Phenylboronic Acid-Functionalized Ratiometric Surface-Enhanced Raman Scattering Nanoprobe for Selective Tracking of Hg 2+ and CH 3 Hg + in Aqueous Media and Living Cells.

The development of appropriate molecular tools to monitor different mercury speciation, especially CH 3 Hg + , in living organisms is attractive because its persistent accumulation and toxicity are very harmful to human health. Herein, we develop a novel activity-based ratiometric SERS nanoprobe to selectively monitor Hg 2+ and CH 3 Hg + in aqueous media and in vivo. In this nanoprobe, a new bifunctional Raman probe bis-s-s'-[(s)-(4-(ethylcarbamoyl)phenyl)boronic acid] (b-(s)-EPBA) was synthesized and immobilized on the surface of gold nanoparticles via a Au-S bond, in which the phenylboronic acid group was employed as the recognition unit for Hg 2+ and CH 3 Hg + based on the Hg-promoted transmetalation reaction. In the presence of Hg 2+ and CH 3 Hg + , a new surface-enhanced Raman scattering (SERS) peak aroused from of C-Hg appeared at 1080 cm -1 , and the SERS intensity at 1002 cm -1 belonged to the B-O symmetric stretching decreased simultaneously. The quantitative tracking of Hg 2+ and CH 3 Hg + was realized based on the SERS intensity ratio ( I 1080 / I 1303 ) with rapid response (∼4 min) and high sensitivity, with detection limits of 10.05 and 25.13 nM, respectively. Moreover, the SERS sensor was used for the quantitative detection of Hg 2+ and CH 3 Hg + in four actual water samples with a high accuracy and excellent recovery. More importantly, cell imaging experiments showed that AuNPs@b-(s)-EPBA could quantitatively detect intracellular CH 3 Hg + and had a good concentration dependence in ratiometric SERS imaging. Meanwhile, we demonstrated that AuNPs@b-(s)-EPBA could detect and image CH 3 Hg + in zebrafish. We anticipate that AuNPs@b-(s)-EPBA could potentially be used to study the physiological functions related to CH 3 Hg + in the future.