Synthesis and characterization of TiO2 NPs by aqueous leaf extract of Coleus aromaticus and assess their antibacterial, larvicidal, and anticancer potential.

The frequent applications of synthetic chemical insecticides and drugs create resistance among insects and microbes, creating a new threat to human and environmental welfare. This investigation focused on evaluating the possibilities of fabricating and characterizing the titanium dioxide nanoparticles (TiO2 NPs) from titanium dioxide (TiO2) through the aqueous leaf extract of Coleus aromaticus. Their biological applications were studied against the larvae of Aedes aegypti human pathogenic bacteria, and cancer cell line. The results revealed that the aqueous leaf extract had the metal reducing proficiency to produce nanoparticles from TiO2. The synthesized TiO2 NPs were initially confirmed by visible color changes and Ultraviolet-Visible Spectrophotometer analysis that showed a predominant peak at 332 nm. Furthermore, the nanocrystals, structural alignment, functional groups and elemental compositions were studied by following standard operating protocol in XRD (X-ray Powder Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), TEM (Transmission Electron Microscopy), and EDX (Energy-Dispersive X-ray Spectroscopy) techniques, respectively. The results attained from these techniques confirmed that the plant mediated and fabricated particles were in the nanoscale range (12-33 nm) with a hexagonal shape. The synthesized TiO2 NPs had an outstanding (1000 μg mL-1) larvicidal activity against the four stages of instars larvae of Ae. aegypti at 1000 μg mL-1. It also had an excellent antibacterial potential against E. faecalis (33 mm), followed by S. boydii (30 mm) at 30 mg L-1 concentration. The green fabricated TiO2 NPs had a fabulous (92.37%) cytotoxic activity on the HeLa cell line at 100 μg mL-1 dosage within one day of exposure. The entire results concluded that the C. aromaticus mediated TiO2 NPs have excellent biological applications and thus, could be considered for the welfare of human beings.