▎ 摘　　要

A biogenic synthesis of Ag NPs adorned Helleborus niger extract-modified graphene oxidenanohybrid material has been demonstrated. Initially, the Helleborus niger extract was functionalized on the surface of graphene oxide. The polyphenolic groups of plant phytochemicals facilitated the green reduction of Ag ions as well as GO to afford the Ag/H.niger@rGO nanocomposite. The nanocomposite was characterized using FT-IR, FE-SEM, EDX, elemental mapping, TEM and XRDanalysis.Towards its application, it was found to be an efficient catalyst in the reductive degradation of toxic water pollutant organic dyes like Methylene blue (MB)and 4-nitrophenol (4-NP) over NaBH4 at room temperature. Time dependent UV-Vis spectroscopy was used to follow up the reactions which revealed that the reactions were completed within very short time (50-60 s). After the chemical applications we also explored the material biologically in the resistance of human colon cancer and thereby studied the cytotoxicity over two standard cell lines, HT-29 and Caco-2. The conventional MTT assay was carried out over them which revealed an increase in % cell viability dose dependently. In addition, DPPH radical scavenging test was performed for studying anti-oxidant activity. The IC50 values observed in the two cell lines were 368.2 mu g/ml and 254.2 mu g/ml respectively.