@article{NieWangXuetal.2019, author = {Nie, Yan and Wang, Weiwei and Xu, Xun and Zou, Jie and Bhuvanesh, Thanga and Schulz, Burkhard and Ma, Nan and Lendlein, Andreas}, title = {Enhancement of human induced pluripotent stem cells adhesion through multilayer laminin coating}, series = {Clinical hemorheology and microcirculation : blood flow and vessels}, volume = {70}, journal = {Clinical hemorheology and microcirculation : blood flow and vessels}, number = {4}, publisher = {IOS Press}, address = {Amsterdam}, issn = {1386-0291}, doi = {10.3233/CH-189318}, pages = {531 -- 542}, year = {2019}, abstract = {Bioengineered cell substrates are a highly promising tool to govern the differentiation of stem cells in vitro and to modulate the cellular behavior in vivo. While this technology works fine for adult stem cells, the cultivation of human induced pluripotent stem cells (hiPSCs) is challenging as these cells typically show poor attachment on the bioengineered substrates, which among other effects causes substantial cell death. Thus, very limited types of surfaces have been demonstrated suitable for hiPSC cultures. The multilayer coating approach that renders the surface with diverse chemical compositions, architectures, and functions can be used to improve the adhesion of hiPSCs on the bioengineered substrates. We hypothesized that a multilayer formation based on the attraction of molecules with opposite charges could functionalize the polystyrene (PS) substrates to improve the adhesion of hiPSCs. Polymeric substrates were stepwise coated, first with dopamine to form a polydopamine (PDA) layer, second with polylysine and last with Laminin-521. The multilayer formation resulted in the variation of hydrophilicity and chemical functionality of the surfaces. Hydrophilicity was detected using captive bubble method and the amount of primary and secondary amines on the surface was quantified by fluorescent staining. The PDA layer effectively immobilized the upper layers and thereby improved the attachment of hiPSCs. Cell adhesion was enhanced on the surfaces coated with multilayers, as compared to those without PDA and/or polylysine. Moreover, hiPSCs spread well over this multilayer laminin substrate. These cells maintained their proliferation capacity and differentiation potential. The multilayer coating strategy is a promising attempt for engineering polymer-based substrates for the cultivation of hiPSCs and of interest for expanding the application scope of hiPSCs.}, language = {en} } @article{SaretiaMachatschekSchulzetal.2019, author = {Saretia, Shivam and Machatschek, Rainhard Gabriel and Schulz, Burkhard and Lendlein, Andreas}, title = {Reversible 2D networks of oligo(epsilon-caprolactone) at the air-water interface}, series = {Biomedical Materials}, volume = {14}, journal = {Biomedical Materials}, number = {3}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1748-6041}, doi = {10.1088/1748-605X/ab0cef}, pages = {10}, year = {2019}, abstract = {Hydroxyl terminated oligo(epsilon-caprolactone) (OCL) monolayers were reversibly cross-linked forming two dimensional networks (2D) at the air-water interface. The equilibrium reaction with glyoxal as the cross-linker is pH-sensitive. Pronounced contraction in the area of the prepared 2DOCL films in dependence of surface pressure and time revealed the process of the reaction. Cross-linking inhibited crystallization and retarded enzymatic degradation of the OCLfilm. Altering the subphase pH led to a cleavage of the covalent acetal cross-links. The reversibility of the covalent acetal cross-links was proved by observing an identical isotherm as non-cross-linked sample. Besides as model systems, these customizable reversible OCL2D networks are intended for use as pHresponsive drug delivery systems or functionalized cell culture substrates.}, language = {en} } @article{BhuvaneshMachatschekLysyakovaetal.2019, author = {Bhuvanesh, Thanga and Machatschek, Rainhard Gabriel and Lysyakova, Liudmila and Kratz, Karl and Schulz, Burkhard and Ma, Nan and Lendlein, Andreas}, title = {Collagen type-IV Langmuir and Langmuir-Schafer layers as model biointerfaces to direct stem cell adhesion}, series = {Biomedical materials : materials for tissue engineering and regenerative medicine}, volume = {14}, journal = {Biomedical materials : materials for tissue engineering and regenerative medicine}, number = {2}, publisher = {Inst. of Physics Publ.