Carbon nanoparticle for highly sensitive and selective fluorescent detection of mercury(II) ion in aqueous solution

In this article, carbon nanoparticles (CNPs) were used as a novel fluorescent sensing platform for highly sensitive and selective Hg2+ detection. To the best of our knowledge, this is the first example of CNPs obtained from candle soot used in this type of sensor. The general concept used in this approach is based on that adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by CNP via π–π stacking interactions between DNA bases and CNP leads to substantial dye fluorescence quenching; however, in the presence of Hg2+, T–Hg2+–T induced hairpin structure does not adsorb on CNP and thus retains the dye fluorescence. A detection limit as low as 10 nM was achieved. The present CNP-based biosensor for Hg2+ detection exhibits remarkable specificity against other possible metal ions. Furthermore, superior selectivity performance was observed when Hg2+ detection was carried out in the presence of a large amount of other interference ions. Finally, in order to evaluate its potential practical application, Hg2+ detection was conducted with the use of lake water other than pure buffer and it is believed that it holds great promise for real sample analysis upon further development.