TY - CONF A1 - Moser, Marko T1 - Spectroscopic Quantification of Thiol Groups and Ligands on Nanomaterials N2 - Thiols have a high binding affinity to noble metals and semiconductor (SC) materials. Thiol ligands enable size control and tuning of the surface during the synthesis of nanoparticles (NP), significantly influence their physico-chemical and optical properties, and allow for their bioconjugation via further functional groups. Thus, simple, inexpensive, robust, and fast methods for the quantification of thiol groups and the characterization of thiol-modified or - stabilized nanomaterials including polymers are of considerable importance. T2 - Innovation Forum Senftenberg 2016 CY - Senftenberg, Germany DA - 01.06.2016 KW - Thiols KW - Ellman KW - Aldrithiol PY - 2016 AN - OPUS4-37243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moser, Marko T1 - Quantification of PEG-Maleimide Ligands on NIR-emissive Nanoparticles for Bioanalytics T2 - Potsdam Days Bioanalysis 2015 CY - Potsdam, Brandenburg DA - 2015-11-04 PY - 2015 AN - OPUS4-34901 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moser, Marko T1 - Spectroscopic Quantification of Thiol Groups and Ligands on Nanomaterials N2 - Thiols have a high binding affinity to noble metals and semiconductor (SC) materials. Thiol ligands enable size control and tuning of the surface during the synthesis of nanoparticles (NP), significantly influence their physico-chemical and optical properties, and allow for their bioconjugation via further functional groups. Thus, simple, inexpensive, robust, and fast methods for the quantification of thiol groups and the characterization of thiol-modified or - stabilized nanomaterials including polymers are of considerable importance. T2 - Innovation Forum Senftenberg 2016 CY - Senftenberg, Germany DA - 01.06.2016 KW - Ellman KW - Aldrithiol KW - Thiols PY - 2016 AN - OPUS4-37245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moser, Marko T1 - Characterization of NIR-Fluorescent PEGylated and Ovalbumin-modified Nanoparticles for Bioanalysis T2 - Anakon 2013 CY - Essen, Germany DA - 2013-03-04 PY - 2013 AN - OPUS4-27855 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moser, Marko T1 - Quantification of PEG-Maleimide Ligands and Coupling Efficiencies on Nanoparticles with Ellman’s Reagent N2 - Emissive nanoparticles (NP) are of ever increasing importance in nanotechnology, optical industries, and life sciences. Applicationrelevant properties determining particle performance and biocompatibility depend mainly on surface functional groups or ligands. Coating with polyethylene glycol (PEG) ligands enhances hydrophilicity and biocompatibility of nanomaterials, and enables subsequent binding of biomolecules. Hence, PEGylated particles must be carefully engineered and monitored with simple and fast methods. T2 - 9th Meeting of Engineering of Functional Interfaces CY - Wildau, Germany DA - 03.07.2016 KW - PEG-Maleimide KW - Ellman PY - 2016 AN - OPUS4-37247 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moser, Marko A1 - Nirmalananthan-Budau, Nithiya A1 - Behnke, Thomas A1 - Geißler, Daniel A1 - Resch-Genger, Ute T1 - Multimodal cleavable reporters versus conventional labels for optical quantification of accessible amino and carboxy groups on nano- and microparticles N2 - Many applications of nanometer- and micrometer-sized particles include their surface functionalization with linkers, sensor molecules, and analyte recognition moieties like (bio)ligands. This requires knowledge of the chemical nature and number of surface groups accessible for subsequent coupling reactions. Particularly attractive for the quantification of these groups are spectrophotometric and fluorometric assays, which can be read out with simple instrumentation. In this respect, we present here a novel Family of cleavable spectrophotometric and multimodal reporters for conjugatable amino and carboxyl surface groups on nano- and microparticles. This allows determination of particle-bound labels, unbound reporters in the supernatant, and reporters cleaved off from the particle surface, as well as the remaining thiol groups on particle, by spectrophotometry and inductively coupled