Figure 4

Changes in the wavelength of maximum fluorescence after the addition of D- and L-cysteine (2 mmol L⁻¹) against time (min). The inset shows fluorescence images of QDs 2 h after the addition of 2 mmol L⁻¹ L-, D-cysteine and 60 mmol L⁻¹ NaOH under UV irradiation.