Polyol-synthesized bismuth oxide nanorods: Interaction with blood protein and antibacterial activity

Bismuth oxide (Bi₂O₃) nanorods (NRs) with rod-like morphology and nanoscale dimensions are emerging as promising candidates for biomedical applications. In this study, we comprehensively evaluated both their antibacterial efficacy and their interaction with a key biological protein, hemoglobin (Hb). Bi₂O₃ NRs were synthesized via a simple solution-based method, producing uniform rods with an average diameter of ∼8 nm and a length of ∼50 nm. Biochemical and biophysical analyses revealed that Bi₂O₃ NRs, which exhibit negligible hemolytic activity, strongly interact with Hb, leading to pronounced changes in hydrodynamic diameter, zeta potential, and aggregation behavior. Spectroscopic and molecular docking studies further confirmed static quenching and hydrophobic interactions, leading to conformational alterations in Hb structure. In addition, the antibacterial activities of both Bi₂O₃ NRs and Bi₂O₃ NR-Hb complexes were examined. Bi₂O₃ NRs exhibited strong antibacterial effects against
Staphylococcus aureus, Escherichia coli
, and
Pseudomonas aeruginosa
, with minimum inhibitory concentrations (MICs) of 50, 25, and 100 µg/mL, respectively. However, upon complexation with Hb, the resulting structural changes were accompanied by a marked reduction in antibacterial efficacy. This dual assessment highlights both the therapeutic promise and potential risks of Bi₂O₃ NRs: while they are potent antibacterial agents, their ability to interact with and perturb protein structure may lead to diminished antimicrobial performance and unintended biological effects. Overall, these findings underscore the importance of simultaneously evaluating antibacterial properties and protein interactions to ensure the safe and effective biomedical application of nanomaterials.