Green synthesis of silver nanoparticles using Senna alexandrina leaf extracts and their antibacterial, larvicidal, nanotoxicity and photocatalytic activity

Abstract

Biological synthesis of metal nanoparticles has been discovered in recent years, and they have been effectively manufactured and studied from diverse plant extracts. Recent research has shown that nanoparticles have extremely promising antibacterial, larvicidal and anticancer effects. The current study aimed to synthesize Senna alexandrina leaf extract-mediated silver nanoparticles (SA-AgNPs) as are reducing and capping agent. The produced SA-AgNPs were characterized by using UV–visible spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS). The result showed synthesized SA-AgNPs were confirmed by UV–visible spectroscopy with 440 nm absorption. FT-IR analysis shows the presence of phosphine, primary amines, carboxylic acids, ether, and alkyl halides biomolecules in both plant extract and SA-AgNPs. XRD findings revealed the crystalline structures of produced SA-AgNPs. The spherical shape of SA-AgNPs with an average size of 20–35 nm was confirmed using FESEM. The SA-AgNPs show better antibacterial activity against E. coli (18.0 ± 0.25 mm), S. aureus (17.2 ± 0.36 mm), P. aeruginosa (16.8 ± 0.12 mm), and leaf extract of S. alexandrina showed minimal antibacterial activity. The SA-AgNPs show 100 % mortality for both Cx. quinquefasciatus and Ae. aegypti after 48 hrs. The brine shrimp lethal assay of the SA-AgNPs shows 100 % at 30 µg after 24 hrs of brine shrimp which indicated the presence of cytotoxicity this suggests that produced SA-AgNPs are slightly toxic. The photocatalytic activity was also tested using reactive orange 16 (RO16) and phenol red (PR) with the percentage of degradation being about 93.95 % and 92.91 % respectively. These results suggest that biosynthesized SA-AgNPs have promising properties that can be used as an effective biomedical and environmental protectant.