Sustainable development through the bio-fabrication of ecofriendly ZnO nanoparticles and its approaches to toxicology and environmental protection

Abstract

Mosquito control is becoming more difficult as a result of the rise in resistance to toxic chemical insecticides. The insecticides of bio-fabrication sources may serve as a convenient alternative to environmentally acceptable methods in the future. The larvicidal and pupicidal activities of bio-fabricated zinc oxide nanoparticles (ZnO NPs) on the different instar larvae and pupae of Anopheles subpictus Grassi (Malaria vector) and Culex quinquefasciatus Say (lymphatic filariasis) were investigated in this study. The results recorded from XRD, FTIR, SEM-EDX, and TEM analyses confirmed the bio-fabrication of ZnO NPs. Such nanoparticles were nearly spherical and agglomerated with a size of 34.21 nm. GC-MS analysis of methanol extract revealed the compound, stigmasterol (C₂₉H₄₈O) as major one. Mosquito larvae and pupae of targeted mosquito were tested against varied concentrations of the bio-fabricated ZnO NPs and methanol extract of Vitex negundo for 24 h. The maximum activity was recorded from ZnO NPs against the larvae and pupae of A. subpictus LC₅₀ which were 1.70 (I), 1.66 (II), 1.93 (III), 2.48 (IV), and 3.63 mg/L (pupa) and C. quinquefasciatus LC₅₀ were 1.95 (I), 2.63 (II), 2.90 (III), 4.32 (IV), and 4.61 mg/L (pupa) respectively. ZnO NPs exhibited strong DPPH radical and FRAP scavengers compared to the aqueous extract of V. negundo. Also, V. negundo leaf methanol extract (VNLME) and ZnO NPs were evaluated for their cytotoxicity on HeLa cells, which exhibited the IC₅₀ values of 72.35 and 43.70μg/mL, respectively. The methylene blue (MB) dye, which is harmful to both aquatic and terrestrial life, was degraded using the biosynthesized ZnO nanoparticles. At 664 nm, 81.2% of the MB dye had degraded after 120 min of exposure to sunlight. Overall, our results revealed that ZnO NPs are the perfect biological agent and economical for the control of malaria, filariasis vectors, antioxidant, HeLa cells, and MB blue dye degradation under sunlight irradiation.

Keywords: DPPH; HeLa cells; Larvicidal; Pupicidal; Solar irradiation; Vitex negundo; XRD.

Fig. 1

XRD pattern of ZnO synthesized using Vitex negundo leaf broth

Fig. 2

a FTIR spectra of the synthesized ZnO NPs and b Leaf aqueous extract of V. negundo.

Fig. 3

a, b SEM micrograph leaf of V. negundo synthesized ZnO with magnification at 10,000× and 15,000×

Fig. 4

Energy-dispersive X-ray spectroscopy exhibiting the chemical components of the synthesized ZnO

Fig. 5

a, b Transmission electron microscopic image showing synthesized ZnO NPs from V. negundo. a 500 nm and b SAED pattern

Fig. 6

a DPPH scavenging efficiency of aqueous extract and fabricated ZnO NPs mediated by V. negundo. b FRAP antioxidant activity of aqueous extract and fabricated ZnO NPs mediated by V. negundo

Fig. 7

GC-MS analysis of leaf methanol extract of V. negundo

Fig. 8

a Photocatalytic degradation of MB dye using 10 mg/L of green-treated V. negundo ZnO NPs. b Photocatalytic degradation percentage of 2, 4, 6, 8, and 10 mg/L of green-treated V. negundo ZnO NPs

Fig. 9

The reusability experiments of 10 mg/L green-treated V. negundo ZnO NPs

Fig. 10

The possible photocatalytic mechanism of V. negundo-derived ZnO NPs