Supporting Information for

Transcription

1 Supporting Information for Aspartame-stabilized gold-silver bimetallic biocompatible nanostructures with plasmonic photothermal properties, antibacterial activity and long-term stability Chiara Fasciani, M. Jazmin Silvero, Maria Alexandra Anghel, Gerardo A. Argüello, Maria Cecilia Becerra and Juan C. Scaiano* Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada and Facultad de Ciencias Químicas. Universidad Nacional de Córdoba, 5000 Córdoba, Argentina and Instituto Multidisciplinario de Biología Vegetal (CONICET), Departamento de Farmacia, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina. S1

2 S1. Materials Silver nitrate and sodium citrate were purchased from Sigma-Aldrich and resuspended in 200 ml solutions of Millipore MilliQ deionized water (18.2 MΩ) for two 10 mm stock solutions. HAuCl4 3H2O was also purchased from Sigma-Aldrich. Aspartame was purchased from Supelcore (Bellefonte, USA) and was resuspended in a 10 ml solution of Millipore MilliQ deionized water in order to prepare a 2 mm stock solution. 2-methyl-1- propanone (Irgacure-2959) was a gift from BASF that was supplied by Dempsey Corporation Canada and recrystallized in ethanol (10 mm stock solution). Modified LL-37, CSG- LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES-NH2, was generously donated to the Scaiano group by Grace Vydac, Helsingborg, Sweden. For any synthesis of nanoparticles, distilled water was prepared using Millipore MilliQ deionized water (18.2 MΩ). S2

3 S2. Representative Energy-dispersive X-ray spectra (EDS) for The table shows the relative atomic % for the 50:50 Au/Ag ratio. Element Peak Area k Abs Weight% Weight% Atomic% Area Sigma factor Corrn. Sigma Ag L Au L Totals S3

4 S3. 96-well plate design for minimal inhibitory experiments (MIC). Blue colored wells on the scheme indicate wells that contain 200 μl of autoclaved water (the water filled wells decrease evaporation risk of actual experiments). The MIC experiment was contained in the center of the plate from B3 to G8. The three strains tested were deposited as follow: Staphylococcus aureus (column 3 to 4), Staphylococcus epidermidis (column 5 to 6) and Escherichia coli (column 7 to 8) respectively. The stock solution of tested nanoparticles (50 μm) was added to row G (black) and was serially diluted by 1 2 from rows F-B. The diagram depicts the diluted concentrations by varying the grayscale of nanoparticles from rows F-B. The tested concentrations ranged from 25 μm to 1.56 μm respectively. Row B was the control row for all bacteria, containing no nanoparticles. Final volume for each well was 200 μl. S4

5 S4. LED exposure panel set-up for MIC and time kill experiments. The exposure panel from Luzchem Research used five 4 watt LED T5 tubes S5

6 S5. 96-well plate design for time kill experiments. Blue colored wells on the scheme indicate wells that contain 200 μl of autoclaved water. The time kill experiment was contained in the center of the plate from C3 to D10. The three strains tested were deposited as follow: Staphylococcus aureus (Red wells), Staphylococcus epidermidis (Green wells) and Escherichia coli (Purple wells) respectively. The stock solution of tested nanoparticles (12.5 μm) was added to row C for all strains of bacteria and yielded a 6.25 μm concentration, when containing the bacteria solution. Row D (darker colored wells) was the control row for all bacteria, containing no nanoparticle solution. Final volume for each well was 200 μl. S6

7 S6. Concentration dependent graphs depicting microbial inhibition action by via measurement of the optical density. Error bars correspond to the standard error for two samples Escherichia coli LIGHT DARK Staphylococcus aureus LIGHT DARK O.D. at 620 nm O.D. at 620 nm Concentration (µm) Staphylococcus epidermidis LIGHT DARK Concentration (µm) O.D. at 620 nm Concentration (µm) The following is the sequence for the LL-37 peptide: CSG-LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES-NH 2, S7

8 S7. Human skin fibroblasts cell cytotoxicity measurements via an MTS colorimetric assay for various materials measured after incubating for 14 hours. The legend depicts the concentrations tested: 6.25 μm and 12.5 μm. Error bars correspond to the standard deviation from ten samples um 12.5 um Survival % Asp@Ag@Au Asp AuNP AgNP S8. Experimental procedure employed for TEM sample preparation. Suspensions of each bacteria strain (10 ml, 10 6 CFU/mL) were first incubated for 1 hour with AuNP@Ag@Asm (10 ml, 2 mm) at room temperature under dark conditions and then centrifuged for 15 min at 1000 rpm. Treated samples were withdrawn and fixed at 1 h in 2 % glutaraldehyde and 4 % formaldehyde solutions in 0.1 M cacodylate buffer for 2 h at room temperature, and post-fixed with osmium tetroxide at 1% in the same buffer, dehydrated and embedded in Araldite. Thin sections were cut with a diamond knife on a JEOL JUM-7 ultramicrotome, mounted on nickel grids and examined in a Zeiss LEO 906E electron microscope. S8

9 S9. Concentration dependent graphs depicting microbial inhibition action by AgNP. Microbial inhibition action by AgNP was determined via measurement of the optical density for E. coli. The legend denotes experiments as either irradiated (LIGHT) or non-irradiated (DARK). Optical density measurements were taken at 620 nm. S9