Synthesis of Iron(III) Oxide-Coated Xanthan Gum Nanospheres as an Antibacterial and High-Efficiency Dye Sensor

The development of core-shell nanostructures using heterogeneous materials in an ordered configuration enhances both antibacterial and electrochemical properties as a result of the synergistic effect of combined materials. In this study, we present a novel biocomposite core-shell nanostructure comprising Fe₂O₃ and xanthan gum (XG) for the electrochemical detection of Rhodamine B (RhB), a commonly used food dye and additive. The composite was synthesized through a simple and efficient method, involving the surface etching of Fe₂O₃ to promote strong interactions with XG. Transmission electron microscopy (TEM) confirmed the formation of the core-shell structure of nanocubes with a layer of ∼17 nm thickness. Electrochemical investigations revealed that Fe₂O₃@XG exhibits excellent electrocatalytic activity toward RhB, facilitated by intermolecular hydrogen bonding and electrostatic interactions. The sensor demonstrated a wide linear detection range from 50 nM to 400 μM, with a limit of detection (LOD) of 12.06 nM and a limit of quantification (LOQ) of 40.21 nM. Additionally, the composite displayed strong anti-interference characteristics, along with good reproducibility and stability. Real sample analysis showed high recovery percentage on spiking tomato sauce and chili powder, confirming its practical applicability. Beyond sensing capabilities, the composite also demonstrated potent antibacterial activity against <i>Klebsiella pneumoniae</i> and <i>Pseudomonas aeruginosa</i>, with inhibition zones measuring 17 ± 1.5 and 13 ± 2.5 mm, respectively. Free radical scavenging ability was confirmed via the DPPH assay, and hemolysis studies indicated excellent biocompatibility with a lysis rate of just 1.48%. Overall, the synthesized Fe₂O₃@XG core-shell biocomposite holds strong promise for designing devices for RhB detection, contributing to food safety monitoring and offering potential in biomedical applications.