Ultrasensitive and selective detection of mercury (II) in serum based on the gold film sensor using a laser scanning confocal imaging-surface plasmon resonance system in real time

Hg 2+ ions are one of the most toxic heavy metal ion pollutants, and are caustic and carcinogenic materials with high cellular toxicity. The Hg 2+ ions can accumulate in the human body through the food chain and cause serious and permanent damage to the brain with both acute and chronic toxicity. According to the US Environment Protection Agency (EPA) guidelines, Hg 2+ ions must be at concentrations below 1 ng/ml (10 nM) in drinking water. If the Hg 2+ ions are higher than 2.5 ng/ml in serum, that will bring mercury poisoning. The traditional testing for Hg 2+ ions includes atomic absorption, atomic fluorescence, and inductively coupled plasma mass spectrometry. These methods are usually coupled with gas chromatography, high-performance liquid chromatography, and capillary electrophoresis. However, these instrument-based techniques are rather complicated, time-consuming, costly, and unsuitable for online and portable use. An ultrasensitive and selective detection of mercury (II) in serum was investigated using a laser scanning confocal imaging-surface plasmon resonance system (LSCI-SPR). The detection limit was as low as 0.01 ng/ml for Hg 2+ ions in fetal calf serum and that is lower than that was required Hg 2+ ions must be at concentrations below 1 ng/ml by the US Environment Protection Agency (EPA) guidelines. This sensor was designed on a T-rich, single-stranded DNA (ssDNA)-modified gold film, which can be individually manipulated using specific T–Hg 2+ –T complex formation. The quenching intensity of the fluorescence images for rhodamine-labeled ssDNA fitted well with the changes in SPR. The changes varied with the Hg 2+ ion concentration, which is unaffected by the presence of other metal ions. A good liner relation was got with the coefficients of 0.9116 in 30% fetal calf serums with the linear part over a range of 0.01 ng/ml to10 ng/ml.