Aptamer based determination of Pb(II) by SERS and by exploiting the reduction of HAuCl4 by H2O2 as catalyzed by graphene oxide nanoribbons.

The authors report that graphene oxide nanoribbons exert a strong catalytic effect on the reduction of HAuCl4 by H2O2 to form gold nanoparticles which display nanoplasmonic surface enhanced Raman scattering (SERS) activity, Rayleigh scattering and absorption. If an aptamer against Pb(II) is present in solution, it will bind to the graphene oxide nanoribbons and thereby inhibit their catalytic activity. Upon addition of Pb(II), it will bind to the aptamer to form stable complexes and release free graphene oxide nanoribbon. These cause the surface enhanced Raman scattering intensity at 1615 cm-1 to increase in the presence of the molecular probe Victoria Blue B. The SERS signal increases linearly in the 0.002-0.075 μmol·L-1 Pb(II) concentration range, and the detection limit is 0.7 nmol·L-1. Toner samples were spiked and then analyzed for Pb(II) by this method. Relative standard deviations are between 6.2% and 12.2%, and recoveries range from of 86.7%-106.7%. Graphic abstract Based on Pb(II) binds to the aptamer to form stable G-quadruplex and release free graphene oxide nanoribbon, a sensitive and selective surface enhanced Raman scattering method was developed for detection of 0.002-0.075 μmol·L-1 Pb(II) by using the molecular probe Victoria Blue B.