TY  - JOUR
A1  - de Ruijter, Mylène
A1  - Hrynevich, Andrei
A1  - Haigh, Jodie N.
A1  - Hochleitner, Gernot
A1  - Castilho, Miguel
A1  - Groll, Jürgen
A1  - Malda, Jos
A1  - Dalton, Paul D.
T1  - Out-of-Plane 3D-Printed Microfibers Improve the Shear Properties of Hydrogel Composites
JF  - Small
N2  - One challenge in biofabrication is to fabricate a matrix that is soft enough to elicit optimal cell behavior while possessing the strength required to withstand the mechanical load that the matrix is subjected to once implanted in the body. Here, melt electrowriting (MEW) is used to direct-write poly(ε-caprolactone) fibers “out-of-plane” by design. These out-of-plane fibers are specifically intended to stabilize an existing structure and subsequently improve the shear modulus of hydrogel–fiber composites. The stabilizing fibers (diameter = 13.3 ± 0.3 µm) are sinusoidally direct-written over an existing MEW wall-like structure (330 µm height). The printed constructs are embedded in different hydrogels (5, 10, and 15 wt% polyacrylamide; 65% poly(2-hydroxyethyl methacrylate) (pHEMA)) and a frequency sweep test (0.05–500 rad s−1, 0.01% strain, n = 5) is performed to measure the complex shear modulus. For the rheological measurements, stabilizing fibers are deposited with a radial-architecture prior to embedding to correspond to the direction of the stabilizing fibers with the loading of the rheometer. Stabilizing fibers increase the complex shear modulus irrespective of the percentage of gel or crosslinking density. The capacity of MEW to produce well-defined out-of-plane fibers and the ability to increase the shear properties of fiber-reinforced hydrogel composites are highlighted.
KW  - biofabrication
KW  - fiber reinforcement
KW  - hydrogels
KW  - mechanical properties
KW  - melt electrowriting
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-223666
VL  - 14
ER  - 
TY  - JOUR
A1  - Diloksumpan, Paweena
A1  - de Ruijter, Mylène
A1  - Castilho, Miguel
A1  - Gbureck, Uwe
A1  - Vermonden, Tina
A1  - van Weeren, P René
A1  - Malda, Jos
A1  - Levato, Riccardo
T1  - Combining multi-scale 3D printing technologies to engineer reinforced hydrogel-ceramic interfaces
JF  - Biofabrication
N2  - Multi-material 3D printing technologies that resolve features at different lengths down to the microscale open new avenues for regenerative medicine, particularly in the engineering of tissue interfaces. Herein, extrusion printing of a bone-biomimetic ceramic ink and melt electrowriting (MEW) of spatially organized polymeric microfibres are integrated for the biofabrication of an osteochondral plug, with a mechanically reinforced bone-to-cartilage interface. A printable physiological temperature-setting bioceramic, based on α-tricalcium phosphate, nanohydroxyapatite and a custom-synthesized biodegradable and crosslinkable poloxamer, was developed as bone support. The mild setting reaction of the bone ink enabled us to print directly within melt electrowritten polycaprolactone meshes, preserving their micro-architecture. Ceramic-integrated MEW meshes protruded into the cartilage region of the composite plug, and were embedded with mechanically soft gelatin-based hydrogels, laden with articular cartilage chondroprogenitor cells. Such interlocking design enhanced the hydrogel-to-ceramic adhesion strength >6.5-fold, compared with non-interlocking fibre architectures, enabling structural stability during handling and surgical implantation in osteochondral defects ex vivo. Furthermore, the MEW meshes endowed the chondral compartment with compressive properties approaching those of native cartilage (20-fold reinforcement versus pristine hydrogel). The osteal and chondral compartment supported osteogenesis and cartilage matrix deposition in vitro, and the neo-synthesized cartilage matrix further contributed to the mechanical reinforcement at the ceramic-hydrogel interface. This multi-material, multi-scale 3D printing approach provides a promising strategy for engineering advanced composite constructs for the regeneration of musculoskeletal and connective tissue interfaces.
KW  - biofabrication
KW  - melt electrowriting
KW  - bioinspired interface
KW  - bone and cartilage tissue engineering
KW  - microfibres
KW  - ceramics
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-254005
VL  - 12
IS  - 2
ER  -