}, address = {Bristol}, issn = {1748-6041}, doi = {10.1088/1748-605X/aaf464}, pages = {17}, year = {2019}, abstract = {In biomaterial development, the design of material surfaces that mimic the extra-cellular matrix (ECM) in order to achieve favorable cellular instruction is rather challenging. Collagen-type IV (Col-IV), the major scaffolding component of Basement Membranes (BM), a specialized ECM with multiple biological functions, has the propensity to form networks by self-assembly and supports adhesion of cells such as endothelial cells or stem cells. The preparation of biomimetic Col-IV network-like layers to direct cell responses is difficult. We hypothesize that the morphology of the layer, and especially the density of the available adhesion sites, regulates the cellular adhesion to the layer. The Langmuir monolayer technique allows for preparation of thin layers with precisely controlled packing density at the air-water (A-W) interface. Transferring these layers onto cell culture substrates using the Langmuir-Schafer (LS) technique should therefore provide a pathway for preparation of BM mimicking layers with controlled cell adherence properties. In situ characterization using ellipsometry and polarization modulation-infrared reflection absorption spectroscopy of Col-IV layer during compression at the A-W interface reveal that there is linear increase of surface molecule concentration with negligible orientational changes up to a surface pressure of 25 mN m(-1). Smooth and homogeneous Col-IV network-like layers are successfully transferred by LS method at 15 mN m(-1) onto poly(ethylene terephthalate) (PET), which is a common substrate for cell culture. In contrast, the organization of Col-IV on PET prepared by the traditionally employed solution deposition method results in rather inhomogeneous layers with the appearance of aggregates and multilayers. Progressive increase in the number of early adherent mesenchymal stem cells (MSCs) after 24 h by controlling the areal Col-IV density by LS transfer at 10, 15 and 20 mN m(-1) on PET is shown. The LS method offers the possibility to control protein characteristics on biomaterial surfaces such as molecular density and thereby, modulate cell responses.}, language = {en} } @article{TarazonaMachatschekSchulzetal.2019, author = {Tarazona, Natalia A. and Machatschek, Rainhard Gabriel and Schulz, Burkhard and Auxiliadora Prieto Jim{\´e}nez, M. and Lendlein, Andreas}, title = {Molecular Insights into the Physical Adsorption of Amphiphilic Protein PhaF onto Copolyester Surfaces}, series = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, volume = {20}, journal = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {1525-7797}, doi = {10.1021/acs.biomac.9b00069}, pages = {3242 -- 3252}, year = {2019}, abstract = {Phasins are amphiphilic proteins located at the polymer-cytoplasm interface of bacterial polyhydroxyalkanoates (PHA). The immobilization of phasins on biomaterial surfaces is a promising way to enhance the hydrophilicity and supply cell- directing elements in bioinstructing processes. Optimizing the physical adsorption of phasins requires deep insights into molecular processes during polymer-protein interactions to preserve their structural conformation while optimizing surface coverage. Here, the assembly, organization, and stability of phasin PhaF from Pseudomonas putida at interfaces is disclosed. The Langmuir technique, combined with in situ microscopy and spectroscopic methods, revealed that PhaF forms stable and robust monolayers at different temperatures, with an almost flat orientation of its alpha-helix at the air-water interface. PhaF adsorption onto preformed monolayers of poly[(3-R-hydroxyoctanoate)-co-(3-R-hydroxyhexanoate)] (PHOHHx), yields stable mixed layers below pi = similar to 15.7 mN/m. Further insertion induces a molecular reorganization. PHOHHx with strong surface hydrophobicity is a more adequate substrate for PhaF adsorption than the less hydrophobic poly[(rac-lactide)-co-glycolide] (PLGA). The observed orientation of the main axis of the protein in relation to copolyester interfaces ensures the best exposure of the hydrophobic residues, providing a suitable coating strategy for polymer functionalization.