Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver Ions
In this study, novel fluorescent DNA biosensors for mercury (Hg<sup>2+</sup>) and silver (Ag<sup>+</sup>) ions were developed based on thymine (T)- and cytosine (C)-rich recognition elements in combination with exonuclease III and a mismatch-catalyzed hairpin assembly (MCHA)-...
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MDPI AG
2025-03-01
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| author | Zhen Liu Xing Liu Jie Sun Xilin Xiao |
| author_facet | Zhen Liu Xing Liu Jie Sun Xilin Xiao |
| author_sort | Zhen Liu |
| collection | DOAJ |
| description | In this study, novel fluorescent DNA biosensors for mercury (Hg<sup>2+</sup>) and silver (Ag<sup>+</sup>) ions were developed based on thymine (T)- and cytosine (C)-rich recognition elements in combination with exonuclease III and a mismatch-catalyzed hairpin assembly (MCHA)-based cascade isothermal signal-amplification strategy. In the presence of the respective target analytes, the recognition element terminals form so-called T-Hg<sup>2+</sup>-T or C-Ag<sup>+</sup>-C structures, resulting in cleavage by Exo III and the release of the trigger strand for MCHA. This binds to the H1 hairpin, which is fluorescently labeled with carboxyfluorescein (FAM) and tetramethylrhodamine (TAMRA), disrupting fluorescence resonance energy transfer between them and, thus, restoring FAM fluorescence, generating a strong signal at 520 nm. The linear range of the Hg<sup>2+</sup> sensor is 0.5 to 3 pM, with a detection limit of 0.07 pM. The recovery range in actual spiked water samples is between 98.5% and 105.2%, with a relative standard deviation (RSD) ranging from 2.0% to 4.2%. The linear range of the Ag<sup>+</sup> sensor is 10 to 90 pM, with a detection limit of 7.6 pM. The recovery range in actual spiked water samples is between 96.2% and 104.1%, with an RSD ranging from 3.2% to 6.3%. The cascade isothermal signal amplification strategy effectively enhances sensor sensitivity, while MCHA decreases the false-positive rate. The aptamer sensor exhibits high specificity, is resistant to interference, and can be used for the detection of Hg<sup>2+</sup> and Ag<sup>+</sup> in environmental water samples. |
| format | Article |
| id | doaj-art-edf2846e5a4f45e1a921f30b516b0c49 |
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| issn | 2079-6374 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
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| series | Biosensors |
| spelling | doaj-art-edf2846e5a4f45e1a921f30b516b0c492025-08-20T02:28:40ZengMDPI AGBiosensors2079-63742025-03-0115421310.3390/bios15040213Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver IonsZhen Liu0Xing Liu1Jie Sun2Xilin Xiao3School of Public Health, Hengyang School of Medicine, University of South China, Hengyang 421001, ChinaSchool of Public Health, Hengyang School of Medicine, University of South China, Hengyang 421001, ChinaSchool of Public Health, Hengyang School of Medicine, University of South China, Hengyang 421001, ChinaSchool of Public Health, Hengyang School of Medicine, University of South China, Hengyang 421001, ChinaIn this study, novel fluorescent DNA biosensors for mercury (Hg<sup>2+</sup>) and silver (Ag<sup>+</sup>) ions were developed based on thymine (T)- and cytosine (C)-rich recognition elements in combination with exonuclease III and a mismatch-catalyzed hairpin assembly (MCHA)-based cascade isothermal signal-amplification strategy. In the presence of the respective target analytes, the recognition element terminals form so-called T-Hg<sup>2+</sup>-T or C-Ag<sup>+</sup>-C structures, resulting in cleavage by Exo III and the release of the trigger strand for MCHA. This binds to the H1 hairpin, which is fluorescently labeled with carboxyfluorescein (FAM) and tetramethylrhodamine (TAMRA), disrupting fluorescence resonance energy transfer between them and, thus, restoring FAM fluorescence, generating a strong signal at 520 nm. The linear range of the Hg<sup>2+</sup> sensor is 0.5 to 3 pM, with a detection limit of 0.07 pM. The recovery range in actual spiked water samples is between 98.5% and 105.2%, with a relative standard deviation (RSD) ranging from 2.0% to 4.2%. The linear range of the Ag<sup>+</sup> sensor is 10 to 90 pM, with a detection limit of 7.6 pM. The recovery range in actual spiked water samples is between 96.2% and 104.1%, with an RSD ranging from 3.2% to 6.3%. The cascade isothermal signal amplification strategy effectively enhances sensor sensitivity, while MCHA decreases the false-positive rate. The aptamer sensor exhibits high specificity, is resistant to interference, and can be used for the detection of Hg<sup>2+</sup> and Ag<sup>+</sup> in environmental water samples.https://www.mdpi.com/2079-6374/15/4/213fluorescent sensormercury ion detectionsilver ion detectioncascade isothermal signal amplificationcatalytic hairpin assembly |
| spellingShingle | Zhen Liu Xing Liu Jie Sun Xilin Xiao Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver Ions Biosensors fluorescent sensor mercury ion detection silver ion detection cascade isothermal signal amplification catalytic hairpin assembly |
| title | Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver Ions |
| title_full | Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver Ions |
| title_fullStr | Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver Ions |
| title_full_unstemmed | Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver Ions |
| title_short | Cascade Fluorescent Sensors Based on Isothermal Signal Amplification for the Detection of Mercury and Silver Ions |
| title_sort | cascade fluorescent sensors based on isothermal signal amplification for the detection of mercury and silver ions |
| topic | fluorescent sensor mercury ion detection silver ion detection cascade isothermal signal amplification catalytic hairpin assembly |
| url | https://www.mdpi.com/2079-6374/15/4/213 |
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