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| Detection of CaMV35S Sequence Using a Fluorescence Sensor Based on Carbon Dots－Silver Nanoclusters Fluorescence Resonance Energy Transfer Nanotags |
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| DOI： |
| KeyWord:catalytic hairpin assembly carbon dots silver nanoclusters CaMV35S sequence ratiometric fluorescence detection |
| Author | Institution |
| ZHAI Ying-hui，WANG Ting-ting，TANG Jia-xuan，ZHANG Hong-yan，CAO Xiao-dong，YE Yong-kang，ZHENG Hai-song，LI Yun-fei |
1. School of Food and Biological Engineering，Hefei University of Technology，Heifei ，China; 2. School of Biological Science and Engineering，North Minzu University，Yinchuan ，China; 3. Technology Center of Hefei Customs District，Hefei ，China |
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| Abstract: |
| A ratiometric fluorescent sensor for genetically modified components was constructed using fluorescence resonance energy transfer（FRET） nanotags combined with catalytic hairpin assembly（CHA） enzyme-free amplification signal amplification pathway in this paper．First，two sequences HP1 and HP2 with hairpin structures were designed for CaMV35S（tDNA）-induced CHA，and then based on the FRET effect，AgNCs and CDs came in close proximity when single-stranded DNA labeled carbon dots（sDNA－CDs） and DNA templated silver nanoclusters（Ts－AgNCs） were hybridized，which led to the fluorescence quenching of CDs．A ratiometric fluorescent probe with sDNA－CDs/Ts－AgNCs fluorescence quenching is obtained．When tDNA is present，through the base complementary pairwise hybridization reaction，tDNA opens the HP1 hairpin to form an HP1－tDNA double-stranded structure．This structure can open the HP2 hairpin structure，thus forming an HP1－HP2 double-stranded structure，in which the tDNA was released into the next round of hybridization，triggering the CHA cycle．Since the affinity between the partial sequence of HP1 and the partial sequence of Ts in HP1－HP2 was stronger than that of sDNA，the fluorescence of CDs（λem = 464 nm） was enhanced by the release of sDNA－CDs from the probe after the addition of sDNA－CDs/Ts－AgNCs．However，AgNCs were still remained in the double-chain structure，leading to the unchanged fluorescence intensity of AgNCs（λem = 560 nm）．Under the optimal conditions，the output signal of IF464/IF560 showed a linear relation for CaMV35S in the concentration range of 0.1－50 nmol/L，and the detection limit（LOD，S/N = 3） was calculated to be 0.02 nmol/L．The prepared probe was used for the detection of CaMV35S components in transgenic tomato leaves with good selectivity and reliable results. |
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