}, language = {en} } @article{MachatschekSchoeneRaschdorfetal.2019, author = {Machatschek, Rainhard Gabriel and Sch{\"o}ne, Anne-Christin and Raschdorf, Elisa and Ihlenburg, Ramona and Schulz, Burkhard and Lendlein, Andreas}, title = {Interfacial properties of morpholine-2,5-dione-based oligodepsipeptides and multiblock copolymers}, series = {MRS Communications}, volume = {9}, journal = {MRS Communications}, number = {1}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {2159-6859}, doi = {10.1557/mrc.2019.21}, pages = {170 -- 180}, year = {2019}, abstract = {Oligodepsipeptides (ODPs) with alternating amide and ester bonds prepared by ring-opening polymerization of morpholine-2,5-dione derivatives are promising matrices for drug delivery systems and building blocks for multifunctional biomaterials. Here, we elucidate the behavior of three telechelic ODPs and one multiblock copolymer containing ODP blocks at the air-water interface. Surprisingly, whereas the oligomers and multiblock copolymers crystallize in bulk, no crystallization is observed at the air-water interface. Furthermore, polarization modulation infrared reflection absorption spectroscopy is used to elucidate hydrogen bonding and secondary structures in ODP monolayers. The results will direct the development of the next ODP-based biomaterial generation with tailored properties for highly sophisticated applications.}, language = {en} } @misc{MachatschekSchoeneRaschdorfetal.2019, author = {Machatschek, Rainhard Gabriel and Sch{\"o}ne, Anne-Christin and Raschdorf, Elisa and Ihlenburg, Ramona and Schulz, Burkhard and Lendlein, Andreas}, title = {Interfacial properties of morpholine-2,5-dione-based oligodepsipeptides and multiblock copolymers}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1106}, issn = {1866-8372}, doi = {10.25932/publishup-46975}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-469755}, pages = {170 -- 180}, year = {2019}, abstract = {Oligodepsipeptides (ODPs) with alternating amide and ester bonds prepared by ring-opening polymerization of morpholine-2,5-dione derivatives are promising matrices for drug delivery systems and building blocks for multifunctional biomaterials. Here, we elucidate the behavior of three telechelic ODPs and one multiblock copolymer containing ODP blocks at the air-water interface. Surprisingly, whereas the oligomers and multiblock copolymers crystallize in bulk, no crystallization is observed at the air-water interface. Furthermore, polarization modulation infrared reflection absorption spectroscopy is used to elucidate hydrogen bonding and secondary structures in ODP monolayers. The results will direct the development of the next ODP-based biomaterial generation with tailored properties for highly sophisticated applications.}, language = {en} } @article{MachatschekSchulzLendlein2018, author = {Machatschek, Rainhard Gabriel and Schulz, Burkhard and Lendlein, Andreas}, title = {The influence of pH on the molecular degradation mechanism of PLGA}, series = {MRS Advances}, volume = {3}, journal = {MRS Advances}, number = {63}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {2059-8521}, doi = {10.1557/adv.2018.602}, pages = {3883 -- 3889}, year = {2018}, abstract = {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.}, language = {en} } @misc{MachatschekSchulzLendlein2018, author = {Machatschek, Rainhard Gabriel and Schulz, Burkhard and Lendlein, Andreas}, title = {Langmuir Monolayers as Tools to Study Biodegradable Polymer Implant Materials}, series = {Macromolecular rapid communications}, volume = {40}, journal = {Macromolecular rapid communications}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201800611}, pages = {11}, year = {2018}, abstract = {Langmuir monolayers provide a fast and elegant route to analyze the degradation behavior of biodegradable polymer materials. In contrast to bulk materials, diffusive transport of reactants and reaction products in the (partially degraded) material can be neglected at the air-water interface, allowing for the study of molecular degradation kinetics in experiments taking less than a day and in some cases just a few minutes, in contrast to experiments with bulk materials that can take years. Several aspects of the biodegradation behavior of polymer materials, such as the interaction with biomolecules and degradation products, are directly observable. Expanding the technique with surface-sensitive instrumental techniques enables evaluating the evolution of the morphology, chemical composition, and the mechanical properties of the degrading material in situ. The potential of the Langmuir monolayer degradation technique as a predictive tool for implant degradation when combined with computational methods is outlined, and related open questions and strategies to overcome these challenges are pointed out.