Sustainable synthesis of Ag-NPs from Cassia auriculata flower extract: synthesis, spectral characterization, its biomedical and environmental applications

The present study describes the environmentally friendly biosynthesis and characterization of silver nanoparticles derived from a medicinal plant in India. The main objective of this investigation was to use green chemistry for producing silver nanoparticles from Cassia auriculata flower extract and their antimicrobial, larvicidal and photocatalytic properties. The synthesized nanoparticles of silver have been evaluated by ultraviolet visible spectroscopy (UV), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), and Fourier transform infrared spectroscope (FTIR). The presence of therapeutic functional molecules was shown by FT-IR, whereas the Ag-NPs UV-Vis spectrum displayed a significant absorption peak at 295 nm. The XRD results demonstrated that NPs are crystalline. The spherical form of Ag NPs and the presence of silver at 3.5 keV using EDAX are proven by the FESEM data. The size and shape of the silver nanoparticles, which ranged in size from 10.3 to 83.1 nm, were determined by HR-TEM analysis. Furthermore, the antibacterial properties of C. auriculata flower produced Ag-NPs (18 nm) for Staphylococcus aureus and Escherichia coli (11.5 mm) towards both gram-positive and gram-negative bacteria was obtained at 100 µg/mL. In further research, investigations on the larvicidal effects of C. auriculata flowers produced Ag-NPs that were effective against Aedes albopictus and Anopheles stephensi larvae during their fourth instar. The mortality rate of the larvae was found following a 24-hour exposure. The efficacy of synthesized Ag-NPs was evaluated concentrations (50, 100, 150, 200, and 250 mg/L) displayed more effective activity against the 4th instar larvae of An. stephensi (LC50 = 24.14; LC90 = 62.58, mg/L) and Ae. albopictus (LC50 = 35.53; LC90 = 65.27 mg/L). Histological patterns were changed after treatments with Ag-NPs at a concentration of 250 mg/L. Based on a pseudo-first order kinetic demonstrate, it was found that 92