Fig. 1. HRTEM image of BSA-AuNCs; Inset is particle size distribution of BSA-AuNCs

Fig. 2. UV absorption spectra of BSA-AuNCs (1); HAuCl₄(2); BSA (3); Fluorescence excitation spectra (4) and emission spectra (5) of BSA-AuNCs; Inset are images of BSA-AuNCs under sunlight and 365 nm light

Fig. 3. UV-vis absorption spectra of different component solutions (1) TMB+H₂O₂;(2) BSA-AuNCs+TMB; (3) BSA-AuNCs+H₂O₂; (4) BSA-AuNCs+TMB+H₂O₂; the illustration is a picture of the corresponding component solution (a); Emission spectra of BSA-AuNCs and UV absorption spectra of ox-TMB; inset are images of the color changes before and after H₂O₂ oxidized TMB catalyzed by BSA-AuNCs (b)

Fig. 4. Fluorescence spectra of different BSA-AuNCs samples
1: BSA-AuNCs only; 2: BSA-AuNCs with 5.0 mmol·L^-1 TMB; 3: BSA-AuNCs with 2.0 mmol·L^-1 H₂O₂; 4: BSA-AuNCs with both 5.0 mmol·L^-1 TMB and 2.0 mmol·L^-1 H₂O₂

Fig. 5. Effects of pH (a), ionic strength (b), temperature (c) and reaction time (d) on fluorescence intensity, BSA-AuNCs containing 50 μmol·L^-1 H₂O₂ and 5 mmol ·L^-1 TMB

Fig. 6. Fluorescence spectra of BSA-AuNCs with different amounts of H₂O₂ and TMB (a);the Stern-Volmer plot showing the linear relationship (b)

Fig. 7. Fluorescence spectra of BSA-AuNCs with different amounts of UA and TMB (a);the Stern-Volmer plot showing the linear relationship (b)

Fig. 8. Effect of potential interfering compounds of UA on BSA-AuNCs fluorescent probe

Fig. 9. Scheme 1 Schematic diagram of BSA-AuNCs fluorescent probe detecting H₂O₂ and UA based on FRET