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

Highlights: • Extracts of Rosa damascena waste were used for green synthesis of Ag nanoparticles. • Nanoparticles were applied for assembling of sensors for H₂O₂ and vanillin detection. • The effect of extractant and extracts on performance of sensors was evaluated. • The influence of the extracted substances on nanoparticles synthesis was investigated. • The TEM and X-ray diffraction analyses confirmed the silver nanoparticle synthesis. -- 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.