multiblock copolymer KW - Enzymatic polymer degradation KW - Oligo(omega-pentadecalactone) KW - Oligo(epsilon-caprolactone) KW - Langmuir monolayer degradation technique Y1 - 2016 U6 - https://doi.org/10.1016/j.polymer.2016.09.001 SN - 0032-3861 SN - 1873-2291 VL - 102 SP - 92 EP - 98 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Bhaskar, Thanga Bhuvanesh Vijaya A1 - Ma, Nan A1 - Lendlein, Andreas A1 - Roch, Toralf T1 - The interaction of human macrophage subsets with silicone as a biomaterial JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - Silicones are widely used as biomaterials for medical devices such as extracorporeal equipments. However, there is often conflicting evidence about their supposed cell-and histocompatibility. Macrophages could mediate silicone-induced adverse responses such as foreign body reaction and fibrous encapsulation. The polarization behaviour of macrophages could determine the clinical outcome after implantation of biomaterials. Induction of classically activated macrophages (CAM) may induce and support uncontrolled inflammatory responses and undesired material degradation. In contrast, polarization into alternatively activated macrophages (AAM) is assumed to support healing processes and implant integration. This study compared the interaction of non-polarized macrophages (M0), CAM, and AAM with commercially available tissue culture polystyrene (TCP) and a medical grade silicone-based biomaterial, regarding the secretion of inflammatory mediators such as cytokines and chemokines. Firstly, by using the Limulus amoebocyte lysate (LAL) test the silicone films were shown to be free of soluble endotoxins, which is the prerequisite to investigate their interaction with primary immune cells. Primary human monocyte-derived macrophages (M0) were polarized into CAM and AAM by addition of suitable differentiation factors. These macrophage subsets were incubated on the materials for 24 hours and their viability and cytokine secretion was assessed. In comparison to TCP, cell adhesion was lower on silicone after 24 hours for all three macrophage subsets. However, compared to TCP, silicone induced higher levels of certain inflammatory and chemotactic cytokines in M0, CAM, and AAM macrophage subsets. Conclusively, it was shown that silicone has the ability to induce a pro-inflammatory state to different magnitudes dependent on the macrophage subsets. This priming of the macrophage phenotype by silicone could explain the incidence of severe foreign body complications observed in vivo. KW - Biomaterials KW - silicone KW - macrophage subsets KW - cytokines/chemokines Y1 - 2015 U6 - https://doi.org/10.3233/CH-151991 SN - 1386-0291 SN - 1875-8622 VL - 61 IS - 2 SP - 119 EP - 133 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Wang, Weiwei A1 - Kratz, Karl A1 - Behl, Marc A1 - Yan, Wan A1 - Liu, Yue A1 - Xu, Xun A1 - Baudis, Stefan A1 - Li, Zhengdong A1 - Kurtz, Andreas A1 - Lendlein, Andreas A1 - Ma, Nan T1 - The interaction of adipose-derived human mesenchymal stem cells and polyether ether ketone JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - Polyether ether ketone (PEEK) as a high-performance, thermoplastic implant material entered the field of medical applications due to its structural function and commercial availability. In bone tissue engineering, the combination of mesenchymal stem cells (MSCs) with PEEK implants may accelerate the bone formation and promote the osseointegration between the implant and the adjacent bone tissue. In this concept the question how PEEK influences the behaviour and functions of MSCs is of great interest. Here the cellular response of human adipose-derived MSCs to PEEK was evaluated and compared to tissue culture plate (TCP) as the reference material. Viability and morphology of cells were not altered when cultured on the PEEK film. The cells on PEEK presented a high proliferation activity in spite of a relatively lower initial cell adhesion rate. There was no significant difference on cell apoptosis and senescence between the cells on PEEK and TCP. The inflammatory cytokines and VEGF secreted by the cells on these two surfaces were at similar levels. The cells on PEEK showed up-regulated BMP2 and down-regulated BMP4 and BMP6 gene expression, whereas no conspicuous differences were observed in the committed osteoblast markers (BGLAP, COL1A1 and Runx2). With osteoinduction the cells on PEEK and TCP exhibited a similar osteogenic differentiation potential. Our results demonstrate the biofunctionality of PEEK for human MSC cultivation and differentiation. Its clinical benefits in bone tissue engineering may be achieved by combining MSCs with PEEK implants. These data may also provide useful information for further modification of PEEK with chemical or physical methods to regulate the cellular processes of MSCs and to consequently improve the efficacy of MSC-PEEK based therapies. KW - Polyether ether ketone KW - mesenchymal stem cells KW - biocompatibility KW - cell-material interaction KW - osteogenic differentiation Y1 - 2015 U6 - https://doi.org/10.3233/CH-152001 SN - 1386-0291 SN - 1875-8622 VL - 61 IS - 2 SP - 301 EP - 321 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Yan, Wan A1 - Fang, Liang A1 - Weigel, Thomas A1 - Behl, Marc A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - The influence of thermal treatment on the morphology in differently prepared films of a oligodepsipeptide based multiblock copolymer JF - Polymers for advanced technologies N2 - Degradable multiblock copolymers prepared from equal weight amounts of poly(epsilon-caprolactone)-diol (PCL-diol) and poly[oligo(3S-iso-butylmorpholine-2,5-dione)]-diol (PIBMD-diol), named PCL-PIBMD, provide a phase-segregated morphology. It exhibits a low melting temperature