Structural and surface functionalized L-tyrosine Iron Oxide (L-tyr-Fe) nanoparticles for antimicrobial impacts

Bacterial resistance results from changes in the ability of microorganisms to withstand antibacterial medicines, which can either render them inactive or reduce their therapeutic efficiency. This results in prolonged infection periods, elevated mortality rates and increased financial strain on healthcare systems. However, iron oxide nanoparticles (Fe NPs) have been explored as a potential candidate to improve the therapeutic and physicochemical activities among the studied metal-oxides due to their exceptional structural, optical, surface and magnetic impacts. The major goal of this research was to design the surface of Fe NPs by co-precipitating them with L-tyrosine (L-tyr-Fe NPs), improving their antimicrobial activity. UV–Vis spectrophotometry showed a characteristic optical absorption at 391 nm for the L-tyr-Fe NPs and 262 nm for pure iron oxide. The surface functionalized L-tyrosine (L-tyr-Fe NPs) was investigated by its vibrational frequencies using Fourier Transform Infrared (FTIR) spectrophotometry. The crystal phase and sizes of the L-tyr-Fe NPs were estimated using X-ray diffractometry (XRD), which revealed crystalline cubic diameters of 33.50 and 12.87 nm for the Fe NPs and L-tyr-Fe NPs, respectively. The particle size of the L-tyr-Fe NPs was 11.8 nm, confirmed by high-resolution transmission electron microscopy (HR-TEM). A DLS study revealed the monodispersed nature of the L-tyr-Fe NPs (polydispersity index, 0.314). The stable nature of the L-tyr-Fe Nps was checked by zeta potential measurements (zeta value −20.14 mV). The bioassay of L-tyr-Fe Nps showed comparable or better results against Escherichia coli and Bacillus subtilis as compared with common antibiotics. The L-tyr-Fe Nps at 150μg/mL showed an effective zone of inhibition of 15 ± 0.00 mm against Bacillus subtilis, which was comparable to streptomycin (16 ± 0.0 mm at 150μg/mL), amoxicillin (16 ± 0.0 mm at 150μg/mL) and chloramphenicol (16 ± 0.0 mm at 100μg/mL) and better than ampicillin (11 ± 0.0 mm at 150μg/mL) for Bacillus subtilis An inhibition zone of 22.66 ± 0.03 mm at 200 μg/mL was observed against Escherichia coli, which was better than streptomycin (17 ± 0.0 mm at 100μg/mL), ampicillin (18.5 ± 0.0 mm at 150μg/mL) and chloramphenicol (17 ± 0.0 mm at 150μg/mL). These discoveries could eventually be exploited to develop novel therapeutic approaches that may use nano-bio conjugates. Such amino acid-coated iron oxide materials are appreciated in the field of medical sciences and technologies. The surface modified iron oxides (Fe3O4) NPs formed using eco-friendly and cost-effective method were found to be potent biomaterials that can be used as antimicrobial agents for Gram-positive and Gram-negative bacteria with multiple antibiotic resistances.