Strategic approaches for highly selective and sensitive detection of Hg2+ ion using mass sensitive sensors

Abstract

Here we present a quartz crystal microbalance (QCM) sensor for the highly selective and sensitive detection of Hg2+ ion, a toxic chemical species and a hazardous environmental contaminant. Hg2+ ion can be quantitatively measured based on changes in the resonance frequency of QCM following mass changes on the QCM sensor surface. The high selectivity for Hg2+ ion in this study can be obtained using a thymine-Hg2+-thymine pair, which is more stable than the adeninethymine base pair in DNA. On the other hand, gold nanoparticles (AuNPs) and their size-enhancement techniques were used to amplify the QCM signals to increase the sensitivity for Hg2+ ion. With this strategic approach, the proposed QCM sensor can be used to quantitatively analyze Hg2+ ion with high selectivity and sensitivity. The detection limit was as low as 98.7 pM. The sensor failed to work with other metal ions at concentrations 1000-times higher than that of the Hg2+ ion. Finally, the recovery does not exceed 10% of the original value for the detection of Hg2+ ion in tap and bottled water. The results indicate acceptable accuracy and precision for practical applications.