Green synthesis, characterization and biochemical properties of waste walnut (Juglans regia L.) inner shell-based silver nanoparticles

Sustainability is important for future ecology and the increase of waste in recent years negatively affects sustainability. The management of waste and using them in the technology field could be a solution for sustain- ability. Nanotechnology is a developing technology aiming to improve the physical, chemical and biological properties of matter with the size of 1-100 nm. Nanoparticles could be synthesized by different methods such as physical, biological, and chemical. The green synthesis (biological synthesis) method is the most preferred when compared to chemical and physical methods because it is eco-friendly, energy-saving, cheaper, less waste-producing, easy to scale, sustainable and biologically compatible. Walnut is a versatile fruit with its leaves, dry and green fruit, timber, inner/outer shell and outer peel. Its inner shell and outer peel are not used as food and are waste. In this study, a waste walnut inner shell was used to synthesize silver nanoparticles (WS-AgNPs). WS-AgNPs were synthesized by green technique, characterized and biochemical properties were determined. WS-AgNPs exhibited the maximum absorbance at 460nm with 46-51 nm size and they inhibited urease enzyme by 82.16 +/- 1.30 %. It was clear that herbal-based wastes could be used in nanotechnology and have the potential to be used in medicine.