Biosynthesis of iron nanoparticles using Trigonella foenum-graecum seed extract for photocatalytic methyl orange dye degradation and antibacterial applications.

Trigonella foenum-graecum is the source of various biological and chemical constituents with a wide area of applications, especially in the treatment/prevention of diabetes and other chronic diseases such as cancer. Multiple biological and organic moieties in the aqueous or the organic phase of Trigonella foenum-graecum carry soft reduction properties to reduce the metal cations to nanoparticles. In this investigation, the Trigonella foenum-graecum was found in the seed extract for the first time in an aqueous medium. We successfully synthesized zero-valent iron nanoparticles (Fe0) (ZV-Fe NPs) and stabilized these nanoparticles in an aqueous medium. The stabilization mechanism of Fe NPs by Trigonella foenum-graecum in an aqueous extract was investigated. Further, Fe NPs were characterized by UV-visible spectrometry, X-ray diffraction (XRD), thermogravimetric analysis - derivative thermo-gravimetric (TGA/DTG), magnetization, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) images. The size of the nanoparticles, calculated using the Debye-Scherer equation and TEM, was found to be approximately 11 nm with the highest particle distribution number. Fe NPs are very effective for methyl orange dye degradation under UV light following pseudo first-order kinetics, and the rate constant kapp was found to be 0.025 min-1. Furthermore, Fe NPs were applied to check the antibacterial activities with microorganisms such as gram-negative E. coli and gram-positive S. aureus. The Minimum Inhibitory Concentration (MIC) of Fe NPs for E. coli and S. aureus was calculated as 32 µg/mL and 64 µg/mL, respectively.