Green Synthesis of Selenium Nanorods Using Muntigia calabura Leaf Extract: Effect of pH on Characterization and Bioactivities

In this study, selenium nanomaterials (nano-Se) were synthesized via a biological route, in which the leaf extract of Muntigia calabura was efficiently utilized as not only a reducing agent but also a surfactant to stabilize the produced nanostructures. In detail, the effect of pH level on the shape and bioactivities of nano-Se were thoroughly investigated, which revealed the formation of selenium nanorods at pH 8 with uniform sizes of 30–50 nm in diameter and several micrometers in length, corresponding to the Se-pH8 sample. Besides, the material also exhibited excellent bactericidal rates against both Gram-negative and Gram-positive strains, while the cytotoxicity test using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay elucidated the notably low toxicity of Se-pH8 towards the normal HEK293 cells. Therefore, the obtained results show the great potential of the nano-Se material in multiple industrial applications, particularly in the medical and pharmaceutical sectors. Graphical Abstract