Synthesis, Characterization and Biological Activity of Gold Nanoparticles Stabilized by Aqueous Extracts of Wild Blackberry (Rubus spp.) Leaves

Abstract

The green synthesis of gold nanoparticles (AuNPs-E) by bioreduction of chloroauric acid (HAuCl₄), using the aqueous extracts (E) of blackberry (Rubus spp.) leaves, was presented in this work. The E were obtained by maceration at room T and reflux extraction at boiling T, while the AuNPs-E were synthesized at room T and T = 80°C. The synthesized AuNPs-E were structurally and physicochemically characterized by UV-Vis and FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS) and zeta potential measuring. The changes in the FTIR spectra suggested that biocompounds containing C=O, C–O–C, and OH functional groups play the main role as capping and stabilizing agents providing the stability of AuNPs-E confirmed by UV-Vis spectroscopy. The crystal structure was proved by XRD analysis confirming the (111) reflection plane at 2θ = 38.2° as dominant in the AuNPs-E face-centered cubic lattice. Negative zeta potential of AuNPs-E in the range of –11.67 ± 0.45 and –17.70 ± 0.27 mV suggests moderate stability of AuNPs-E with the average size in the range of 61.6 ± 11.5 to 93.9 ± 1.4 nm determined by DLS. The qualitative and quantitative presence of Au in the formed AuNPs-E, together with the elements from the extracts’ biomolecules, was proven by the EDX spectroscopy. Finally, the antioxidant and antibacterial activities of AuNPs-E were tested by DPPH test and disc diffusion method, respectively, suggesting that AuNPs-E synthesized by described method should be certainly taken into consideration, alone or in combination with the silver nanoparticles, in dermal and cosmetic preparations design.