Localized surface plasmon resonance light-scattering sensor for mercury(II) ion with label-free gold nanoparticles

A localized surface plasmon resonance (LSPR) light-scattering sensor for Hg2+ was developed with unmodified gold nanoparticles (AuNPs) based upon the specific recognition property of Hg2+ with T-T mismatched base pair. Oligonucleotide 5'-GTTCTTTGTCTTCA-3'(oligo-1) and 5'-TGTAGTCTATGTAC-3'(oligo-2) can adsorb on the surface of AuNPs, which can prevent them from aggregation because of electrostatic repulsion. However, the DNA hybridization occurred between oligo-1 and oligo-2 upon addition of Hg2+, can induce the desorption of oligonucleotide from the surface of AuNPs, and trigger the aggregation of AuNPs accompany with the increase of LSPR light-scattering intensity. Under the optimum conditions, the intensity was proportional to the concentration of Hg2+ over the range 53.1-530 nM, and the detection limit was 29.4 nM.