Biosynthesized δ-BiO Nanoparticles from Flower Extract for Photocatalytic Dye Degradation and Molecular Docking.

Bioinspired delta-bismuth oxide nanoparticles (δ-BiO NPs) have been synthesized using a greener reducing agent and surfactant co-precipitation method. The originality of this work is the use of flower extract for the first time for the fabrication of NPs, which were further calcined at 800 °C to obtain δ-BiO NPs. Physicochemical studies such as FTIR spectroscopy and XPS confirmed the formation of BiO NPs, whereas XRD and Raman verified the formation of the cubic delta (δ) phase of BiO NPs. However, HRTEM revealed the spherical shape with diameter 10-20 nm, while BET studies expose mesoporous nature with a surface area of 71 m/gm. The band gap for δ-BiO NPs was estimated to be 3.45 eV, which ensured δ-BiO to be a promising photocatalyst under visible-light irradiation. Therefore, based on the results of physicochemical studies, the bioinspired δ-BiO NPs were explored as active photocatalysts for the degradation of toxic dyes, ., Thymol blue (TB) and Congo red (CR) under visible-light irradiation. The study showed 98.26% degradation of TB in 40 min and 69.67% degradation of CR in 80 min by δ-BiO NPs. The photogenerated holes and electrons were found responsible for this enhancement. Furthermore, molecular docking investigations were also performed for δ-BiO NPs to understand its biological function as New Delhi metallo-β-lactamase 1 (NDM-1) [PDB ID 5XP9] enzyme inhibitor, and studies revealed good interaction with various amino acid residues and found good hydrogen bonding with a fine pose energy of -3.851 kcal/mole.