Thiodisuccinic Acid Functionalized Silver Nanoparticles Used as a Colorimetric Sensor for Lead Ion

We reported herein the preparation of thiodisuccinic acid-capped silver nanoparticles (TDSA-AgNPs) in water solution and their visual detection for lead ions. The freshly synthesized TDSA-AgNPs were yellow in color due to the intense surface plasmon absorption band. In the presence of Pb²⁺, the yellow TDSA-AgNPs solution turned to a deep orange color accompanying with the peak broadening. However, the sensitivity of TDSA-AgNPs towards other representative metal ions (Cu²⁺, Mn²⁺, Mg²⁺, Fe³⁺, Zn²⁺, Ni²⁺, Ca²⁺, Sr²⁺) could be negligible. Furthermore, the effect of the concentration of Pb²⁺ to the modified AgNPs was investigated and the limit of detection for Pb²⁺ was 8×10^-5 mol/L by the naked eye. Meanwhile, the possible mechanism of the aggregated TDSA-AgNPs was discussed by the simultaneous addition of ethylenediaminetetraacetate (EDTA) and Pb²⁺ in the TDSA-AgNPs colloids.