@article{RajuLiebigKlemkeetal.2020, author = {Raju, Rajarshi Roy and Liebig, Ferenc and Klemke, Bastian and Koetz, Joachim}, title = {Ultralight magnetic aerogels from Janus emulsions}, series = {RSC Advances}, volume = {10}, journal = {RSC Advances}, number = {13}, publisher = {RSC Publishing}, address = {London}, issn = {2046-2069}, doi = {10.1039/c9ra10247g}, pages = {7492 -- 7499}, year = {2020}, abstract = {Magnetite containing aerogels were synthesized by freeze-drying olive oil/silicone oil-based Janus emulsion gels containing gelatin and sodium carboxymethylcellulose (NaCMC). The magnetite nanoparticles dispersed in olive oil are processed into the gel and remain in the macroporous aerogel after removing the oil components. The coexistence of macropores from the Janus droplets and mesopores from freeze-drying of the hydrogels in combination with the magnetic properties offer a special hierarchical pore structure, which is of relevance for smart supercapacitors, biosensors, and spilled oil sorption and separation. The morphology of the final structure was investigated in dependence on initial compositions. More hydrophobic aerogels with magnetic responsiveness were synthesized by bisacrylamide-crosslinking of the hydrogel. The crosslinked aerogels can be successfully used in magnetically responsive clean up experiments of the cationic dye methylene blue.}, language = {en} } @article{LiebigSarhanBargheeretal.2020, author = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Bargheer, Matias and Schmitt, Clemens Nikolaus Zeno and Poghosyan, Armen H. and Shahinyanf, Aram A. and Koetz, Joachim}, title = {Spiked gold nanotriangles}, series = {RSC Advances}, volume = {10}, journal = {RSC Advances}, number = {14}, publisher = {RSC Publishing}, address = {London}, issn = {2046-2069}, doi = {10.1039/d0ra00729c}, pages = {8152 -- 8160}, year = {2020}, abstract = {We show the formation of metallic spikes on the surface of gold nanotriangles (AuNTs) by using the same reduction process which has been used for the synthesis of gold nanostars. We confirm that silver nitrate operates as a shape-directing agent in combination with ascorbic acid as the reducing agent and investigate the mechanism by dissecting the contribution of each component, i.e., anionic surfactant dioctyl sodium sulfosuccinate (AOT), ascorbic acid (AA), and AgNO3. Molecular dynamics (MD) simulations show that AA attaches to the AOT bilayer of nanotriangles, and covers the surface of gold clusters, which is of special relevance for the spike formation process at the AuNT surface. The surface modification goes hand in hand with a change of the optical properties. The increased thickness of the triangles and a sizeable fraction of silver atoms covering the spikes lead to a blue-shift of the intense near infrared absorption of the AuNTs. The sponge-like spiky surface increases both the surface enhanced Raman scattering (SERS) cross section of the particles and the photo-catalytic activity in comparison with the unmodified triangles, which is exemplified by the plasmon-driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4'-dimercaptoazobenzene (DMAB).}, language = {en} } @article{HenningLiebigPrietzeletal.2020, author = {Henning, Ricky and Liebig, Ferenc and Prietzel, Claudia Christina and Klemke, Bastian and Koetz, Joachim}, title = {Gold nanotriangles with magnetite satellites}, series = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, volume = {600}, journal = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2020.124913}, pages = {7}, year = {2020}, abstract = {This work describes the synthesis of hybrid particles of gold nanotriangles (AuNTs) with magnetite nanoparticles (MNPs) by using 1-mercaptopropyl-3-trimethoxysilan (MPTMS) and L-cysteine as linker molecules. Due to the combination of superparamagnetic properties of MNPs with optical properties of the AuNTs, nanoplatelet-satellite hybrid nanostructures with combined features become available. By using MPTMS with silan groups as linker molecule a magnetic "cloud" with embedded AuNTs can be separated. In presence of L-cysteine as linker molecule at pH > pH(iso) a more unordered aggregate structure of MNPs is obtained due to the dimerization of the L-cysteine. At pH < pH(iso) water soluble positively charged AuNTs with satellite MNPs can be synthesized. The time-dependent loading with MNP satellites under release of the extinction and magnetization offer a hybrid material, which is of special relevance for biomedical applications and plasmonic catalysis.}, language = {en} } @article{LiebigSarhanSchmittetal.2020, author = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Schmitt, Clemens Nikolaus Zeno and Th{\"u}nemann, Andreas F. and Prietzel, Claudia Christina and Bargheer, Matias and Koetz, Joachim}, title = {Gold nanotriangles with crumble topping and their influence on catalysis and surface-enhanced raman spectroscopy}, series = {ChemPlusChem}, volume = {85}, journal = {ChemPlusChem}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2192-6506}, doi = {10.1002/cplu.201900745}, pages = {519 -- 526}, year = {2020}, abstract = {By adding hyaluronic acid (HA) to dioctyl sodium sulfosuccinate (AOT)-stabilized gold nanotriangles (AuNTs) with an average thickness of 7.5 +/- 1 nm and an edge length of about 175 +/- 17 nm, the AOT bilayer is replaced by a polymeric HA-layer leading to biocompatible nanoplatelets. The subsequent reduction process of tetrachloroauric acid in the HA-shell surrounding the AuNTs leads to the formation of spherical gold nanoparticles on the platelet surface. With increasing tetrachloroauric acid concentration, the decoration with gold nanoparticles can be tuned. SAXS measurements reveal an increase of the platelet thickness up to around 14.5 nm, twice the initial value of bare AuNTs. HRTEM micrographs show welding phenomena between densely packed particles on the platelet surface, leading to a crumble formation while preserving the original crystal structure. Crumbles crystallized on top of the platelets enhance the Raman signal by a factor of around 20, and intensify the plasmon-driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4 '-dimercaptoazobenzene in a yield of up to 50 \%. The resulting crumbled nanotriangles, with a biopolymer shell and the absorption maximum in the second window for in vivo imaging, are promising candidates for biomedical sensing.}, language = {en} }