TY  - JOUR
A1  - Zhang, Zishuai
A1  - Ye, Siyu
A1  - Gbureck, Uwe
A1  - Barralet, Jake E.
A1  - Merle, Géraldine
T1  - Cavitation Mediated 3D Microstructured Architectures from Nanocarbon
JF  - Advanced Functional Materials
N2  - Here, the formation of high surface area microscale assemblies of nanocarbon through phosphate and ultrasound cavitation treatment is reported. Despite high conductivity and large surface area, potential health and safety concerns limit the use of nanocarbon and add challenges to handling. Previously, it is shown that phosphate ultrasonic bonding is ineffective for organic materials but in this study, it is found that by a preliminary oxidizing treatment, several carbons can be readily assembled from xerogels. Assembling nanocarbon into microparticles can usually require a binder or surfactants, which can reduce surface area or conductivity and generate a low microsphere yield. Carbon nanotube microspheres are nitrogen-doped and flower-like nanostructured Pt deposited on their surface, and finally showcased as efficient cathode electrocatalysts for the oxygen reduction reaction (half-wave potential 0.78 V vs reversible hydrogen electrode) and methanol oxidation (417 mA mg−1). In particular, no significant degradation of the catalysts is detected after 12 000 cycles (26.6 h). These results indicate the potential of this multimaterial assembly method and open a new way to improve handling of nanoscale materials.
KW  - carbon nanotube microspheres
KW  - cavitation
KW  - oxygen reduction reaction
KW  - platinum nanostructures
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-233926
VL  - 28
ER  - 
TY  - JOUR
A1  - Meininger, Susanne
A1  - Blum, Carina
A1  - Schamel, Martha
A1  - Barralet, Jake E.
A1  - Ignatius, Anita
A1  - Gbureck, Uwe
T1  - Phytic acid as alternative setting retarder enhanced biological performance of dicalcium phosphate cement in vitro
JF  - Scientific Reports
N2  - Dicalcium phosphate cement preparation requires the addition of setting retarders to meet clinical requirements regarding handling time and processability. Previous studies have focused on the influence of different setting modifiers on material properties such as mechanical performance or injectability, while ignoring their influence on biological cement properties as they are used in low concentrations in the cement pastes and the occurrence of most compounds in human tissues. Here, analyses of both material and biological behavior were carried out on samples with common setting retardants (citric acid, sodium pyrophosphate, sulfuric acid) and novel (phytic acid). Cytocompatibility was evaluated by in vitro tests with osteoblastic (hFOB 1.19) and osteoclastic (RAW 264.7) cells. We found cytocompatibility was better for sodium pyrophosphate and phytic acid with a three-fold cell metabolic activity by WST-1 test, whereas samples set with citric acid showed reduced cell number as well as cell activity. The compressive strength (CS) of cements formed with phytic acid (CS = 13 MPa) were nearly equal to those formed with citric acid (CS = 15 MPa) and approximately threefold higher than for other setting retardants. Due to a proven cytocompatibility and high mechanical strength, phytic acid seems to be a candidate replacement setting retardant for dicalcium phosphate cements.
KW  - implants
KW  - biomedical materials
KW  - dicalcium phosphate cement
KW  - phytic acid
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-171047
VL  - 7
IS  - 558
ER  -