SERS active gold nanostructures for selective and ultrabright biolabelling: synthesis and quantitative study

Surface enhanced Raman scattering (SERS) probes based on gold nanoparticles (AuNPs) – organic dyes nanocomposites disclosed new opportunities for multiplexed ultrasensitive biolabelling in vitro or in vivo. SERS labels also have excellent biocompatibility and can be excited with near infrared laser sources, that match the transparency window of biological tissues. Here we report about the preparation of AuNPs obtained by laser ablation synthesis in solution (LASiS)[1,2] and their functionalization with a series of Raman reporter with different spectral fingerprints. The effective differential Raman scattering cross section of these labels were evaluated using liquid Raman standards and the analysis of the surface plasmon band of AuNPs with the Mie – Gans models.[3] We estimated that few (<10) SERS labels are enough to collect a clear Raman spectrum with a common Raman spectrometer. SERS labels were used for the study of nanoparticles uptake in macrophages[4] in order to quantify the number of nanoparticles phagocytized after different times. The conjugation of SERS labels with antibodies that selectively binds antigens over-expressed by specific types of cancerous cells is under investigation for the antibody – directed selective ultrasensitive detection and imaging of cancer. [1] V. Amendola, M. Meneghetti, Phys. Chem. Chem. Phys. 2009, [2] V. Amendola, M. Meneghetti; J. Mater. Chem. 2007, 17, 4705–4710. [3] V. Amendola, M. Meneghetti, J. Phys. Chem. C 2009, 113, 4277–4285. [4] V. Amendola, M. Meneghetti, S. Fiameni, G. Fracasso, A. Boscaini, M. Colombatti; Submitted