TY  - JOUR
A1  - Zou, Jie
A1  - Wang, Weiwei
A1  - Neffe, Axel T.
A1  - Xu, Xun
A1  - Li, Zhengdong
A1  - Deng, Zijun
A1  - Sun, Xianlei
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Adipogenic differentiation of human adipose derived mesenchymal stem cells in 3D architectured gelatin based hydrogels (ArcGel)
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - Polymeric matrices mimicking multiple functions of the ECM are expected to enable a material induced regeneration of tissues. Here, we investigated the adipogenic differentiation of human adipose derived mesenchymal stem cells (hADSCs) in a 3D architectured gelatin based hydrogel (ArcGel) prepared from gelatin and L-lysine diisocyanate ethyl ester (LDI) in an one-step process, in which the formation of an open porous morphology and the chemical network formation were integrated. The ArcGel was designed to support adipose tissue regeneration with its 3D porous structure, high cell biocompatibility, and mechanical properties compatible with human subcutaneous adipose tissue. The ArcGel could support initial cell adhesion and survival of hADSCs. Under static culture condition, the cells could migrate into the inner part of the scaffold with a depth of 840 +/- 120 mu m after 4 days, and distributed in the whole scaffold (2mm in thickness) within 14 days. The cells proliferated in the scaffold and the fold increase of cell number after 7 days of culture was 2.55 +/- 0.08. The apoptotic rate of hADSCs in the scaffold was similar to that of cells maintained on tissue culture plates. When cultured in adipogenic induction medium, the hADSCs in the scaffold differentiated into adipocytes with a high efficiency (93 +/- 1%). Conclusively, this gelatin based 3D scaffold presented high cell compatibility for hADSC cultivation and differentiation, which could serve as a potential implant material in clinical applications for adipose tissue reparation and regeneration.
KW  - Mesenchymal stem cells
KW  - gelatin based scaffold
KW  - adipose tissue regeneration
KW  - adipogenic differentiation
Y1  - 2017
U6  - https://doi.org/10.3233/CH-179210
SN  - 1386-0291
SN  - 1875-8622
VL  - 67
IS  - 3-4
SP  - 297
EP  - 307
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Li, Zhengdong
A1  - Xu, Xun
A1  - Wang, Weiwei
A1  - Kratz, Karl
A1  - Sun, Xianlei
A1  - Zou, Jie
A1  - Deng, Zijun
A1  - Jung, Friedrich Wilhelm
A1  - Gossen, Manfred
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Modulation of the mesenchymal stem cell migration capacity via preconditioning with topographic microstructure
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - Controlling mesenchymal stem cells (MSCs) behavior is necessary to fully exploit their therapeutic potential. Various approaches are employed to effectively influence the migration capacity of MSCs. Here, topographic microstructures with different microscale roughness were created on polystyrene (PS) culture vessel surfaces as a feasible physical preconditioning strategy to modulate MSC migration. By analyzing trajectories of cells migrating after reseeding, we demonstrated that the mobilization velocity of human adipose derived mesenchymal stem cells (hADSCs) could be promoted by and persisted after brief preconditioning with the appropriate microtopography. Moreover, the elevated activation levels of focal adhesion kinase (FAK) and mitogen-activated protein kinase (MAPK) in hADSCs were also observed during and after the preconditioning process. These findings underline the potential enhancement of in vivo therapeutic efficacy in regenerative medicine via transplantation of topographic microstructure preconditioned stem cells.
KW  - Mesenchymal stem cells
KW  - precondition
KW  - microstructure
KW  - migration
KW  - FAK-MAPK
Y1  - 2017
U6  - https://doi.org/10.3233/CH-179208
SN  - 1386-0291
SN  - 1875-8622
VL  - 67
SP  - 267
EP  - 278
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - You, Zewang
A1  - Behl, Marc
A1  - Löwenberg, Candy
A1  - Lendlein, Andreas
T1  - pH-sensitivity and conformation change of the n-terminal methacrylated peptide VK20
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - N-terminal methacrylation of peptide MAXI, which is capable of conformational changes variation of the pH, results in a peptide, named VK20. Increasing the reactivity of this terminal group enables further coupling reactions or chemical modifications of the peptidc. However, this end group functionalization may influence the ability of confonnational changes of VK20; as well as its properties. In this paper; the influence of pH on the transition between random coil and beta-sheet conformation of VK20; including the transition kinetics, were investigated. At pH values of 9 and higher, the kinetics beta-sheet formation increased tor VK(2 0, compared to MAXI. The self-assembly into beta-sheets recognized by the formation of a physically crosslinked gel was furthermore indicated by a significant increase of G. An increase in pH (from 9 to 9.5) led to a faster gelation of the peptide VK20. Simultaneously, G was increased from 460 +/- 70 Pa (at pH 9) to 1520 +/- 180 Pa (at pH 9.5). At the nanoscale, the gel showed a highly interconnected fibrillar/network structure with uniform fibril widths of approximately 3.4 +/- 0.5 nm (N=30). The recovery of the peptide conformation back to random coil resulted in the dissolution of the gel; whereby the kinetics of the recovery depended on the pH. Conclusively, the ability of MAXI to undergo confommtional changes was not affected by N-terminal methacrylation whereas the kinetics of pH-sensitive beta-sheet formations has been increased.
