Cr(3+) Binding to DNA Backbone Phosphate and Bases: Slow Ligand Exchange Rates and Metal Hydrolysis.

The interaction between chromium ions and DNA is of great interest in inorganic chemistry, toxicology, and analytical chemistry. Most previous studies focused on in situ reduction of Cr(VI), producing Cr(3+) for DNA binding. Recently, Cr(3+) was reported to activate the Ce13d DNAzyme for RNA cleavage.

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

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 Cr(3+) . The most active DNAzyme turned out to be the previously reported lanthanide-dependent Ce13d DNAzyme.

In Vitro Selection of a DNAzyme Cooperatively Binding Two Lanthanide Ions for RNA Cleavage.

Trivalent lanthanide ions (Ln(3+)) were recently employed to select RNA-cleaving DNAzymes, and three new DNAzymes have been reported so far. In this work, dysprosium (Dy(3+)) was used with a library containing 50 random nucleotides. After six rounds of in vitro selection, a new DNAzyme named Dy10a was obtained and characterized.

Desulfurization Activated Phosphorothioate DNAzyme for the Detection of Thallium.

Thallium (Tl) is a highly toxic heavy metal situated between mercury and lead in the periodic table. While its neighbors have been thoroughly studied for DNA-based sensing, little is known about thallium detection. In this work, in vitro selection of RNA-cleaving DNAzymes is carried out using Tl(3+) as the target metal cofactor.

Biochemical Characterization of a Lanthanide-Dependent DNAzyme with Normal and Phosphorothioate-Modified Substrates.

A trivalent lanthanide (Ln(3+))-dependent RNA-cleaving DNAzyme, Ce13d, was recently isolated via in vitro selection. Ce13d is active in the presence of all Ln(3+) ions. Via introduction of a single phosphorothioate (PS) modification at the cleavage site, its activity with Ln(3+) decreases while all thiophilic metals can activate this DNAzyme.

A new heavy lanthanide-dependent DNAzyme displaying strong metal cooperativity and unrescuable phosphorothioate effect.

In vitro selection of RNA-cleaving DNAzymes was performed using three heavy lanthanide ions (Ln(3+)): Ho(3+), Er(3+) and Tm(3+). The resulting sequences were aligned together and about half of the library contained a new family of DNAzyme. These DNAzymes have a simple loop structure, and they are active only with the seven heavy Ln(3+).

In vitro selection of a new lanthanide-dependent DNAzyme for ratiometric sensing lanthanides.

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 Lu(3+), since Lu(3+) 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.

Ultrasensitive DNAzyme beacon for lanthanides and metal speciation.

Metal-ion detection and speciation analysis is crucial for environmental monitoring. Despite the importance of lanthanides, few sensors are available for their detection. DNAzymes have been previously used to detect divalent metals, while no analytical work was carried out for trivalent and tetravalent ions.