}, language = {en} } @misc{SchoeneRochSchulzetal.2017, author = {Sch{\"o}ne, Anne-Christin and Roch, Toralf and Schulz, Burkhard and Lendlein, Andreas}, title = {Evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer techniques}, series = {Interface : journal of the Royal Society}, volume = {14}, journal = {Interface : journal of the Royal Society}, publisher = {Royal Society}, address = {London}, issn = {1742-5689}, doi = {10.1098/rsif.2016.1028}, pages = {18}, year = {2017}, abstract = {Polymeric biomaterials are of specific relevance in medical and pharmaceutical applications due to their wide range of tailorable properties and functionalities. The knowledge about interactions of biomaterials with their biological environment is of crucial importance for developing highly sophisticated medical devices. To achieve optimal in vivo performance, a description at the molecular level is required to gain better understanding about the surface of synthetic materials for tailoring their properties. This is still challenging and requires the comprehensive characterization of morphological structures, polymer chain arrangements and degradation behaviour. The review discusses selected aspects for evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer methods as powerful techniques for studying interfacial properties, such as morphological and degradation processes. The combination of spectroscopic, microscopic and scattering methods with the Langmuir techniques adapted to polymers can substantially improve the understanding of their in vivo behaviour.}, language = {en} } @article{BhuvaneshSaretiaRochetal.2017, author = {Bhuvanesh, Thanga and Saretia, Shivam and Roch, Toralf and Sch{\"o}ne, Anne-Christin and Rottke, Falko O. and Kratz, Karl and Wang, Weiwei and Ma, Nan and Schulz, Burkhard and Lendlein, Andreas}, title = {Langmuir-Schaefer films of fibronectin as designed biointerfaces for culturing stem cells}, series = {Polymers for advanced technologies}, volume = {28}, journal = {Polymers for advanced technologies}, publisher = {Wiley}, address = {Hoboken}, issn = {1042-7147}, doi = {10.1002/pat.3910}, pages = {1305 -- 1311}, year = {2017}, abstract = {Glycoproteins adsorbing on an implant upon contact with body fluids can affect the biological response in vitro and in vivo, depending on the type and conformation of the adsorbed biomacromolecules. However, this process is poorly characterized and so far not controllable. Here, protein monolayers of high molecular cohesion with defined density are transferred onto polymeric substrates by the Langmuir-Schaefer (LS) technique and were compared with solution deposition (SO) method. It is hypothesized that on polydimethylsiloxane (PDMS), a substrate with poor cell adhesion capacity, the fibronectin (FN) layers generated by the LS and SO methods will differ in their organization, subsequently facilitating differential stem cell adhesion behavior. Indeed, atomic force microscopy visualization and immunofluorescence images indicated that organization of the FN layer immobilized on PDMS was uniform and homogeneous. In contrast, FN deposited by SO method was rather heterogeneous with appearance of structures resembling protein aggregates. Human mesenchymal stem cells showed reduced absolute numbers of adherent cells, and the vinculin expression seemed to be higher and more homogenously distributed after seeding on PDMS equipped with FN by LS in comparison with PDMS equipped with FN by SO. These divergent responses could be attributed to differences in the availability of adhesion molecule ligands such as the Arg-Gly-Asp (RGD) peptide sequence presented at the interface. The LS method allows to control the protein layer characteristics, including the thickness and the protein orientation or conformation, which can be harnessed to direct stem cell responses to defined outcomes, including migration and differentiation. Copyright (c) 2016 John Wiley \& Sons, Ltd.}, language = {en} }