Antioxidant, antimicrobial and cytotoxic activities of gold nanoparticles capped with quercetin

In the present work, we report the antioxidant, antimicrobial and cytotoxic activities of quercetin-capped gold nanoparticles (AuNPsQct). The synthesis of AuNPsQct was confirmed by UV–Vis spectroscopy, FTIR and transmission electron microscopy (TEM) analyses. The FTIR spectrum showed the integrity of the quercetin molecules on the nanoparticle surface. The TEM images showed sizes less than 100 nm and a slight spherical shape. The electrostatic stability was confirmed by the zeta potential method. The antioxidant activity of quercetin, evaluated by DPPH, ABTS and nitric oxide free radical scavenging methods, was preserved in the gold nanoparticles, furthermore quercetin-capped gold nanoparticles (IR(50) 0.37 µg/mL) demonstrated a higher antioxidant activity than free quercetin (IR(50) 0.57 µg/mL) by nitric oxide free radical scavenging method. Strong antifungal activity was observed for Aspergillus fumigatus with concentrations ranging from 0.1 to 0.5 mg/mL. The nanoparticles with quercetin did not exhibit cytotoxicity to human fibroblasts (L929 cells). In conclusion, these results suggest that AuNPsQct, produced by cost-effective method, can act as a promising candidate for different medical applications.