Figure 5.

(a) Fluorescence intensity rate (F/F₀) of UCNP-Apt (0.05 mg mL^–1) by 10 ng mL^–1 HA with various concentrations of graphene oxide (excitation wavelength 980 nm). (b) Effect of GO concentration on the fluorescence intensity of UCNP-Apt in the presence (F) and absence (F₀) of 10 ng mL^–1 HA. (c) Time dependence of the fluorescence quenching degree with UCNP-Apt (0.05 mg mL^–1) and 100 μg mL^–1 GO. All experiments were performed in borate buffer (10 mM, 5 mM KCl, pH 7.8) under excitation at 980 nm. (d) Quenching using various reaction buffers (the concentration of buffer solutions is 20 mM with the same pH). (e) pH dependence of the fluorescence intensity. (f) Quenching efficiency with various concentrations of KCl in borate buffer.