Chowdhury Neelika Roy, MacGregor-Ramiasa Melanie, Zilm Peter, Majewski Peter, Vasilev Krasimir
School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia.
Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
J Colloid Interface Sci. 2016 Nov 15;482:151-158. doi: 10.1016/j.jcis.2016.08.003. Epub 2016 Aug 2.
Silver nanoparticles (AgNPs) have emerged as a powerful weapon against antibiotic resistant microorganisms. However, most conventional AgNPs syntheses require the use of hazardous chemicals and generate toxic organic waste. Hence, in recent year's, plant derived and biomolecule based synthetics have has gained much attention. Cacao has been used for years for its medicinal benefits and contains a powerful reducing agent - oxalic acid. We hypothesized that, due to the presence of oxalic acid, cacao extract is capable of reducing silver nitrate (AgNO3) to produce AgNPs.
In this study, AgNPs were synthesized by using natural cacao extract as a reducing and stabilizing agent. The reaction temperature, time and reactant molarity were varied to optimize the synthesis yield.
UV-visible spectroscopy (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization demonstrated that the synthesized AgNPs were spherical particles ranging in size from 35 to 42.5nm. The synthesized AgNPs showed significant antibacterial activity against clinically relevant pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis. Importantly, these green AgNPs are not cytotoxic to human dermal fibroblasts (HDFs) at concentrations below 32μg/ml. We conclude that cacao-based synthesis is a reproducible and sustainable method for the generation of stable antimicrobial silver nanoparticles with low cytotoxicity to human cells. The AgNPs synthesized in this work have promising properties for applications in the biomedical field.
银纳米颗粒（AgNPs）已成为对抗抗生素耐药微生物的有力武器。然而，大多数传统的银纳米颗粒合成方法需要使用有害化学物质并产生有毒有机废物。因此，近年来，基于植物和生物分子的合成方法备受关注。可可多年来因其药用价值而被使用，并且含有一种强大的还原剂——草酸。我们假设，由于草酸的存在，可可提取物能够将硝酸银（AgNO₃）还原以产生银纳米颗粒。
在本研究中，使用天然可可提取物作为还原剂和稳定剂来合成银纳米颗粒。改变反应温度、时间和反应物摩尔浓度以优化合成产率。
紫外可见光谱（UV-vis）、动态光散射（DLS）和透射电子显微镜（TEM）表征表明，合成的银纳米颗粒是尺寸在35至42.5纳米范围内的球形颗粒。合成的银纳米颗粒对临床相关病原体如大肠杆菌、铜绿假单胞菌、金黄色葡萄球菌和表皮葡萄球菌表现出显著的抗菌活性。重要的是，这些绿色银纳米颗粒在浓度低于32μg/ml时对人皮肤成纤维细胞（HDFs）无细胞毒性。我们得出结论，基于可可的合成是一种可重复且可持续的方法，用于生成对人类细胞具有低细胞毒性的稳定抗菌银纳米颗粒。在这项工作中合成的银纳米颗粒在生物医学领域的应用具有广阔前景。
