# Synthesis of Silver Nanoparticles by Using Quercus Robur Knopper Gall Extracts

## TL;DR

This study shows how to make silver nanoparticles using extracts from Knopper galls, which can inhibit bacterial growth and offer an eco-friendly alternative.

## Contribution

The paper introduces a novel green synthesis method using Quercus robur Knopper gall extracts for producing biologically active silver nanoparticles.

## Key findings

- AgNPs synthesized using Knopper gall extracts showed a surface plasmon resonance peak at 418 nm.
- The nanoparticles had a face-centered cubic structure with an average size of 12 nm.
- The AgNPs exhibited strong antibacterial activity against B. subtilis and S. aureus.

## Abstract

Galls of the Cynipidae, such as the Knopper gall, are abnormal plant outgrowths induced by insect activity. These structures not only protect the developing larvae but also alter the biochemical properties of host plant tissues. In this study, we report the green synthesis of silver nanoparticles (AgNPs) using ethanolic extracts of Quercus robur Knopper galls. AgNPs were synthesized via reduction of AgNO3 and characterized using ATR-FTIR analysis, UV-Vis spectrophotometry, powder X-ray diffraction (PXRD), and transmission electron microscopy (TEM). The UV-Vis analysis showed a strong surface plasmon resonance (SPR) peak at 418 nm. A face-centered cubic (fcc) crystalline structure with an average crystallite size of about 12 nm was verified by PXRD patterns. TEM imaging revealed well-dispersed spherical nanoparticles, consistent with the size obtained via PXRD. ATR-FTIR analysis indicated the involvement of polyphenolic and protein-related functional groups in reduction and stabilization. The synthesized AgNPs exhibited strong growth inhibition capacity against B. subtilis and S. aureus, and moderate capacity against E. coli and P. aeruginosa. These findings highlight the potential of Knopper gall extract as a sustainable source for the eco-friendly synthesis of biologically active nanoparticles.