L-arginine functionalized NiFe₂O₄ nanoparticles: synthesis, characterization, antimicrobial activity, and biocompatibility evaluation in a zebrafish model.

NiFe₂O₄ nanoparticles and L-arginine–functionalized NiFe₂O₄ (NiFe₂O4–LA) were synthesized, characterized, and evaluated for antimicrobial performance and in vivo biocompatibility in a zebrafish embryo model. The XRD and HRTEM studies confirmed the formation of single-phase cubic spinel NiFe₂O₄ with average crystallite size ≈ 20–30 nm. Surface modification with LA preserved the spinel structure while reducing crystallinity and hydrodynamic size 128.7 nm. FTIR and XPS verified successful surface functionalization. UV vis measurements showed band-gap narrowing after La conjugation (Eg ≈ 3.23 → 3.15 eV). NiFe₂O₄–LA exhibited enhanced antimicrobial activity compared with bare NiFe₂O₄ against MRSA and C. albicans an effect attributed to enhanced surface interaction and ROS-mediated oxidative damage. The MIC values of C. albicans is found to 1200 µg/mL while in the case MRSA is about 900 µg/mL. The ROS assays with histidine modulation supported a role for redox activity in antimicrobial action. In vivo zebrafish embryo assays showed minimal developmental toxicity at tested exposures with better viability for the LA coated material.