Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA Functionalized Gold Nanoparticles

A new colorimetric detection of methylmercury (CH(3)Hg(+)) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (H(T7)) recognizing CH(3)Hg(+), which was used to capture and separate CH(3)Hg(+) by centrifugation. It was found that the CH(3)Hg(+) reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H(2)O(2) was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH(3)Hg(+) with a linear range of 10–200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH(3)Hg(+) detection in environmental samples.