TY - CONF A1 - Graf, Nora A1 - Gross, Thomas A1 - Wirth, Thomas A1 - Weigel, W. A1 - Unger, Wolfgang T1 - Surface chemical imaging (XPS, ToF-SIMS) of DNA microarrays T2 - AOFA 15 (Arbeitstagung Angewandte Oberflächen-Analytik) T2 - AOFA 15 (Arbeitstagung Angewandte Oberflächen-Analytik) CY - Soest, Germany DA - 2008-09-08 PY - 2008 AN - OPUS4-17928 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Gross, Thomas A1 - Wirth, Thomas A1 - Unger, Wolfgang A1 - Weigel, W. T1 - Surface chemical imaging (XPS, ToF-SIMS) of DNA microarrays T2 - Nano-Molecular Analysis for Emerging Technologies III & Surface Science of Biologically Important Interfaces 10 - NMAET III & SSBII 10 T2 - Nano-Molecular Analysis for Emerging Technologies III & Surface Science of Biologically Important Interfaces 10 - NMAET III & SSBII 10 CY - London, England DA - 2008-11-05 PY - 2008 AN - OPUS4-17931 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Wirth, Thomas A1 - Gross, Thomas A1 - Unger, Wolfgang A1 - Weigel, W. T1 - Surface analysis of DNA microarrays and their substrates T2 - SIMS Europe 2008 T2 - SIMS Europe 2008 CY - Münster, Germany DA - 2008-09-14 PY - 2008 AN - OPUS4-17933 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weigel, W. A1 - Unger, Wolfgang A1 - Graf, Nora A1 - Gross, Thomas A1 - Wirth, Thomas T1 - Surface Chemical Analysis of DNA Microarrays - Application of XPS and ToF-SIMS for Surface Chemical Imaging on the µm Scale JF - BioForum Europe KW - Microarrays KW - Oberflächenanalytik KW - XPS KW - ToF-SIMS KW - Chemical imaging PY - 2008 SN - 1611-597X VL - 12 IS - 10 SP - 14 EP - 16 PB - GIT-Verlag CY - Darmstadt AN - OPUS4-18307 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Yegen, E. A1 - Lippitz, Andreas A1 - Treu, Dieter A1 - Wirth, Thomas A1 - Unger, Wolfgang T1 - Optimization of cleaning and aminosilanization protocols for Si wafers to be used as platforms for biochip microarrays by surface analysis (XPS, ToF-SIMS and NEXAFS spectroscopy) JF - Surface and interface analysis N2 - It is known that aminosilanized Si wafers may be used as microarray platforms. Results of an XPS study of a cleaning applied to Si wafers prior to aminosilanization are presented and discussed. Furthermore, the results of an aminosilanization protocol optimized in terms of nitrogen chemistry are described. After optimization of the protocol a free amine content of 94% was reached. The surface chemistry was investigated in this study by using XPS, time of flight (ToF)-SIMS and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Reference to aminosilanization protocols reported in the literature has been made. KW - Aminosilanization KW - Si wafers KW - Microarray KW - XPS KW - ToF-SIMS KW - NEXAFS PY - 2008 DO - https://doi.org/10.1002/sia.2621 SN - 0142-2421 SN - 1096-9918 VL - 40 IS - 3-4 SP - 180 EP - 183 PB - Wiley CY - Chichester AN - OPUS4-17192 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Weigel, W. A1 - Jagst, Eda A1 - Lippitz, Andreas A1 - Treu, Dieter A1 - Wirth, Thomas A1 - Unger, Wolfgang T1 - Surface analysis (XPS, ToF-SIMS, NEXAFS) of organosilane functionalized substrates to be used as microarray platforms T2 - Bunsen Discussion Meeting T2 - Bunsen Discussion Meeting CY - Heidelberg, Germany DA - 2007-06-30 PY - 2007 N1 - Geburtsname von Jagst, Eda: Yegen, E. - Birth name of Jagst, Eda: Yegen, E. AN - OPUS4-15701 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Weigel, W. A1 - Jagst, Eda A1 - Lippitz, Andreas A1 - Treu, Dieter A1 - Wirth, Thomas A1 - Unger, Wolfgang T1 - Surface analysis (XPS, ToF-SIMS, NEXAFS) of organosilane functionalized substrates to be used as microarray platforms T2 - BESSY User´s Meeting T2 - BESSY User´s Meeting CY - Berlin, Germany DA - 2007-12-06 PY - 2007 AN - OPUS4-17605 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Unger, Wolfgang T1 - Surface analysis of microarray platforms T2 - Seminar an der Harvard University T2 - Seminar an der Harvard University CY - Cambridge, MA, USA DA - 2008-03-05 PY - 2008 AN - OPUS4-17606 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Unger, Wolfgang T1 - Surface analysis of microarrays and SAMs T2 - Seminar Free University of Berlin T2 - Seminar Free University of Berlin CY - Berlin, Germany DA - 2008-06-04 PY - 2008 AN - OPUS4-17601 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Jagst, Eda A1 - Lippitz, Andreas A1 - Treu, Dieter A1 - Wirth, Thomas A1 - Unger, Wolfgang T1 - Optimization of cleaning and aminosilanization protocols for Si wafers to be used as platforms for biochip microarrays by surface analysis (XPS, ToF-SIMS and NEXAFS spectroscopy) T2 - 4th International Symposium on Practical Surface Analysis (PSA-07) and 6th Korea-Japan International Symposium on Surface Analysis T2 - 4th International Symposium on Practical Surface Analysis (PSA-07) and 6th Korea-Japan International Symposium on Surface Analysis