In Vitro Selection of Chromium‐Dependent DNAzymes for Sensing Chromium(III) and Chromium(VI) |
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| Authors: | Wenhu Zhou Mahsa Vazin Tianmeng Yu Prof?Dr Jinsong Ding Prof?Dr Juewen Liu |
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| Affiliation: | 1. School of Pharmaceutical Sciences, Central South University, Changsha, Hunan, P.R. China;2. Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, Canada |
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| Abstract: | 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. |
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| Keywords: | chromium DNA polymerase chain reaction sensors water chemistry |
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