Nanotechnology and nanomedicine have excellent potential in dealing with a range of different health problems, including viruses, which are considered to be a serious challenge in the medical field... Graphical abstract

Central composite design (CCD) was applied to optimize the synthesis condition of silver nanoparticles (AgNPs) using the extract of Plantago major (P. major) seeds via a low cost and single-step process. The aqueous seed extract was applied as both reducing element and capping reagent for green production of AgNPs. Five empirical factors of synthesis including temperature (Temp), pH, volume of P. major extract (V_ex), volume of AgNO₃ solution (V_Ag) and synthesis time were used as independent variables of model and peak intensity of Surface Plasmon Resonance (SPR) originated from NPs as the dependent variable. The predicted optimal conditions was determined to be: Temp = 55 °C, pH = 9.9,V_ex = 1.5 mL, V_Ag = 30 mL, time = 60 min. The characterization of the prepared AgNPs at these optimum conditions was conducted by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) to determine the surface bio-functionalities. Bio-activity of these AgNPs against bacteria and fungi were evaluated based on its assay against Micrococcus luteus, Escherichia coli and Penicillium digitatum. Furthermore, antioxidant capacity of these NPs was checked using the ferric reducing antioxidant power (FRAP) assay.

Aqueous mango leaf extract was used as a reducing and capping agent for the biosynthesis of silver nanoparticles (AgNPs) via a single-step, low cost and green process. The formation of nanoparticles was investigated under various experimental conditions such as pH, concentration of Ag⁺ solution, quantity of leaf extract, temperature and incubation time. The AgNPs synthesized under optimum conditions were characterized by UV-Vis, XRD, TEM and FTIR to verify the production, crystallinity, morphology and surface bio-functionalities of the biosynthesized AgNPs. The catalytic activities of the as-synthesized AgNPs in the reduction of azo dyes, methylene blue (MB) and rhodamine B (RhB) by NaBH₄ were studied. Furthermore, the biological activities of these nanoparticles were confirmed based on their anti-cancer effects by MTT assay against HCT116 and SW480 human colon cancer cell lines and antioxidant capacity by the ferric reducing antioxidant power (FRAP) assay. Moreover, as an application in chemical sensing, colorimetric studies of the as-synthesized AgNPs showed selective sensing of toxic Hg²⁺ ion in water without further modification. This sensor had a wide linear dynamic range from 0.2 to 103.7 ppm with the aid of principal component analysis (PCA), followed by an artificial neural network (ANN). Finally, it is worthy to note that the effective catalytic and mercury detecting properties coupled with low-cost and low-toxicity can make these AgNPs attractive choices for wastewater management systems.

Adsorption techniques are widely used to remove industrial wastewater contaminants, especially non-biodegradable colourants. In this study, Iranian zeolite clinoptilolite was synthesised using magnetic iron oxide as an inexpensive and efficient adsorbent. The results showed that using natural zeolite, the removal efficiency of 26.8.6% at pH = 3 reached 48% at pH = 9. However, the adsorption capacity of the modified clinoptilolite did not change by increasing pH; it ranged from 96.4% to 98.6%. Moreover, increase in the initial concentration of the dye did not have any effects on the removal efficacy of the modified clinoptilolite. Using natural zeolite, on the other hand, the adsorption capacity showed a significant decrease and reached less than 10% at the 200 mg/l dye concentration. At the optimal contact time of 45 min, the dye removal rate by the modified zeolite was more than 98% at the optimal dose of 0.5 g. Indeed, the adsorption isotherm complied with Freundlich equation. Overall, the results showed that in comparison to the natural zeolite, the adsorption capacity of the clinoptilolite modified by iron nanoparticles increased significantly due to the uniformity of the cavities and increase in the surface of the adsorbent.