Core-shell In@In₂O₃ NPs from rosemary extract and bioactivity study

In this study, a phytochemical-mediated synthesis approach was used to prepare indium oxide-coated indium nanoparticles (In@In2O3NPs). This environmentally friendly method employed aqueous rosemary extract rich in bioactive phytochemicals that act as reducing, capping, and stabilizing agents during NPs synthesis. The NPs were characterized using FTIR, XRD, EDX, FESEM, TEM, BET, and zeta potential. The particle size was 10-60 nm, and they were irregularly spherical. The specific surface area determined by BET analysis was 128.53 m²/g. The zeta potential was -39.9 mV, indicating strong electrostatic repulsion between the particles, thereby ensuring their stability and preventing agglomeration. Bioactivity was measured against Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, and Escherichia coli. The minimum inhibitory concentrations (MICs) and sub-MICs of In@In2O3 NPs were found to be 234.38, 234.38, 117.19, and 234.38 µg/mL, and 117.19, 117.19, 58.60, and 117.19 µg/mL, respectively. At a concentration of 234.38 µg/mL, the In@In2O3 NPs exhibited low toxicity (5.6%). The tested bacterial isolates exhibited weak to moderate biofilm-forming ability, and In@In₂O₃ NPs effectively inhibited biofilm formation. The antioxidant activity of the resulting NPs was examined using the DPPH assay. A relationship was found between the concentration of the In@In2O3 NPs solution and the inhibition rate, with inhibition increasing as the concentration increased. KEY WORDS: Phytochemical-mediated synthesis, In@In₂O₃ nanoparticle, Rosemary, Bioactivity Bull. Chem. Soc. Ethiop. 2027, 41(1), 1-13. DOI: https://dx.doi.org/10.4314/bcse.v41i1.1