Refine
Has Fulltext
- no (209) (remove)
Year of publication
Document Type
- Article (193)
- Review (5)
- Conference Proceeding (4)
- Other (4)
- Preprint (3)
Language
- English (209) (remove)
Is part of the Bibliography
- yes (209)
Keywords
- biomaterials (9)
- Biomaterial (6)
- Polymer (6)
- polymer (6)
- shape-memory effect (6)
- Hydrogel (5)
- biomaterial (5)
- electrospinning (5)
- stimuli-sensitive polymers (5)
- Langmuir monolayer (4)
- morphology (4)
- multiblock copolymer (4)
- shape memory (4)
- Biomaterials (3)
- Degradation (3)
- Polymers (3)
- cell adhesion (3)
- endothelial cells (3)
- hemocompatibility (3)
- mesenchymal stem cells (3)
- microparticles (3)
- microstructure (3)
- poly(ether imide) (3)
- shape-memory polymers (3)
- Actuation (2)
- Biomimetic (2)
- Biopolymer (2)
- Degradable (2)
- Depsipeptide (2)
- Enzymatic degradation (2)
- Gelatin (2)
- Hyaluronic acid (2)
- Hydrolytic degradation (2)
- Membrane (2)
- Mesenchymal stem cells (2)
- Molecular modeling (2)
- Nanostructure (2)
- Oligo(epsilon-caprolactone) (2)
- Phase morphology (2)
- Poly(epsilon-caprolactone) (2)
- Rheology (2)
- Shape memory (2)
- Shape-memory effect (2)
- Shape-memory polymer (2)
- Temperature-memory effect (2)
- Thin film (2)
- actuation (2)
- artificial muscles (2)
- atomic force microscopy (2)
- biodegradable polymers (2)
- cell culture (2)
- crystallization (2)
- crystallization behavior (2)
- degradation (2)
- ellipsometry (2)
- gelatin (2)
- hydrogel (2)
- hydrogels (2)
- mechanical (2)
- migration (2)
- multifunctional polymers (2)
- oligodepsipeptides (2)
- phase morphology (2)
- platelets (2)
- poly(epsilon-caprolactone) (2)
- poly(ethylene glycol) (2)
- polyester (2)
- polyesterurethanes (2)
- polyglycerol (2)
- properties (2)
- protein adsorption (2)
- ring-opening polymerization (2)
- soft actuators (2)
- soft robotics (2)
- spectroscopic ellipsometry (2)
- stem cell adhesion (2)
- surface functionalization (2)
- thrombogenicity (2)
- (NMR) (1)
- 2D materials (1)
- 3D-printing (1)
- 4D-actuation (1)
- Actuators (1)
- Additive manufacturing (1)
- Adipocyte (1)
- Adsorption of uremic toxins (1)
- Aerophobicity (1)
- Ageing (1)
- Air bubble repellence (1)
- Angle-dependent X-ray induced photoelectron spectroscopy (1)
- Antiviral (1)
- Biocompatibility testing (1)
- Biocompatible polymers (1)
- Biomolecules coupling (1)
- Biopolymer material (1)
- Biopolymers (1)
- Brewster angle microscopy (1)
- COVID-19 (1)
- Cartilage repair (1)
- Chondrocytes (1)
- Chronic kidney disease (1)
- Chronic kidney disease (CKD) (1)
- Cinnamylidene acetic acid (1)
- Click chemistry (1)
- Collagen-binding peptide (1)
- Composite (1)
- Crosslinking (1)
- Deformation (1)
- Degradable polymer (1)
- Docking study (1)
- Drug delivery systems (1)
- Drug loading (1)
- Electrospinning (1)
- Endothelial cells (1)
- Endothelialization (1)
- Energy (1)
- Energy storage (1)
- Enzymatic polymer degradation (1)
- FAK-MAPK (1)
- Fastener (1)
- Fiber (1)
- Function by design (1)
- Functionalization (1)
- Gripper (1)
- HDAC1 (1)
- High-throughput (1)
- Hydrogels (1)
- Hydrolytic stability (1)
- Hydroxyapatite (1)
- Hypoxia (1)
- In situ (1)
- Inflammation (1)
- Ink (1)
- Ki67 (1)
- Langmuir layers (1)
- Langmuir monolayer degradation technique (1)
- Langmuir monolayers (1)
- Langmuir technique (1)
- Langmuir thin-films (1)
- Langmuir-Schaefer method (1)
- Langmuir-Schafer films (1)
- Macrophage (1)
- Magnetic composites (1)
- Magnetite nanoparticles (1)
