Plant extract-mediated biosynthesis of sulphur nanoparticles and their antibacterial and plant growth-promoting activity.

This study reports green synthesis of sulphur nanoparticles using sodium thiosulfate pentahydrate (NaSO5HO) and leaf extracts. X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM) was employed to examine the crystallinity of the particles and morphological characteristics, proved both spherical and rod-shaped morphology of the S NPs having porous nature. The FTIR spectra revealed the interaction of the synthesized SNPs with the biomolecules present in the leaf extract. UV-VIS spectral investigations confirmed the production of SNPs from leaf extract and that these SNPs can be used for visible region photocatalysis for the removal of pollutants from wastewater. Energy dispersive X-ray (EDX) spectrum of the SNP shows a single peak around 2.4 keV, confirmed S NPs purity. TEM image revealed the formation of mainly nanorods having a width of ∼20-25 nm and a length of 50-100 nm. Furthermore, some spherical particles (∼20-30 nm) were also formed. HRTEM image of the rod-shaped particles clearly shows the crystal fringe spacing of 0.38 nm. Further, disc diffusion method (DDM) was used to check the antibacterial activity of S NPs against gram-positive (MTCC737) 18 ± 0.12 mm and gram-negative bacteria against (MTCC443) 21.5 ± 0.12 mm, (MTCC1522) 19.1 ± 0.12 mm, (MTCC3384) 17.8 ± 0.10 mm. Among all the strains of bacteria, (MTCC443) showed a maximum zone of inhibition of 21.5 ± 0.12 mm and its antibacterial activity is somewhat like streptomycin sulfate. These SNPs also promote growth of in pot experiment, resulting in a 30 % increase in biomass, 90 cm in shoot length and 28 cm in root length and higher fresh and dry weight (50g and 20g, respectively) with 1.0 mg mL NPs treatment. In addition, SEM-EDX confirmed the accumulation of nanomaterial in plant leaves. This environmentally friendly approach to SNP synthesis using extracts demonstrates both potent antibacterial properties and plant growth-promoting effects, making it a promising solution for agriculture and biomedicine.