Core-shell nanoparticles are preferable due to their new and/or improved properties over monometallic nanoparticles. Shell metals are present as a film on the surface of a core metal, which leads to an increase in reactivity of the surface. The synthesis of core-shell nanoparticles using biomolecules is an important strategy to get more activity with less toxicity. The present work was intended to prepare bimetallic nanoparticle preparation by green synthetic method. Aqueous extract of Muntingia calabura flowers was used for the preparation of metal core-shell nanoparticles where flower extract acted as both reducing agent and stabilizing agent. Monometallic gold nanoparticles (AuNPs) and silver nanoparticles (AgNP) were prepared using metal precursors chloroauric acid (HAuCl₄) and silver nitrate (AgNO₃), respectively. For the preparation of bimetallic core-shell nanoparticles, a shell metal precursor (copper acetate) was added. The obtained nanoparticles were characterized by various instrumental methods including UV–Vis spectrophotometry, TEM and SEM techniques, and EDX spectral analysis. Preliminary antibacterial screening of Au@Cu NP and Ag@Cu NP was performed by disk diffusion assay. TEM and SEM images showed that Au@Cu NPs were spherical whereas Ag@Cu NPs had irregular shapes. The EDX analysis revealed that more Cu was deposited in AuCuNPs than in AgCuNPs. The antibacterial activity assay proved that spherical AuCuNPs were more potent than irregular shaped AgCuNPs.

优选核-壳纳米颗粒，因为它们比单金属纳米颗粒具有新的和/或改进的性能。壳金属以膜的形式存在于芯金属的表面上，这导致表面反应性的提高。利用生物分子合成核-壳纳米粒子是获得更多活性，更少毒性的重要策略。本工作旨在通过绿色合成方法制备双金属纳米颗粒制剂。将Muntingia calabura花的水提取物用于制备金属核-壳纳米粒子，其中花提取物既是还原剂又是稳定剂。使用金属前体氯金酸（HAuCl ₄）制备单金属金纳米颗粒（AuNPs）和银纳米颗粒（AgNP））和硝酸银（AgNO ₃）。为了制备双金属核-壳纳米颗粒，添加了壳金属前体（乙酸铜）。所获得的纳米颗粒通过多种仪器方法进行了表征，包括UV-Vis分光光度法，TEM和SEM技术以及EDX光谱分析。通过圆盘扩散法对Au @ Cu NP和Ag @ Cu NP进行了初步的抗菌筛选。TEM和SEM图像显示Au @ Cu NP为球形，而Ag @ Cu NP为不规则形状。EDX分析表明，与AuCuNP相比，AuCuNP中沉积的Cu更多。抗菌活性测定证明球形AuCuNPs比不规则形状的AgCuNPs更有效。