Supporting Information Chemicals and materials. Fmoc-amino acids were obtained from GL Biochem. (Shanghai). All the other starting materials were obtained from Alfa (Beijing). Commercially available reagents and solvents were used without further purification, unless noted otherwise. General methods: The synthesized compounds were characterized by 1H NMR (Bruker ARX-300) using DMSO-d6 as the solvent. HPLC was conducted at LUMTECH HPLC (Germany) system using a C 18 RP column with MeOH (0.05% of TFA) and water (0.05% of TFA) as the eluents. LC-MS was conducted at the LCMS-20AD (Shimadzu) system. Synthesis of β-alanine conjugated NBD-Cl (Scheme S-1, also see Ref. 17): To a solution of β-alanine (98 mg, 1.1 mmol) and K2CO3 in MeOH and H2 O under N2 , 5 mL of 4-Chloro-7-nitrobenzo-2-oxa-1,3-diazole (200 mg, 1 mmol) solution was injected slowly. The reaction was completed 5 hours later at room temperature. The reaction mixture was concentrated by vacuum to remove the MeOH, then the pH of the resulted solution was adjusted to 1~2 by HCl (2 mol/L). The aqueous mixture was extracted with diethyl ether (50 mL * 2) and dichloromethane (50 mL * 2), the organic layer was combined and concentrated to give crude 200 mg, which was directly reacted for next step without purification. O O N N O N O + Cl H2N K2CO3 OH O O N N O N MeOH/H2O O N H OH NBD--Alanine Scheme S1. The synthetic route for NBD--Alanine Peptide synthesis: The peptide derivative was prepared by solid phase peptide synthesis (SPPS) using 2-chlorotrityl chloride resin and the corresponding N-Fmoc protected amino acids with side chains properly protected by a tert-butyl group . 20% piperidine in anhydrous N,N’-dimethylformamide (DMF) was used during deprotection of Fmoc group. Then the next Fmoc-protected amino acid was coupled to the free amino group using O-(Benzotriazol-1-yl)-N,N,N’,N’-tetramethyluroniumhexafluorophosphate (HBTU) as the coupling reagent. The growth of the peptide chain was according to the established Fmoc SPPS protocol. In the last coupling step, NBD--Alanine was used to produce NBD-peptides. After the last coupling step, excessive reagents were removed by a single DMF wash for 5 minutes (5 mL per gram 1 of resin), followed by five steps of washing using DCM for 2 min (5 mL per gram of resin). The peptide derivative was cleaved using 95% of trifluoroacetic acid with 2.5% of trimethylsilane (TMS) and 2.5% of H2O for 30 minutes. 20 mL per gram of resin of ice-cold diethylether was then added to cleavage reagent. The resulting precipitate was centrifuged for 10 min at 4 0C at 10,000 rpm. Afterward the supernatant was decanted and the resulting solid was dissolved in DMSO for HPLC separation using MeOH and H2O containing 0.05% of TFA as eluents. O O N N O N N H COOH O N H H N O O N H H N O O N H OH H N O O N H H N O OH O OH Compound 1: NBD-FFETIGGY Scheme S2. Chemical structure of compound 1 NBD-FFETIGGY (1): 1H NMR (300 MHz, DMSO-d6) δ 9.25 (d, J = 42.4 Hz, 2H), 8.49 (d, J = 8.6 Hz, 1H), 8.38 – 8.15 (m, 4H), 8.10 (d, J = 8.1 Hz, 1H), 7.98 (t, J = 5.8 Hz, 1H), 7.83 (d, J = 8.0 Hz, 1H), 7.77 (d, J = 8.3 Hz, 1H), 7.62 – 7.20 (m, 5H), 7.13 (dt, J = 28.1, 13.5 Hz, 5H), 7.00 (d, J = 8.5 Hz, 2H), 6.65 (d, J = 8.5 Hz, 2H), 6.34 (d, J = 8.6 Hz, 1H), 4.54 (dd, J = 9.4, 4.0 Hz, 2H), 4.47 – 4.38 (m, 1H), 4.40 – 4.28 (m, 2H), 4.25 – 4.16 (m, 1H), 4.04 – 3.95 (m, 1H), 3.80 – 3.61 (m, 4H), 3.55 (d, J = 24.8 Hz, 3H), 3.18 (s, 1H), 3.05 (d, J = 10.2 Hz, 1H), 3.00 – 2.89 (m, 2H), 2.86 – 2.73 (m, 2H), 2.71 – 2.63 (m, 1H), 2.54 (d, J = 9.6 Hz, 1H), 2.31 – 2.22 (m, 2H), 1.94 (s, 1H), 1.86 – 1.52 (m, 3H), 1.45 (s, 1H), 1.39 – 1.08 (m, 2H), 1.03 (d, J = 6.2 Hz, 3H), 0.83 (dd, J = 12.6, 7.1 Hz, 6H). HR-MS: calc. M+ = 1166.47, obsvd. (M-H)- = 1165.47. Figure S1. 1H-NMR of NBD-FFETIGGY 2 Figure S2. MS spectrum of NBD-FFETIGGY COOH H N H2N O H N N H O O HO O H N N H O O N H H N O OH O OH Scheme S3. Chemical structure of compound 2 Inten.