Biocompatibility of Human Fibroblast Cells Exposed to Gold Nanoparticles Synthesized by Environmentally Friendly Route.

Green toxicology emphasizes the need for safe, efficient, and environmentally clean processes for the production and manipulation of AuNPs. Given the significant concerns regarding health and environmental hazards, the biocompatibility of AuNPs must be thoroughly investigated at both cellular and molecular levels. Here, gold nanoparticles were synthesized by magnetron sputtering on a solid powder substrate through a new and innovative top-down physical method, which is free of chemical waste that could directly harm the environment. The nanoparticles were first characterized by UV/vis, DLS, Zeta potential, TEM and SAXS, and biological tests were further performed to evaluate cytotoxicity and cell death metabolism. Characterization of AuNPs revealed an absorption peak at 537 nm, with moderate stability according to the ζ potential. Transmission electron microscopy evidenced a higher frequency of spherical nanoparticles with diameters around 15-20 nm. These results were consistent to the ones presented by SAXS, in which a polymeric outer core-shell was seen in spherical AuNPs. The biological results demonstrated biocompatibility of AuNP, presenting no cytotoxic activity after 24-48 h of exposure at up to 20 μg/mL against MRC-5 cells. Gold nanoparticles were able to induce initial apoptosis only at higher concentrations (>35 μg/mL), possibly through the accumulation of AuNPs in autophagosomes, as observed in indirect immunofluorescence tests. This work was effective in producing biocompatible AuNPs, using the magnetron sputtering technique on powdered solid substrates, standing out as a clean, fast, and low-cost method. Additionally, AuNPs can be potentially applied at minimal concentrations, boosting the use in several biotechnology and health applications.