optical emission spectrometry (32S ICP-OES). Comparison of the performance of these cleavable reporters with conductometry and conventional labels, utilizing changes in intensity or Color of absorption or emission, underlines the analytical potential of this versatile concept which elegantly circumvents Signal distortions by scattering and Encoding dyes and enables straightforward validation by method comparison. KW - Polymer particles KW - Cleavable reporter KW - Optical quantification KW - Validation PY - 2018 DO - https://doi.org/10.1021/acs.analchem.8b00666 SN - 1520-6882 SN - 0003-2700 N1 - Geburtsname von Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. - Birth name of Nirmalananthan-Budau, Nithiya: Nirmalananthan, N. VL - 90 IS - 9 SP - 5887 EP - 5895 PB - ACS Publ. CY - Washington, DC AN - OPUS4-44830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moser, Marko T1 - Quantification of PEG-Maleimide Ligands and Coupling Efficiencies on Nanoparticles with Ellman’s Reagent N2 - Emissive nanoparticles (NP) are of ever increasing importance in nanotechnology, optical industries, and life sciences. Applicationrelevant properties determining particle performance and biocompatibility depend mainly on surface functional groups or ligands. Coating with polyethylene glycol (PEG) ligands enhances hydrophilicity and biocompatibility of nanomaterials, and enables subsequent binding of biomolecules. Hence, PEGylated particles must be carefully engineered and monitored with simple and fast methods. T2 - 9th Meeting of Engineering of Functional Interfaces CY - Wildau, Germany DA - 03.07.2016 KW - PEG-Maleimide KW - Ellman PY - 2016 AN - OPUS4-37244 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nirmalananthan-Budau, Nithiya A1 - Rühle, Bastian A1 - Geißler, Daniel A1 - Moser, Marko A1 - Kläber, Christopher A1 - Schäfer, A. A1 - Resch-Genger, Ute T1 - Multimodal cleavable reporters for quantifying carboxy and amino groups on organic and inorganic nanoparticles N2 - Organic and inorganic nanoparticles (NPs) are increasingly used as drug carriers, fluorescent sensors, and multimodal labels in the life and material sciences. These applications require knowledge of the chemical nature, total number of surface groups, and the number of groups accessible for subsequent coupling of e.g., antifouling ligands, targeting bioligands, or sensor molecules. To establish the concept of catch-and-release assays, cleavable probes were rationally designed from a quantitatively cleavable disulfide moiety and the optically detectable reporter 2-thiopyridone (2-TP). For quantifying surface groups on nanomaterials, first, a set of monodisperse carboxy-and amino-functionalized, 100 nm-sized polymer and silica NPs with different surface group densities was synthesized. Subsequently, the accessible functional groups (FGs) were quantified via optical spectroscopy of the cleaved off reporter after its release in solution. Method validation was done with inductively coupled plasma optical emission spectroscopy (ICP-OES) utilizing the sulfur atom of the cleavable probe. This comparison underlined the reliability and versatility of our probes, which can be used for surface group quantification on all types of transparent, scattering, absorbing and/or fluorescent particles. The correlation between the total and accessible number of FGs quantified by conductometric titration, qNMR, and with our cleavable probes, together with the comparison to results of conjugation studies with differently sized biomolecules reveal the potential of catch-and-release reporters for surface analysis. Our findings also underline the importance of quantifying particularly the accessible amount of FGs for many applications of NPs in the life sciences. KW - Advanced Materials KW - Surface Chemistry KW - Organic–inorganic nanostructures KW - Funtional Groups KW - Quantitative Analysis PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-499081 DO - https://doi.org/10.1038/s41598-019-53773-3 VL - 9 SP - 17577-1 EP - 17577-11 PB - Springer Nature CY - London AN - OPUS4-49908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moser, Marko A1 - Behnke, Thomas A1 - Hamers-Allin, Carolina A1 - Klein-Hartwig, Karin A1 - Falkenhagen, Jana A1 - Resch-Genger, Ute T1 - Quantification of PEG-maleimide ligands and coupling efficiencies on nanoparticles with Ellman's reagent N2 - The surface modification of nanometer- and micrometer-sized particles and planar substrates with polyethylene glycol (PEG) ligands of varying length is a very common strategy to tune the hydrophilicity and biocompatibility of such materials, minimize unspecific interactions, improve biofunctionalization efficiencies, and enhance blood circulation times. Nevertheless, simple methods for the quantification of PEG ligands are comparatively rare. Here, we present a new concept for the quantification of PEG ligands for maleimide-functionalized PEG molecules and the determination of PEG coupling efficiencies, exploiting the quantitative reaction of maleimide with ʟ-cysteine, and the subsequent determination of the unreacted thiol with the photometric Ellman's test. This is shown for heterobifunctional PEG spacers of varying length and amino-functionalized polystyrene nanoparticles (PS NP) without and with differently charged encoding dyes. The reaction of ʟ-cysteine with the Ellman's reagent was monitored photometrically and with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) to derive the reaction mechanism and to obtain the stoichiometry factor for ʟ-cysteine quantification. Mass balances and quantification of ʟ-cysteine via its sulfur concentration using elemental analysis and inductively coupled plasma mass spectrometry (ICP-MS) confirmed the accuracy and reliability of this approach that can be extended to other surface groups and ligands. KW - Photometric assay KW - Surface analysis KW - Nanoparticle KW - Polyethylene glycol KW - PEG quantification KW - Ellman's test PY - 2015 DO - https://doi.org/10.1021/acs.analchem.5b02173 SN - 0003-2700 SN - 1520-6882 VL - 87 IS - 18 SP - 9376 EP - 9383 PB - American Chemical Society CY - Washington, DC AN - OPUS4-34468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moser, Marko A1 - Schneider, Ralf A1 - Behnke, Thomas A1 - Schneider, Thomas A1 - Falkenhagen, Jana A1 - Resch-Genger, Ute T1 - Ellman’s and aldrithiol assay as versatile and complementary tools for the quantification of thiol groups and ligands on nanomaterials N2 - Simple, fast, and versatile methods for the quantification of thiol groups are of considerable interest not only for protein analysis but also for the characterization of the surface chemistry of nanomaterials stabilized with thiol ligands or bearing thiol groups for the subsequent (bio-) functionalization via maleimide−thiol chemistry. Here, we compare two simple colorimetric assays, the widely used Ellman’s assay performed at alkaline pH and the aldrithiol assay executed at acidic and neutral pH, with respect to their potential for the quantification of thiol groups and thiol ligands on different types of nanoparticles like polystyrene nanoparticles, semiconductor nanocrystals (SC NC), and noble metal particles, and we derive criteria for their use. In order to assess the underlying reaction mechanisms and to obtain stoichiometry factors mandatory for reliable thiol quantification, both methods were studied photometrically and with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), thereby demonstrating the influence of different thiols on the reaction mechanism. Our results underline the suitability of both methods for the quantification of directly accessible thiol groups or ligands on the surface of 2D- and 3D-supports, here exemplarily polystyrene nanoparticles. Moreover, we could derive strategies for the use of these simple assays for the determination of masked (i.e., not directly accessible) thiol groups like disulfides such as lipoic acid and thiol stabilizing ligands coordinatively bound to Cd and/or Hg surface atoms of II/VI and ternary SC NC and to gold and silver nanoparticles. KW - Nanoparticles KW - Ligands KW - Ellman KW - Aldrithiol KW - Quantification PY - 2016 DO - https://doi.org/10.1021/acs.analchem.6b01798 SN - 0003-2700 SN - 1520-6882 VL - 88 IS - 17 SP - 8624 EP - 8631 PB - ACS Publications CY - Washington AN - OPUS4-37561 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -