TY - JOUR A1 - Kneipp, Janina A1 - Kneipp, H. A1 - Rajadurai, A. A1 - Redmond, R.W. A1 - Kneipp, K. T1 - Optical probing and imaging of live cells using SERS labels N2 - During surface-enhanced Raman scattering (SERS), molecules exhibit a significant increase in their Raman signals when attached, or in very close vicinity, to gold or silver nanostructures. This effect is exploited as the basis of a new class of optical labels. Here we demonstrate robust and sensitive SERS labels as probes for imaging live cells. These hybrid labels consist of gold nanoparticles with Rose Bengal or Crystal Violet attached as reporter molecules. These new labels are stable and nontoxic, do not suffer from photobleaching, and can be excited at any excitation wavelength, even in the near infrared. SERS labels can be detected and imaged through the specific Raman signatures of the reporters. In addition, surface-enhanced Raman spectroscopy in the local optical fields of the gold nanoparticles also provides sensitive information on the immediate molecular environment of the label in the cell and allows imaging of the native constituents of the cell. This is demonstrated by images based on a characteristic Raman line of the reporter as well as by displaying lipids based on the SERS signal of the C—H deformation/bending modes at ~ 1470 cm-1. KW - Surface-enhanced Raman scattering KW - Gold nanoparticles KW - Cells KW - SERS imaging PY - 2008 DO - https://doi.org/10.1002/jrs.2060 SN - 0377-0486 SN - 1097-4555 IS - -Early View- SP - 1 EP - 5 PB - Wiley CY - Chichester AN - OPUS4-18232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Zhiyang A1 - Merk, V. A1 - Müller, Anja A1 - Unger, Wolfgang A1 - Kneipp, Janina T1 - Role of metal cations in plasmon-catalyzed oxidation: A case study of p-aminothiophenol dimerization N2 - The mechanism of the plasmon-catalyzed reaction of p-aminothiophenol (PATP) to 4,4′-dimercaptoazobenzene (DMAB) on the surface of metal nanoparticles has been discussed using data from surface-enhanced Raman scattering of DMAB. Oxides and hydroxides formed in a plasmon-catalyzed process were proposed to play a central role in the reaction. Here, we report DMAB formation on gold nanoparticles occurring in the presence of the metal cations Ag+, Au3+, Pt4+, and Hg2+. The experiments were carried out under conditions where formation of gold oxide or hydroxide from the nanoparticles can be excluded and at high pH where the formation of the corresponding oxidic species from the metal ions is favored. On the basis of our results, we conclude that, under these conditions, the selective oxidation of PATP to DMAB takes place via formation of a metal oxide from the ionic species in a plasmon-catalyzed process. By evidencing the necessity of the presence of the metal cations, the reported results underpin the importance of metal oxides in the reaction. KW - Metal ions KW - Plasmonic catalysis KW - p-aminothiophenol KW - 4,4'-dimercaptoazobenzene KW - Surface-enhanced Raman scattering PY - 2017 UR - http://pubs.acs.org/doi/abs/10.1021/acscatal.7b02700 DO - https://doi.org/10.1021/acscatal.7b02700 SN - 2155-5435 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. VL - 7 IS - 11 SP - 7803 EP - 7809 PB - American Chemical Society CY - Washington AN - OPUS4-43001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Matschulat, Andrea A1 - Drescher, Daniela A1 - Kneipp, Janina T1 - Surface-enhanced Raman scattering hybrid nanoprobe multiplexing and imaging in biological systems N2 - Surface-enhanced Raman scattering (SERS) labels and probes consisting of gold and silver nanoaggregates and attached reporter molecules can be identified by the Raman signature of the reporter molecule. At the same time, SERS hybrid probes deliver sensitive molecular structural information on their nanoenvironment. Here we demonstrate full exploitation of the multifunctional and multiplexing capabilities inherent to such nanoprobes by applying cluster methods and principal components approaches for discrimination beyond the visual inspection of individual spectra that has been practiced so far. The reported results indicate that fast, multivariate evaluation of whole sets of multiple probes is feasible. Spectra of five different reporters were shown to be separable by hierarchical clustering and by principal components analysis (PCA). In a duplex imaging approach in live cells, hierarchical cluster analysis, K-means clustering, and PCA were used for imaging the positions of different types of SERS probes along with the spectral information from cellular constituents. Parallel to cellular imaging experiments, cytotoxicity of the SERS hybrid probes containing aromatic thiols as reporters is assessed. The reported results suggest multiplexing applications of the nontoxic SERS nanoprobes in high density sensing and imaging in complex biological structures. KW - Surface-enhanced Raman scattering KW - Nanosensor KW - Para-aminobenzenethiol KW - 2-naphthalenethiol KW - 3T3 cells KW - Principal component analysis KW - Hierarchical cluster analysis KW - Cytotoxicity KW - Imaging PY - 2010 DO - https://doi.org/10.1021/nn100280z SN - 1936-0851 VL - 4 IS - 6 SP - 3259 EP - 3269 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-23212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simo, A. A1 - Merk, Virginia A1 - Fenger, R. A1 - Kneipp, Janina A1 - Rademann, K. T1 - Long-term stable silver subsurface ion-exchanged glasses for SERS applications N2 - We report on the formation of silver subsurface ion-exchanged metal oxide (silver SIMO) glasses and their surface-enhanced Raman scattering (SERS) activity. The samples were prepared by a combined thermal and chemical three-step methodology and characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), environmental electron scanning microscopy (ESEM), and UV/Vis spectroscopy. This unique method provides SERS substrates with protection against contamination and strong, reliable and reproducible SERS enhancement. The Raman enhancement factors of the long-term stable SIMO glasses were estimated to approximately 107. KW - AFM/TEM/SEM KW - Ion-exchange KW - Nanoparticles KW - Glasses KW - Surface-enhanced Raman scattering PY - 2011 DO - https://doi.org/10.1002/cphc.201100098 SN - 1439-4235 N1 - Geburtsname von Merk, Virginia: Joseph, V. - Birth name of Merk, Virginia: Joseph, V. VL - 12 IS - 9 SP - 1683 EP - 1688 PB - Wiley-VCH CY - Weinheim AN - OPUS4-23872 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Joseph, Viginia A1 - Matschulat, Andrea A1 - Polte, Jörg A1 - Rolf, Simone A1 - Emmerling, Franziska A1 - Kneipp, Janina T1 - SERS enhancement of gold nanospheres of defined size N2 - Monodisperse, citrate-stabilized gold nanoparticles of sizes ranging from 15 to 40 nm were synthesized and characterized by small angle X-ray scattering and UV-vis experiments. Identical surface properties of nanoparticles of different sizes to avoid variation in the chemical surface-enhanced Raman scattering (SERS) enhancement, as well as selection of experimental conditions so that no aggregation took place, enabled the investigation of enhancement of individual nanospheres. Enhancement factors (EFs) for SERS were determined using the dye crystal violet (CV). EFs for individual gold nanospheres ranged from 102 to 103, in agreement with theoretical predictions. An increase of the EFs of individual spheres with size can be correlated to changes in the extinction spectra of nanoparticle solutions. This confirms that the increase in enhancement with increasing size results from an increase in electromagnetic enhancement. Beyond this dependence of EFs of isolated gold spheres on their size, EFs were shown to vary with analyte concentration as a result of analyte-induced aggregation. This has implications for the application of nanoparticle solutions as SERS substrates in quantitative analytical tasks. KW - Surface-enhanced Raman scattering KW - Electromagnetic enhancement factor KW - Crystal violet KW - Citrate reduction KW - Gold nanoparticles PY - 2011 DO - https://doi.org/10.1002/jrs.2939 SN - 0377-0486 SN - 1097-4555 VL - 42 IS - 9 SP - 1736 EP - 1742 PB - Wiley CY - Chichester AN - OPUS4-24483 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eichelbaum, M. A1 - Kneipp, Janina A1 - Schmidt, B.E. A1 - Panne, Ulrich A1 - Rademann, K. T1 - SERS and Multiphoton-Induced Luminescence of Gold Micro- and Nanostructures Fabricated by NIR Femtosecond-Laser Irradiation KW - Gold KW - Luminescence KW - Multiphoton fabrication KW - Sol-gel processes KW - Surface-enhanced Raman scattering PY - 2008 DO - https://doi.org/10.1002/cphc.200800417 SN - 1439-4235 SN - 1439-7641 VL - 9 IS - 15 SP - 2163 EP - 2167 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-18233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Drescher, Daniela