Plaza D O, Gallardo C, Straub Y D, Bravo D, Pérez-Donoso J M
BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Facultad de Ciencias Biológicas, Universidad Andres Bello, República # 239, Santiago, Chile.
Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Sergio Livingstone Pohlhammer # 1007, Santiago, Chile.
Microb Cell Fact. 2016 May 6;15:76. doi: 10.1186/s12934-016-0477-8.
Fluorescent nanoparticles or quantum dots (QDs) have been intensely studied for basic and applied research due to their unique size-dependent properties. There is an increasing interest in developing ecofriendly methods to synthesize these nanoparticles since they improve biocompatibility and avoid the generation of toxic byproducts. The use of biological systems, particularly prokaryotes, has emerged as a promising alternative. Recent studies indicate that QDs biosynthesis is related to factors such as cellular redox status and antioxidant defenses. Based on this, the mixture of extreme conditions of Antarctica would allow the development of natural QDs producing bacteria.
In this study we isolated and characterized cadmium and tellurite resistant Antarctic bacteria capable of synthesizing CdS and CdTe QDs when exposed to these oxidizing heavy metals. A time dependent change in fluorescence emission color, moving from green to red, was determined on bacterial cells exposed to metals. Biosynthesis was observed in cells grown at different temperatures and high metal concentrations. Electron microscopy analysis of treated cells revealed nanometric electron-dense elements and structures resembling membrane vesicles mostly associated to periplasmic space. Purified biosynthesized QDs displayed broad absorption and emission spectra characteristic of biogenic Cd nanoparticles.
Our work presents a novel and simple biological approach to produce QDs at room temperature by using heavy metal resistant Antarctic bacteria, highlighting the unique properties of these microorganisms as potent natural producers of nano-scale materials and promising candidates for bioremediation purposes.
荧光纳米颗粒或量子点（QDs）因其独特的尺寸依赖性特性而受到基础研究和应用研究的广泛关注。由于它们能提高生物相容性并避免产生有毒副产物，开发生态友好型合成这些纳米颗粒的方法的兴趣与日俱增。利用生物系统，特别是原核生物，已成为一种有前景的替代方法。最近的研究表明，量子点的生物合成与细胞氧化还原状态和抗氧化防御等因素有关。基于此，南极洲的极端条件混合物将有助于开发能产生天然量子点的细菌。
在本研究中，我们分离并鉴定了对镉和亚碲酸盐具有抗性的南极细菌，这些细菌在暴露于这些氧化性重金属时能够合成硫化镉和碲化镉量子点。在暴露于金属的细菌细胞上测定了荧光发射颜色随时间从绿色到红色的变化。在不同温度和高金属浓度下生长的细胞中观察到了生物合成。对处理过的细胞进行电子显微镜分析，发现了纳米级电子致密元素和类似于膜泡的结构，这些结构大多与周质空间相关。纯化的生物合成量子点显示出生物源性镉纳米颗粒特有的宽吸收和发射光谱。
我们的工作提出了一种新颖且简单的生物学方法，即在室温下利用耐重金属的南极细菌生产量子点，突出了这些微生物作为纳米级材料的有效天然生产者以及生物修复目的的有前途候选者的独特特性。
