Sensitive determination of Hg(II) based on a hybridization chain recycling amplification reaction and surface-enhanced Raman scattering on gold nanoparticles.

A method was developed for the determination of mercuric ion Hg(II). It is based on hybridization chain reaction (HCR) and surface-enhanced Raman scattering (SERS). Raman signal DNA and streptavidin were self-assembled on gold nanoparticles as a novel signal nanoprobe (AuNP-sDNA). A thymine-mercury(II)-thymine structure was immobilized on magnetic beads (MBs). The HCR makes use of two hairpin probes that are initiated by the trigger DNA to form a stable nicked dsDNA structure (MB-TS-hDNAs). A large number of the binding sites is provided to connect the signal nanoprobe. The stable sandwich structure (MB-TS-hDNA/AuNP-sDNA) was isolated by applying a magnetic field and used in the amplification step. In this way, Hg(II) can be determined sensitively after multiple signal amplification. The SERS signal, measured at 1499 cm, increases linearly in the 0.1 pM to 10 nM Hg(II) concentration range, and the limit of detection is 0.08 pM (at an S/N ratio of 3). The method was applied to the detection of Hg(II) in spiked environment water samples, with recoveries ranging from 96 to 119%. Graphical abstract Schematic of a method based on the use of a stable T-Hg(II)-T structure and a self-assembled nanoprobe. It was applied to the trace Hg(II) detection based on hybridization chain reaction (HCR) and surface-enhanced Raman scattering (SERS).