TY - JOUR A1 - Schmidt, Carsten A1 - Schierack, Peter A1 - Gerber, Ulrike A1 - Schroeder, Christian A1 - Choi, Youngeun A1 - Bald, Ilko A1 - Lehmann, Werner A1 - Rödiger, Stefan 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 mu m 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 degrees 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. Y1 - 2020 U6 - https://doi.org/10.1021/acs.langmuir.9b02339 SN - 0743-7463 VL - 36 IS - 2 SP - 628 EP - 636 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Carsten A1 - Roediger, Stefan A1 - Gruner, Melanie A1 - Moncsek, Anja A1 - Stohwasser, Ralf A1 - Hanack, Katja A1 - Schierack, Peter A1 - Schroeder, Christian T1 - Multiplex localization of sequential peptide epitopes by use of a planar microbead chip JF - Analytica chimica acta : an international journal devoted to all branches of analytical chemistry N2 - Epitope mapping is crucial for the characterization of protein-specific antibodies. Commonly, small overlapping peptides are chemically synthesized and immobilized to determine the specific peptide sequence. In this study, we report the use of a fast and inexpensive planar microbead chip for epitope mapping. We developed a generic strategy for expressing recombinant peptide libraries instead of using expensive synthetic peptide libraries. A biotin moiety was introduced in vivo at a defined peptide position using biotin ligase. Peptides in crude Escherichia coli lysate were coupled onto streptavidin-coated microbeads by incubation, thereby avoiding tedious purification procedures. For read-out we used a multiplex planar microbead chip with size- and fluorescence-encoded microbead populations. For epitope mapping, up to 18 populations of peptide-loaded microbeads (at least 20 microbeads per peptide) displaying the primary sequence of a protein were analyzed simultaneously. If an epitope was recognized by an antibody, a secondary fluorescence-labeled antibody generated a signal that was quantified, and the mean value of all microbeads in the population was calculated. We mapped the epitopes for rabbit anti-PA28 gamma (proteasome activator 28 gamma) polyclonal serum, for a murine monoclonal antibody against PA28 gamma, and for a murine monoclonal antibody against the hamster polyoma virus major capsid protein VP1 as models. In each case, the identification of one distinct peptide sequence out of up to 18 sequences was possible. Using this approach, an epitope can be mapped multiparametrically within three weeks. (C) 2016 Elsevier B.V. All rights reserved. KW - Epitope mapping KW - In vivo biotinylation KW - Multiplexed assays KW - Microbeads KW - VideoScan technology Y1 - 2016 U6 - https://doi.org/10.1016/j.aca.2015.12.030 SN - 0003-2670 SN - 1873-4324 VL - 908 SP - 150 EP - 160 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Choi, Youngeun A1 - Schmidt, Carsten A1 - Tinnefeld, Philip A1 - Bald, Ilko A1 - Rödiger, Stefan T1 - A new reporter design based on DNA origami nanostructures for quantification of short oligonucleotides using microbeads JF - Scientific Reports N2 - The DNA origami technique has great potential for the development of brighter and more sensitive reporters for fluorescence based detection schemes such as a microbead-based assay in diagnostic applications. The nanostructures can be programmed to include multiple dye molecules to enhance the measured signal as well as multiple probe strands to increase the binding strength of the target oligonucleotide to these nanostructures. Here we present a proof-of-concept study to quantify short oligonucleotides by developing a novel DNA origami based reporter system, combined with planar microbead assays. Analysis of the assays using the VideoScan digital imaging platform showed DNA origami to be a more suitable reporter candidate for quantification of the target oligonucleotides at lower concentrations than a conventional reporter that consists of one dye molecule attached to a single stranded DNA. Efforts have been made to conduct multiplexed analysis of different targets as well as to enhance fluorescence signals obtained from the reporters. We therefore believe that the quantification of short oligonucleotides that exist in low copy numbers is achieved in a better way with the DNA origami nanostructures as reporters. KW - nucleic-acids KW - hybridization KW - microrna KW - flourescence KW - biomarkers KW - platform KW - particle KW - binding KW - array KW - gene Y1 - 2019 U6 - https://doi.org/10.1038/s41598-019-41136-x SN - 2045-2322 IS - 9 PB - Macmillan Publishers Limited CY - London ER -