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

Figure 2

(a) Photographic images, (b) UV-Vis absorption spectra, (c) absorption ratios (A₇₀₀/A₅₁₄) of PEI-AuNPs with 5.0 μM·Hg²⁺ ion and 50 μM various ions at pH 7, 50°C, and 500 mM·NaCl concentration, and (d) absorption ratios (A₇₀₀/A₅₁₄) of PEI-AuNPs with 50 μM various ions in the presence and absence of 5.0 μM·Hg²⁺.

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