@article{FrascaRojasSalewskietal.2012,
  author    = {Frasca, Stefano and Rojas, Oscar and Salewski, Johannes and Neumann, Bettina and Stiba, Konstanze and Weidinger, Inez M. and Tiersch, Brigitte and Leimk{\"u}hler, Silke and Koetz, Joachim and Wollenberger, Ursula},
  title     = {Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode},
  series = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  volume    = {87},
  journal   = {Bioelectrochemistry : an international journal devoted to electrochemical aspects of biology and biological aspects of electrochemistry ; official journal of the Bioelectrochemical Society},
  publisher = {Elsevier},
  address   = {Lausanne},
  issn      = {1567-5394},
  doi       = {10.1016/j.bioelechem.2011.11.012},
  pages     = {33 -- 41},
  year      = {2012},
  abstract  = {The present study reports a facile approach for sulfite biosensing, based on enhanced direct electron transfer of a human sulfite oxidase (hSO) immobilized on a gold nanoparticles modified electrode. The spherical core shell AuNPs were prepared via a new method by reduction of HAuCl4 with branched poly(ethyleneimine) in an ionic liquids resulting particles with a diameter less than 10 nm. These nanoparticles were covalently attached to a mercaptoundecanoic acid modified Au-electrode where then hSO was adsorbed and an enhanced interfacial electron transfer and electrocatalysis was achieved. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry, are employed for the characterization of the system and reveal no perturbation of the structural integrity of the redox protein. The proposed biosensor exhibited a quick steady-state current response, within 2 s, a linear detection range between 0.5 and 5.4 mu M with a high sensitivity (1.85 nA mu M-1). The investigated system provides remarkable advantages in the possibility to work at low applied potential and at very high ionic strength. Therefore these properties could make the proposed system useful in the development of bioelectronic devices and its application in real samples.},
  language  = {en}
}
@article{TheteRojasNeumeyeretal.2013,
  author    = {Thete, Aniket and Rojas, Oscar and Neumeyer, David and Koetz, Joachim and Dujardin, Erik},
  title     = {Ionic liquid-assisted morphosynthesis of gold nanorods using polyethyleneimine-capped seeds},
  series = {RSC Advances},
  volume    = {3},
  journal   = {RSC Advances},
  number    = {34},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2046-2069},
  doi       = {10.1039/c3ra22112a},
  pages     = {14294 -- 14298},
  year      = {2013},
  abstract  = {Seed-mediated gold nanorods with tunable lengths are prepared using new polyethyleneimine-capped gold nanoparticles synthesized in ionic liquid. The effect of polyethyleneimine and ionic liquid during nanorod growth is investigated and shows a marked effect on their final aspect ratio.},
  language  = {en}
}
@article{DolyaRojasKosmellaetal.2013,
  author    = {Dolya, Natalya and Rojas, Oscar and Kosmella, Sabine and Tiersch, Brigitte and Koetz, Joachim and Kudaibergenov, Sarkyt},
  title     = {"One-Pot" in situ frmation of Gold Nanoparticles within Poly(acrylamide) Hydrogels},
  series = {Macromolecular chemistry and physics},
  volume    = {214},
  journal   = {Macromolecular chemistry and physics},
  number    = {10},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1022-1352},
  doi       = {10.1002/macp.201200727},
  pages     = {1114 -- 1121},
  year      = {2013},
  abstract  = {This paper focuses on two different strategies to incorporate gold nanoparticles (AuNPs) into the matrix of polyacrylamide (PAAm) hydrogels. Poly(ethyleneimine) (PEI) is used as both reducing and stabilizing agent for the formation of AuNPs. In addition, the influence of an ionic liquid (IL) (i.e., 1-ethyl-3-methylimidazolium ethylsulfate) on the stability of the nanoparticles and their immobilization in the hydrogel is investigated The results show that AuNPs surrounded by a shell containing PEI and IL, synthesized according to the one-pot approach, are much better immobilized within the PAAm hydrogel. Hereby, the IL is responsible for structural changes in the hydrogel as well as the improved stabilization and embedding of the AuNPs into the polymer gel matrix.},
  language  = {en}
}
@article{RojasTierschRabeetal.2013,
  author    = {Rojas, Oscar and Tiersch, Brigitte and Rabe, Christian and Stehle, Ralf and Hoell, Armin and Arlt, Bastian and Koetz, Joachim},
  title     = {Nonaqueous Microemulsions Based on N,N '-Alkylimidazolium Alkylsulfate Ionic Liquids},
  series = {Langmuir},
  volume    = {29},
  journal   = {Langmuir},
  number    = {23},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/la401080q},
  pages     = {6833 -- 6839},
  year      = {2013},
  abstract  = {The ternary system composed of the ionic liquid surfactant (IL-S) 1-butyl-3-methylimidazolium dodecylsulfate ([Bmim][DodSO(4)]), the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO4]), and toluene has been investigated. Three major mechanisms guiding the structure of the isotropic phase were identified by means of conductometric experiments, which have been correlated to the presence of oil-in-IL, bicontinuous, and IL-in-oil microemulsions. IL-S forms micelles in toluene, which swell by adding RTIL as to be shown by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) experiments. Therefore, it is possible to form water free IL-in-oil reverse microemulsions <= 10 nm in size as a new type of nanoreactor.},
  language  = {en}
}
@article{TheteRojasNeumeyeretal.2013,
  author    = {Thete, Aniket and Rojas, Oscar and Neumeyer, David and Koetz, Joachim and Dujardin, Erik},
  title     = {Ionic liquid-assisted morphosynthesis of gold nanorods using polyethyleneimine-capped seeds},
  doi       = {10.1039/C3RA22112A},
  year      = {2013},
  abstract  = {Seed-mediated gold nanorods with tunable lengths are prepared using new polyethyleneimine-capped gold nanoparticles synthesized in ionic liquid. The effect of polyethyleneimine and ionic liquid during nanorod growth is investigated and shows a marked effect on their final aspect ratio.},
  language  = {en}
}
@article{RojasKoetzKosmellaetal.2009,
  author    = {Rojas, Oscar and Koetz, Joachim and Kosmella, Sabine and Tiersch, Brigitte and Wacker, Philipp and Kramer, Markus},
  title     = {Structural studies of ionic liquid-modified microemulsions},
  issn      = {0021-9797},
  doi       = {10.1016/j.jcis.2009.02.039},
  year      = {2009},
  abstract  = {This work is focused on the influence of an ionic liquid (IL), i.e. ethyl-methylimidazolium hexylsulfate, on the spontaneous formation of microemulsions with ionic surfactants. The influence of the ionic liquid on Structure formation in the optically clear phase region in water/toluene/pentanol mixtures in presence of the cationic surfactant CTAB was studied in more detail. The results show a significant increase of the transparent phase region by adding the ionic liquid. Conductometric investigations demonstrate that adding the ionic liquid can drastically reduce the droplet- droplet interactions in the L-2 phase. H-1 nuclear magnetic resonance (H-1 NMR) diffusion coefficient measurements in combination with dynamic light scattering measurements clearly show that inverse microemulsion droplets still exist, but the droplet size is decreased to 2 nm. A more detailed characterisation of the isotropic phase channel by means of conductivity measurements, dynamic light scattering (DLS), H-1 NMR and cryo-scanning electron microscopy (SEM), allows the identification of a bicontinuous sponge phase between the L-1 and L-2 phase. When the poly(ethyleneimine) is added, the isotropic phase range is reduced drastically, but the inverse microemulsion range still exists.},
  language  = {en}
}