TY  - JOUR
A1  - Geffers, Martha
A1  - Groll, Jürgen
A1  - Gbureck, Uwe
T1  - Reinforcement strategies for load-bearing calcium phosphate biocements
JF  - Materials
N2  - Calcium phosphate biocements based on calcium phosphate chemistry are well-established biomaterials for the repair of non-load bearing bone defects due to the brittle nature and low flexural strength of such cements. This article features reinforcement strategies of biocements based on various intrinsic or extrinsic material modifications to improve their strength and toughness. Altering particle size distribution in conjunction with using liquefiers reduces the amount of cement liquid necessary for cement paste preparation. This in turn decreases cement porosity and increases the mechanical performance, but does not change the brittle nature of the cements. The use of fibers may lead to a reinforcement of the matrix with a toughness increase of up to two orders of magnitude, but restricts at the same time cement injection for minimal invasive application techniques. A novel promising approach is the concept of dual-setting cements, in which a second hydrogel phase is simultaneously formed during setting, leading to more ductile cement-hydrogel composites with largely unaffected application properties.
KW  - in vitro
KW  - synergistic reinforcement
KW  - dihydrate cement
KW  - porosity
KW  - mechanical properties
KW  - dual setting
KW  - calcium phosphate cements
KW  - fiber reinforcement
KW  - polyacrylic acid
KW  - compressive strength
KW  - balloon kyphoplasty
KW  - brushite cement
KW  - bone cement
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148636
VL  - 8
ER  - 
TY  - JOUR
A1  - Hochleitner, Gernot
A1  - Jüngst, Tomasz
A1  - Brown, Toby D
A1  - Hahn, Kathrin
A1  - Moseke, Claus
A1  - Jakob, Franz
A1  - Dalton, Paul D
A1  - Groll, Jürgen
T1  - Additive manufacturing of scaffolds with sub-micron filaments via melt electrospinning writing
JF  - Biofabrication
N2  - The aim of this study was to explore the lower resolution limits of an electrohydrodynamic process combined with direct writing technology of polymer melts. Termed melt electrospinning writing, filaments are deposited layer-by-layer to produce discrete three-dimensional scaffolds for in vitro research. Through optimization of the parameters (flow rate, spinneret diameter, voltage, collector distance) for poly-ϵ-caprolactone, we could direct-write coherent scaffolds with ultrafine filaments, the smallest being 817 ± 165 nm. These low diameter filaments were deposited to form box-structures with a periodicity of 100.6 ± 5.1 μm and a height of 80 μm (50 stacked filaments; 100 overlap at intersections). We also observed oriented crystalline regions within such ultrafine filaments after annealing at 55 °C. The scaffolds were printed upon NCO-sP(EO-stat-PO)-coated glass slide surfaces and withstood frequent liquid exchanges with negligible scaffold detachment for at least 10 days in vitro.
KW  - additive manufacturing
KW  - 3D printing
KW  - biodegradable polymers
KW  - microstructures
KW  - nanostructures
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-254053
VL  - 7
IS  - 3
ER  -