title: Biomimetic synthesis of selenium nanospheres by bacterial strain JS-11 and its role as a biosensor for nanotoxicity assessment: a novel se-bioassay.
abstract: Selenium nanoparticles (Se-NPs) were synthesized by green technology using the bacterial isolate Pseudomonas aeruginosa strain JS-11. The bacteria exhibited significant tolerance to selenite (SeO3(2-)) up to 100 mM concentration with an EC50 value of 140 mM. The spent medium (culture supernatant) contains the potential of reducing soluble and colorless SeO3(2-) to insoluble red elemental selenium (Se(0)) at 37°C. Characterization of red Se° product by use of UV-Vis spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) with energy dispersive X-ray spectrum (EDX) analysis revealed the presence of stable, predominantly monodispersed and spherical selenium nanoparticles (Se-NPs) of an average size of 21 nm. Most likely, the metabolite phenazine-1-carboxylic acid (PCA) released by strain JS-11 in culture supernatant along with the known redox agents like NADH and NADH dependent reductases are responsible for biomimetic reduction of SeO3(2-) to Se° nanospheres. Based on the bioreduction of a colorless solution of SeO3(2-) to elemental red Se(0), a high throughput colorimetric bioassay (Se-Assay) was developed for parallel detection and quantification of nanoparticles (NPs) cytotoxicity in a 96 well format. Thus, it has been concluded that the reducing power of the culture supernatant of strain JS-11 could be effectively exploited for developing a simple and environmental friendly method of Se-NPs synthesis. The results elucidated that the red colored Se° nanospheres may serve as a biosensor for nanotoxicity assessment, contemplating the inhibition of SeO3(2-) bioreduction process in NPs treated bacterial cell culture supernatant, as a toxicity end point.
authors.affiliation: Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Sourabh
authors.initials: S
authors.lastname: Dwivedi
authors.forename: Abdulaziz A
authors.initials: AA
authors.lastname: Alkhedhairy
authors.forename: Maqusood
authors.initials: M
authors.lastname: Ahamed
authors.forename: Javed
authors.initials: J
authors.lastname: Musarrat
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D001681:Biological Assay / Q000379:methods*; D032701:Biomimetics / Q000379:methods*; D015374:Biosensing Techniques / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005453:Fluorescence; D009243:NAD / Q000378:metabolism; D054118:Nanospheres / Q000633:toxicity*; D010084:Oxidation-Reduction / Q000187:drug effects; D010619:Phenazines / Q000378:metabolism; D025341:Principal Component Analysis; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D012643:Selenium / Q000633:toxicity*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D018675:Toxicity Tests / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D003470:Culture Media; D010619:Phenazines; D009243:NAD; C037165:1-phenazinecarboxylic acid; D012643:Selenium