CY - Kanazawa, Japan DA - 2007-11-25 PY - 2007 AN - OPUS4-16382 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Gross, Thomas A1 - Wirth, Thomas A1 - Weigel, W. A1 - Unger, Wolfgang T1 - Application of XPS and ToF-SIMS for surface chemical analysis of DNA microarrays and their substrates JF - Analytical and bioanalytical chemistry N2 - The chemical composition of the functional surfaces of substrates used for microarrays is one of the important parameters that determine the quality of a microarray experiment. In addition to the commonly used contact angle measurements to determine the wettability of functionalized supports, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) are more specific methods to elucidate details about the chemical surface constitution. XPS yields information about the atomic composition of the surface, whereas from ToF-SIMS, information on the molecular species on the surface can be concluded. Applied on printed DNA microarrays, both techniques provide impressive chemical images down to the micrometer scale and can be utilized for label-free spot detection and characterization. Detailed information about the chemical constitution of single spots of microarrays can be obtained by high-resolution XPS imaging. KW - Microarrays KW - Surface analysis KW - XPS KW - ToF-SIMS KW - Chemical imaging PY - 2009 DO - https://doi.org/10.1007/s00216-009-2599-x SN - 1618-2642 SN - 1618-2650 VL - 393 IS - 8 SP - 1907 EP - 1912 PB - Springer CY - Berlin AN - OPUS4-19245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Lippitz, Andreas A1 - Gross, Thomas A1 - Pippig, F. A1 - Holländer, A. A1 - Unger, Wolfgang T1 - Determination of accessible amino groups on surfaces by chemical derivatization with 3,5-bis(trifluoromethyl)phenyl isothiocyanate and XPS/NEXAFS analysis JF - Analytical and bioanalytical chemistry N2 - The determination of amino groups on surfaces capable of binding biomolecules is important for the understanding and optimization of technologically relevant coupling processes. In this study, three different types of amino-functionalized model surfaces, amino thiolate on Au, amino siloxane on Si, and polyethylene (PE) foils and films reacted with 1,2-diaminoethane (DAE) were derivatized with 3,5-bis(trifluoromethyl)phenyl isothiocyanate. Subsequently, these samples were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The determination of amino groups by this analytical approach allows gaining insight into the availability of groups on surfaces that can actually serve as attachment sites for biomolecules in technical applications. In the case of the amino thiolate on Au, almost 90% of the expected amino groups were detected by CD-XPS. Investigation of the amino siloxane films revealed lower yields for the derivatization reaction in the order of 30%. The lowered reaction yields are thought to be due to interactions between the amino siloxane`s amino and silanol groups or the underlying substrate, making them inaccessible to the derivatization agent. The aminated PE samples are characterized by a complex surface chemistry and structure, and reaction yields of the derivatization reaction cannot be unequivocally derived. However, 1-3% of the total carbon atoms in the surface layer were found to be bound to amino groups accessible to the derivatization agent. It can be concluded that, depending on the detailed character of the investigated amino-terminated surface, the amount of amino groups accessible to CD-XPS can be substantially lower than the total amount of amino groups present at the surface. KW - XPS/ESCA KW - NEXAFS/XANES KW - CD-XPS KW - Amino-functionalized surfaces KW - SAM PY - 2010 DO - https://doi.org/10.1007/s00216-009-3233-7 SN - 1618-2642 SN - 1618-2650 VL - 396 IS - 2 SP - 725 EP - 738 PB - Springer CY - Berlin AN - OPUS4-20744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Graf, Nora A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Schüpbach, B. A1 - Bashir, A. A1 - Wöll, Ch. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - Self-assembled monolayers of aromatic omega-aminothiols on gold: surface chemistry and reactivity JF - Langmuir N2 - Amino-terminated self-assembled monolayers on gold substrates were studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) measurements, and atomic force microscopy (AFM). Two different ω-amino-4,4'-terphenyl substituted alkanethiols of the general structure H2N-(C6H4)3-(CH2)n-SH (ATPn) were used: 2-(4''-amino-1,1':4',1''-terphenyl-4-yl)ethane-1-thiol (n = 2, ATP2) and 3-(4''-amino-1,1':4',1''-terphenyl-4-yl)propane-1-thiol (n = 3, ATP3). Moreover, the addressability of amino groups within the films was investigated by chemical derivatization of ATPn SAMs with 3,5-bis(trifluoromethyl)phenyl isothiocyanate (ITC) forming fluorinated thiourea ATPn-F films. Evaluation of high-resolution C 1s and N 1s XPS data