Abstract: Herein, we demonstrated a low-cost and eco-friendly method for the synthesis of gold nanoparticles (AuNPs) using waste black sunflower seed shell extract as both a reducing agent and protectant. The as-prepared sample was characterized by UV-vis spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the synthesized AuNPs using 80% (V/V) of waste black sunflower seed shell extract had a characteristic absorption peak at 526 nm in the UV-vis spectrum. The mean particle size of the AuNPs was observed to be (7.25 ± 2.24) nm. The FTIR spectrum and the XRD pattern indicated that the extract could form a protective layer on the AuNPs surface, which conferred the AuNPs not only with high stability toward storage, heat, pH and salt, but also with strong antioxidant activity in scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Furthermore, the AuNPs showed good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH4. We proposed that the AuNPs could be a potential catalyst for applications in food, biomedical and biopharmaceutical industries.

Key words: gold nanoparticles, green synthesis, catalytic activity, antioxidant activity, stability