Y1  - 2017
U6  - https://doi.org/10.1557/adv.2017.491
SN  - 2059-8521
VL  - 2
SP  - 2571
EP  - 2579
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Peng, Xingzhou
A1  - Behl, Marc
A1  - Zhang, Pengfei
A1  - Mazurek-Budzyńska, Magdalena
A1  - Feng, Yakai
A1  - Lendlein, Andreas
T1  - Synthesis and characterization of multiblock poly(ester-amide-urethane)s
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - In this study, a multiblock copolymer containing oligo(3-methyl-morpholine-2, 5-dione) (oMMD) and oligo(3-sec-butyl-morpholine-2, 5-dione) (oBMD) building blocks obtained by ring-opening polymerization (ROP) of the corresponding monomers, was synthesized in a polyaddition reaction using an aliphatic diisocyanate. The multiblock copolymer (pBMD-MMD) provided a molecular weight of 40, 000 g·mol−1, determined by gel permeation chromatography (GPC). Incorporation of both oligodepsipeptide segments in multiblock copolymers was confirmed by 1H NMR and Matrix Assisted Laser Desorption/Ionization Time Of Flight Mass Spectroscopy (MALDI-TOF MS) analysis. pBMD-MMD showed two separated glass transition temperatures (61 °C and 74 °C) indicating a microphase separation. Furthermore, a broad glass transition was observed by DMTA, which can be attributed to strong physical interaction i.e. by H-bonds formed between amide, ester, and urethane groups of the investigated copolymers. The obtained multiblock copolymer is supposed to own the capability to exhibit strong physical interactions.
Y1  - 2017
U6  - https://doi.org/10.1557/adv.2017.486
SN  - 2059-8521
VL  - 2
SP  - 2551
EP  - 2559
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Liu, Yue
A1  - Razzaq, Muhammad Yasar
A1  - Rudolph, Tobias
A1  - Fang, Liang
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Two-Level Shape Changes of Polymeric Microcuboids Prepared from Crystallizable Copolymer Networks
JF  - Macromolecules : a publication of the American Chemical Society
N2  - Polymeric microdevices bearing features like nonspherical shapes or spatially segregated surface properties are of increasing importance in biological and medical analysis, drug delivery, and bioimaging or microfluidic systems as well as in micromechanics, sensors, information storage, or data carrier devices. Here, a method to fabricate programmable microcuboids with shape-memory capability and the quantification of their recovery at different levels is reported. The method uses the soft lithographic technique to create microcuboids with well-defined sizes and surface properties. Microcuboids having an edge length of 25 mu m and a height of 10 mu m were prepared from cross-linked poly[ethylene-co-(vinyl acetate)] (cPEVA) with different vinyl acetate contents and were programmed by compression with various deformation degrees at elevated temperatures. The microlevel shape-recovery of the cuboidal geometry during heating was monitored by optical microscopy (OM) and atomic force microscopy (AFM) studying the related changes in the projected area (PA) or height, while the nanolevel changes of the nanosurface roughness were investigated by in situ AFM. The shape-memory effect at the microlevel was quantified by the recovery ratio of cuboids (R-r,R-micro), while at the. nanolevel, the recovery ratio of the nanoroughness (R-r,R-nano) was measured. The values of R-r,R-micro,,micro could be tailored in a range from 42 +/- 1% to 102 +/- 1% and Rr,nano from 89 +/- 6% to 136 +/- 21% depending on the applied compression ratio and the amount of vinyl acetate content in the cPEVA microcuboids.
