TY - CONF A1 - Heck, Christian A1 - Bald, Ilko A1 - Prinz, J. A1 - Merk, V. A1 - Kneipp, Janina T1 - Gold nanolenses on DNA origami substrates for surface-enhanced Raman scattering N2 - Surface-enhanced Raman scattering (SERS) exploits the enhancement of electromagnetic fields in close vicinity of plasmonic nanostructures, enabling characterization of analytes at the single-molecule level. The nanometer-scale spatial arrangement of plasmonic metal nanoparticles and analyte molecules has a significant effect on the observed signal enhancements and represents a great challenge in this technique. In our work, DNA origami is used as platform for precise positioning of gold nanoparticles (AuNPs). Especially high sensitivities are expected for gold nanolenses (AuNLs), consisting of rows of three or more differently-sized AuNPs. We assembled different AuNL designs and determined respective SERS enhancement factors by collecting Raman spectra from single AuNLs. Finite difference time domain calculations estimate attainable electromagnetic field enhancements. Ultimately, we aim to develop a versatile platform for various SERS applications. T2 - DNA meets Plasmonics Konferenz CY - Bad Honnef, Germany DA - 07.12.2015 KW - DNA origami KW - SERS KW - Plasmonics PY - 2015 AN - OPUS4-35906 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heck, Christian A1 - Bald, Ilko A1 - Prinz, J. A1 - Merk, V. A1 - Kneipp, Janina A1 - Dathe, André A1 - Fritzsche, W. T1 - Plasmonic gold nanolenses self-assembled by DNA origami N2 - Surface-enhanced Raman scattering (SERS) exploits the enhancement of electromagnetic fields in close vicinity of plasmonic nanostructures. The nanometer-scale spatial arrangement of plasmonic metal nanoparticles and analyte molecules has a significant effect on the observed signal enhancements and represents a great challenge in this technique. Especially interesting effects are expected for complex gold nanolenses (AuNLs), consisting of three or more differently-sized AuNPs. We use DNA origami to assemble AuNLs with 10, 20 and 60 nm AuNPs, arranged in three different geometries. Using correlated AFM and Raman spectroscopy, and probing single AuNLs, we systematically examined the SERS properties of the three different assemblies. T2 - DNA Nanotechnology 2016 CY - Jena, Germany DA - 19.05.2016 KW - gold nanoparticles KW - DNA origami KW - plasmonics PY - 2016 AN - OPUS4-36205 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heck, Christian A1 - Kanehira, Y. A1 - Kneipp, Janina A1 - Bald, Ilko T1 - Placement of single proteins within the SERS hot spots of self-assembled silver nanolenses N2 - This study demonstrates the bottom-up synthesis of silver nanolenses.Arobust coating protocol enabled the functionalization of differently sized silver nanoparticles with DNAsingle strands of orthogonal sequence.Coated particles 10 nm, 20 nm, and 60 nm in diameter were self-assembled by DNAorigami 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.Bycorre- lated Raman mapping and atomic force microscopy, SERS signals of the alkyne labels of asingle streptavidin molecule, from asingle silver nanolens,were detected. The discrete,self- similar aggregates of solid silver nanoparticles are promising for plasmonic applications. KW - DNA origami KW - Surface enhanced Raman scattering KW - Protein KW - Single molecule KW - Nanotechnology PY - 2018 DO - https://doi.org/10.1002/anie.201801748 SN - 1433-7851 VL - 57 IS - 25 SP - 7444 EP - 7447 PB - WILEY AN - OPUS4-45743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heck, Christian A1 - Kanehira, Yuya A1 - Kneipp, Janina A1 - Bald, Ilko T1 - Platzierung einzelner Proteine in den SERS-Hot-Spots selbstorganisierte Silbernanolinsen N2 - Diese Studie demonstriert die Bottom-up-Synthese von Silbernanolinsen. Ein robustes Beschichtungsprotokoll ermçglichte die Funktionalisierung unterschiedlich großer Silbernanopartikel mit einzelstr-ngiger DNAunterschiedlicher Sequenz. Derartig beschichtete Partikel mit Durchmessern von 10 nm, 20 nm und 60 nm wurden mithilfe von DNA-Origami- Gergsten zu Silbernanolinsen angeordnet. Ein einzelnes Mo- lekgldes Proteins Streptavidin ist in demjenigen Spalt zwi- schenden Partikeln immobilisiert worden, der die hçchste Feldverst-rkung zur Verfggung stellt. Streptavidin war dabei mit Alkin-Gruppen modifiziert und fungierte als Modellanalyt in Experimenten zur oberfl-chenverst-rkten Raman-Streuung (SERS). Korrelierte Raman- und Rasterkraftmikroskopie- Messungen ermçglichten die Aufnahme von SERS-Signalen der Alkingruppen eines einzelnen Streptavidins,von einer einzelnen Silbernanolinse.Diese diskreten, selbst-hnlichen Silbernanopartikelaggregate versprechen vielf-ltige Anwen- dungen im Feld der Plasmonik KW - DNA Origami KW - Oberflächen verstärkte Raman Streuung KW - Proteine KW - Einzelmolekülspektroskopie KW - Nanotechnologie PY - 2018 DO - https://doi.org/10.1002/ange.201801748 SN - 1521-3757 SN - 0044-8249 VL - 130 IS - 25 SP - 7566 EP - 7569 PB - WILEY AN - OPUS4-45744 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prinz, J. A1 - Heck, Christian A1 - Ellerik, L. A1 - Merk, V. A1 - Bald, Ilko T1 - DNA origami based Au–Ag-core–shell nanoparticle dimers with single-molecule SERS sensitivity N2 - DNA origami nanostructures are a versatile tool to arrange metal nanostructures and other chemical entities with nanometer precision. In this way gold nanoparticle dimers with defined distance can be constructed, which can be exploited as novel substrates for surface enhanced Raman scattering (SERS). We have optimized the size, composition and arrangement of Au/Ag nanoparticles to create intense SERS hot spots, with Raman enhancement up to 10^10, which is sufficient to detect single molecules by Raman scattering. This is demonstrated using single dye molecules (TAMRA and Cy3) placed into the center of the nanoparticle dimers. In conjunction with the DNA origami nanostructures novel SERS substrates are created, which can in the future be applied to the SERS analysis of more complex biomolecular targets, whose position and conformation within the SERS hot spot can be precisely controlled. KW - single molecule spectroscopy KW - DNA origami KW - SERS KW - gold nanoparticles KW - silver nanoparticles PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-358761 UR - http://pubs.rsc.org/en/content/articlelanding/2016/nr/c5nr08674d#!divAbstract DO - https://doi.org/10.1039/C5NR08674D SP - 5612 EP - 5620 PB - Royal Society of Chemistry CY - Cambridge, England AN - OPUS4-35876 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heck, Christian A1 - Kanehira, Y. A1 - Kneipp, Janina A1 - Bald, Ilko T1 - Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures N2 - 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. KW - Amorphous carbon KW - DNA origami KW - SERS KW - Nanoparticle dimers KW - Nanolenses PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-486484 DO - https://doi.org/10.3390/molecules24122324 SN - 1420-3049 VL - 24 IS - 12 SP - Article Number: 2324-1 EP - 10 PB - MDPI AN - OPUS4-48648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heck, Christian A1 - Prinz, Julia A1 - Dathe, A. A1 - Merck, V. A1 - Stranik, O. A1 - Fritzsche, W. A1 - Kneipp, Janina A1 - Bald, Ilko T1 - Gold nanolenses self-assembled by DNA origami N2 - 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. KW - DNA origami KW - SERS KW - Gold nanoparticles KW - Plasmonics PY - 2017 UR - http://pubs.acs.org/doi/pdf/10.1021/acsphotonics.6b00946 DO - https://doi.org/10.1021/acsphotonics.6b00946 SN - 2330-4022 VL - 4 IS - 5 SP - 1123 EP - 1130 AN - OPUS4-40587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogel, Stefanie A1 - Ebel, Kenny A1 - Schürmann, Robin M. A1 - Heck, Christian A1 - Meiling, T. A1 - Milosavljevic, A. A1 - Giuliani, A. A1 - Bald, Ilko T1 - Vacuum-UV and low-energy electron induced DNA strand breaks - Influence of the DNA sequence and substrate N2 - DNA is effectively damaged by radiation, which can on the one hand lead to cancer and is on the other hand directly exploited in the treatment of tumor tissue. DNA strand breaks are already induced by photons having an energy below the ionization energy of DNA. At high photon energies, most of the DNA strand breaks are induced by low-energy secondary electrons. In the present study we quantified photon and electron induced DNA strand breaks in four different 12mer oligonucleotides. They are irradiated directly with 8.44 eV vacuum ultraviolet (VUV) photons and 8.8 eV low energy electrons (LEE). By using Si instead of VUV transparent CaF2 as a substrate the VUV exposure leads to an additional release of LEEs, which have a maximum energy of 3.6 eV and can significantly enhance strand break cross sections. Atomic force microscopy is used to visualize strand breaks on DNA origami platforms and to determine absolute values for the strand break cross sections. Upon irradiation with 8.44 eV photons all the investigated sequences show very similar strand break cross sections in the range of 1.7 - 2.3 x 10-16 cm2. The strand break cross sections for LEE irradiation at 8.8 eV are one to two orders of magnitude larger than the ones for VUV photons, and a slight sequence dependence is observed. The sequence dependence is even more pronounced for LEEs with energies < 3.6 eV. The present results help to assess DNA damage by photons and electrons close to the ionization threshold. KW - Vacuum-UV KW - Low-Energy KW - DNA KW - DNA-Sequence PY - 2019 DO - https://doi.org/10.1002/cphc.201801152 SN - 1439-7641 VL - 20 IS - 6 SP - 823 EP - 830 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-47464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -