TY - JOUR A1 - Kneipp, Janina A1 - Kneipp, H. A1 - Kneipp, K. T1 - Two-photon vibrational spectroscopy for biosciences based on surface-enhanced hyper-Raman scattering JF - Proceedings of the national academy of sciences of the United States of America : PNAS PY - 2006 SN - 0027-8424 SN - 1091-6490 VL - 103 IS - 46 SP - 17149 EP - 17153 PB - National Academy of Sciences CY - Washington, DC AN - OPUS4-13934 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kneipp, Janina A1 - Kneipp, H. A1 - McLaughlin, M. A1 - Brown, D. A1 - Kneipp, K. T1 - In Vivo Molecular Probing of Cellular Compartments with Gold Nanoparticles and Nanoaggregates JF - Nano letters N2 - Surface-enhanced Raman (SERS) signatures were measured from single living cells at different times after the uptake of gold nanoparticles. The spectra are indicative of chemical changes in the environment of the nanostructures over time. The increase of the SERS signal strength and parallel TEM studies indicate the formation of nanoaggregates providing optimum SERS enhancement for ultrasensitive probing inside the endosomal compartment. The results have implications for medical and biotechnology applications of SERS nanosensors in cells. PY - 2006 DO - https://doi.org/10.1021/nl061517x SN - 1530-6984 SN - 1530-6992 VL - 6 IS - 10 SP - 2225 EP - 2231 PB - American Chemical Society CY - Washington, DC AN - OPUS4-13935 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kneipp, Janina A1 - Kneipp, H. A1 - Wittig, B. A1 - Kneipp, K. T1 - One- and Two-Photon Excited Optical pH Probing for Cells Using Surface-Enhanced Raman and Hyper-Raman Nanosensors JF - Nano letters N2 - We demonstrate spatially resolved probing and imaging of pH in live cells by mobile and biocompatible nanosensors using surface-enhanced Raman scattering (SERS) of 4-mercaptobenzoic acid (pMBA) on gold nanoaggregates. Moreover, we also show that this concept of pH nanosensors can be extended to two-photon excitation by using surface-enhanced hyper-Raman scattering (SEHRS). In addition to the advantages of two-photon excitation, the SEHRS sensor enables measurements over a wide pH range without the use of multiple probes. PY - 2008 DO - https://doi.org/10.1021/nl071418z SN - 1530-6984 SN - 1530-6992 VL - 7 IS - 9 SP - 2819 EP - 2823 PB - American Chemical Society CY - Washington, DC AN - OPUS4-18230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 JF - Journal of raman spectroscopy 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 - Kneipp, Janina A1 - Kneipp, H. A1 - Wittig, B. A1 - Kneipp, K. T1 - Following the dynamics of pH in endosomes of live cells with SERS nanosensors JF - The journal of physical chemistry / C N2 - The surface enhanced Raman scattering (SERS) spectrum of a reporter molecule attached to gold or silver nanostructures, which is pH-sensitive, can deliver information on the local pH in the environment of the nanostructure. Here, we demonstrate the use of a mobile SERS nanosensor made from gold nanaoaggregates and 4-mercaptobenzoic acid (pMBA) attached as a reporter for monitoring changes in local pH of the cellular compartments of living NIH/3T3 cells. We show that SERS nanosensors enable the dynamics of local pH in individual live cells to be followed at subendosomal resolution in a timeline of cellular processes. This information is of basic interest for a better understanding of a broad range of physiological and metabolic processes as well as for a number of biotechnological applications. PY - 2010 DO - https://doi.org/10.1021/jp910034z SN - 1932-7447 SN - 1089-5639 VL - 114 IS - 16 SP - 7421 EP - 7426 PB - Soc. CY - Washington, DC AN - OPUS4-23214 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kneipp, Janina A1 - Kneipp, H. A1 - Wittig, B. A1 - Kneipp, K. T1 - Novel optical nanosensors for probing and imaging live cells JF - Nanomedicine / Nanotechnology, biology and medicine N2 - This review introduces multifunctional optical nanosensors based on surface-enhanced Raman scattering (SERS) and demonstrates their application in live cells. The novel nanosensors have the potential to improve our understanding of cellular processes on the molecular level. The hybrid sensor consists of gold or silver nanoparticles with an attached reporter species. The sensor can be detected and imaged based on the SERS signature of the reporter. This results in several advantages, such as high spectral specificity, multiplex capabilities, improved contrast, and photostability. SERS sensors not only highlight cellular structures, based on enhanced Raman spectra of intrinsic cellular molecules measured in the local optical fields of the gold nanoparticles, they also provide molecular structural information on their cellular environment. Moreover, the SERS signature of the reporter can deliver information on the local pH value inside a cell at subendosomal resolution. SERS sensors are suitable for one- and two-photon excitation. KW - Cells KW - Optical nanosensors KW - Nano gold KW - Spectroscopy KW - SERS KW - ph probing PY - 2010 DO - https://doi.org/10.1016/j.nano.2009.07.009 SN - 1549-9634 SN - 1549-9642 VL - 6 IS - 2 SP - 214 EP - 226 PB - Elsevier CY - New York AN - OPUS4-23943 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kneipp, Janina A1 - Li, X. A1 - Sherwood, M. A1 - Panne, Ulrich A1 - Kneipp, H. A1 - Stockman, M.I. A1 - Kneipp, K. T1 - Gold Nanolenses Generated by Laser Ablation-Efficient Enhancing Structure for Surface Enhanced Raman Scattering Analytics and Sensing JF - Analytical chemistry N2 - Nanoaggregates formed by metal spheres of different radii and interparticle distances represent finite, deterministic, self-similar systems that efficiently concentrate optical fields and act as “nanolenses”. Here we verify experimentally the theoretical concept of nanolenses and explore their potential as enhancing nanostructures in surface enhanced Raman scattering (SERS). Self-similar structures formed by gold nanospheres of different sizes are generated by laser ablation from solid gold into water. These nanolenses exhibit SERS enhancement factors on the order of 109. The “chemically clean” preparation process provides several advantages over chemically prepared nanoaggregates and makes the stable and biocompatible gold nanolenses potent enhancing structures for various analytical and sensing applications. KW - SERS KW - Ablation KW - Gold-Nanopartikel PY - 2008 DO - https://doi.org/10.1021/ac8002215 SN - 0003-2700 SN - 1520-6882 VL - 80 IS - 11 SP - 4247 EP - 4251 PB - American Chemical Society CY - Washington, DC AN - OPUS4-18231 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kneipp, Janina A1 - Wittig, B. A1 - Bohr, H. A1 - Kneipp, Janina T1 - Surface-enhanced Raman scattering: a new optical probe in molecular biophysics and biomedicine JF - Theoretical chemistry accounts N2 - Sensitive and detailed molecular structural information plays an increasing role in molecular biophysics and molecular medicine. Therefore, vibrational spectroscopic techniques, such as Raman scattering, which provide high structural information content are of growing interest in biophysical and biomedical research. Raman spectroscopy can be revolutionized when the inelastic scattering process takes place in the very close vicinity of metal nanostructures. Under these conditions, strongly increased Raman signals can be obtained due to resonances between optical fields and the collective oscillations of the free electrons in the metal. This effect of surface-enhanced Raman scattering (SERS) allows us to push vibrational spectroscopy to new limits in detection sensitivity, lateral resolution, and molecular structural selectivity. This opens up exciting perspectives also in molecular biospectroscopy. This article highlights three directions where SERS can offer interesting new capabilities. This includes SERS as a technique for detecting and tracking a single molecule, a SERS-based nanosensor for probing the chemical composition and the pH value in a live cell, and the effect of socalled surface-enhanced Raman optical activity, which provides information on the chiral organization of molecules on surfaces. KW - Nanosensor KW - Raman spectroscopy KW - Cells KW - Single molecule KW - Plasmonics PY - 2010 DO - https://doi.org/10.1007/s00214-009-0665-2 SN - 1432-881X VL - 125 IS - 3-6 SP - 319 EP - 327 PB - Springer CY - Berlin ; Heidelberg AN - OPUS4-23213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Giesen, Charlotte A1 - Müller, Larissa A1 - Mairinger, T. A1 - Drescher, Daniela A1 - Kneipp, Janina A1 - Roos, P.H. A1 - Panne, Ulrich A1 - Jakubowski, Norbert T1 - Iodine as an elemental marker for imaging of single cells and tissue sections by laser ablation inductively coupled plasma mass spectrometry JF - Journal of analytical atomic spectrometry N2 - A new laser ablation (LA)-ICP-MS method for single cell and cell nucleus imaging was developed. Therein, iodine was employed as an elemental dye for fibroblast cells and for thin tissue sections. At an incubation time of 60 s, iodine is located mainly within the cell nuclei. This effect was illustrated in fibroblast cells, and iodine signal within the cell nucleus was as high as 5 × 104 cps at 4 µm laser spot size. The surrounding cytoplasm was iodinated as well, but to a lesser extent. The spatial resolution attained was sufficient to detect even smaller cell nuclei within a liver biopsy tissue. Furthermore, iodine was successfully employed for biomolecule labeling and we demonstrated that iodine signal increased with increasing thickness of a palatine tonsil tissue. Thus, the use of iodine as an internal standard to correct for tissue inhomogeneities in LA-ICP-MS was investigated for the simultaneous detection of two tumor markers (Her 2 and CK 7) in breast cancer tissue. Additionally, lanthanide background resulting from glass ablation can be corrected for by Eu standardization. PY - 2011 DO - https://doi.org/10.1039/c1ja10227c SN - 0267-9477 SN - 1364-5544 N1 - Geburtsname von Müller, Larissa: Wäntig, L. - Birth name of Müller, Larissa: Wäntig, L. VL - 26 IS - 11 SP - 2160 EP - 2165 PB - Royal Society of Chemistry CY - London AN - OPUS4-24964 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -