Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence Sensing
Tetracyclines are a widely used group of antibiotics, many of which are currently only used in veterinary medicine and animal husbandry due to their adverse side effects. For the detection of tetracyclines, we previously reported a DNA aptamer named OTC5 that binds to tetracycline, oxytetracycline,...
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MDPI AG
2022-09-01
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| Sarja: | Biosensors |
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| Linkit: | https://www.mdpi.com/2079-6374/12/9/717 |
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| author | Yichen Zhao Biwen Gao Peihuan Sun Jiawen Liu Juewen Liu |
| author_facet | Yichen Zhao Biwen Gao Peihuan Sun Jiawen Liu Juewen Liu |
| author_sort | Yichen Zhao |
| collection | DOAJ |
| description | Tetracyclines are a widely used group of antibiotics, many of which are currently only used in veterinary medicine and animal husbandry due to their adverse side effects. For the detection of tetracyclines, we previously reported a DNA aptamer named OTC5 that binds to tetracycline, oxytetracycline, and doxycycline with similar <i>K</i><sub>D</sub>’s of ~100 nM. Tetracyclines have an intrinsic fluorescence that is enhanced upon binding to OTC5, which can be used as a label-free and dye-free sensor. In this work, the effect of pH and metal ions on the sensor was studied. Mg<sup>2+</sup> ions are required for the binding of OTC5 to its target with an optimal concentration of 2 mM. Other metal ions including Ca<sup>2+</sup> and Zn<sup>2+</sup> can also support aptamer binding. Although Mn<sup>2+</sup> barely supported binding, the binding can be rescued by Mg<sup>2+</sup>. ITC studies confirmed that OTC5 had a <i>K</i><sub>D</sub> of 0.2 μM at a pH of 6.0 and 0.03 μM at a pH of 8.3. Lower pH (pH 6) showed better fluorescence enhancement than higher pH (pH 8.3), although a pH of 6.0 had slightly higher <i>K</i><sub>D</sub> values. Under optimized sensing conditions, sensors with limit of detections (LODs) of 0.1–0.7 nM were achieved for tetracycline, oxytetracycline, and doxycycline, which are up to 50-fold lower than previously reported. Milk samples were also tested yielding an LOD of 16 nM oxytetracycline at a pH of 6.0. |
| first_indexed | 2024-03-10T00:35:14Z |
| format | Article |
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| issn | 2079-6374 |
| language | English |
| last_indexed | 2024-03-10T00:35:14Z |
| publishDate | 2022-09-01 |
| publisher | MDPI AG |
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| series | Biosensors |
| spelling | doaj.art-40ce2aa7ff8a477fb99b2bc05f77bc432023-11-23T15:17:59ZengMDPI AGBiosensors2079-63742022-09-0112971710.3390/bios12090717Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence SensingYichen Zhao0Biwen Gao1Peihuan Sun2Jiawen Liu3Juewen Liu4Department of Chemistry, Waterloo Institute for Nanotechnology, Water Institute, University of Waterloo, Waterloo, ON N2L 3G1, CanadaDepartment of Chemistry, Waterloo Institute for Nanotechnology, Water Institute, University of Waterloo, Waterloo, ON N2L 3G1, CanadaDepartment of Chemistry, Waterloo Institute for Nanotechnology, Water Institute, University of Waterloo, Waterloo, ON N2L 3G1, CanadaDepartment of Chemistry, Waterloo Institute for Nanotechnology, Water Institute, University of Waterloo, Waterloo, ON N2L 3G1, CanadaDepartment of Chemistry, Waterloo Institute for Nanotechnology, Water Institute, University of Waterloo, Waterloo, ON N2L 3G1, CanadaTetracyclines are a widely used group of antibiotics, many of which are currently only used in veterinary medicine and animal husbandry due to their adverse side effects. For the detection of tetracyclines, we previously reported a DNA aptamer named OTC5 that binds to tetracycline, oxytetracycline, and doxycycline with similar <i>K</i><sub>D</sub>’s of ~100 nM. Tetracyclines have an intrinsic fluorescence that is enhanced upon binding to OTC5, which can be used as a label-free and dye-free sensor. In this work, the effect of pH and metal ions on the sensor was studied. Mg<sup>2+</sup> ions are required for the binding of OTC5 to its target with an optimal concentration of 2 mM. Other metal ions including Ca<sup>2+</sup> and Zn<sup>2+</sup> can also support aptamer binding. Although Mn<sup>2+</sup> barely supported binding, the binding can be rescued by Mg<sup>2+</sup>. ITC studies confirmed that OTC5 had a <i>K</i><sub>D</sub> of 0.2 μM at a pH of 6.0 and 0.03 μM at a pH of 8.3. Lower pH (pH 6) showed better fluorescence enhancement than higher pH (pH 8.3), although a pH of 6.0 had slightly higher <i>K</i><sub>D</sub> values. Under optimized sensing conditions, sensors with limit of detections (LODs) of 0.1–0.7 nM were achieved for tetracycline, oxytetracycline, and doxycycline, which are up to 50-fold lower than previously reported. Milk samples were also tested yielding an LOD of 16 nM oxytetracycline at a pH of 6.0.https://www.mdpi.com/2079-6374/12/9/717aptamersbiosensorstetracyclineoxytetracyclinefluorescence |
| spellingShingle | Yichen Zhao Biwen Gao Peihuan Sun Jiawen Liu Juewen Liu Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence Sensing Biosensors aptamers biosensors tetracycline oxytetracycline fluorescence |
| title | Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence Sensing |
| title_full | Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence Sensing |
| title_fullStr | Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence Sensing |
| title_full_unstemmed | Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence Sensing |
| title_short | Metal and pH-Dependent Aptamer Binding of Tetracyclines Enabling Highly Sensitive Fluorescence Sensing |
| title_sort | metal and ph dependent aptamer binding of tetracyclines enabling highly sensitive fluorescence sensing |
| topic | aptamers biosensors tetracycline oxytetracycline fluorescence |
| url | https://www.mdpi.com/2079-6374/12/9/717 |
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