@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{FangGouldLysyakovaetal.2018,
  author    = {Fang, Liang and Gould, Oliver E. C. and Lysyakova, Liudmila and Jiang, Yi and Sauter, Tilman and Frank, Oliver and Becker, Tino and Schossig, Michael and Kratz, Karl and Lendlein, Andreas},
  title     = {Implementing and quantifying the shape-memory effect of single polymeric micro/nanowires with an atomic force microscope},
  series = {ChemPhysChem : a European journal of chemical physics and physical chemistry},
  volume    = {19},
  journal   = {ChemPhysChem : a European journal of chemical physics and physical chemistry},
  number    = {16},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1439-4235},
  doi       = {10.1002/cphc.201701362},
  pages     = {2078 -- 2084},
  year      = {2018},
  abstract  = {The implementation of shape-memory effects (SME) in polymeric micro- or nano-objects currently relies on the application of indirect macroscopic manipulation techniques, for example, stretchable molds or phantoms, to ensembles of small objects. Here, we introduce a method capable of the controlled manipulation and SME quantification of individual micro- and nano-objects in analogy to macroscopic thermomechanical test procedures. An atomic force microscope was utilized to address individual electro-spun poly(ether urethane) (PEU) micro- or nanowires freely suspended between two micropillars on a micro-structured silicon substrate. In this way, programming strains of 10 +/- 1\% or 21 +/- 1\% were realized, which could be successfully fixed. An almost complete restoration of the original free-suspended shape during heating confirmed the excellent shape-memory performance of the PEU wires. Apparent recovery stresses of sigma(max,app)=1.2 +/- 0.1 and 33.3 +/- 0.1MPa were obtained for a single microwire and nanowire, respectively. The universal AFM test platform described here enables the implementation and quantification of a thermomechanically induced function for individual polymeric micro- and nanosystems.},
  language  = {en}
}