Green production of biologically active Ag and Ag-Cu nanoparticles from Prosopis cineraria pod waste extract and their application in epoxidation

Bio-nanotechnologically produced nanoparticles (NPs) utilizing waste materials have been the main focus of the current research. There is a need for developing an advanced technology to reduce waste in an eco-friendly way. Therefore, presently the discarded aqueous portion of Prosopis cineraria pods was used after boiling to synthesize Ag and Ag-Cu NPs. FT-IR spectra illustrated the presence of phenyl propenoids and flavonoids were displaying capping and reducing properties. TEM and SEM imaging exhibited an average size of Ag NPs (14 nm) and Ag-Cu NPs (27 nm). The crystallinity nature was confirmed by XRD, and the Cu in Ag-Cu NPs was validated through energy dispersive X-ray analysis. According to the antimicrobial data, Saccharomyces cerevisiae displayed a zone of inhibition (ZOI) of 42.85% (Ag NPs) and 33.98% (Ag-Cu NPs) at lower concentrations (0.0321 mg/ml), while Bacillus subtilis was found most susceptible (85% ZOI) to Ag NPs at 0.5 mg/ml concentration. Further, these NPs (Ag and Ag-Cu) were utilized in the epoxidation of alkene moieties. Ag NPs showed lower conversion (65%) while, Ag-Cu NPs were very active for epoxidation of linalool (93% conversion), suggesting the presence of Cu was facilitated epoxidation. To the best of our knowledge for the first time, the aqueous waste was applied to prepare green NPs for using as antimicrobial agents and synthesis of platform chemical (epoxide) for industrial aspects. These inexpensive ways of producing green NPs is utilized several times and have found potential applications in nano-medicine, therapeutics, modification of monoterpenoids to fine fragrance, etc.