Construction of SERS substrates by gold nanoparticles assembly on polymeric matrices

Abstract

This study reported the fabrication of stable and reproducible large-area SERS substrates based on the assembly of pre-synthesized gold nanoparticles on reconstructed poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) films with different molecular weights and PS/P2VP volume fractions. PS-b-P2VP films on a glass substrate were submitted to different reconstruction procedures: immersion in deionized water or ethanol, exposure to toluene/THF vapor, or thermal annealing. These reconstructed films were immersed in citrate-stabilized gold NPs suspension for different time intervals. P2VP microdomains acted selectively as a binding site for the negatively-charged nanoparticles through electrostatic interactions. The substrates were characterized by UV–vis spectroscopy and atomic force microscopy. The SERS activity was tested using the Nile Blue (NB) dye as a molecular probe. The results demonstrated that the annealing treatment and the molecular weight of the copolymers strongly influence the NPs dispersion and, consequently, the SERS enhancements. Moreover, we established that water and ethanol swelling of the micelles allowed a high uniformity of nanoparticle deposition over the films. In contrast, more efficient SERS enhancement was observed in the nanocomposites treated with toluene/THF vapor annealing and thermal annealing.