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

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 Fe ₂ O ₃ -NPs. GT-Fe ₂ O ₃ -NPs were synthesized following co-precipitation of FeCl ₃ and FeSO ₄ ·7H ₂ O with GT. Fe ₂ O ₃ -NPs absorbed light at 380 nm. Physicochemically, Fe ₂ O ₃ -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-Fe ₂ O ₃ -NPs per ml. In synergy, Fe ₂ O ₃ -NPs enhanced the efficiency of some antibiotics. GT-Fe ₂ O ₃ 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-Fe ₂ O ₃ -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 Fe ₂ O ₃ -NPs as an alternative antibacterial, antiquorum sensing, antibiofilm, antifungal, and anti-proliferative agent.
Competing Interests: The authors declare that there are no conflicts of financial or personal interest.
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