Preparation of gold nanoparticles using pyridine-formaldehyde as a reducing agent and its application in high sensitivity colorimetric detection of Pb2+

Recently, functionalized Au nanoparticles (AuNPs) have become fascinating nanomaterials for colorimetric detection of heavy metal ions. In this paper, AuNPs were for the first time prepared by using pyridine-formaldehyde as a reducing agent under alkaline conditions in aqueous solution. In this procedure, pyridine-formaldehyde acts as a reducing agent to reduce HAuCl4 to AuNPs, and is itself oxidized to pyridine carboxylic acid simultaneously and adsorbed on the surface of AuNPs, avoiding the use of any other special stabilizing agent. The prepared AuNPs were used in colorimetric sensor for detection of Pb2+ in aqueous solutions. The Pb2+ induced aggregation could be detected quickly by a colorimetric method with the naked eye and UV-vis absorption spectra with a detection limit of 4 and 1 mu M, respectively.