Gold nanomaterials based absorption and fluorescence detection of mercury, lead, and copper

Gold nanomaterials (Au NMs) such as Au nanoparticles (Au NPs) and fluorescent Au nanodots (Au NDs) have been widely used for monitoring the levels of potentially toxic metal (PTM) ions (e.g., Hg²⁺, Pb²⁺, Cu²⁺) in aquatic ecosystems. We focus on the absorption and fluorescence assays for Hg²⁺, Pb²⁺, and Cu²⁺ ions using functionalized Au NPs and Au NDs. The preparation of functionalized Au NPs and Au NDs are discussed. The optical sensing systems is divided into four parts including Au NP-based colorimetric systems, catalytic Au NPs-based systems, Au NPs-based quenching systems, and Au NDs-based systems. Factors controlling the selectivity and sensitivity of the nanosensors toward the analytes are discussed, including the size of Au NMs, length and sequence of DNA, nature of ligands, and sensing conditions. To show the merits of Au NMs, their practicality for the detection of Hg²⁺, Pb²⁺, and Cu²⁺ ions are highlighted.