revealed successful derivatization of at least 50% of surface amino species. Furthermore, it could be demonstrated by angle-resolved NEXAFS spectroscopy that chemical derivatization with ITC has no noticeable influence on the preferential upright orientation of the molecules in the SAMs. KW - Gold KW - Self-assembled monolayer KW - Thiols KW - Amino surfaces KW - XPS KW - NEXAFS PY - 2010 DO - https://doi.org/10.1021/la903293b SN - 0743-7463 SN - 1520-5827 VL - 26 IS - 6 SP - 3949 EP - 3954 PB - American Chemical Society CY - Washington, DC AN - OPUS4-20990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Dietrich, Paul A1 - Weigel, W. A1 - Lippitz, Andreas A1 - Wirth, Thomas A1 - Unger, Wolfgang T1 - Surface analytical measurements (XPS, ToF-SIMS, NEXAFS) of organosilane functionalized substrates to be used as microarray platforms T2 - 11th Status Seminar "Chip Technologies" (Dechema) T2 - 11th Status Seminar "Chip Technologies" (Dechema) CY - Frankfurt am Main, Germany DA - 2009-03-05 PY - 2009 AN - OPUS4-19028 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Graf, Nora A1 - Dietrich, Paul A1 - Gross, Thomas A1 - Wirth, Thomas A1 - Weigel, W. A1 - Unger, Wolfgang T1 - Surface chemical Imaging (XPS, ToF-SIMS) of DNA microarrays T2 - 11th Status Seminar "Chip Technologies" (Dechema) T2 - 11th Status Seminar "Chip Technologies" (Dechema) CY - Frankfurt am Main, Germany DA - 2009-03-05 PY - 2009 AN - OPUS4-19029 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Yegen, E. A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Weigel, W. A1 - Krakert, S. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - XPS and NEXAFS studies of aliphatic and aromatic amine species on functionalized surfaces JF - Surface science N2 - The chemical constitution of functionalized supports is an important parameter that determines their performance in a broad range of applications, e.g. for immobilization of biomolecules. Supports with amino functionalized surfaces are also often used for DNA microarray experiments. However, spectral data which have been reported for surfaces with amino functionalities suffer from some inconsistencies. In this article a detailed XPS (X-ray photoelectron spectroscopy) and NEXAFS (Near edge X-ray absorption fine structure) database for amino functionalized surfaces is presented. Amino-terminated surfaces prepared from aliphatic and aromatic aminosilanes or aminothiols and a field sample are considered. Effects of aging in air and damage by radiation are addressed as well. KW - Near edge X-ray absorption fine structure (NEXAFS) KW - Self-assembled monolayers KW - Amino-functionalized surfaces KW - X-ray photoelectron spectroscopy (XPS) PY - 2009 DO - https://doi.org/10.1016/j.susc.2009.07.029 SN - 0039-6028 VL - 603 IS - 18 SP - 2849 EP - 2860 PB - Elsevier CY - Amsterdam AN - OPUS4-19832 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Dietrich, Paul A1 - Graf, Nora A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Schüpbach, B. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - Characterization of self-assembled monolayers of terphenylthiols with amine head groups T2 - BESSY II Annual Report 2008 KW - Terphenylthiolate SAMs KW - Gold KW - Microarray KW - NEXAFS PY - 2008 SP - 195 EP - 197 AN - OPUS4-22909 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Graf, Nora A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Krakert, S. A1 - Schüpbach, B. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - Amine species on self-assembled monolayers of omega-aminothiolates on gold as identified by XPS and NEXAFS spectroscopy JF - Surface and interface analysis N2 - Functionalised surfaces are of interest in many fields, e.g. in biomedicine, materials science and molecular electronics. In this study a series of self-assembled aliphatic and aromatic monolayers on gold substrates with terminal amino groups was investigated. Four different thiol molecules were used: aliphatic 11-aminoundecane-1-thiol (AUDT), aromatic 4-aminobenzenethiol (ABT) and aromatic ω-amino thiols with an alkyl spacer as 4-aminophenylbutane-1-thiol (APBT) and 3-(4''-amino-1,1':4',1''-terphenyl-4-yl)propane-1-thiol (ATPT). Evaluation of N 1s XPS data revealed that on the aromatic self-assembled monolayers (SAMs) amino groups exist preferentially as primary amines, whereas on the aliphatic SAM protonated and/or hydrogen-bonded amines are the major species. This result is crosschecked by N K edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy and can be rationalised by the different basicity of aliphatic and aromatic amines. KW - Self-assembled monolayer KW - Amines KW - XPS KW - NEXAFS KW - Surface analysis PY - 2010 DO - https://doi.org/10.1002/sia.3224 SN - 0142-2421 SN - 1096-9918 VL - 42 SP - 1184 EP - 1187 PB - Wiley CY - Chichester AN - OPUS4-21498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -