Additional file 1 of Ligand-modulated synthesis of gold nanoclusters for sensitive and selective detection of folic acid

Additional file 1: Supplementary information. Figure S1. Synthesis schematic illustration of AuNCs capped with D-Trp, D-Trp-OBzl, D-Trp-OMe and 1-Me-D-Trp, respectively. Figure S2. (A) Photographs of AuNCs capped with D-Trp (a), D-Trp-OMe (b), D-Trp-OBzl (c) and 1-Me-D-Trp (d) from left to right under daylight (upper row) and 365 nm UV irradiation (bottom row); (B) Fluorescence emission spectra of D-Trp@AuNCs (a), D-Trp-OMe@AuNCs (b), D-Trp-OBzl@AuNCs (c) and 1-Me-D-Trp@AuNCs (d). Figure S3. Fluorescence emission spectra of D-Trp-OMe@AuNCs (A), D-Trp-OBzl@AuNCs (B), 1-Me-D-Trp@AuNCs (C) and D-Trp@AuNCs (D) in the absence and presence of FA (a: 0.0 μM; b: 25.0 μM; c: 75.0 μM). Figure S4. The zeta potential difference of AuNCs in the absence and presence of FA: 1. D-Trp-OMe@AuNCs, 2. D-Trp-OBzl@AuNCs, 3. 1-Me-D-Trp@AuNCs and 4. D-Trp@AuNCs; where Z0 and Z are the potentials of AuNCs in the absence and presence of FA, respectively. Figure S5. Effects of concentrations of D-Trp (A), HAuCl4 (B), synthesis time (C) and synthesis temperature (D) on relative fluorescence intensity of the fluorescent probe. Figure S6. XPS spectra of Au 4f of D-Trp@AuNCs (A) and D-Trp@AuNCs-FA (B). Figure S7. FT-IR spectrum of D-Trp (a) and D-Trp@AuNCs (b). Figure S8. (A) Stern-Volmer plot of fluorescence quenching; (B) Fluorescence lifetime of D-Trp@AuNCs in the absence and presence of FA. Figure S9. The zeta potential of D-Trp@AuNCs, FA and D-Trp@AuNCs-FA (pH 7.0). Figure S10. Effects of pH (A); NaCl concentration (B) and incubation time (C) on F/ F0. Figure S11. Stability of the prepared D-Trp@AuNCs. Table S1. Comparison with the reported AuNCs for detection of FA