Green synthesis and characterization of silver nanoparticles using Prunus persica L. (peach pomace) with natural deep eutectic solvent and plasma-liquid process
This study reports two different innovation "green" protocols for the extraction of fruit waste (peach pomace (PP) and subsequent synthesis of silver nanoparticles that were used. In one case, extraction of PP was performed using natural ionic solvent (lactic acid, glucose, and water (5:1:3 molar ratio) with the following chemical synthesis of the AgNPs in the second step. In the second case, a one-step extraction/synthesis of silver nanoparticles under a short-term (5–10 min) plasma-liquid atmospheric discharge process was used. Various techniques used to characterize synthesized nanoparticles are SAED, SEM, TEM, and UV–visible spectrophotometer. It was found that for both methods, the hydromodule (ratio of raw materials to solvent) is one of the main factors that determines the absorption spectra and particle size of the synthesized AgNPs. The simultaneously plasma chemical-assisted extraction and synthesis NPs protocol with hydromodule ~ [1]:[10] ÷ [1]:[60] provides the formation surface plasmon resonance (SPR) of absorption spectra at 420–430 nm with average size of NPs 15–27 nm for 1 min of processing; λmax = 550–570 nm, λmax = 670 nm with average size of NPs 100–150 nm. NADES-assisted extraction and synthesis NPs with hydromodule ~ [1]:[20] ÷ [1]:[45] provides SPR at 405–430 nm with average size of NPs 10–20 nm. It was established that plasma-assisted extraction provides a greater degree of extraction total phenolic content (TPC) compared to NADES extraction. As a consequence, it provides correspondingly higher indicators of antioxidant activity of plasma-synthesized silver nanoparticles (IC50 of 0.81–1.33 mg/mL, DPPH at 2.5 mg/mL was: 73–88% for AgNPs). In return NADES extraction provides higher antimicrobial and catalytic activity of the AgNPs because they are depended by the average size of nanoparticles, which are much smaller in the synthesis of this method. The AgNPs showed antimicrobial activity against pathogenic Escherichia coli, Staphylococcus aureus, and Candida albicans antimicrobial activity in low concentrations (23–36 nM).