Synthesis of Zinc Oxide Nanoparticles using Extract of Cynodon dactylon and Assessment of their Biological Activity against Staphylococcus aureus and Escherichia coli

Abstract

Nanotechnology is a groundbreaking technology that that has been widely applied in creating materials which are useful in various fields. It's important to maintain eco-friendly approaches for synthesis of nanoparticles by diversifying the substrate sources. In this study, the researchers used aqueous extract of Cynodon dactylon to synthesize zinc oxide nanoparticles (ZnONPs). Quantitative phytochemical analysis of the extract showed high concentrations of alkaloids, flavonoids, carbohydrates, proteins, amino acids, and phenolic compounds. In contrast, moderate concentrations of tannins, oils, and fats, and low concentrations of phlorotannins, saponin, triterpenoids, and cardiac glycosides were found. Sterols, anthraquinone glycosides, gums, and mucilages were not detected in the extract. The synthesized ZnONPs showed absorbance ranging from 293 nm to 336 nm, with a peak at 307 nm. Fourier transform infrared (FTIR) spectroscopy revealed that the surface of the ZnONPs contained alcohol (intermolecular bonded), alkyne, amine salt, alkane, alkyne, aromatic compounds, conjugated alkene, amine, nitro compound, sulfonyl chloride, alkylaryl ether, and sulfoxide. Dynamic light scatering (DLS) analysis of the ZnONPs showed that its average size was 35.34±1.64 nm, and the polydispersity index was 0.6335. Spectrum of X ray diffraction indicated that peaks formed at 2θ and their corresponding orientation planes are 31.92o (100), 34.62o (002), 36.44o (101), 47.64o (102), 56.84o (110), 63.3o (200), and 68.16o (112). Transmission electron micrograph revealed the spherical shape, and nonuniform sizes of ZnONPs, which ranged from 0.52 nm to 8.32 nm. Antibacterial analysis of biosynthesized ZnONPs recorded 16±3.2 mm and 6.0±2.2 mm; 6.7±2.1 mm and 4.33±1.3 mm, 0.0±0.0 mm and 1.0±1.41 mm, against Staphylococcus aureus and Escherichia coli, at 53.3 mg/mL, 26.7 mg/mL and 13.3 mg/ml concentrations, respectively. At sub-inhibitory concentrations, biosynthesized ZnONPs demonstrated effective dose-dependent antibiofilm formation activity against E. coli and S. aureus. Consequently, extract of Cynodon dactylon is suitable for biosynthesis of ZnONPs with effective antibacterial and antibiofilm formation activities.