A regenerative electrochemical sensor based on oligonucleotide for the selective determination of mercury(ii)

Abstract

We have developed a selective, sensitive, and re-usable electrochemical sensor for Hg2+ ion detection. This sensor is based on the Hg2+-induced conformational change of a single-stranded DNA (ssDNA) which involves an electroactive, ferrocene-labeled DNA hairpin structure and provides strategically the selective binding of a thymine-thymine mismatch for the Hg2+ ion. The ferrocene-labeled DNA is self-assembled through S-Au bonding on a polycrystalline gold electrode surface and the surface blocked with 3-mercapto-1-propanol to form a mixed monolayer. The modified electrode showed a voltammetric signal due to a one-step redox reaction of the surface-confined ferrocenyl moiety. The 'signal-on' upon mercury binding could be attributed to a change in the conformation of ferrocene-labeled DNA from an open structure to a restricted hairpin structure. The differential pulse voltammetry (DPV) of the modified electrode showed a linear response of the ferrocene oxidation signal with increase of Hg2+ concentration in the range between 0.1 and 2 microM with a detection limit of 0.1 microM. The molecular beacon mercury(II) ion sensor was amenable to regeneration by simply unfolding the ferrocene-labeled DNA in 10 microM cysteine, and could be regenerated with no loss in signal gain upon subsequent mercury(II) ion binding.

Au NPs-enhanced surface plasmon resonance for sensitive detection of mercury(II) ions

“…In particular, PDCA had no obvious influence on the target ion Hg 2+ , which was consistent with the previous report (Nolan and Lippard, 2008). The results for detection of Hg 2+ were comparable with that of electrochemical and optical sensors (Han et al, 2009;Wang et al, 2008a,b; and much superior to the detection results obtained by some common SPR sensor (Chah et al, 2004;Yu et al, 2004).…”

“…With the introduction of Au NPs amplification, as low as 5 nM Hg 2+ could be detected. The results for detection of Hg 2+ were comparable with that of electrochemical and optical sensors (Han et al, 2009;Wang et al, 2008a,b;Zhu et al, 2009) and much superior to the detection results obtained by common SPR sensor (Chah et al, 2004;Yu et al, 2004). The SPR-based Hg 2+ sensor also exhibited excellent selectivity over a spectrum of interference metal ions such as Cu 2+ , Pb 2+ , Mg 2+ and so on.…”

Synthesis and electroactivated addressing of ferrocenyl and azido-modified stem-loop oligonucleotides on an integrated electrochemical device

“…Previous thermodynamic studies demonstrated that the folded structure was not destabilized by incorporating numerous Fc molecules inside or at the extremities of the hairpin [7].Ferrocenes bound to oligonucleotide probes act as electrochemical markers, affording a sharp electrochemical response which is highly sensitive to ionic and steric surrounding media. In the literature, Fc modified stem-loop structures have already been described as efficient probes for electrochemical DNA detection after anchoring on electrode surfaces [20][21][22].In comparison to the papers already published in this field, the main advantage of our work lies in the easy incorporation of numerous ferrocenes in the probes to enhance the electrochemical response of the DNA sensor. The melting temperature (Tm) values were calculated directly from the sequences.…”

A dual functional electrochemical “on–off” switch sensor for the detection of mercury(II) and melamine

“…Due to their serious harm to biological systems, great attention has been directed to develop new efficient, rapid, facile and applicable methods for sensitive and selective detection of Hg 2+ . It has been reported that there is specific and strong coordination between Hg 2+ and the thymine-thymine mismatched pairs [6] and this specific thymine-Hg 2+ -thymine (T-Hg 2+ -T) interaction has been used to develop a wide variety of electrochemical [7][8][9], colorimetric [10][11][12][13] and fluorescent [14][15][16] sensors for Hg 2+ detection. Among these detection techniques, electrochemical methods have received particular attention due to their high sensitivity and selectivity, simple instrumentation, low production cost, and the fact that they are fast, accurate, compact, portable, and inexpensive.…”