Strong improvements of LSPR sensitivity by using Au/Ag bi-metallic nanostructures modified with poly-dopamine films Kun Jia,a Mohammad Y. Khaywah,a Yugang Li,b Jean L. Bijeon,a Pierre M. Adam,a Régis Déturche,a Bruno Guelorget,b Manuel François,b Guy Louarn, c and Rodica E. Ionescu a,* a
Laboratoire de Nanotechnologie et d’Instrumentation Optique, UMR-STMR CNRS 6279, Institute
Charles Delaunay, Université de Technologie de Troyes, 12 Rue Marie Curie CS 42060, 10004 Troyes Cedex, France. b
Laboratoire des Systèmes Mécaniques et d'Ingénierie Simultanée, UMR-STMR CNRS 6279, Institute
Charles Delaunay, Université de Technologie de Troyes, 12 Rue Marie Curie CS 42060, 10004 Troyes Cedex, France c
Laboratoire de Physique des Matériaux et Nanostructures, UMR 6502, Institut des Matériaux Jean
Rouxel, 2 Rue de la Houssinière BP 32229, 44322 Nantes Cedex 03, France.
Corresponding Author *Rodica E. Ionescu, E-mail:
[email protected] Tel: + (33) 3 25 75 97 28 Fax: + (33) 3 25 71 84 56
Figure S1. LSPR spectra of glass samples modified with evaporated silver of different thickness of 4 nm (A) and 6 nm (B). The photos of samples before and after annealing treatment are included. Interestingly, the silver-modified glasses expose unstable NPs after annealing at 500 °C for 8 hr.
Figure S2. LSPR spectra of glass samples modified with two successive evaporated bi-metallic layers of either Ag (4 nm)/ Au (2 nm) (A) or Ag (2 nm)/Au (4 nm) (B) before and after annealing at 500 °C for 8 hr.
Figure S3. Gold (Au) nanoparticles size distribution. Film of 4 nm Au thickness is evaporated onto glass and annealed at 500° C for 8hr.
Figure S4. SEM image of Au NPs (A) and gold nanoparticles size distribution (B). Film of 6 nm Au thickness is evaporated onto glass and annealed at 500° C.
Figure S5. Au/Ag bi-metallic nanoparticles size distribution. Films of 4 nm Au and 2 nm Ag thicknesses are consecutively evaporated onto glass and annealed at 500° C for 8 hr.
Figure S6. The LSPR spectra for Au/Ag bi-metallic NPs obtained by annealing Au4nm/Ag2nm sample at 500 °C (A) and 200 °C (B) for 8 hr, the LSPR spectra were measured for 6 days and the sample were washed with ethanol and ddH2O before measurement and stored at 4 °C between measurements.
Figure S7. The surface morphology of EDS analyzed areas from Au 4nm/Ag 2nm bimetallic sample before annealing (A) and after annealing (B) at 500 °C for 8 hr.
Figure S8. XPS spectra of C 1s for the high temperature annealed monometallic Au NPs, Ag NPs, and bimetallic Au/Ag NPs.
. Figure S9. LSPR spectra of Au NPs (4 nm) (A) and Au (4 nm) /Ag (2 nm) bi-metallic NPs (B) exposed to dopamine solution (10 mM) for different periods of time. The dopamine solution is prepared with Tris-HCl buffer (pH=8.5) and stored in a sealed plastic tube at room temperature.
Figure S10. LSPR spectra recorded in the control experiments using Au-Ag-dopamine NPs modified with BSA non-specific antibody (anti-human IgG). Clearly, the different concentrations of BSA (from 0.1 ng/mL up to 10 µg/mL) cannot be detected from such control experiments.
