Antimicrobial Activity and Degradation Effect of Green Iron Nanoparticles Synthesized Using Galinsoga parviflora (Cav.), Conyza bonariensis (L.) and Bidens pilosa (L.) Leaves

Abstract

Infectious bacterial diseases remain a major global problem due to antibiotic resistance caused by the misuse of antibiotic drugs. Green nanoparticles have rare and unique applicability in various fields: medicine, nutrition, agriculture and environmental wastewater treatment. This study aimed to synthesize iron nanoparticles by reacting a 0.1 M Iron Chloride (FeCl3) solution with aqueous leaf extracts from Galinsoga parviflora (G. parviflora), Conyza bonariensis (C. bonariensis) and Bidens pilosa (B. pilosa), and determining their antimicrobial effects against Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), Pseudomonas arureginosa (P. aureginosa) and Candida albicans (C. albicans). The degradation effects of Rifampicin and Methylene blue (MB) dye were also determined. Secondary metabolites from the plants’ leaf extracts were screened for the presence of flavonoids, polyphenols, and phytosterols. C. bonariensis had the highest concentration of flavonoids (45.50±0.59 mg (Rutin Equivalent/Dry weight) while B. pilosa had the highest concentration of reducing polyphenol compounds at 126.27±0.01 mg (Gallic Acid Equivalent/Dry weight). Characterization of the green nanoparticles was done using several techniques: Ultraviolet–Visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Fluorescence (XRF), X-ray Diffraction (XRD), and Scanning Electron Microscope (SEM). The sizes of B. pilosa nanoparticles (BpNPs), G. parviflora nanoparticles (GpNPs), and C. bonariensis nanoparticles (CbNPs) ranged from 60–90 nm and the mean sizes were 84, 51, and 78 nm, respectively. The formation of green iron nanoparticles was further confirmed by the absorption shifts in the UV–Vis and FTIR spectra. The green iron nanoparticles exhibited antimicrobial activity effects against S. aureus, B. subtilis, E. coli, P. aureginosa and C. albicans compared to the ampicillin standard. The percentage degradation efficiency of Methylene blue and Rifampicin increased with an increase in temperature, dosage and pH change with efficiencies of over 90%. Sunlight–assisted degradation of Rifampicin and Methylene blue by nanoparticles with H2O2 was over 93% in less than 20 minutes. The results from this study demonstrated that green iron nanoparticles had antimicrobial and degradation properties that can be exploited in the field of medicine and environmental degradation of dyes, such as Methylene blue.