A comparative study of different reagentless plasmon sensors based on Ag-Au alloy nanoparticles for detection of Hg

The analytical performance of three Ag-Au alloy nanoparticles (Ag-AuNPs) based plasmonic sensorsfor the detection of Hg(II) ions were compared. First, Ag-AuNPs were synthesized by the wet chemical method. Then, the nanoparticles were immobilized on a transparent indium tin oxide (ITO) glass surface using poly dimethyl diallyl ammonium chloride (PDDA) as the binding material or by embedding in a polyvinyl alcohol (PVA) film. The optimum composition of the Ag-AuNPs was found to be 0.7 of the Ag content in the alloy. The blue shift of the plasmonic peak wavelength of the Ag-AuNPs could be used for the detection of Hg(II) ions without adding any reagents. The plasmonic sensor based on the Ag-AuNPs/PVA/ITO probe exhibited a much higher sensitive than the Ag-Au colloid or Ag-AuNPs/PDDA/ITO probe. The changes in the peak wavelength were linearly proportional to the logarithm of the Hg(II) ion concentration in the range 0.02-100 ppb, with a detection limit of 0.01 ppb. The proposed sensor was successfully applied to the detection of Hg(II) ions in drinking water, environment, and food samples. (C) 2014 Elsevier B.V. All rights reserved.