(x1,000,000) 933.60 1.25 1.00 0.75 934.60 0.50 0.25 936.65 0.00 932.0 933.0 934.0 935.0 936.0 938.70 937.0 938.0 939.0 940.0 m/z Figure S3. MS spectrum of FFETIGGY Critical micelle concentration (CMC): The CMC values of peptides in water (pH=7.4) were measured by dynamic light scattering (DLS). The peptides with high concentration were diluted successively and the light scattering intensities were recorded for each sample. Dynamic Light Scattering (DLS) was performed on a laser light scattering spectrometer (BI-200SM) equipped with a digital correlator (BI-9000AT) at 532nm under room temperature (22-25 0C). 3 Figure S4. CMC of NBD-FFETIGGY and FFETIGGY Transmission electron microscopy (TEM): TEM sample (0.2mg/mL NBD-FFETIGGY) was prepared at 25 °C. A micropipet was used to load 5 µL of sample solution to a carbon coated copper grid. The excess solution was removed by a piece of filter paper. The sample was dried overnight in a desicator and then conducted on a Tecnai G2 F20 system, operating at 200 kV. Figure S5. A TEM image of Tris-HCl solution of 1 (0.02 wt%) 4 Figure S6. Emission spectra of Tris-HCl solution of 1 (0.1 wt%, pH = 7.4) in the absence and presence of different metal ions (150 mM of KCl, CaCl2, NaCl and MgSO4; the concentration of ZnCl2, FeCl2, and CuSO4 was 3 mM, 0.9 mM, and 3 mM, respectively) (excitation wavelength = 470 nm) Fluorescence microscopy to determine cellular distribution of nanofibers in different cells. Fluorescence images were obtained by an inverted fluorescence microscope (Leica DMI 3000 B). The DMEM solution containing 0.2 mg/mL of 1 was added to the NIH 3T3, HepG2, Cos7 and HeLa cells. The images were recorded after 2 hours culture. (excitation wavelength = 478-498 nm). For imaging of living plants with laser scanning confocal microscopy, seven-day-old Arabidopsis thaliana seedlings were incubated in 500 μM of 1 for 1 hour, and then washed three times with distilled water before scanning. The root hair zone of the plants was scanned. For imaging of leaf epidermal cells, four-week-old Nicotianabenthamiana leaves were incubated in 500 μM of 1 for 1 hour, and then washed three times with distilled water before scanning. Figure S7. Tandem MS analysis indicates the most abundant hydrogel bound cytosolic proteins by sequence coverage for band I in Figure 3 5 Figure S8. Tandem MS analysis indicates the most abundant hydrogel bound cytosolic proteins by sequence coverage for band II in Figure 3 Determination of IC50 values on different cells: Four cells of 3T3, HepG2, Cos7 and Hela were seeded in a 96-well plate with the density of 1,0000 cells per-well (total medium volume of 100 μL ). 24 hours post seeding, the solutions with a serial of concentrations (8 concentrations) of the compound in 100 μL of medium were added to each well (five wells for each concentration). Cells without the treatment of the compound were used as the control. The MTT assays were performed after an extra culture time of 48 hours. All compounds were removed and 90 μL fresh medium was added for each well, 10 μL of MTT solution (5 mg/mL) was added and incubated for 4 hours in 370C. Pipette out the spent media, formazon crystals at the bottom of each well were dissolved in 100 μL DMSO. After 15 minutes at room temperature, absorbance at wavelength of 490 nm was tested using a microplate reader (BIO-RAD, iMark TM ). IC 50 values for the inhibition of cell viability were calculated from pharmacological inhibitory response curves using software Prism 5.0. Figure S9. Congress curve of cell inhibition assay of 3T3 cell treated with different concentrations of 1 6 Figure S10. Congress curve of cell inhibition assay of HepG2 cell treated with different concentrations of 1 Figure S11. Congress curve of cell inhibition assay of Cos7 cell treated with different concentrations of 1 Figure S12. Congress curve of cell inhibition assay of Hela cell treated with different concentrations of 1 7 Figure S13. Bright field optical images of HepG2 cells left) without and right) with the treatment of nanofibers of 1 (0.25 mg/mL) for 48h Figure S14. Bright field optical images of Cos7 cells left) without and right) with the treatment of nanofibers of 1 (0.25 mg/mL) for 48h Figure S15. Bright field optical images of HeLa cells left) without and right) with the treatment of nanofibers of 1 (0.25 mg/mL) for 48h 8