Visual and colorimetric detection of Hg2+ by cloud point extraction with functionalized gold nanoparticles as a probe

Association with Hg2+ enhances the hydrophobicity and triggers the cloud point extraction of ∼4 nm-diameter gold nanoparticle probes functionalized with mercaptopropionic acid and homocystine, which results in the color change of the TX-114-rich phase from colorless to red, and therefore provides a novel approach for visual and colorimetric detection of Hg2+ with ultrahigh sensitivity and selectivity.