Comparative study of biogenically synthesized silver and gold nanoparticles of Acacia auriculiformis leaves and their efficacy against Alzheimer's and Parkinson's disease

The present article reports the biogenic synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) from the extract of Acacia auriculiformis (AA) leaves using biogenic approach. Several spectral and morphological studies namely UV-vis, Fourier transform infrared (FT-IR), tunneling electron microscopy along with selected area electron diffraction (TEM/SAED), scanning electron microscopy along with energy dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD) were carried out which ascertains the successful formation of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) starting from Silver nitrate and Chloroauric acid respectively. On the basis of TEM/SAED and SEM-EDX, AgNPs were found to be more regular with smaller particle size and hence they were selected for biological studies. Thermal techniques like thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were also performed to study the comparative thermal stability of AgNPs and AuNPs where AgNPs were found to be thermally more stable. Several biophysical techniques including Thioflavin T assay, ANS assay, Rayleigh scattering method and turbidity assay were also performed. These assays confirm that AgNPs possess better inhibitory property. Moreover, antioxidant activity of AgNPs was also carried out using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and AgNPs were found to be good antioxidant.