Y1  - 2017
U6  - https://doi.org/10.1021/acs.macromol.6b02237
SN  - 0024-9297
SN  - 1520-5835
VL  - 50
SP  - 2518
EP  - 2527
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Haase, Tobias
A1  - Krost, Annalena
A1  - Sauter, Tilman
A1  - Kratz, Karl
A1  - Peter, Jan
A1  - Kamann, Stefanie
A1  - Jung, Friedrich
A1  - Lendlein, Andreas
A1  - Zohlnhöfer, Dietlind
A1  - Rüder, Constantin
T1  - In vivo biocompatibility assessment of poly (ether imide) electrospun scaffolds
JF  - Journal of Tissue Engineering and Regenerative Medicine
N2  - Poly(ether imide) (PEI), which can be chemically functionalized with biologically active ligands, has emerged as a potential biomaterial for medical implants. Electrospun PEI scaffolds have shown advantageous properties, such as enhanced endothelial cell adherence, proliferation and low platelet adhesion in in vitro experiments. In this study, the in vivo behaviour of electrospun PEI scaffolds and PEI films was examined in a murine subcutaneous implantation model. Electrospun PEI scaffolds and films were surgically implanted subcutaneously in the dorsae of mice. The surrounding subcutaneous tissue response was examined via histopathological examination at 7 and 28days after implantation. No serious adverse events were observed for both types of PEI implants. The presence of macrophages or foreign body giant cells in the vicinity of the implants and the formation of a fibrous capsule indicated a normal foreign body reaction towards PEI films and scaffolds. Capsule thickness and inflammatory infiltration cells significantly decreased for PEI scaffolds during days 7-28 while remaining unchanged for PEI films. The infiltration of cells into the implant was observed for PEI scaffolds 7days after implantation and remained stable until 28days of implantation. Additionally some, but not all, PEI scaffold implants induced the formation of functional blood vessels in the vicinity of the implants. Conclusively, this study demonstrates the in vivo biocompatibility of PEI implants, with favourable properties of electrospun PEI scaffolds regarding tissue integration and wound healing.
KW  - poly(ether imide)
KW  - in vivo study
KW  - electrospun scaffold
KW  - capsule formation
KW  - foreign body giant cells
KW  - vascularization
Y1  - 2017
U6  - https://doi.org/10.1002/term.2002
SN  - 1932-6254
SN  - 1932-7005
VL  - 11
IS  - 4
SP  - 1034
EP  - 1044
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Zhang, Nan
A1  - Said, Andre
A1  - Wischke, Christian
A1  - Kral, Vivian
A1  - Brodwolf, Robert
A1  - Volz, Pierre
A1  - Boreham, Alexander
A1  - Gerecke, Christian
A1  - Li, Wenzhong
A1  - Neffe, Axel T.
A1  - Kleuser, Burkhard
A1  - Alexiev, Ulrike
A1  - Lendlein, Andreas
A1  - Schäfer-Korting, Monika
T1  - Poly[acrylonitrile-co-(N-vinyl pyrrolidone)] nanoparticles - Composition-dependent skin penetration enhancement of a dye probe and biocompatibility
JF  - European Journal of Pharmaceutics and Biopharmaceutics
N2  - Nanoparticles can improve topical drug delivery: size, surface properties and flexibility of polymer nanoparticles are defining its interaction with the skin. Only few studies have explored skin penetration for one series of structurally related polymer particles with systematic alteration of material composition. Here, a series of rigid poly[acrylonitrile-co-(N-vinyl pyrrolidone)] model nanoparticles stably loaded with Nile Red or Rhodamin B, respectively, was comprehensively studied for biocompatibility and functionality. Surface properties were altered by varying the molar content of hydrophilic NVP from 0 to 24.1% and particle size ranged from 35 to 244 nm. Whereas irritancy and genotoxicity were not revealed, lipophilic and hydrophilic nanoparticles taken up by keratinocytes affected cell viability. Skin absorption of the particles into viable skin ex vivo was studied using Nile Red as fluorescent probe. Whilst an intact stratum corneum efficiently prevented penetration, almost complete removal of the horny layer allowed nanoparticles of smaller size and hydrophilic particles to penetrate into viable epidermis and dermis. Hence, systematic variations of nanoparticle properties allows gaining insights into critical criteria for biocompatibility and functionality of novel nanocarriers for topical drug delivery and risks associated with environmental exposure.
