Green synthesis of nanostructured zinc oxide by Ocimum tenuiflorum extract: characterization, adsorption modeling, cytotoxic screening, and metal ions adsorption applications

Abstract

Nano-ZnO was synthesized by the reduction of Zn (CH3COO)2.2H2O salt using the extract of Ocimum tenuiflorum leaves. The generated ZnO NPs were characterized by FT-IR, XRD, SEM, and EDX techniques. FT-IR results approved the characteristic peaks, the formation of ZnO bonds, and the morphology changes after the adsorption of Cd2+ and Pb2+ from solutions. The outlined data of the XRD pointed to the formation of a hexagonal wurtzite structure. SEM images showed the spherical nature of the synthesized particles with an average diameter of 19 nm. Moreover, the best conditions for the adsorption of Cd2+ and Pb2+ by ZnO NPs were evaluated and fitted to isotherm and kinetic models. Short contact time of ~ 20 min and a small sorbent dosage of 40 mg were sufficient conditions for attaining maximum Pb2+ adsorption capacity. Based on the modeling parameters, the adsorption follows pseudo-second-order kinetics where ZnO and metal ions are involved in the rate-determining step. Two important applications were thoroughly studied. The nanoparticles significantly removed Pb2+ and Cd2+ contaminants from real environmental water samples collected from different locations in Egypt. Additionally, the cytotoxic activity results provided perfect evidence for the higher efficacy of the synthesized ZnO NPs as an anticancer agent against Panc-1, PC-3, and CACO-2 cell lines with IC50 of 1.70, 3.67, and 5.70 μgml−1, respectively, compared to cisplatin (IC50 = 3.57, 5.09, and 7.75 μgml−1). Furthermore, a low cytotoxic effect was observed on the normal human lung cell line (MRC-5, IC50 = 22.40 μgml−1). The data can be used as a preliminary study for anticancer drug design after further clinical investigations. Graphical Abstract

Role of zinc oxide nanoparticles in alleviating sodium chloride-induced salt stress in sweet basil (Ocimum basilicum L.)

“…ZnO nanoparticles (ZnO NPs) are produced by various processes such as ball milling, co-precipitation, microemulsion, laser vaporization, and sol-gel processes [23]. Recently, the trend of nanoparticle production by leaf extracts on the boom and various plant leaf extracts has been reported to produce ZnO nanoparticles efficiently [24,25]. ZnO NPs function as simulation agents that have been reported to alter various physiochemical and biochemical processes in plants [26].…”

“…Due to their small size and large surface area, ZnO nanoparticles applied by foliar spray easily uptake and absorb by the plant surface, get attached and bind to the active site of metabolic enzymes, and enhance their activity, resulting in better growth and yield attributes [27]. In addition, at optimum concentrations, it provides a favorable response against abiotic stresses in field plants [20][21][22][23][24][25][26][27][28]. ZnO improves plant tolerance against abiotic stress in various plants by causing in vitro shoot proliferation and boosting various secondary metabolites in Ochradenus arabicus [29].…”

Biosynthesis, Characterization and Antimicrobial Efficacy of Zinc Oxide Nanoparticles via Plectranthus amboinicus Leaf Extract

“…Different researchers utilized different parts of different plants e.g. Myristica fragrans [19], Elaeagnus angustifolia [20], Cassia fistula [21], Melia azedarach [21], Acalypha indica [22], Calotropis gigantean [23], Ocimum sanctum [24], Coriandrum sativum [25], Mussaenda frondosa [26], Eucalyptus globulus Labill. [27], Ocimum americanum [28], Trifolium pratense [29], Sambucus ebulus [30], Acalypha fruticosa [31], etc.…”