Cationic Cyclodextrin Polymer vs Chitosan for SERS-nanoTags fabrication

SERS-nanoTags are Raman-active systems that typically consist of a metal nanoparticle encoded with a Raman reporter molecule and coated with a stabilizing, biocompatible layer.[1] Due to their high sensitivity and specificity, Raman measurements under scanning confocal microscopy are a powerful tool for real-time imaging of the nanoparticle’s localization and distribution inside cells and tissue. In our work, we investigate the cellular internalization of SERS-nanoTags inside NIH:OVCAR-3 cells by monitoring the SERS fingerprint signal of mercaptophenyl boronic acid (MPBA) and paramercaptobenzoic acid (MBA) grafted to the metal surface of bimetallic gold-silver nanoparticles (Au@Ag BMNPs). Au@Ag BMNPs with typical core shell architecture [2] were synthesized by exploiting the unique properties of carbohydrate polymers, such as cationic polymeric cyclodextrin (PolyCD) and chitosan. Carbohydrate-driven protocol includes the synthesis of polymer-coated Au MNPs (monometallic nanoparticles) as a seed material for the subsequent growing of a silver shell. The morphology, size and colloidal stability of Au@Ag BMNPs were investigated by UV-vis spectroscopy, zeta potential, dynamic light scattering (DLS) measurements, and transmission electron microscopy (TEM). The capacity of PolyCD SERS nanotags vs Chitosan SERS nanotags to operate as bright SERS nanotags with precise localization at a single cell level will be discussed.