KW  - Biocompatibility testing
KW  - Drug delivery systems
KW  - Nanoparticle
KW  - Poly[acrylonitrile-co-(N-vinyl pyrrolidone)]
KW  - Polymers
KW  - Skin absorption
Y1  - 2017
U6  - https://doi.org/10.1016/j.ejpb.2016.10.019
SN  - 0939-6411
SN  - 1873-3441
VL  - 116
SP  - 66
EP  - 75
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Brunacci, Nadia
A1  - Wischke, Christian
A1  - Naolou, Toufik
A1  - Neffe, Axel T.
A1  - Lendlein, Andreas
T1  - Influence of surfactants on depsipeptide submicron particle formation
JF  - European Journal of Pharmaceutics and Biopharmaceutics
N2  - Surfactants are required for the formation and stabilization of hydrophobic polymeric particles in aqueous environment. In order to form submicron particles of varying sizes from oligo[3-(S)-sec-butylmorpholine-2,5-dione]diols ((OBMD)-diol), different surfactants were investigated. As new surfactants, four-armed star-shaped oligo(ethylene glycol)s of molecular weights of 5-20 kDa functionalized with desamino-tyrosine (sOEG-DAT) resulted in smaller particles with lower PDI than with desaminotyrosyl tyrosine (sOEG-DATT) in an emulsion/solvent evaporation method. In a second set of experiments, sOEG-DAT of M-n= 10 kDa was compared with the commonly employed emulsifiers polyvinylalcohol (PVA), polyoxyethylene (20) sorbitan monolaurate (Tween 20), and D-alpha-tocopherol polyethylene glycol succinate (VIT E-TPGS) for OBMD particle preparation. sOEG-DAT allowed to systematically change sizes in a range of 300 up to 900 nm with narrow polydispersity, while in the other cases, a lower size range (250-400 nm, PVA; 300 nm, Tween 20) or no effective particle formation was observed. The ability of tailoring particle size in a broad range makes sOEG-DAT of particular interest for the formation of oligodepsipeptide particles, which can further be investigated as drug carriers for controlled delivery. (C) 2016 Elsevier B.V. All rights reserved.
KW  - Depsipeptide
KW  - Particle size
KW  - Surfactants
KW  - Submicron particles
Y1  - 2017
U6  - https://doi.org/10.1016/j.ejpb.2016.11.011
SN  - 0939-6411
SN  - 1873-3441
VL  - 116
SP  - 61
EP  - 65
PB  - Elsevier
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  - Piluso, Susanna
A1  - Lendlein, Andreas
A1  - Neffe, Axel T.
T1  - Enzymatic action as switch of bulk to surface degradation of clicked gelatin-based networks
JF  - Polymers for advanced technologies
N2  - Polymer degradation occurs under physiological conditions in vitro and in vivo, especially when bonds susceptible to hydrolysis are present in the polymer. Understanding of the degradation mechanism, changes of material properties over time, and overall rate of degradation is a necessary prerequisite for the knowledge-based design of polymers with applications in biomedicine. Here, hydrolytic degradation studies of gelatin-based networks synthesized by copper-catalyzed azide-alkyne cycloaddition reaction are reported, which were performed with or without addition of an enzyme. In all cases, networks with a stilbene as crosslinker proofed to be more resistant to degradation than when an octyl diazide was used. Without addition of an enzyme, the rate of degradation was ruled by the crosslinking density of the network and proceeded via a bulk degradation mechanism. Addition of Clostridium histolyticum collagenase resulted in a much enhanced rate of degradation, which furthermore occurred via surface erosion. The mesh size of the hydrogels (>7nm) was in all cases larger than the hydrodynamic radius of the enzyme (4.5nm) so that even in very hydrophilic networks with large mesh size enzymes may be used to induce a fast surface degradation mechanism. This observation is of general interest when designing hydrogels to be applied in the presence of enzymes, as the degradation mechanism and material performance are closely interlinked. Copyright (c) 2016 John Wiley & Sons, Ltd.
