TGreen Synthesis of ZnO and α-Fe2O3 Nanoparticles Using Chinese Palm Leaf Extract and Their Biological and Photocatalytic Evaluation

Abstract

This study reports the synthesis of ZnO and α-Fe2O3nanoparticles (NPs) mediated by Livistona chinensis leaf extract, which acts as a reducing agent and capping agent. The composition and morphology of the NPs were studied by different characterization techniques. The NPs were tested for their antibacterial, antibiofilm and antioxidant potential. Furthermore, ZnO NPs were tested for their photocatalytic activity against malachite green (MG) dye. Molecular docking studies were also conducted using three particular proteins: the LasR and LasI proteins of Pseudomonas aeruginosa, and the AgrA protein of Staphylococcus aureus. ZnO NPs showed a UV absorption band at 377 nm, whereas UV absorption of α-Fe2O3 NPs was observed at 418 nm. The Zn-O formation was confirmed by the FT-IR characteristic band at 513 cm-1, and Fe-O stretching was observed at 574 cm-1. The average crystallite size of ZnO and α-Fe2O3 NPs was 25.40 nm and 12.37 nm, respectively. The FE-SEM studies confirmed the formation of non-spherical, triangular-shaped ZnO NPs, whereas α-Fe2O3 NPs exhibited spherical morphology. The ZnO NPs exhibited substantial antibacterial activity against M. luteus and S. abony with a zone of inhibition (mm) of 15±0.20, 15±0.90, as compared to standard Gentamicin (28±0.02) mm at a concentration of 50 µg/mL, whereas α-Fe2O3 NPs NPs exhibited significant antibacterial activity against B. subtilis, S. aureus, E. coli with zone of inhibition19±0.7, 19±0.1, 21±0.13 mm at 100 µg/mL, respectively. Both the NPs showed significant antibiofilm activity against B. subtilis. ZnO and α-Fe2O3 NPs NPs also exhibited moderate antioxidant activity, showing 48.63% and 36.79% scavenging of DPPH free radicals. The photocatalytic potential of the ZnO NPs against MG dye, showed 79% photodegradation after 90 minutes when exposed to visible light, while for α-Fe2O3 NPs showed only 68% photodegradation efficiency. Molecular docking studies with ZnO NPs and their interaction with the LasI protein culminated in a binding energy of -3.86 kcal/mol and a Ki of 1480.2 µM, whereas against the same protein, α-Fe2O3 NPs had a binding energy of -10.33 kcal/mol.

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