Biomolecules in grape leaf extract involved in one-step synthesis of iron-based nanoparticles

Abstract

Biomolecules in plant extracts are often used to reduce metal ions to nanoparticles in a single-step green synthesis process that is environment friendly and sustainable. However, our understanding of biomolecules as reducing and capping agents in plant extracts involved in green synthesis of metal nanoparticles is limited. In this paper, grape leaves which are the major waste generated in winemaking in Australia are utilized. Their components have an important environmental impact on waste reduction. Furthermore they permit the production of added value products such as iron-based nanoparticles (Fe NPs). To understand biomolecules involved in the synthesis of Fe NPs, the reactivity of Fe NPs synthesized using methanolic extract of grape leaves (∼80.0%) was much higher than that of water extraction (∼4.0%), where a high concentration of biomolecules in methanolic extract of grape leaves was monitored by UV-vis. Gas chromatography-mass spectrometry (GC-MS) analysis of before and after methanol extraction to synthesize Fe NPs shows that the main biomolecules included phytols, terpenoids (α, and β amyrins, β and δ sitosterols), and antioxidants (δ-stan-3,5-diene, vitamin E) as reducing and capping agents. The potential biomolecules that can reduce Fe precursors were confirmed by Fourier Transform Infrared Spectroscopy (FTIR). Well-dispersed and capped Fe NPs with an average size of 60 nm were observed by scanning electron microscopy (SEM), while the amorphous crystalline structure of Fe NPs was identified by X-ray diffraction (XRD). Finally, approximately 80.0% of acid Orange II was removed using Fe NPs, while only 2.0% of acid Orange II was removed by the extract, indicating the high reactivity of Fe NPs synthesized by the methanolic extract of grape leaves. And such grape leaf extracts make Fe NPs a potential low cost and environmentally friendly remediation technique.