KW  - Hydrogel
KW  - Biopolymer
KW  - Degradation
Y1  - 2017
U6  - https://doi.org/10.1002/pat.3962
SN  - 1042-7147
SN  - 1099-1581
VL  - 28
SP  - 1318
EP  - 1324
PB  - Wiley
CY  - Hoboken
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  - Heuchel, Matthias
A1  - Gerber, David
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Morphological analysis of differently sized highly porous poly(ether imide) microparticles by mercury porosimetry
JF  - Polymers for advanced technologies
N2  - Highly porous poly(ether imide) (PEI) microparticles prepared by a spraying/coagulation process are discussed as candidate adsorber materials for apheresis applications, i.e. removal of uremic toxins from the blood of renal failure patients. PEI particles obtained by the aforementioned procedure can have a broad size distribution with particle diameters ranging from 20 to 800 mu m. In order to further estimate the adsorption behavior of PEI microparticles packed in application relevant apheresis modules, a quantitative information about the relation between particle size and pore morphology is required. In this study, we explored whether the intraparticle porosity of PEI microparticles varies with altering the diameter of the particulate adsorbers. By an analytical wet sieving procedure, the obtained PEI microparticles were separated into five size fractions, which were analyzed by mercury intrusion porosimetry, nitrogen adsorption, and scanning electron microscopy. Mercury intrusion porosimetry revealed for all size fractions high porosity values in the range from 78% to 84% with pore diameters in the range from 10 to 1000nm. A bimodal pore size distribution was found having a first peak at around 100nm, while a second pronounced peak maximum was found at higher pore sizes that increased with raising particle diameter from 300nm for the smallest particle size fraction (50-100 mu m) to 700nm for particles with a diameter of 200 to 250 mu m. Based on these findings, it can be assumed that the main PEI particle size fraction (200-250 mu m) should exhibit the highest adsorption capacity in an apheresis module. Copyright (c) 2016 John Wiley & Sons, Ltd.
KW  - porous microparticles
KW  - poly(ether imide)
KW  - mercury intrusion porosimetry
KW  - adsorber materials
Y1  - 2017
U6  - https://doi.org/10.1002/pat.3973
SN  - 1042-7147
SN  - 1099-1581
VL  - 28
SP  - 1269
EP  - 1277
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Dal Bianco, Andrea
A1  - Wischke, Christian
A1  - Zhou, Shuo
A1  - Lendlein, Andreas
T1  - Controlling surface properties and permeability of polyglycerol network films
JF  - Polymers for advanced technologies
N2  - While branched polyglycerol (PG)-based molecules are well established as hydrophilic particles, the capacity of utilizing PG in bulk materials and opportunities arising by their further surface functionalization have only recently been considered. Here we investigated how the mold used in PG network synthesis may affect surface composition and how the permeability of substances through PG can be controlled by altering network structure, i.e. introducing 20mol% oligoethylene glycol (OEG) bifunctional spacer molecules. Overall, PG-based bulk network materials were shown to be tailorable, hydrophilic, low swelling and relatively stiff polyether-based materials, with low impact of salt onto material properties. Based on these features, but also on the principal capacity of free hydroxyl groups to be used for functionalization reactions, these materials may be an interesting platform for medical and technical applications, e.g. as diffusion-rate controlling membrane in aqueous environment. Copyright (c) 2016 John Wiley & Sons, Ltd.
KW  - polyglycerol
KW  - surface properties
KW  - diffusion
KW  - network structure
Y1  - 2017
U6  - https://doi.org/10.1002/pat.3917
SN  - 1042-7147
SN  - 1099-1581
VL  - 28
SP  - 1263
EP  - 1268
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Blocki, Anna
A1  - Löwenberg, Candy
A1  - Jiang, Yi
A1  - Kratz, Karl
A1  - Neffe, Axel T.
A1  - Jung, Friedrich
A1  - Lendlein, Andreas
T1  - Response of encapsulated cells to a gelatin matrix with varied bulk and microenvironmental elastic properties
JF  - Polymers for advanced technologies
N2  - Gelatin-based hydrogels offer various biochemical cues that support encapsulated cells and are therefore suitable as cell delivery vehicles in regenerative medicine. However, besides the biochemical signals, biomechanical cues are crucial to ensure an optimal support of encapsulated cells. Hence, we aimed to correlate the cellular response of encapsulated cells to macroscopic and microscopic elastic properties of glycidylmethacrylate (GMA)-functionalized gelatin-based hydrogels. To ensure that different observations in cellular behavior could be attributed to differences in elastic properties, an identical concentration as well as degree of functionalization of biopolymers was utilized to form covalently crosslinked hydrogels. Elastic properties were merely altered by varying the average gelatin-chain length. Hydrogels exhibited an increased degree of swelling and a decreased bulk elastic modulus G with prolonged autoclaving of the starting solution. This was accompanied by an increase of hydrogel mesh size and thus by a reduction of crosslinking density. Tougher hydrogels retained the largest amount of cells; however, they also interfered with cell viability. Softer gels contained a lower cell density, but supported cell elongation and viability. Observed differences could be partially attributed to differences in bulk properties, as high crosslinking densities interfere with diffusion and cell spreading and thus can impede cell viability. Interestingly, a microscopic elastic modulus in the range of native soft tissue supported cell viability and elongation best while ensuring a good cell entrapment. In conclusion, gelatin-based hydrogels providing a soft tissue-like microenvironment represent adequate cell delivery vehicles for tissue engineering approaches. Copyright (c) 2016 John Wiley & Sons, Ltd.
