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- 2018 (2) (entfernen)
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- Englisch (2) (entfernen)
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- DNA origami (1)
- Electrochemistry (1)
- FRET (1)
- Fluorescence (1)
- Ionophore Antibiotics (1)
- Ratiometric sensing (1)
- Sensing (1)
- Transformation Product (1)
Organisationseinheit der BAM
Ionophore antibiotics are used to cure and prevent coccidiosis by chicken especially in broiler farming. The residues are found not only in food products (chicken and eggs) but also in the environment (manure, soil or water). In this work the ionophores monensin (MON), salinomycin (SAL), maduramicin (MAD) and lasalocid (LAS) are investigated aiming to study their transformation products (TPs) through biotransformation processes. Biotransformation can be divided into two phases, phase I: oxidation, reduction or hydrolysis and Phase II: conjugation reactions. It is necessary to further examine the biotransformation pathways to determine TPs to be able to detect residues more specifically in different matrices.
The technique of electrochemistry (EC) offers the opportunity to simulate biotransformation processes and to generate TPs for further analysis. The combination of EC with liquid chromatography and mass spectrometry (EC-LC-MS) provide a fast and simple tool to separate and determine the EC-generated TPs. The electrochemical flow through cell is coupled to the (LC)-MS system, allowing the reaction mixture to be separated by a RP-18 column and then analyzed in the MS. The oxidation products are generated at different potentials between 0.0 – 2.5 V vs. Pd/H2 using glassy carbon or boron doped diamond as working electrode materials .
The results show a broad spectrum of different TPs depending on used solvents and working electrode materials. Among the generated TPs already known as well as unknown TPs of the drugs can be found. Further investigations on structure elucidation of unkown TPs are planned.
DNA origami nanostructures provide a platform where dye molecules can be arranged with nanoscale accuracy allowing to assemble multiple fluorophores without dye–dye aggregation. Aiming to develop a bright and sensitive ratiometric sensor system, we systematically studied the optical properties of nanoarrays of dyes built on DNA origami platforms using a DNA template that provides a high versatility of label choice at minimum cost. The dyes are arranged at distances, at which they efficiently interact by Förster resonance energy transfer (FRET). To optimize array brightness, the FRET efficiencies between the donor fluorescein (FAM) and the acceptor cyanine 3 were determined for different sizes of the array and for different arrangements of the dye molecules within the array. By utilizing nanoarrays providing optimum FRET efficiency and brightness, we subsequently designed a ratiometric pH nanosensor using coumarin 343 as a pH-inert FRET donor and FAM as a pH-responsive acceptor. Our results indicate that the sensitivity of a ratiometric sensor can be improved simply by arranging the dyes into a well-defined array. The dyes used here can be easily replaced by other analyte-responsive dyes, demonstrating the huge potential of DNA nanotechnology for light harvesting, signal enhancement, and sensing schemes in life sciences.