Aggregation-based determination of mercury(II) using DNA-modified single gold nanoparticle, T-Hg(II)-T interaction,...

An ultrasensitive assay is described for the detection and determination of Hg²⁺(aq) in water samples based on single-particle inductively-coupled plasma/mass spectrometry (spICP-MS). In the presence of Hg²⁺(aq), AuNPs modified with a segment of single-stranded DNA aggregate due to the formation of the well-known thymine (T)-Hg²⁺-T complex. Single particle (sp) ICP-MS is used quantify the degree of aggregation by the overall decrease in number of detected AuNPs or NP aggregates. Compared with most other Hg²⁺ assays that use the same principle of aggregation-dispersion with DNA modified AuNPs, this method has a much lower detection limit of (0.031 ng L^-1, 155 fM) and a wider (10,000-fold) linear range (up to 1 μg L^-1). The method also showed good practical potential because of its minimal interference from the water sample matrix. Graphical abstractSchematic representation of Hg²⁺ determination by using modified AuNP probes measured by spICP-MS. AuNPs pulses detected in ICP-MS is relative to the aggregation status of AuNPs based on thymine-Hg²⁺-thymine interaction.