A new and facile nanosilver SPR colored method for ultratrace arsenic based on aptamer regulation of Au-doped carbon dot catalytic amplification.

Here, Au-doped carbon dots (CDAu) nanosols with good stability were prepared by hydrothermal reaction method. We found that CDAu can efficiently catalyze the nanoreaction of reducing AgNO3 by glucose, and at 420 nm，the reaction products of yellow spherical silver nanosol exhibit an intense surface plasmon resonance (SPR) absorption peak. The nucleic acid aptamers (Apt) can be adsorbed on the surface of carbon dots, so that their catalytic activity was suppressed, the nanosilvers were reduced, the solution color becomes lighter, and the Abs value was weakened. When As3+ was added, it forms a stable conjugate with the Apt, releases free carbon dots, restored its catalytic activity, and the color and Abs signals enhanced linearly. Based on the Apt regulation and the catalytic amplification effect of CDAu on AgNO3-glucose, a new extremely sensitive SPR spectrophotometric method for the determination of arsenic ion content of 0.025-0.75 µg/L was established, and the detection limit of As3+ is 0.01 µg/L.