In Vitro Selection of Chromium-Dependent DNAzymes for Sensing Chromium(III) and Chromium(VI)

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• 作者：Wenhu Zhou ; Mahsa Vazin ; Tianmeng Yu ; Prof. Dr. Jinsong Ding and Prof. Dr. Juewen Liu
• 刊名：Chemistry - A European Journal
• 出版年：2016
• 出版时间：July 4, 2016
• 年：2016
• 卷：22
• 期：28
• 页码：9835-9840
• 全文大小：1036K
• ISSN：1521-3765

文摘

Chromium is a very important analyte for environmental monitoring, and developing biosensors for chromium is a long-standing analytical challenge. In this work, in vitro selection of RNA-cleaving DNAzymes was carried out in the presence of Cr³⁺. The most active DNAzyme turned out to be the previously reported lanthanide-dependent Ce13d DNAzyme. Although the Ce13d activity was about 150-fold lower with Cr³⁺ than that with lanthanides, the activity of lanthanides and other competing metals was masked by using a phosphate buffer; this left Cr³⁺ as the only metal that could activate Ce13d. With 100 μm Cr³⁺, the cleavage rate is 1.6 h⁻¹ at pH 6. By using a molecular beacon design, Cr³⁺ was measured with a detection limit of 70 nm, which was significantly lower than the United States Environmental Protection Agency (EPA) limit (11 μm). Cr⁴⁺ was measured after reduction by NaBH₄ to Cr³⁺, and it could be sensed with a similar detection limit of 140 nm Cr⁴⁺; this value was lower than the EPA limit of 300 nm. This sensor was tested for chromium speciation analysis in a real sample, and the results supported its application for environmental monitoring. At the same time, it has enhanced our understanding of the interactions between chromium and DNA.