@article{ZivanovicKochovskiArenzetal.2018,
  author    = {Zivanovic, Vesna and Kochovski, Zdravko and Arenz, Christoph and Lu, Yan and Kneipp, Janina},
  title     = {SERS and Cryo-EM Directly Reveal Different Liposome Structures during Interaction with Gold Nanoparticles},
  series = {The journal of physical chemistry letters},
  volume    = {9},
  journal   = {The journal of physical chemistry letters},
  number    = {23},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1948-7185},
  doi       = {10.1021/acs.jpclett.8b03191},
  pages     = {6767 -- 6772},
  year      = {2018},
  abstract  = {The combination of gold nanoparticles with liposomes is important for nano- and biotechnology. Here, we present direct, label-free characterization of liposome structure and composition at the site of its interaction with citrate-stabilized gold nanoparticles by surface-enhanced Raman scattering (SERS) and cryogenic electron microscopy (cryo-EM). Evidenced by the vibrational spectra and cryo-EM, the gold nanoparticles destroy the bilayer structure of interacting liposomes in the presence of a high amount of citrate, while at lower citrate concentration the nanoparticles interact with the surface of the intact liposomes. The spectra of phosphatidylcholine and phosphatidylcholine/sphingomyelin liposomes show that at the site of interaction the lipid chains are in the gel phase. The SERS spectra indicate that cholesterol has strong effects on the contacts of the vesicles with the nanoparticles. By combining cryo-EM and SERS, the structure and properties of lipid nanoparticle composites could be tailored for the development of drug delivery systems.},
  language  = {en}
}
@misc{HeckKanehiraKneippetal.2019,
  author    = {Heck, Christian and Kanehira, Yuya and Kneipp, Janina and Bald, Ilko},
  title     = {Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures},
  series = {Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Mathematisch-Naturwissenschaftliche Reihe},
  number    = {732},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43081},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-430812},
  pages     = {10},
  year      = {2019},
  abstract  = {Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.},
  language  = {en}
}
@article{HeckKanehiraKneippetal.2019,
  author    = {Heck, Christian and Kanehira, Yuya and Kneipp, Janina and Bald, Ilko},
  title     = {Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures},
  series = {Molecules},
  volume    = {24},
  journal   = {Molecules},
  number    = {12},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1420-3049},
  doi       = {10.3390/molecules24122324},
  pages     = {10},
  year      = {2019},
  abstract  = {Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.},
  language  = {en}
}
@article{HeckKanehiraKneippetal.2018,
  author    = {Heck, Christian and Kanehira, Yuya and Kneipp, Janina and Bald, Ilko},
  title     = {Placement of Single Proteins within the SERS Hot Spots of Self-Assembled Silver Nanolenses},
  series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition},
  volume    = {57},
  journal   = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition},
  number    = {25},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1433-7851},
  doi       = {10.1002/anie.201801748},
  pages     = {7444 -- 7447},
  year      = {2018},
  abstract  = {This study demonstrates the bottom-up synthesis of silver nanolenses. A robust coating protocol enabled the functionalization of differently sized silver nanoparticles with DNA single strands of orthogonal sequence. Coated particles 10nm, 20nm, and 60nm in diameter were self-assembled by DNA origami scaffolds to form silver nanolenses. Single molecules of the protein streptavidin were selectively placed in the gap of highest electric field enhancement. Streptavidin labelled with alkyne groups served as model analyte in surface-enhanced Raman scattering (SERS) experiments. By correlated Raman mapping and atomic force microscopy, SERS signals of the alkyne labels of a single streptavidin molecule, from a single silver nanolens, were detected. The discrete, self-similar aggregates of solid silver nanoparticles are promising for plasmonic applications.},
  language  = {en}
}
@article{HeckPrinzDatheetal.2017,
  author    = {Heck, Christian and Prinz, Julia and Dathe, Andre and Merk, Virginia and Stranik, Ondrej and Fritzsche, Wolfgang and Kneipp, Janina and Bald, Ilko},
  title     = {Gold Nanolenses Self-Assembled by DNA Origami},
  series = {ACS Photonics},
  volume    = {4},
  journal   = {ACS Photonics},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {2330-4022},
  doi       = {10.1021/acsphotonics.6b00946},
  pages     = {1123 -- 1130},
  year      = {2017},
  abstract  = {Nanolenses are self-similar chains of metal nanoparticles, which can theoretically provide extremely high field enhancements. Yet, the complex structure renders their synthesis challenging and has hampered closer analyses so far. Here, DNA origami is used to self-assemble 10, 20, and 60 nm gold nanoparticles as plasmonic gold nanolenses (AuNLs) in solution and in billions of copies. Three different geometrical arrangements are assembled, and for each of the three designs, surface-enhanced Raman scattering (SERS) capabilities of single AuNLs are assessed. For the design which shows the best properties, SERS signals from the two different internal gaps are compared by selectively placing probe dyes. The highest Raman enhancement is found for the gap between the small and medium nanoparticle, which is indicative of a cascaded field enhancement.},
  language  = {en}
}