A1 - Zeise, Ingrid A1 - Traub, Heike A1 - Guttmann, P. A1 - Seifert, Stephan A1 - Büchner, Tina A1 - Jakubowski, Norbert A1 - Schneider, G. A1 - Kneipp, Janina T1 - In situ characterization of SiO2 nanoparticle biointeractions using BrightSilica N2 - By adding a gold core to silica nanoparticles (BrightSilica), silica-like nanoparticles are generated that, unlike unmodified silica nanoparticles, provide three types of complementary information to investigate the silica nano-biointeraction inside eukaryotic cells in situ. Firstly, organic molecules in proximity of and penetrating into the silica shell in live cells are monitored by surface-enhanced Raman scattering (SERS). The SERS data show interaction of the hybrid silica particles with tyrosine, cysteine and phenylalanine side chains of adsorbed proteins. Composition of the biomolecular corona of BrightSilica nanoparticles differs in fibroblast and macrophage cells. Secondly, quantification of the BrightSilica nanoparticles using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) micromapping indicates a different interaction of silica nanoparticles compared to gold nanoparticles under the same experimental conditions. Thirdly, the metal cores allow the investigation of particle distribution and interaction in the cellular ultrastructure by cryo nanoscale X-ray tomography (cryo-XT). In 3D reconstructions the assumption is confirmed that BrightSilica nanoparticles enter cells by an endocytotic mechanism. The high SERS intensities are explained by the beneficial plasmonic properties due to agglomeration of BrightSilica. The results have implications for the development of multi-modal qualitative and quantitative characterization in comparative nanotoxicology and bionanotechnology. KW - Silica nanoparticles KW - Surface-enhanced Raman scattering KW - X-ray tomography KW - LA-ICP-MS KW - Core–shell structures PY - 2014 DO - https://doi.org/10.1002/adfm.201304126 SN - 1616-301X SN - 1616-3028 VL - 24 IS - 24 SP - 3765 EP - 3775 PB - Wiley-VCH CY - Weinheim AN - OPUS4-30924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Büchner, Tina A1 - Drescher, Daniela A1 - Traub, Heike A1 - Schrade, P. A1 - Bachmann, S. A1 - Jakubowski, Norbert A1 - Kneipp, Janina T1 - Relating surface-enhanced Raman scattering signals of cells to gold nanoparticle aggregation as determined by LA-ICP-MS micromapping N2 - The cellular response to nanoparticle exposure is essential in various contexts, especially in nanotoxicity and nanomedicine. Here, 14-nm gold nanoparticles in 3T3 fibroblast cells are investigated in a series of pulse-chase experiments with a 30-min incubation pulse and chase times ranging from 15 min to 48 h. The gold nanoparticles and their aggregates are quantified inside the cellular ultrastructure by laser ablation inductively coupled plasma mass spectrometry micromapping and evaluated regarding the surface-enhanced Raman scattering (SERS) signals. In this way, both information about their localization at the micrometre scale and their molecular nanoenvironment, respectively, is obtained and can be related. Thus, the nanoparticle pathway from endocytotic uptake, intracellular processing, to cell division can be followed. It is shown that the ability of the intracellular nanoparticles and their accumulations and aggregates to support high SERS signals is neither directly related to nanoparticle amount nor to high local nanoparticle densities. The SERS data indicate that aggregate geometry and interparticle distances in the cell must change in the course of endosomal maturation and play a critical role for a specific gold nanoparticle type in order to act as efficient SERS nanoprobe. This finding is supported by TEM images, showing only a minor portion of aggregates that present small interparticle spacing. The SERS spectra obtained after different chase times show a changing composition and/or structure of the biomolecule corona of the gold nanoparticles as a consequence of endosomal processing. KW - Gold nanoparticles KW - Surface-enhanced Raman scattering KW - LA-ICP-MS KW - Fibroblast KW - Cell KW - Particle aggregation KW - Endosome PY - 2014 DO - https://doi.org/10.1007/s00216-014-8069-0 SN - 1618-2642 SN - 1618-2650 VL - 406 IS - 27 SP - 7003 EP - 7014 PB - Springer CY - Berlin AN - OPUS4-31718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -