Zinc oxide nanoparticles (ZnO-NPs) have been produced by physical and chemical methods. Here, the comparative evaluation of both chemically-synthesised ZnO-NPs (C-ZNPs) and in-vitro cultured S. marianum mediated green-synthesised ZnO-NPs (G-ZNPs) were investigated on seed germination frequency, root and shoot growth, callus induction and biochemical profile of medicinally important plant Silybum marianum. Of all the treatments, callus-mediated ZnO-NPs gave optimum results for seed germination (65%), plantlet's root length (4.3 cm), shoot length (5.3 cm) and fresh and dry weights (220.4 g L À1 and 21.23 g L À1 , respectively). Similarly, the accumulation of phenolic (12.3 mg/mg DW) and flavonoid (2.8 mg/mg DW) contents were also enhanced in callus cultures treated with G-ZNPs. We also observed maximum antioxidant activity (99%) in callus cultures treated with G-ZNPs, however, in case of plantlets, these activities were found highest for in-vitro whole plant-mediated ZnO-NPs. Moreover, G-ZNPs also enhanced total protein content (265.32 BSAE/20g FW) in callus cultures. G-ZNPs were further assessed for their effects on several multidrug resistant bacterial strains and human liver carcinoma (HepG2) cells and our findings revealed that callus extracts treated with G-ZNPs show ameliorated antibacterial (highest zone of inhibition (19 mm) against Klebsiella pneumonia) and anticancer (highest cytotoxicity of 64%) activities.

Dengue is a growing mosquito-borne viral disease prevalent in 128 countries, while 3.9 billion people are at high risk of acquiring the infection. With no specific treatment available, the only way to mitigate the risk of dengue infection is through controlling of vector, i.e., Aedes aegypti. Nanotechnology-based prevention strategies like biopesticides with nanoformulation are now getting popular for preventing dengue fever. Metal nanoparticles (NPs) synthesized by an eco-friendly process, through extracts of medicinal plants have indicated potential anti-dengue applications. Green synthesis of metal NPs is simple, cost-effective, and devoid of hazardous wastes. The recent progress in the phyto-synthesized multifunctional metal NPs for anti-dengue applications has encouraged us to review the available literature and mechanistic aspects of the dengue control using green-synthesized NPs. Furthermore, the molecular bases of the viral inhibition through NPs and the nontarget impacts or hazards with reference to the environmental integrity are discussed in depth. Till date, major focus has been on green synthesis of silver and gold NPs, which need further extension to other innovative composite nanomaterials. Further detailed mechanistic studies are required to critically evaluate the mechanistic insights during the synthesis of the biogenic NPs. Likewise, detailed analysis of the toxicological aspects of NPs and their long-term impact in the environment should be critically assessed.