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 (Na₂S₂O₃5H₂O) and <i>Cannabis sativa</i> 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 <i>C. sativa</i> 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 <i>S. aureus</i> (MTCC737) 18 ± 0.12 mm and gram-negative bacteria against <i>E. coli</i> (MTCC443) 21.5 ± 0.12 mm, <i>A. salmonicida</i> (MTCC1522) 19.1 ± 0.12 mm, <i>K. pneumoniae</i> (MTCC3384) 17.8 ± 0.10 mm. Among all the strains of bacteria, <i>E. coli</i> (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 <i>C. sativa</i> 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^-1 NPs treatment. In addition, SEM-EDX confirmed the accumulation of nanomaterial in plant leaves. This environmentally friendly approach to SNP synthesis using <i>C. sativa</i> extracts demonstrates both potent antibacterial properties and plant growth-promoting effects, making it a promising solution for agriculture and biomedicine.