Cationic Conjugated Polyelectrolyte/Molecular Beacon Complex for Sensitive, Sequence-Specific, Real-Time DNA Detection

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• 作者：Xuli Feng ; Xinrui Duan ; Libin Liu ; Lingling An ; Fude Feng ; Shu Wang
• 刊名：Langmuir
• 出版年：2008
• 出版时间：November 4, 2008
• 年：2008
• 卷：24
• 期：21
• 页码：12138-12141
• 全文大小：187K
• 年卷期：v.24,no.21(November 4, 2008)
• ISSN：1520-5827

文摘

A new fluorescence method has been developed for DNA detection at room temperature in a sensitive, selective, economical, and real-time manner that interfaces the superiority of a molecular beacon in mismatch discrimination with the light-harvesting property of water-soluble conjugated polyelectrolytes. The probe solution contains a cationic conjugated polyelectrolyte (PFP-NMe₃⁺), a molecular beacon with a five base pairs double-stranded stem labeled at the 5′-terminus with fluorescein (DNA_P-Fl), and ethidium bromide (EB, a specific intercalator of dsDNA). The electrostatic interactions between DNA_P-Fl and PFP-NMe₃⁺ keep them in close proximity, facilitating the fluorescence resonance energy transfer (FRET) from PFP-NMe₃⁺ to fluorescein. Upon adding a complementary strand to the probe solution, the conformation of DNA_P-Fl transits into dsDNA followed by the intercalation of EB into the grooves. Two-step FRET, from PFP-NMe₃⁺ to DNA_P-Fl (FRET-1), followed by FRET from DNA_P-Fl to EB (FRET-2) takes place. In view of the observed fluorescein or EB emission changes, DNA can be detected in aqueous solution. Because the base mismatch in target DNA inhibits the transition of DNA_P-Fl from the stem-loop to duplex structure, single nucleotide mismatch can be clearly detected.