Figure 2

Emission spectra of the co-doped silica particles and molecular structures of FITC under different pH. (A) Emission spectra of the co-doped silica particles dispersed in BR buffers with pH of 2.1, 3.3, 4.1, 4.9, 5.8, 6.8, 7.8, 8.9, and 9.9. The excitation wavelength was at 450 nm. Insert gives the photos of the particles dispersed in BR buffers with different pH under a 365 nm UV lamp. (B) Molecular structures of FITC under different pH.