from PCL domains (T-m,T-PCL) of 382 degrees C and a high T-m,T-PIBMD of 170 +/- 2 degrees C with a glass transition temperature (T-g,T-PIBMD) at 42 +/- 2 degrees C from PIBMD domains. In this study, we explored the influence of applying different thermal treatments on the resulting morphologies of solution-cast and spin-coated PCL-PIBMD thin films, which showed different initial surface morphologies. Differential scanning calorimetry results and atomic force microscopy images after different thermal treatments indicated that PCL and PIBMD domains showed similar crystallization behaviors in 270 +/- 30 mu m thick solution-cast films as well as in 30 +/- 2 and 8 +/- 1nm thick spin-coated PCL-PIBMD films. Existing PIBMD crystalline domains highly restricted the generation of PCL crystalline domains during cooling when the sample was annealed at 180 degrees C. By annealing the sample above 120 degrees C, the PIBMD domains crystallized sufficiently and covered the free surface, which restricted the crystallization of PCL domains during cooling. The PCL domains can crystallize by hindering the crystallization of PIBMD domains via the fast vitrification of PIBMD domains when the sample was cooled/quenched in liquid nitrogen after annealing at 180 degrees C. These findings contribute to a better fundamental understanding of the crystallization mechanism of multi-block copolymers containing two crystallizable domains whereby the T-g of the higher melting domain type is in the same temperature range as the T-m of the lower melting domain type. Copyright (c) 2016 John Wiley & Sons, Ltd. KW - multiblock copolymer KW - oligodepsipeptides KW - phase morphology KW - thermal treatments KW - crystallization behavior Y1 - 2017 U6 - https://doi.org/10.1002/pat.3953 SN - 1042-7147 SN - 1099-1581 VL - 28 SP - 1339 EP - 1345 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Heilmann, Katja A1 - Groth, Thomas A1 - Behrsing, Olaf A1 - Wagner, Albrecht A1 - Schossig-Tiedemann, Michael A1 - Lendlein, Andreas A1 - Micheel, Burkhard T1 - The influence of the chemical composition of cell culture material on the growth and antibody production of hybridoma cells N2 - The multiplication and antibody production of murine hybridoma cells cultured on five different polymer membranes were tested and compared with conventional tissue culture polystyrene (TCPS). Membranes were prepared from polyacrylonitrile (PAN) and acrylonitrile copolymerized with N-vinylpyrrolidone (NVP20, NVP30), Na-methallylsulfonate (NaMAS) and N-(3-amino-propyl-methacrylamide-hydrochloride) (APMA). Cell number and antibody concentration were quantified as criteria for viability and productivity. Adhesion of hybridoma cells was characterized by vital and scanning electron microscopy. The results suggest that a strong adhesion of cells, observed on APMA and TCPS, increased cell growth but reduced monoclonal antibody production. In contrast membranes with lowered adhesivity such as NVP20 provided favourable conditions for monoclonal antibody production. In addition it was shown that this membrane also possessed a minor fouling as indicated by the low decrease of water flux across the membrane after protein adsorption. It was concluded that NVP20 could be a suitable material for the development of hollow fibre membranes for bioreactors. Y1 - 2005 UR - http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T3C-4DPYNGY- 4&_coverDate=02%2F09%2F2005&_alid=268995355&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=4943&_sort=d&view=c&_acct=C000053886&_v e ER - TY - JOUR A1 - Machatschek, Rainhard Gabriel A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - The influence of pH on the molecular degradation mechanism of PLGA JF - MRS Advances N2 - Poly[(rac-lactide)-co-glycolide] (PLGA) is used in medicine to provide mechanical support for healing tissue or as matrix for controlled drug release. The properties of this copolymer depend on the evolution of the molecular weight of the material during degradation. which is determined by the kinetics of the cleavage of hydrolysable bonds. The generally accepted description of the degradation of PLGA is a random fragmentation that is autocatalyzed by the accumulation of acidic fragments inside the bulk material. Since mechanistic studies with lactide oligomers have concluded a chain-end scission mechanism and monolayer degradation experiments with polylactide found no accelerated degradation at lower pH, we hypothesize that the impact of acidic fragments on the molecular degradation kinetics of PLGA is overestimated By means of the Langmuir monolayer degradation technique. the molecular degradation kinetics of PLGA at different pH could be determined. Protons did not catalyze the degradation of PLGA. The molecular mechanism at neutral pH and low pH is a combination of random and chainend-cut events, while the degradation under strongly alkaline conditions is determined by rapid chainend cuts. We suggest that the degradation of bulk PLGA is not catalyzed by the acidic degradation products. Instead. increased concentration of small fragments leads to accelerated mass loss via fast chain-end cut events. In the future, we aim to substantiate the proposed molecular degradation mechanism of PLGA with interfacial rheology. Y1 - 2018 U6 - https://doi.org/10.1557/adv.2018.602 SN - 2059-8521 VL - 3 IS - 63 SP - 3883 EP - 3889 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Rickert, D. A1 - Moses, M. A. A1 - Lendlein, Andreas A1 - Kelch, S. A1 - Franke, R. P. T1 - The importance of angiogenesis in the interaction between polymeric biomaterials and surrounding tissue Y1 - 2003 ER - TY - JOUR A1 - Kelch, S. A1 - Lendlein, Andreas A1 - Müllen, A. A1 - Ridder, U. T1 - Textile Polymer Scaffolds for Tissue Engineering Y1 - 2003 ER -