da Silva Ferreira Veronica, ConzFerreira Mateus Eugenio, Lima Luís Maurício T R, Frasés Susana, de Souza Wanderley, Sant'Anna Celso
Laboratory of Microscopy Applied to Life Science - Lamav, National Institute of Metrology, Quality and Technology - Inmetro, Duque de Caxias, RJ 25250-020, Brazil; Post-graduation Program on Translational Biomedicine - Biotrans, Duque de Caxias, RJ 25071-202, Brazil.
Laboratory of Pharmaceutical Biotechnology, School of Pharmacy, Federal University of Rio de Janeiro - UFRJ, Rio de Janeiro, RJ 21949-900, Brazil.
Enzyme Microb Technol. 2017 Feb;97:114-121. doi: 10.1016/j.enzmictec.2016.10.018. Epub 2016 Oct 29.
Silver nanoparticles are powerful antimicrobial agents. Here, the synthesis of silver chloride nanoparticles (AgCl-NPs) was consistently evidenced from a commercially valuable microalgae species, Chlorella vulgaris. Incubation of C. vulgaris conditioned medium with AgNO resulted in a medium color change to yellow/brown (with UV-vis absorbance at 415nm), indicative of silver nanoparticle formation. Energy-dispersive X-ray spectroscopy (EDS) of purified nanoparticles confirmed the presence of both silver and chlorine atoms, and X-ray diffraction (XRD) showed the typical pattern of cubic crystalline AgCl-NPs. Transmission electron microscopy (TEM) showed that most particles (65%) were spherical, with average diameter of 9.8±5.7nm. Fourier transform infrared spectroscopy (FTIR) of purified nanoparticle fractions suggested that proteins are the main molecular entities involved in AgCl-NP formation and stabilization. AgCl-NPs (from 10μg/mL) decreased by 98% the growth of Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae bacterial pathogens, and had a dose-dependent effect on cell viability, which was measured by automated image-based high content screening (HCS). Ultrastructural analysis of treated bacteria by TEM revealed the abnormal arrangement of the chromosomal DNA. Our findings strongly indicated that the AgCl-NPs from C. vulgaris conditioned medium is a promising 'green' alternative for biomedical application as antimicrobials.
银纳米颗粒是强大的抗菌剂。在此，从一种具有商业价值的微藻物种——普通小球藻中持续证明了氯化银纳米颗粒（AgCl-NPs）的合成。将普通小球藻条件培养基与硝酸银一起孵育导致培养基颜色变为黄棕色（在415nm处有紫外可见吸收），这表明形成了银纳米颗粒。纯化纳米颗粒的能量色散X射线光谱（EDS）证实了银和氯原子的存在，X射线衍射（XRD）显示出立方晶型AgCl-NPs的典型图谱。透射电子显微镜（TEM）显示大多数颗粒（65%）是球形的，平均直径为9.8±5.7nm。纯化纳米颗粒组分的傅里叶变换红外光谱（FTIR）表明蛋白质是参与AgCl-NP形成和稳定的主要分子实体。AgCl-NPs（从10μg/mL起）使革兰氏阳性金黄色葡萄球菌和革兰氏阴性肺炎克雷伯菌等细菌病原体的生长减少了98%，并且对细胞活力有剂量依赖性影响（通过基于图像的自动高内涵筛选（HCS）测量）。通过TEM对处理过的细菌进行超微结构分析揭示了染色体DNA的异常排列。我们的研究结果有力地表明，来自普通小球藻条件培养基的AgCl-NPs作为抗菌剂在生物医学应用中是一种有前景的“绿色”替代品。
