Green synthesis of Silver and Silver-gold core-shell nanoparticles using Pineapple leaf extract (Ananas comosus) and study of their antibacterial properties

The advantage of using plants and plant metabolites over expansive and toxic chemical methods for nanoparticles (NPs) synthesis has fascinated researchers to investigate the mechanisms of bio-reduction of metal ion for various biomedical applications. Herein, pineapple leaf extract was used for the synthesis of silver (Ag) and bimetallic silver-gold (Ag-Au) core-shell NPs which offered an economic and sustainable synthetic route compared to toxic chemical method. The synthesized NPs were further subjected to UV-visible spectrometer to investigate the formation kinetics at specific time intervals. To reveal the presence of various functional groups in the leaf extract responsible for bio-reduction of Ag ions and subsequent formation of core-shell nanostructure, FTIR study was conducted. Morphology and structural properties were examined by TEM and XRD. Further, disc diffusion test was employed to reveal the antibacterial effectiveness of NPs against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The study revealed that both Ag and Ag-Au NPs are good antibacterial candidates and bacterial sensitivity to NPs was found to vary depending on bacterial species.