TY - JOUR A1 - Schmidt, C. A1 - Schierack, P. A1 - Gerber, U. A1 - Schröder, C. A1 - Choi, Youngeun A1 - Bald, Ilko A1 - Lehmann, W. A1 - Rödiger, S. T1 - Streptavidin Homologues for Applications on Solid Surfaces at High Temperatures JF - Langmuir N2 - One of the most commonly used bonds between two biomolecules is the bond between biotin and streptavidin (SA) or streptavidin homologues (SAHs). A high dissociation constant and the consequent high-temperature stability even allows for its use in nucleic acid detection under polymerase chain reaction (PCR) conditions. There are a number of SAHs available, and for assay design, it is of great interest to determine as to which SAH will perform the best under assay conditions. Although there are numerous single studies on the characterization of SAHs in solution or selected solid phases, there is no systematic study comparing different SAHs for biomolecule-binding, hybridization, and PCR assays on solid phases. We compared streptavidin, core streptavidin, traptavidin, core traptavidin, neutravidin, and monomeric streptavidin on the surface of microbeads (10–15 μm in diameter) and designed multiplex microbead-based experiments and analyzed simultaneously the binding of biotinylated oligonucleotides and the hybridization of oligonucleotides to complementary capture probes. We also bound comparably large DNA origamis to capture probes on the microbead surface. We used a real-time fluorescence microscopy imaging platform, with which it is possible to subject samples to a programmable time and temperature profile and to record binding processes on the microbead surface depending on the time and temperature. With the exception of core traptavidin and monomeric streptavidin, all other SA/SAHs were suitable for our investigations. We found hybridization efficiencies close to 100% for streptavidin, core streptavidin, traptavidin, and neutravidin. These could all be considered equally suitable for hybridization, PCR applications, and melting point analysis. The SA/SAH–biotin bond was temperature-sensitive when the oligonucleotide was mono-biotinylated, with traptavidin being the most stable followed by streptavidin and neutravidin. Mono-biotinylated oligonucleotides can be used in experiments with temperatures up to 70 °C. When oligonucleotides were bis-biotinylated, all SA/SAH–biotin bonds had similar temperature stability under PCR conditions, even if they comprised a streptavidin variant with slower biotin dissociation and increased mechanostability. KW - Biopolymers Probes KW - Hybridization KW - Fluorescence KW - Genetics PY - 2020 DO - https://doi.org/10.1021/acs.langmuir.9b02339 VL - 36 IS - 2 SP - 628 EP - 636 PB - American Chemical Society Publication CY - Washington AN - OPUS4-50357 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ramirez, Alejandra A1 - Pauli, Jutta A1 - Crasselt, C. A1 - Simon, S. A1 - Schmidt, W. A1 - Resch-Genger, Ute T1 - The effect of a polycarboxylate ether on C3A / CaSO4.2H2O passivation monitored by optical spectroscopy JF - Construction and Building Materials N2 - Polycarboxylate ethers (PCEs) are widely used in construction, but the exact nature of their interaction with cement is still debated. Aiming at a better understanding of the role of tricalcium Aluminate (C3A) in cement hydration, we assessed the potential of optical spectroscopy in combination with a water-soluble fluorescent organic reporter dye (S0586) to monitor the early hydration of C3A in the presence of 26 wt% CaSO4.2H2O (C3A26G-S) with and without PCE. As optical methods, steady-state fluorescence and diffuse reflectance (UV–VisDR) spectroscopy were employed. Phase characterization and particle size distribution were performed with in-situ X-ray diffraction (in-situ XRD) and dynamic light scattering (DLS). Our results show that fluorescence and UV–VisDR spectroscopy can be used to monitor the formation of metastable phases by the disaggregation of the dye S0586 in a cement paste as well as changes in ettringite formation. Addition of PCE slowed down the disaggregation of the dye as reflected by the corresponding changes of the dyes absorption and fluorescence. This prolonged induction period is a well-known side effect of PCEs and agrees with previous reported calorimetric studies and the Inhibition of gypsum dissolution observed by in-situ XRD. This demonstrates that fluorescence and UV–VisDR spectroscopy together with a suitable optical probe can provide deeper insights into the influence of PCE on C3A-gypsum hydration which could be e.g., utilized as screening method for comparing the influences of different types of PCEs. KW - Fluorescence KW - Cement KW - Nano KW - Particle KW - Optical spectroscopy KW - PCE KW - XRD KW - Calorimetry KW - Monitoring KW - Diffuse KW - Reflection KW - Phase KW - Dye KW - Optical probe KW - Cyanine KW - Sensor KW - Method KW - Analysis PY - 2020 DO - https://doi.org/10.1016/j.conbuildmat.2020.121856 VL - 270 SP - 121856 PB - Elsevier Ltd. AN - OPUS4-52118 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -