Rosa damascena waste mediated synthesis of silver nanoparticles: Characteristics and application for an electrochemical sensing of hydrogen peroxide and vanillin

Abstract

Silver nanoparticles (AgNPs) were synthesized by reduction of Ag+ with four extracts of Rosa damascena waste: post-distillation water (PW), water extract (WE), 30% (30 EE) and 70% (70 EE) ethanol extracts. The ethanolic extracts were rich in polyphenols and particularly catechin and epicatechin (1388.01 ± 2.27 and 677.47 ± 2.03 μgmL−1, respectively) while the water extracts were rich in reducing sugars, proteins and pectic substances (for WE 254.21 ± 1.26, 296.89 ± 2.01 and 242.14 ± 1.38 μgmL−1, and for PW 185.72 ± 1.47, 298.30 ± 1.57 and 181.78 ± 1.39 μgmL−1, respectively). The morphology of AgNPs was characterized by transmission electron microscopy and the calculated average size of the AgNPs synthesized using WE and PW was 25.8 ± 11.5 nm and 11.5 ± 8.4 nm, respectively. The X-ray diffraction analysis suggested presence of silver phase which crystallized in a face centered cubic space group Fm-3m with unit cell parameter 4.085 (2) Å and mean coherent domain size 10.9 (3)nm. Biosynthesized AgNPs were deposited onto a spectroscopic graphite electrode (GE), applying two different procedures, and stabilized using chitosan to build modified electrodes-catalysts. The electrochemical performances of the modified electrodes AgNPs/GE and AgNPs/CS/GE were studied by means of cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry at pH 7.0 and their applicability for amperometric detection of H2O2 and vanillin was investigated. The developed electrodes exhibited a sensitive and reproducible response for quantitative determination of H2O2 at applied potentials of −0.2, −0.25 and −0.3 V (vs. Ag/AgCl, 3 M KCl). Constant potential amperometry studies with AgNPs/CS/GE showed sensitive response to H2O2 (115.2 μA mM−1 cm−2) up to 6.6 mM at −0.3 V, and to vanillin (56.8 μA μM−1 cm−2) up to 0.5 mM with detection limit of 8.4 μM at 0.58 V. The results obtained from the quantitative electrochemical measurements of H2O2 and vanillin offer potential applications of the graphite electrodes modified with the biosynthesized AgNPs in electrochemical sensor devices for monitoring of these analytes.