Fig 1.
Syntheses of the fluorescent probe L and proposed binding mode of L to Cu2+.
Fig 2.
UV-vis spectra of the fluorescent probe L (10 μM) upon addition of various metal ions (4 equiv.) in CH3CN:HEPES (3:2, v/v, pH = 7.4).
Fig 3.
UV-vis spectra of fluorescent probe L (10 μM) upon addition of Cu2+ ions in CH3CN:HEPES (3:2, v/v, pH = 7.4) solution.
Insert: UV-vis titration profile of the fluorescent probe L at 465 nm.
Fig 4.
The fluorescence spectra titration of fluorescent probe L (10 μM) upon the addition of Cu2+ ions in CH3CN: HEPES (3:2, v/v, pH = 7.4) solution.
Insert: Fluorescence titration profile of the fluorescent probe L at 575 nm (excited at 465 nm).
Fig 5.
Benesi-Hildebrand linear fitting demonstrated a 1:1 stoichiometry for the L-Cu2+ complexation species.
Fig 6.
The fluorescence spectra selectivity of the fluorescent probe L (10 μM) upon the addition of various metal ions (4 equiv.) in CH3CN:HEPES (3:2, v/v, pH = 7.4) solution (pink bars): (1) Cu2+, (2) Mn2+, (3) Fe2+, (4) Fe3+, (5) Ni2+, (6) K+, (7) Cd2+, (8) Mg2+, (9) Na+, (10) Al3+, (11) Co2+, (12) Pb2+, (13) Hg2+, (14) Cr3+, (15) Ag+, (16) Ca2+, (17) Zn2+.
The blue bars indicated the fluorescence intensity of L after adding Cu2+ ions to the above solutions except 1.
Fig 7.
The fluorescence images of LO-2 cells incubated with probe L (3 μM) (A); probe L after addition of 5 equivalents of Cu2+ ions (C); and their corresponding bright field images (B and D).