Bioinspired Ag/CeO2 and Ag/Bi2O3 nanohybrids synthesized with Nauplius graveolens for antioxidant, antibacterial, and insecticidal applications

Abstract

Abstract A rising number of challenges of antibiotic resistance worldwide requires the creation of new antimicrobial and insecticidal agents. This incident stimulates a bioinspired methodology for the biosynthesis of novel and sustainable Ag/CeO 2 and Ag/Bi 2 O 3 nanohybrids. The high phytochemical contents of Nauplius graveolens extract, such as phenolics, flavonoids, and tannins, act as effective reducingand stabilizing agents for the synthesis of nanocomposites. N. graveolens extract and the synthesized nanohybrids also demonstrated a good antioxidant capacity; e.g., in DPPH assay, the extract had an IC 50 of 0.067 mg/mL, whereas the IC 50 of Ag/CeO 2 and Ag/Bi 2 O 3 NCs were 1.073 and 1.068 mg/mL, respectively. The reducible capacity by the FRAP assay is in line with the results of the DPPH assay. Notably, the nanohybrids exhibit a broad spectrum against different pathogenic bacterial species. The results of the insecticidal bioassays showed that both nanocomposites exhibited high dose-dependent insecticidal efficacy towards Brevicoryne brassicae and Aphis craccivora , with significantly lower values for the LC 50 and significantly higher values for the toxicity index. The results indicated the novelty of these bioinspired nanohybrids as potential fighters against drug-resistant bacteria, as well as in the multifunctional effectiveness of antioxidant and insecticidal applications.