Synthesis of gallotannin capped iron oxide nanoparticles and their broad spectrum biological applications

Abstract

Green synthesized nanoparticles (NPs) have attracted enormous attention for their clinical and non-clinical applications. A natural polyphenol, gallo-tannin (GT) was used to reduce and cap the Fe₂O₃-NPs. GT-Fe₂O₃-NPs were synthesized following co-precipitation of FeCl₃ and FeSO₄·7H₂O with GT. Fe₂O₃-NPs absorbed light at 380 nm. Physicochemically, Fe₂O₃-NPs were spherical with slight aggregation and average diameter of 12.85 nm. X-ray diffraction confirmed crystallinity and EDX revealed the elemental percentage of iron and oxygen as 21.7% and 42.11%, respectively. FT-IR data confirmed the adsorption of gallo-tannin functional groups. Multiple drug-resistant (MDR) Escherichia coli (ESβL), Pseudomonas aeruginosa (ESβL), and Staphylococcus aureus were found susceptible to 500–1000 μg GT-Fe₂O₃-NPs per ml. In synergy, Fe₂O₃-NPs enhanced the efficiency of some antibiotics. GT-Fe₂O₃ NPs showed significant (P ≤ 0.05) inhibition of growth and biofilm against MDR E. coli, P. aeruginosa, and S. aureus causing morphological and biofilm destruction. Violacein production (quorum sensing mediated) by C. violaceum was inhibited by GT-Fe₂O₃-NPs in a concentration-dependent manner with a maximum decrease of 3.1-fold. A decrease of 11-fold and 2.32-fold in fungal mycelial growth and human breast cancer (MCF-7) cell viability, respectively was evident. This study suggests a plausible role of gallo-tannin capped Fe₂O₃-NPs as an alternative antibacterial, antiquorum sensing, antibiofilm, antifungal, and anti-proliferative agent.