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) <i>Escherichia coli</i> (ESβL), <i>Pseudomonas aeruginosa</i> (ESβL), and <i>Staphylococcus aureus</i> 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 (<i>P</i> ≤ 0.05) inhibition of growth and biofilm against MDR <i>E. coli</i>, <i>P. aeruginosa</i>, and <i>S. aureus</i> causing morphological and biofilm destruction. Violacein production (quorum sensing mediated) by <i>C. violaceum</i> 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.