Figure 3

a Fluorescence spectra of solutions of 100 μL BSA-GNPs on addition of 400 μL other ions (500 μM Cd²⁺, Cr³⁺, Ba²⁺, Zn²⁺, Ca²⁺, Mn²⁺, Mg²⁺, Fe²⁺, Co²⁺, 50 μM Ni²⁺, Cu²⁺, Pb²⁺ and 4 μM Hg²⁺. b Enhanced ratios (I/I₀) of the fluorescence intensity (640 nm) of solution in (a). Excitation wavelength: 470 nm. c Fluorescence photographs of 100 μL BSA-GNPs upon addition of 400 μL of other ions other ions (50 μM) and Hg²⁺ (4 μM)