TY  - JOUR
A1  - Schöne, Anne-Christin
A1  - Schulz, Burkhard
A1  - Richau, Klaus
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Characterization of Langmuir films prepared from copolyesterurethanes based on oligo(omega-pentadecalactone) and oligo(epsilon-caprolactone)segments
JF  - Macromolecular chemistry and physics
N2  - A series of multiblock copolymers (PDLCL) synthesized from oligo(omega-pentadecalactone) diol (OPDL) and oligo(epsilon-caprolactone) diol (OCL), which are linked by 2,2(4), 4-trimethyl-hexamethylene diisocyanate (TMDI), is investigated by the Langmuir monolayer technique at the air-water interface. Brewster angle microscopy (BAM) and spectroscopic ellipsometry are employed to characterize the polymer film morphologies in situ. PDLCL containing >= 40 wt% OCL segments form homogeneous Langmuir monofilms after spreading. The film elasticity modulus decreases with increasing amounts of OPDL segments in the copolymer. In contrast, the OCL-free polyesterurethane OPDL-TMDI cannot be spread to monomolecular films on the water surface properly, and movable slabs are observed by BAM even at low surface pressures. The results of the in situ morphological characterization clearly show that essential information concerning the reliability of Langmuir monolayer degradation (LMD) experiments cannot be obtained from the evaluation of the pi-A isotherms only. Consequently, in situ morphological characterization turns out to be indispensable for characterization of Langmuir layers before LMD experiments.
KW  - brewster angle microscopy
KW  - ellipsometry
KW  - Langmuir layers
KW  - morphology
KW  - polyesterurethanes
Y1  - 2014
U6  - https://doi.org/10.1002/macp.201400377
SN  - 1022-1352
SN  - 1521-3935
VL  - 215
IS  - 24
SP  - 2437
EP  - 2445
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Bhuvanesh, Thanga
A1  - Machatschek, Rainhard Gabriel
A1  - Lysyakova, Liudmila
A1  - Kratz, Karl
A1  - Schulz, Burkhard
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Collagen type-IV Langmuir and Langmuir-Schafer layers as model biointerfaces to direct stem cell adhesion
JF  - Biomedical materials :  materials for tissue engineering and regenerative medicine
N2  - 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.
KW  - collagen-IV
KW  - basement membrane
KW  - Langmuir-Schafer films
KW  - stem cell adhesion
KW  - protein
KW  - ellipsometry
Y1  - 2019
U6  - https://doi.org/10.1088/1748-605X/aaf464
SN  - 1748-6041
SN  - 1748-605X
VL  - 14
IS  - 2
PB  - Inst. of Physics Publ.
CY  - Bristol
ER  -