Colorimetric Assay of Lead Ions in Biological Samples Using a Nanogold-Based Membrane

We have developed a simple paper-based colorimetric membrane for sensing lead ions (Pb2+) in aqueous solutions. The nitrocellulose membrane (NCM) was used to trap bovine serum albumin (BSA) modified 13.3-nm Au nanoparticles (BSA-Au NPs), leading to the preparation of a nanocomposite film of a BSA-Au NP-decorated membrane (BSA-Au NPs/NCM). The BSA-Au NPs/NCM operates on the principle that Pb2+ ions accelerate the rate of leaching of Au NPs induced by thiosulfate (S2O3 2–) and 2-mercaptoethanol (2-ME). The BSA-Au NPs/NCM allowed for the detection of Pb2+ by the naked eye in nanomolar aqueous solutions in the presence of leaching agents such as S2O3 2– and 2-ME. We employed the assistance of microwave irradiation to shorten the reaction time (