Field and pretreatment-free detection of heavy-metal ions in organic polluted water is important but still challenging in current water pollution emergency response systems. Here we report a polyadenine-DNA-mediated approach for a rationally designed alkyne-coded surface enhanced Raman scattering (SERS) test kit, enabling rapid and simultaneous detection of Hg2+ and Ag+ by a portable spectrometer, impervious to organic interferences. Because of the formation of thymine (T)-Hg2+-T and cytosine (C)-Ag+-C, highly recognizable SERS signals are rapidly detected when two different alkyne-labeled gold nanoparticles (AuNPs) are induced to undergo controllable bridging upon the addition of low-volume targets. For multiplex detection through a portable spectrometer, the limits of detection reach 0.77 and 0.86 nM for Hg2+ and Ag+, respectively. Of particular significance, the proposed C C-containing Raman reporters provide an extremely effective solution for multiplex sensing in a spectral silent region, when the hyperspectral and fairly intense optical noises originating from lower wavenumber region (<1800 cm(-1)) are inevitable under complex ambient conditions.