A Highly Sensitive and Selective Colorimetric Hg²⁺ Ion Probe Using Gold Nanoparticles Functionalized with Polyethyleneimine

Figure 6

Photographic images, UV-Vis absorption spectra, and absorption ratios (A₇₀₀/A₅₁₄) of the color change of PEI-AuNPs upon addition of (a) Hg²⁺, (b) MeHg⁺, (c) EtHg⁺, and (d) PhHg⁺ with various concentrations (0.05, 0.15, 0.25, 0.5, 1.5, 2.5, 3.5, and 5.0 μM from left to right) in the presence of 300 mM·NaCl. Inset: plot of A₇₀₀/A₅₁₄ versus (a) Hg²⁺, (b) MeHg⁺, (c) EtHg⁺, and (d) PhHg⁺ ion concentration (0–50 nM).

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