KW  - mechanotransduction
KW  - hydrogel
KW  - gelatin
KW  - cell encapsulation
KW  - matrix elasticity
Y1  - 2017
U6  - https://doi.org/10.1002/pat.3947
SN  - 1042-7147
SN  - 1099-1581
VL  - 28
SP  - 1245
EP  - 1251
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Bhuvanesh, Thanga
A1  - Saretia, Shivam
A1  - Roch, Toralf
A1  - Schöne, Anne-Christin
A1  - Rottke, Falko O.
A1  - Kratz, Karl
A1  - Wang, Weiwei
A1  - Ma, Nan
A1  - Schulz, Burkhard
A1  - Lendlein, Andreas
T1  - Langmuir-Schaefer films of fibronectin as designed biointerfaces for culturing stem cells
JF  - Polymers for advanced technologies
N2  - 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.
KW  - Langmuir-Schaefer method
KW  - protein adsorption
KW  - stem cell adhesion
KW  - cell culture
KW  - fibronectin
Y1  - 2017
U6  - https://doi.org/10.1002/pat.3910
SN  - 1042-7147
SN  - 1099-1581
VL  - 28
SP  - 1305
EP  - 1311
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Farhan, Muhammad
A1  - Rudolph, Tobias
A1  - Nöchel, Ulrich
A1  - Yan, Wan
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Noncontinuously Responding Polymeric Actuators
JF  - ACS applied materials & interfaces
N2  - Reversible movements of current polymeric actuators stem from the continuous response to signals from a controlling unit, and subsequently cannot be interrupted without stopping or eliminating the input trigger. Here, we present actuators based on cross-linked blends of two crystallizable polymers capable of pausing their movements in a defined manner upon continuous cyclic heating and cooling. This noncontinuous actuation can be adjusted by varying the applied heating and cooling rates. The feasibility of these devices for technological applications was shown in a 140 cycle experiment of free-standing noncontinuous shape shifts, as well as by various demonstrators.
KW  - soft robotics
KW  - polymer actuators
KW  - thermo-sensitivity
KW  - shape shifting materials
KW  - crystallization behavior
Y1  - 2017
U6  - https://doi.org/10.1021/acsami.7b11316
SN  - 1944-8244
VL  - 9
SP  - 33559
EP  - 33564
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Wang, Weiwei
A1  - Naolou, Toufik
A1  - Ma, Nan
A1  - Deng, Zijun
A1  - Xu, Xun
A1  - Mansfeld, Ulrich
A1  - Wischke, Christian
A1  - Gossen, Manfred
A1  - Neffe, Axel T.
A1  - Lendlein, Andreas
T1  - Polydepsipeptide Block-Stabilized Polyplexes for Efficient Transfection of Primary Human Cells
JF  - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences
N2  - The rational design of a polyplex gene carrier aims to balance maximal effectiveness of nucleic acid transfection into cells with minimal adverse effects. Depsipeptide blocks with an M (n) similar to 5 kDa exhibiting strong physical interactions were conjugated with PEI moieties (2.5 or 10 kDa) to di- and triblock copolymers. Upon nanoparticle formation and complexation with DNA, the resulting polyplexes (sizes typically 60-150 nm) showed remarkable stability compared to PEI-only or lipoplex and facilitated efficient gene delivery. Intracellular trafficking was visualized by observing fluorescence-labeled pDNA and highlighted the effective cytoplasmic uptake of polyplexes and release of DNA to the perinuclear space. Specifically, a triblock copolymer with a middle depsipeptide block and two 10 kDa PEI swallowtail structures mediated the highest levels of transgenic VEGF secretion in mesenchymal stem cells with low cytotoxicity. These nanocarriers form the basis for a delivery platform technology, especially for gene transfer to primary human cells.
Y1  - 2017
U6  - https://doi.org/10.1021/acs.biomac.7b01034
SN  - 1525-7797
SN  - 1526-4602
VL  - 18
SP  - 3819
EP  - 3833
PB  - American Chemical Society
CY  - Washington
ER  -