Green synthesis of silver nanoparticles using aqueous extract of the leaves of fine aroma cocoa Theobroma cacao linneu (Malvaceae): Optimization by electrochemical techniques

Abstract

In this study, green synthesis of silver nanoparticles using aqueous extract of the leaves of fine aroma cocoa Theobroma cacao linneu (Malvaceae) were optimized by electrochemical techniques. Electrochemical analyzes were carried out by cyclic voltammetry and differential pulse voltammetry. The antioxidant index (AI50) of the optimized extract with and without nanoparticles was 0.74 ± 0.01 ppm and 0.65 ± 0.05 ppm, respectively; while the electrochemical index (EI) was 0.713± 0.03 mA/V and 1.137 ± 0.06 mA/V, respectively. Results of the electrochemical analyzes trend were consistent with that found for spectrophotometric analyzes using 1,1-diphenyl-2-picrylhydrazyl radical and Folin Ciocalteu methods. The most optimal nanoparticles were obtained with the aqueous extract with the highest antioxidant capacity. The mean size of the obtained nanoparticles was 10.3 ± 1.7 nm as characterized by Transmission Electron Microscopy, X-ray diffraction, UV–Vis Spectroscopy and Cyclic Voltammetry. It is concluded that the electrochemical techniques were effective in the process of optimizing the green synthesis and characterization of the Ag nanoparticles using aqueous extract of the leaves of fine aroma cocoa, Theobroma cacao linneu (Malvaceae).