“…5,6 Recently, nanomaterials have also been extensively used to fabricate different sensors for detecting heavy metals in aqueous solutions owing to their strong surface Plasmon resonance (SPR) and ease of functionalization. 7,8 Among them, gold nanoparticles (AuNPs) have received the most attention because of their high-performance sensing, environmental friendliness, tunable properties and photostability. 9 Several colorimetric sensors based on AuNPs have been designed for the quantitative analysis of different heavy metals such as Hg 2+ , 10 Fe 3+ , 11 Al 3+ , 12 Cd 2+ , 13 and Pb 2+ ions 14 , 15 .…”