In Vitro Selection of a New Lanthanide-Dependent DNAzyme for Ratiometric Sensing Lanthanides

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• 作者：Po-Jung Jimmy Huang ; Mahsa Vazin ; Juewen Liu
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：October 7, 2014
• 年：2014
• 卷：86
• 期：19
• 页码：9993-9999
• 全文大小：469K
• ISSN：1520-6882

文摘

Developing biosensors for lanthanides is an important but challenging analytical task. To address this problem, in vitro selection of RNA-cleaving DNAzymes was carried out using a library containing a region of 35 random nucleotides in the presence of Lu³⁺, since Lu³⁺ was reported to be the most efficient lanthanide for RNA cleavage. The resulting DNA sequences can be aligned to a single family with two conserved stretches of nucleotides. One of the representative DNAzymes (named Lu12) was further studied. Lu12 is more active with smaller lanthanides and has the lowest activity in the presence of the largest lanthanide (lutetium). Its cleavage rate is 0.12 min^鈥? in the presence of 10 渭M Nd³⁺ at pH 6.0. This is a new DNAzyme, and a catalytic beacon sensor is designed by attaching a fluorophore/quencher pair, detecting Nd³⁺ down to 0.4 nM (72 parts-per-trillion). This DNAzyme is highly selective for lanthanides as well, showing cleavage only with two nonlanthanide ions: Y³⁺ and Pb²⁺. We previously reported a DNAzyme named Ce13d, which has similar responses to all the trivalent lanthanides. Combining these two allows for a ratiometric assay that identifies a few large lanthanides.