Synthesis of functionalized gold nanoparticles capped with 3-mercapto-1-propansulfonate and 1-thioglucose mixed thiols and "in vitro" bioresponse.

The synthesis, characterization and assessment of biological behavior of innovative negatively charged functionalized gold nanoparticles is herein reported, for potential applications in the field of radiotherapy and drug delivery. Gold nanoparticles (AuNPs) functionalized with two capping agents, i.e., the 3-mercapto-1-propansulfonate (3-MPS) and 1-β-thio-D-glucose (TG), have been on purpose synthesized and fully characterized. Advanced characterization techniques including X-Ray Photoelectron Spectroscopy (XPS) were applied to probe the chemical structure of the synthesized nanomaterials. Z-potential and Dynamic Light Scattering measurements allowed assessing the nanodimension, dispersity, surface charge and stability of AuNPs. Transmission Electron Microscopy (TEM) and Flame Atomic Absorption Spectroscopy (FAAS) were applied to the "in vitro" HSG cell model, to investigate the nanoparticles-cells interaction and to evaluate the internalization efficiency, whereas short term cytotoxicity and long term cell killing were evaluated by means of MTT and SRB assays, respectively. In conclusion, in order to increase the amount of gold atoms inside the cell we have optimized the synthesis for a new kind of biocompatible and very stable negatively charged TG-functionalized nanoparticles, with diameters in a range that maximize the uptake in cells (i.e., ∼15nm). Such particles are very promising for radiotherapy and drug delivery application.