- Mass spectrometry (1)
- Matrix metalloproteinase (1)
- Mechanical properties (1)
- Methacrylate (1)
- Microindentation (1)
- Microstructure (1)
- Modeling (1)
- Modelling (1)
- Molecular (1)
- Molecular dynamics simulation (1)
- Molecular interaction design (1)
- Molecular orientation (1)
- Molecular weight (1)
- Monolayer (1)
- Morpholindione (1)
- Multiblock copolymer (1)
- Multiblock copolymers (1)
- Multifunctional polyester networks (1)
- Multifunctionality (1)
- NICE-2014 (1)
- Nanofiber (1)
- Nanoparticle (1)
- Nanoparticles (1)
- Near infrared light triggered shape-recovery (1)
- Negative control (1)
- Nuclear magnetic resonance (1)
- OEG-OPG-OEG triblock copolymer (1)
- Oligo(ethylene glycol) (1)
- Oligo(ethylene glycol) derivatization (1)
- Oligo(omega-pentadecalactone) (1)
- Oligodepsipeptide (1)
- Oligoglycerols (1)
- On-demand release (1)
- PDLLGA (1)
- PHA-depolymerases (1)
- Packaging (1)
- Particle shape (1)
- Particle size (1)
- Phagocytosis (1)
- Photoresponsive polymers (1)
- Physical Network (1)
- Platelet (1)
- Poly(carbonate-urea-urethane)s (1)
- Poly(epsilon-caprolactone) networks (1)
- Poly(ether imide) (1)
- Poly(n-butyl acrylate) (1)
- Poly[acrylonitrile-co-(N-vinyl pyrrolidone)] (1)
- Polyesterurethane (1)
- Polyether ether ketone (1)
- Polylactide stereocomplex (1)
- Polymer architecture (1)
- Polymer functionalization (1)
- Polymer micronetwork colloids (1)
- Polymer network properties (1)
- Polymer networks (1)
- Polymeric substrate (1)
- Porous poly(ether imide) microparticulate absorbers (1)
- Protein (1)
- Proteins (1)
- RGD peptides (1)
- RGD-peptide (1)
- RUNX2 (1)
- Raman spectroscopy (1)
- Random copolymer (1)
- Rheological characterization (1)
- Ring-opening polymerization (1)
- Robotic synthesis (1)
- Robotics (1)
- SAXS (1)
- Scaffold contraction (1)
- Scaffold degradation (1)
- Scaffold stiffness (1)
- Scanning probe microscopy (SPM) (1)
- Sequence structure (1)
- Shape-memory (1)
- Simulation (1)
- Skin absorption (1)
- Sn(IV) alkoxide (1)
- Submicron particles (1)
- Sulfated polymer (1)
- Surface functionalization (1)
- Surface reaction (1)
- Surfactants (1)
- Switchable wettability (1)
- TCP (1)
- THP-1 cells (1)
- Telechel (1)
- Thermo-responsive polymer (1)
- Thermomechanical history (1)
- Tin octanoate (1)
- UV crosslinking (1)
- Uremic toxins (1)
- VEGF (1)
- WAXS (1)
- Water (1)
- X-ray scattering (1)
- actin cytoskeleton (1)
- active polymer (1)
- active scaffold (1)
- adipogenic differentiation (1)
- adipose tissue regeneration (1)
- adsorber materials (1)
- air - water interface (1)
- amide ligand (1)
- amorphous polymers (1)
- assembly capabilities (1)
- atomic force microscopy (AFM) (1)
- basement membrane (1)
- beta-galactosidase (1)
- biocompatibility (1)
- biofunctionalization (1)
- bioinspired materials (1)
- bioinstructive implants (1)
- bioinstructive materials (1)
- biological applications of polymers (1)
- biological membrane (1)
- biomaterial characterization (1)
- biomaterial-tissue interface (1)
- biomedical (1)
- biomimetic (chemical reaction) (1)
- biopolymer (1)
- bioprinting (1)
- blend (1)
- block copolymers (1)
- blood tests (1)
- body temperature (1)
- brewster angle microscopy (1)
- broad melting temperature range (1)
- calcium influx (1)
- capsule formation (1)
- cardiac regeneration (1)
- cardiovascular disease (1)
- cardiovascular implant (1)
- catalyst (1)
- cavitation-based mechanical force (1)
- cell culture device (1)
- cell cycle inhibitors (1)
- cell encapsulation (1)
- cell selectivity (1)
- cell-material interaction (1)
- cells (1)
- chain-extended (1)
- chemical synthesis (1)
- chronic kidney disease (CKD) (1)
- co-expression (1)
- cold (1)
- collagen (1)
- collagen-IV (1)
- composite (1)
- controlled release (1)
- coordination bonds (1)
- copolymer networks (1)
- copper-catalyzed alkyne-azide cycloaddition (1)
- critical micellation temperature (1)
- cross-linking (1)
- crosslinking (1)
- crystal structures (1)
- crystalline (1)
- crystallinity (1)
- cyclic olefin copolymer (1)
- cyclic thermomechanical testing (1)
- cyclodextrin (1)
- cytokine release (1)
- cytokines/chemokines (1)
- cytotoxicity (1)
- dedifferentiation (1)
- degradable (1)
- degradable polyester (1)
- degradable polymer (1)
- degradable polymers (1)
- dendritic cells (1)
- differentiation (1)
- diffusion (1)
- drug eluting stent (1)
- efficient (1)
- elastomers (1)
- electron microscopy (1)
- electrospun scaffold (1)
- ellipsometric mapping (1)
- endothelial basement membrane (1)
- engineering (1)
- enzymatic-degradation (1)
- enzyme (1)
- ethylene oxide (1)
- excimer UV light (1)
- extracellular matrix modifying enzymes (1)
- fiber actuators (1)
- fiber meshes (1)
- fibers (1)
- fibrinogen (1)
- fibroblast (1)
- fibronectin (1)
- fluorescence stimuli‐ responsivity (1)
- foam (1)
- focal adhesion (1)
- foreign body giant cells (1)
- form stability (1)
- function (1)
- function by structure; (1)
- functional (1)
- functionalization of polymers (1)
- gelatin based scaffold (1)
- gelatin-based hydrogels (1)
- gels (1)
- gene delivery (1)
- glass (1)
- hemodialysis (1)
- human induced pluripotent stem cell (1)
- human monocytic (THP-1) cells (1)
- hydrophobic uremic toxins (1)
- immunogenicity (1)
- implants (1)
- in vitro (1)
- in vitro synthesized mRNA (1)
- in vitro thrombogenicity testing (1)
- in vivo study (1)
- inclusion complex (1)
- induced pluripotent stem cells (1)
- integrated co-transfection (1)
- inverse (1)
- iron (1)
- langmuir monolayer (1)
- langmuir monolayers (1)
- libraries (1)
- library (1)
- life cycle assessment (1)
- lipase release (1)
- lipases (1)
- lipid (1)
- lipoplexes (1)
- liquid-crystalline polymers (1)
- lung organoid (1)
- macrophage subsets (1)
- magnetic (1)
- magnetic nanoparticles (1)
- magnetosensitivity (1)
- materials science (1)
- matrix elasticity (1)
- mechanical property (1)
- mechanotransduction (1)
- mediated delivery (1)
- mercury intrusion porosimetry (1)
- microgels (1)
- microporous (1)
- microscale (1)
- modulation of in vivo regeneration (1)
- molecular dynamics simulations (1)
- molecular modeling (1)
- multiblock copolymers (1)
- multifunctional biomaterials (1)
- multiple functions (1)
- nanocomposites (1)
- nanoparticle characterization (1)
- nanoscale (1)
- nanostructure (1)
- network structure (1)
- networks (1)
- on demand particle release (1)
- optical imaging (1)
- orientational memory (1)
- osteogenic differentiation (1)
- oxygen plasma (1)
- p16 (1)
- p21 (1)
- parallel co-transfection (1)
- particulate (1)
- pathways (1)
- peptides (1)
- photoinduced radical polymerization (1)
- platelet activation (1)
- platelet adhesion (1)
- platelet aging (1)
- platelet function (1)
- platelet rich plasma (1)
- platelet storage (1)
- platelet-rich plasma (1)
- polarization (1)
- poly(e-caprolactone) (1)
- poly(epsilon-caprolactone) methacrylate (1)
- poly(ether imide) microparticles (1)
- poly(n-butyl acrylate) (1)
- poly(tetrafluoroethylene) (1)
- poly[(rac-lactide)-co-glycolide] (1)
- polyamines (1)
- polycaprolactone (1)
- polydepsipeptide (1)
- polyesters (1)
- polyesterurethane (1)
- polyhydroxyalkanoates (PHA) (1)
- polyimides (1)
- polymer actuators (1)
- polymer degradation (1)
- polymer foams (1)
- polymer surface (1)
- polymer-based biomaterials (1)
- polymers (1)
- polysiloxanes (1)
- population doubling time (1)
- pore-size distribution (1)
- porosity (1)
- porous microparticles (1)
- precondition (1)
- predictive characterization tools (1)
- processing (1)
- protein (1)
- protein Langmuir layers (1)
- protein-protein interactions (1)
- reactive oxygen species (ROS) (1)
- reference (1)
- renewable (1)
- reshaping abilities (1)
- resistive heating (1)
- responsive (1)
- reversible bidirectional shape-memory polymer (1)
- reversible shape-memory actuator (1)
- reversible shape-memory effect (1)
- rheology (1)
- rhodium(I)– phosphine (1)
- rhodium-phosphine coordination bonds (1)
- ring opening polymerization (1)
- root mean square roughness (1)
- scaffold (1)
- self-healing (1)
- semi-IPN hydrogels (1)
- semi-crystalline (1)
- senescence-associated (1)
- sequence structures (1)
- shape change (1)
- shape shifting materials (1)
- shape-memory (1)
- shape-memory hydrogel (1)
- shape-memory polymer (1)
- shape-memory polymer actuators (1)
- shape-memory properties (1)
- shape‐memory polymer actuators (1)
- side reaction (1)
- side-chains functionalization (1)
- silicone (1)
- sirna transfection (1)
- soft matter micro- and nanowires (1)
- solvent resistance (1)
- stent coatings (1)
- stereocomplexes (1)
- sterilization (1)
- stimuli-sensitive materials (1)
- successive (1)
- sulfation (1)
- supramolecular polymer network (1)
- surface chemistry (1)
- surface coating (1)
- surface properties (1)
- sustainability (1)
- switch (1)
- telechelics (1)
- temperature (1)
- temperature-memory effect (1)
- temperature-memory polymers (1)
- therapeutics (1)
- thermal properties (1)
- thermal treatments (1)
- thermo-sensitivity (1)
- thermomechanical properties (1)
- thermoplastic elastomer (1)
- thermoplastics (1)
- thermoresponsive polymers (1)
- thermosensitive (1)
- thrombocyte adhesion (1)
- tin(II) 2-ethylhexanoate (1)
- tissue (1)
- transfection (1)
- transfection methods (1)
- triple-shape effect (1)
- two dimensional network (1)
- ultrasound (1)
- uremia (1)
- vascular graft (1)
- vascular grafts (1)
- vascularization (1)
- viability (1)
- whole blood (1)
- wide angle x‐ ray scattering (1)
In vitro thrombogenicity test systems require co-cultivation of endothelial cells and platelets under blood flow-like conditions. Here, a commercially available perfusion system is explored using plasma-treated cyclic olefin copolymer (COC) as a substrate for the endothelial cell layer. COC was characterized prior to endothelialization and co-cultivation with platelets under static or flow conditions. COC exhibits a low roughness and a moderate hydrophilicity. Flow promoted endothelial cell growth and prevented platelet adherence. These findings show the suitability of COC as substrate and the importance of blood flow-like conditions for the assessment of the thrombogenic risk of drugs or cardiovascular implant materials.
In vitro transcribed (IVT)-mRNA has been accepted as a promising therapeutic modality. Advances in facile and rapid production technologies make IVT-mRNA an appealing alternative to protein- or virus-based medicines.
Robust expression levels, lack of genotoxicity, and their manageable immunogenicity benefit its clinical applicability.
We postulated that innate immune responses of therapeutically relevant human cells can be tailored or abrogated by combinations of 5'-end and internal IVT-mRNA modifications.
Using primary human macrophages as targets, our data show the particular importance of uridine modifications for IVT-mRNA performance.
Among five nucleotide modification schemes tested, 5-methoxy-uridine outperformed other modifications up to 4-fold increased transgene expression, triggering moderate proinflammatory and non-detectable antiviral responses.
Macrophage responses against IVT-mRNAs exhibiting high immunogenicity (e.g., pseudouridine) could be minimized upon HPLC purification. Conversely, 5'-end modifications had only modest effects on mRNA expression and immune responses.
Our results revealed how the uptake of chemically modified IVT-mRNA impacts human macrophages, responding with distinct patterns of innate immune responses concomitant with increased transient transgene expression.
We anticipate our findings are instrumental to predictively address specific cell responses required for a wide range of therapeutic applications from eliciting controlled immunogenicity in mRNA vaccines to, e.g., completely abrogating cell activation in protein replacement therapies.
Structure, mechanical properties and degradation behavior of electrospun PEEU fiber meshes and films
(2021)
The capability of a degradable implant to provide mechanical support depends on its degradation behavior. Hydrolytic degradation was studied for a polyesteretherurethane (PEEU70), which consists of poly(p-dioxanone) (PPDO) and poly(epsilon-caprolactone) (PCL) segments with a weight ratio of 70:30 linked by diurethane junction units. PEEU70 samples prepared in the form of meshes with average fiber diameters of 1.5 mu m (mesh1.5) and 1.2 mu m (mesh1.2), and films were sterilized and incubated in PBS at 37 degrees C with 5 vol% CO2 supply for 1 to 6 weeks. Degradation features, such as cracks or wrinkles, became apparent from week 4 for all samples. Mass loss was found to be 11 wt%, 6 wt%, and 4 wt% for mesh1.2, mesh1.5, and films at week 6. The elongation at break decreased to under 20% in two weeks for mesh1.2. In case of the other two samples, this level of degradation was achieved after 4 weeks. The weight average molecular weight of both PEEU70 mesh and film samples decreased to below 30 kg/mol when elongation at break dropped below 20%. The time period of sustained mechanical stability of PEEU70-based meshes depends on the fiber diameter and molecular weight.
Human induced pluripotent stem cells (hiPSCs) are a promising cell source to generate the patient-specific lung organoid given their superior differentiation potential. However, the current 3D cell culture approach is tedious and time-consuming with a low success rate and high batch-to-batch variability.
Here, we explored the establishment of lung bud organoids by systematically adjusting the initial confluence levels and homogeneity of cell distribution.
The efficiency of single cell seeding and clump seeding was compared. Instead of the traditional 3D culture, we established a 2.5D organoid culture to enable the direct monitoring of the internal structure via microscopy.
It was found that the cell confluence and distribution prior to induction were two key parameters, which strongly affected hiPSC differentiation trajectories. Lung bud organoids with positive expression of NKX 2.1, in a single-cell seeding group with homogeneously distributed hiPSCs at 70% confluence (SC 70% hom) or a clump seeding group with heterogeneously distributed cells at 90% confluence (CL 90% het), can be observed as early as 9 days post induction.
These results suggest that a successful lung bud organoid formation with single-cell seeding of hiPSCs requires a moderate confluence and homogeneous distribution of cells, while high confluence would be a prominent factor to promote the lung organoid formation when seeding hiPSCs as clumps. 2.5D organoids generated with defined culture conditions could become a simple, efficient, and valuable tool facilitating drug screening, disease modeling and personalized medicine.
Sulfated biomolecules are known to influence numerous biological processes in all living organisms. Particularly, they contribute to prevent and inhibit the hypercoagulation condition. The failure of polymeric implants and blood contacting devices is often related to hypercoagulation and microbial contamination. Here, bioactive sulfated biomacromolecules are mimicked by sulfation of poly(glycerol glycidyl ether) (polyGGE) films. Autoclaving, gamma-ray irradiation and ethylene oxide (EtO) gas sterilization techniques were applied to functionalized materials. The sulfate group density and hydrophilicity of sulfated polymers were decreased while chain mobility and thermal degradation were enhanced post autoclaving when compared to those after EtO sterilization. These results suggest that a quality control after sterilization is mandatory to ensure the amount and functionality of functionalized groups are retained.
Guidance of postinfarct myocardial remodeling processes by an epicardial patch system may alleviate the consequences of ischemic heart disease. As macrophages are highly relevant in balancing immune response and regenerative processes their suitable instruction would ensure therapeutic success. A polymeric mesh capable of attracting and instructing monocytes by purely physical cues and accelerating implant degradation at the cell/implant interface is designed. In a murine model for myocardial infarction the meshes are compared to those either coated with extracellular matrix or loaded with induced cardiomyocyte progenitor cells. All implants promote macrophage infiltration and polarization in the epicardium, which is verified by in vitro experiments. 6 weeks post-MI, especially the implantation of the mesh attenuates left ventricular adverse remodeling processes as shown by reduced infarct size (14.7% vs 28-32%) and increased wall thickness (854 mu m vs 400-600 mu m), enhanced angiogenesis/arteriogenesis (more than 50% increase compared to controls and other groups), and improved heart function (ejection fraction = 36.8% compared to 12.7-31.3%). Upscaling as well as process controls is comprehensively considered in the presented mesh fabrication scheme to warrant further progression from bench to bedside.
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.
Toll-like receptor (TLR) can trigger an immune response against virus including SARS-CoV-2. TLR expression/distribution is varying in mesenchymal stromal cells (MSCs) depending on their culture environments. Here, to explore the effect of periodic thermomechanical cues on TLRs, thermally controlled shape-memory polymer sheets with programmable actuation capacity were created. The proportion of MSCs expressing SARS-CoV-2-associated TLRs was increased upon stimulation. The TLR4/7 colocalization was promoted and retained in the endoplasmic reticula. The TLR redistribution was driven by myosin-mediated F-actin assembly. These results highlight the potential of boosting the immunity for combating COVID-19 via thermomechanical preconditioning of MSCs.
Rapid migration of mesenchymal stem cells (MSCs) on device surfaces could support in vivo tissue integration and might facilitate in vitro organoid formation. Here, polydopamine (PDA) is explored as a biofunctional coating to effectively promote MSC motility. It is hypothesized that PDA stimulates fibronectin deposition and in this way enhances integrin-mediated migration capability. The random and directional cell migration was investigated by time-lapse microscopy and gap closure assay respectively, and analysed with softwares as computational tools. A higher amount of deposited fibronectin was observed on PDA substrate, compared to the non-coated substrate. The integrin beta 1 activation and focal adhesion kinase (FAK) phosphorylation at Y397 were enhanced on PDA substrate, but the F-actin cytoskeleton was not altered, suggesting MSC migration on PDA was regulated by integrin initiated FAK signalling. This study strengthens the biofunctionality of PDA coating for regulating stem cells and offering a way of facilitating tissue integration of devices.
Copolyesterurethanes (PDLCLs) based on oligo(epsilon-caprolactone) (OCL) and oligo(omega-pentadecalactone) (OPDL) segments are biodegradable thermoplastic temperature-memory polymers. The temperature-memory capability in these polymers with crystallizable control units is implemented by a thermomechanical programming process causing alterations in the crystallite arrangement and chain organization. These morphological changes can potentially affect degradation. Initial observations on the macroscopic level inspire the hypothesis that switching of the controlling units causes an accelerated degradation of the material, resulting in programmable degradation by sequential coupling of functions. Hence, detailed degradation studies on Langmuir films of a PDLCL with 40 wt% OPDL content are carried out under enzymatic catalysis. The temperature-memory creation procedure is mimicked by compression at different temperatures. The evolution of the chain organization and mechanical properties during the degradation process is investigated by means of polarization-modulated infrared reflection absorption spectroscopy, interfacial rheology and to some extend by X-ray reflectivity. The experiments on PDLCL Langmuir films imply that degradability is not enhanced by thermal switching, as the former depends on the temperature during cold programming. Nevertheless, the thin film experiments show that the leaching of OCL segments does not induce further crystallization of the OPDL segments, which is beneficial for a controlled and predictable degradation.
Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) alpha,omega-dithiols of varying crosslinker length and amount. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The ability to form triple helices increased with the molar mass of the crosslinker. Hydrogels had storage moduli of 0.27-23 kPa and Young's moduli of 215-360 kPa at 4 degrees C. The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 degrees C and pH = 7.4. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates R-r close to 100% were observed. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix.
Monocytes and macrophages are key players in maintaining immune homeostasis. Identifying strategies to manipulate their functions via gene delivery is thus of great interest for immunological research and biomedical applications. We set out to establish conditions for mRNA transfection in hard-to-transfect primary human monocytes and monocyte-derived macrophages due to the great potential of gene expression from in vitro transcribed mRNA for modulating cell phenotypes. mRNA doses, nucleotide modifications, and different carriers were systematically explored in order to optimize high mRNA transfer rates while minimizing cell stress and immune activation. We selected three commercially available mRNA transfection reagents including liposome and polymer-based formulations, covering different application spectra. Our results demonstrate that liposomal reagents can particularly combine high gene transfer rates with only moderate immune cell activation. For the latter, use of specific nucleotide modifications proved essential. In addition to improving efficacy of gene transfer, our findings address discrete aspects of innate immune activation using cytokine and surface marker expression, as well as cell viability as key readouts to judge overall transfection efficiency. The impact of this study goes beyond optimizing transfection conditions for immune cells, by providing a framework for assessing new gene carrier systems for monocyte and macrophage, tailored to specific applications.
Stem cells are capable of sensing and processing environmental inputs, converting this information to output a specific cell lineage through signaling cascades. Despite the combinatorial nature of mechanical, thermal, and biochemical signals, these stimuli have typically been decoupled and applied independently, requiring continuous regulation by controlling units. We employ a programmable polymer actuator sheet to autonomously synchronize thermal and mechanical signals applied to mesenchymal stem cells (MSC5). Using a grid on its underside, the shape change of polymer sheet, as well as cell morphology, calcium (Ca2+) influx, and focal adhesion assembly, could be visualized and quantified. This paper gives compelling evidence that the temperature sensing and mechanosensing of MSC5 are interconnected via intracellular Ca2+. Up-regulated Ca2+ levels lead to a remarkable alteration of histone H3K9 acetylation and activation of osteogenic related genes. The interplay of physical, thermal, and biochemical signaling was utilized to accelerate the cell differentiation toward osteogenic lineage. The approach of programmable bioinstructivity provides a fundamental principle for functional biomaterials exhibiting multifaceted stimuli on differentiation programs. Technological impact is expected in the tissue engineering of periosteum for treating bone defects.
The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(epsilon-caprolactone) (OCL) are prepared at the air-water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH similar to 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices.
The production and consumption of commodity polymers have been an indispensable part of the development of our modern society. Owing to their adjustable properties and variety of functions, polymer-based materials will continue playing important roles in achieving the Sustainable Development Goals (SDG)s, defined by the United Nations, in key areas such as healthcare, transport, food preservation, construction, electronics, and water management. Considering the serious environmental crisis, generated by increasing consumption of plastics, leading-edge polymers need to incorporate two types of functions: Those that directly arise from the demands of the application (e.g. selective gas and liquid permeation, actuation or charge transport) and those that enable minimization of environmental harm, e.g., through prolongation of the functional lifetime, minimization of material usage, or through predictable disintegration into non-toxic fragments. Here, we give examples of how the incorporation of a thoughtful combination of properties/functions can enhance the sustainability of plastics ranging from material design to waste management. We focus on tools to measure and reduce the negative impacts of plastics on the environment throughout their life cycle, the use of renewable sources for their synthesis, the design of biodegradable and/or recyclable materials, and the use of biotechnological strategies for enzymatic recycling of plastics that fits into a circular bioeconomy. Finally, we discuss future applications for sustainable plastics with the aim to achieve the SDGs through international cooperation. <br /> Leading-edge polymer-based materials for consumer and advanced applications are necessary to achieve sustainable development at a global scale. It is essential to understand how sustainability can be incorporated in these materials via green chemistry, the integration of bio-based building blocks from biorefineries, circular bioeconomy strategies, and combined smart and functional capabilities.
