Detection of Mercury Ions at ng/L Scale by Surface Plasmon Resonance (SPR) on DNA Aptamer Biochips
Résumé
Mercury pollution is an important environmental problem due to its toxicity to humans, even at very low concentrations. Presently, several methods enable the detection of this element at environmental concentrations. Although sufficiently sensitive in most cases, measurements are typically made punctually. Here, we present the development of a continuous flow detection system for two mercury forms: the mercuric ion (Hg2+ ) and the methylmercury ion (CH3-Hg+). We used a compact SPR device based on gold chips functionalized with tailored aptamers. Leveraging the specific affinity between DNA aptamers and mercuric ions, this reliable technique allowed the detection of mercuric ion concentrations in the ng/L range. The high sensitivity is attributed to the expected DNA folding into a hairpin shape in the presence of mercuric ions. Circular Dichroism (CD) spectroscopy confirmed that a conformational change in the DNA occurs starting from 3 mercuric ions per aptamer. Below this threshold (1 or 2 ions), the strand does not fold, whereas from 3 ions onward, folding is observed. This study highlights the strong potential of compact SPR associated with specific DNA aptamers for the realization of a portable real-time detection device.
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