Phytosynthesis, Kinetics and Antioxidant Activity of Waltham Butternut Squash Aqueous Extracts and Metallic Nanoparticles Thereof

摘要

Phytosynthesis can certainly be considered next generation's technology that enables the development of novel nanoparticles and nanomaterials with various applications in multidisciplinary scientific areas. Squash (Cucurbita maxima) is a fruit rich in beta-carotene, calcium, potassium and has numerous health benefits. This paper describes recent researches in the field of metallic nanoparticles, namely silver and gold, prepared via phytosynthesis from aqueous extracts of Waltham butternut squash. Silver and gold nanoparticles can be prepared using conventional routes that have numerous drawbacks. Phytosynthesis has multiple advantages: is cost effective, environmentally - friendly, doesn't require high pressure and no hazardous chemicals are used. Aqueous extracts were prepared from different parts of Waltham butternut squash (e.g.: shell, core and seeds) and their phytochemical content was evaluated using standard qualitative and quantitative analyses. The metallic nanoparticles were phytosynthesized from the aqueous extracts and corresponding metallic salts using two different conditions: room temperature, no stirring, overnight and 50°C, under continuous stirring for 30 minutes. The phytosynthesized metallic nanoparticles were characterized by recording UV-Vis spectra at different time intervals in order to determine their stability in time. The characteristic absorptions maxima were recorded at 435 - 450 nm for silver nanoparticles and at 535 - 550 nm for gold nanoparticles. The antioxidant activity was recorded using DPPH (2,2 - diphenyl - 1 - picryl - hydrazyl - hydrate) assay and the calculated values were clearly higher for the phytosynthesized metallic nanoparticles compared to the aqueous extracts.