Identification of patterns in chemical reaction pathways aids in the effective design of molecules for specific applications. Here, we report on model reactions with a water-soluble single thiol-thioester exchange (TTE) reaction substrate, which was designed taking in view biological and medical applications. This substrate consists of the thio-depsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) and does not yield foul-smelling thiol exchange products when compared with aromatic thiol containing single TTE substrates. TDP generates an alpha,omega-dithiol crosslinker in situ in a 'pseudo intramolecular' TTE. Competitive intermolecular TTE of TDP with externally added "basic" thiols increased the crosslinker concentration whilst "acidic" thiols decreased its concentration. TDP could potentially enable in situ bioconjugation and crosslinking applications.
The degradation of polymers is described by mathematical models based on bond cleavage statistics including the decreasing probability of chain cuts with decreasing average chain length. We derive equations for the degradation of chains under a random chain cut and a chain end cut mechanism, which are compared to existing models. The results are used to predict the influence of internal molecular parameters. It is shown that both chain cut mechanisms lead to a similar shape of the mass or molecular mass loss curve. A characteristic time is derived, which can be used to extract the maximum length of soluble fragments l of the polymer. We show that the complete description is needed to extract the degradation rate constant k from the molecular mass loss curve and that l can be used to design polymers that lose less mechanical stability before entering the mass loss phase.
Functionalization of gelatin with glycidylmethacrylate (GMA-gelatin) enables network formation employing the double bond, so that the reaction is orthogonal to the inherent functional groups in the biomacromolecule. Here, network formation by crosslinking of GMA-gelatin with hexane 1,6-dithiol or nonane 1,9-dithiol to tailor properties and enable a shape-memory effect is shown by H-1 NMR and FT-IR spectroscopy. Hydrogel swelling (460-1900 vol%) and mechanical properties (Young's modulus E = 59-512 kPa, elongation at break epsilon(b) = 44-127%) depended on the molecular composition of the networks and temperature. Increased crosslinker length, thiol:methacrylate molar ratio, and precursor concentrations led to denser networks. Change of properties with temperature suggested adoption of triple helices by gelatin chains, forming physical netpoints at lower temperatures (< 20 degrees C). However, the limited freedom of the gelatin chains to move allowed only a minimal extent of triple helices formation, as it became apparent from the related signal in wide-angle X-ray scattering and the thermal transition associated to triple helices in some networks by DSC. The presented strategy is likely transferable to other biomacromolecules, and the results suggest that too short crosslinkers may result in a significant amount of grafting rather than network formation.
Effect of endothelial culture medium composition on platelet responses to polymeric biomaterials
(2021)
Near-physiological in vitro thrombogenicity test systems for the evaluation of blood-contacting endothelialized biomaterials requires co-cultivation with platelets (PLT). However, the addition of PLT has led to unphysiological endothelial cell (EC) detachment in such in vitro systems. A possible cause for this phenomenon may be PLT activation triggered by the applied endothelial cell medium, which typically consists of basal medium (BM) and nine different supplements. To verify this hypothesis, the influence of BM and its supplements was systematically analyzed regarding PLT responses. For this, human platelet rich plasma (PRP) was mixed with BM, BM containing one of nine supplements, or with BM containing all supplements together. PLT adherence analysis was carried out in six-channel slides with plasma-treated cyclic olefin copolymer (COC) and poly(tetrafluoro ethylene) (PTFE, as a positive control) substrates as part of the six-channel slides in the absence of EC and under static conditions. PLT activation and aggregation were analyzed using light transmission aggregometry and flow cytometry (CD62P). Medium supplements had no effect on PLT activation and aggregation. In contrast, supplements differentially affected PLT adherence, however, in a polymer- and donor-dependent manner. Thus, the use of standard endothelial growth medium (BM + all supplements) maintains functionality of PLT under EC compatible conditions without masking the differences of PLT adherence on different polymeric substrates. These findings are important prerequisites for the establishment of a near-physiological in vitro thrombogenicity test system assessing polymer-based cardiovascular implant materials in contact with EC and PLT.