Wirwis Anna, Sadowski Zygmunt
Department of Process Engineering and Technology of Polymer and Carbon Materials, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wrocław, Poland.
ACS Omega. 2023 Aug 10;8(33):30532-30549. doi: 10.1021/acsomega.3c03775. eCollection 2023 Aug 22.
In this paper, we present the optimization of green tea leaf ( L.) extraction, carried out using water and hydroalcoholic solvents, for the subsequent synthesis of silver nanoparticles (AgNPs). The value ranges for independent variables, including pH, time, and temperature, were selected based on single-factor experiments and used for extraction in the order presented by the Box-Behnken design. Three-dimensional response surface graphs were used to visually present the optimization results and determine the optimal extraction conditions: pH = 7, 30 min, 80 °C for water and pH = 5.5, 50 min, and 80 °C for water-ethanol. Our findings indicate that the water-ethanol mixture extracted more polyphenols. We compared the physicochemical properties of AgNPs obtained using both types of extractants via DLS and TEM analysis. We proposed a predicted mechanism for the reduction and stabilization of AgNPs based on the Fourier transform infrared data. The hydroethanolic extract leads to significant nanoparticle aggregation, which can be explained by the nucleation theory and agglomeration of nanoparticles in the presence of excess macromolecular organic substances (flocculation).
在本文中，我们展示了使用水和水醇混合溶剂对绿茶（L.）提取物进行优化，用于后续银纳米颗粒（AgNPs）的合成。基于单因素实验选择了包括pH值、时间和温度在内的自变量取值范围，并按照Box-Behnken设计给出的顺序用于提取。使用三维响应面图直观呈现优化结果并确定最佳提取条件：水提取时pH = 7、30分钟、80°C，水 - 乙醇提取时pH = 5.5、50分钟、80°C。我们的研究结果表明，水 - 乙醇混合物提取出了更多的多酚。我们通过动态光散射（DLS）和透射电子显微镜（TEM）分析比较了使用两种类型提取剂获得的AgNPs的物理化学性质。基于傅里叶变换红外数据，我们提出了一种AgNPs还原和稳定化的预测机制。水醇提取物导致显著的纳米颗粒聚集，这可以通过成核理论以及在存在过量大分子有机物质（絮凝）的情况下纳米颗粒的团聚来解释。
