Photocatalytic degradation of Rhodamine B (RhB) dye in waste water and enzymatic inhibition study using cauliflower shaped ZnO nanoparticles synthesized by a novel One-pot green synthesis method

The ZnO nanoparticles (NPs) are considered to be one of the inexpensive and very important bioactive materials widely used in drug delivery, as a photo-catalyst material, antibacterial, bioimaging, anticancer, anti-inflammation, wound healing, and diabetes treatment. Therefore, we have prepared ZnO NPs using Alchemilla vulgaris (Lady’s mantle) leaves and investigated their anti-enzymatic properties. Phases of the ZnO NPs were determined from X-Ray diffraction (XRD) spectra. The shape and size of the green synthesized NPs were investigated by scanning electron microscopy (SEM) and it confirms the cauliflower shape with an average size of 120 nm. But the beads inside the cauliflower shape are 20 nm in size. The prepared ZnO NPs show the cumulative median particle size of 550 nm. The thermogravimetric (TG) and differential thermal analysis (DTA) were performed at different heating rates to study the percentage of weight loss, and activation energy. The activation energy was calculated to be 4.98 kJ/moles using Kissinger method. We also studied the enzyme inhibition effect of ZnO NPs containing biologically active groups on important metabolic enzymes like butyrylcholinesterase(BChE), acetylcholinesterase (AChE) and α-glycosidase (α-Gly) enzymes. The bandgap of ZnO NPs was also studied by UV–Vis spectroscopy via Tauc's method and it was determined to be 3.27 eV. The photocatalytic property of the ZnO NPs was executed against rhodamine B (RhB) under the illumination of an AM 1.5 solar simulator.