Structural and Surface Properties of pH-Varied Fe₂O₃ Nanoparticles: Correlation with Antibacterial Properties

Hematite (Fe₂O₃) nanoparticles were synthesized using a hydrothermal synthesis route under different pH conditions (pH ∼8,10,11.5) (i.e., different ratios of H⁺/OH^- ions). The sample synthesized at pH 10 had better motility toward the bacterial surface due to having an overall positive charge (ξ-potential = +11.10), leading to a minimal hydrodynamic size (D_τ = 186.6). The results are discussed in light of the relative ratio of H⁺/OH^- that may affect bond formation by influencing the electronic clouds of the participating ions that can modify the structure. This, in turn, modifies crystallinity, strain, disorder, surface termination, and thereby, the surface charge, which has been correlated to the antibacterial properties of the nanoparticles due to the interaction between the respective opposite charges on the nanoparticle surface and bacterial cell wall. The structural modifications were correlated to all of these parameters in this work.