Green synthesis of AgCl/AgPO nanoparticle using cyanobacteria and assessment of its antibacterial, colorimetric detection of heavy metals and antioxidant properties.

In this study, the extract of two strains of cyanobacteria was used for the synthesis of silver nanoparticles (NPs). UV-vis spectroscopy, X-ray diffraction, dynamic light scattering and field emission scanning electron microscopy (FESEM) analyses were carried out to characterise the NPs. The antioxidant activity and heavy metal detection properties were investigated; moreover, their minimum inhibitory concentration and minimum bactericidal concentration against the multi-drug resistant bacteria were determined. The most abundant materials in these extracts were carbohydrates, so the biosynthesis of NPs using exopolysaccharide (EPS) was also investigated. The surface plasmon resonance of NPs had a peak at 435 nm and EPS NPs at 350-450 nm. The NPs produced by sp. IBRC-M5064 extract revealed the face-centred cubic (fcc) structure of AgCl, while NPs of showed the fcc crystalline structure of AgPO and AgCl. The FESEM showed the spherical shape of these NPs. The AgCl/AgPO colloid, in comparison with AgCl, showed better antioxidant activity and antibacterial effect. The heavy metal detection analysis of NPs revealed that the NPs of both stains involved in Hg (NO) detection.