TY  - JOUR
A1  - Wischke, Christian
A1  - Baehr, Elen
A1  - Racheva, Miroslava
A1  - Heuchel, Matthias
A1  - Weigel, Thomas
A1  - Lendlein, Andreas
T1  - Surface immobilization strategies for tyrosinase as biocatalyst applicable to polymer network synthesis
JF  - MRS Advances
N2  - Enzymes have recently attracted increasing attention in material research based on their capacity to catalyze the conversion of polymer-bound moieties for synthesizing polymer networks, particularly bulk hydrogels. hi this study. the surface immobilization of a relevant enzyme. mushroom tyrosinase, should be explored using glass as model surface. In a first step. the glass support was functionalized with silanes to introduce either amine or carboxyl groups, as confirmed e.g. by X-ray photoelectron spectroscopy. By applying glutaraldehyde and EDC/NHS chemistry, respectively, surfaces have been activated for subsequent successful coupling of tyrosinase. Via protein hydrolysis and amino acid characterization by HPLC, the quantity of bound tyrosinase was shown to correspond to a full surface coverage. Based on the visualized enzymatic conversion of a test substrate at the glass support. the functionalized surfaces may be explored for surface-associated material synthesis in the future.
Y1  - 2018
U6  - https://doi.org/10.1557/adv.2018.630
SN  - 2059-8521
VL  - 3
IS  - 63
SP  - 3875
EP  - 3881
PB  - Cambridge Univ. Press
CY  - New York
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  - Sauter, Tilman
A1  - Kratz, Karl
A1  - Farhan, Muhammad
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Design and fabrication of fiber mesh actuators
JF  - Applied materials today
N2  - Soft actuator performance can be tuned by chemistry or mechanical manipulation, but this adjustability is limited especially in view of their growing technological relevance. Inspired from textile engineering, we designed and fabricated fiber mesh actuators and introduced new features like anisotropic behavior and soft-tissue like elastic deformability. Design criteria for the meshes are the formation of fiber bundles, the angle between fiber bundles in different stacked layers and covalent crosslinks forming within and between fibers at their interfacial contact areas. Through crosslinking the interfiber bond strength increased from a bond transmitting neither axial nor rotational loads (pin joint) to a bond strength capable of both (welded joint). For non-linear elastic stiffening, stacked fiber bundles with four embracing fibers were created forming microstructural rhombus shapes. Loading the rhombus diagonally allowed generation of “soft tissue”-like mechanics. By adjustment of stacking angles, the point of strong increase in stress is tuned. While the highest stresses are observed in aligned and crosslinked fiber mats along the direction of the fiber, the strongest shape-memory actuation behavior is found in randomly oriented fiber mats. Fiber mesh actuators controlled by temperature are of high significance as soft robot skins and as for active patches supporting tissue regeneration.
Y1  - 2022
U6  - https://doi.org/10.1016/j.apmt.2022.101562
SN  - 2352-9407
VL  - 29
PB  - Elsevier
CY  - Amsterdam
ER  -