Figure 5

(a) The emission ratios (I₅₁₂/I₆₀₄) of Au NCs-Cy1 (25 μg ml⁻¹) in PBS buffer, in NaCl solution (50 mM) and in a cell culture, DMEM, before and after 100 μM NaHS was added; (b) stability of the emission ratio (I₅₁₂/I₆₀₄) of Au NCs-Cy1 (25 μg ml⁻¹) at different pH values; (c) cytotoxicity of Au NCs-Cy1 on living HeLa cells analyzed via the MTT experiment; (d) photostability of Au NCs-Cy1 (25 μg ml⁻¹) in live cells. Emission wavelengths: 520±10 nm and 610±20 nm; excitation wavelength: 405 nm.