作者非常感谢化学系和研究生院在密苏里州立大学的鼎力支持这个项目。我们也承认在弗雷德里克国家癌症研究实验室的电子显微镜实验室使用其透射电子显微镜和碳包覆电网。

1.磷化铟/硫化锌（磷化铟/硫化锌）量子点的合成<ol><li> 磷化铟（InP）量子点核心的合成 <ol><li>适合的100ml圆底三颈烧瓶中在12英寸的冷凝器。加30毫升油胺（OLA），0.398克铟（III），氯化（包括3），0.245克锌（II）氯化物（ 氯化锌 ）并搅拌，同时用真空1小时在室温下抽空。该溶液应出现无色白色沉淀。 </li><li>用加热罩有热电偶和比例 - 积分 - 微分（PID）温度控制器，增加溶液的温度升高到120℃。抽空真空下将溶液进行20分钟，以除去可能影响核心增长低沸点的杂质。 注意:虽然可以使用沙浴和温度计，用加热罩和PID增加反应产物的均匀性和再现性。 </li><li>在惰性气体下（例如N 2），回流溶液，提高温度至220℃15分钟。的INCL 3和 氯化锌完全溶解，得到浅黄色溶液。使温度稳定10分钟。 </li><li>清除一次性，将3ml塑料注射器和4英寸，22克针氮气。使用注射器，快速交付0.5毫升三（二甲氨基）膦（TDMAP）将包括3溶液 。溶液温度略有下降，并返回到220℃。从透明的解决方案的变化，淡黄色至不透明，黑色。 </li><li> 9.5分钟后，从加热套除去反应烧瓶，直到温度降低到低于200℃。为了保护在InP核心的完整性，在步骤1.2.1直接进入硫化锌涂层。 </li></ol></li><li> 硫化锌（硫化锌）量子点壳的合成 <ol><li>放置在加热罩步骤1.1.5反应瓶中，稳定的Temperature在200℃。慢慢地在15秒的过程中添加3.58克十二硫醇（DDT）含有磷化铟量子点的解决方案。使该溶液1小时反应。 注意:硫化锌壳厚度可通过增加或减少在步骤1.2.4添加的硬脂酸锌的量而变化。改变在步骤1.1.1和1.2.1的ZnCl 2的量或十二硫醇可以通过改变反应动力学显著影响量子点的质量。 <ol><li>之后，取出从加热套的反应烧瓶中，并使溶液冷却至约60℃。 </li></ol></li><li>一旦在InP /硫化锌溶液达到〜60℃，加入10 mL己烷和的大约45毫升整个溶液转移至50ml聚丙烯离心管中。离心样品（3,000×g离心10分钟）以除去未反应的固体前体。 </li><li>小心将上清转移到250毫升聚丙烯离心瓶中，加入200毫升丙酮，并离心溶液（3,000×克10分钟），沉淀的InP / ZnS量子点。这个体积也可以被均匀地分为四个50ml试管离心如果必要的转子/附件离心机不可用。倒出上清液并以氮气彻底干燥QD沉淀以除去丙酮。 </li><li>重悬采用超声在20毫升OLA的量子点，转移到50毫升圆底三颈瓶中含有0.474克硬脂酸锌，搅拌。疏散在室温20分钟在真空下该溶液中。 </li><li>在氮气下，将温度升至180℃，并允许反应进行3小时。虽然没有显着的视觉变化在该反应过程中发生的反应溶液，加入硬脂酸锌增加的ZnS壳的厚度，从而通过改善量子点12的表面钝化增加QY。一旦反应完成后，从加热套除去烧瓶并允许该溶液冷却至约60℃。 </li><li>一旦磷化铟/硫化锌soluti上达到〜60℃，添加20毫升己烷和转移至50ml聚丙烯离心管中。离心样品（3,000×g离心10分钟），以除去未反应的硬脂酸锌。 </li><li>小心将上清转移到250毫升聚丙烯离心瓶中，加入200毫升丙酮，并离心溶液（3,000×g离心10分钟）以沉淀的InP / ZnS量子点。小心倒出上清液并以氮气彻底干燥以除去丙酮。 </li><li>溶解在30毫升正己烷在InP / QD硫化锌颗粒。涡旋和超声处理的溶液简短地，以确保完全分散。 </li><li>重复纯化步骤1.2.6-1.2.8两次以确保彻底除去过量的有机配体的。两亲聚合物，并且在步骤1.2量子点之间的相互作用可以在过量的配位体的存在下受到损害。 </li><li>随着等 [16]谢详细的计算，确定使用紫外-可见光谱法合成的InP / ZnS量子点的大小和浓度。 <br/&gt;注:此分析的重要光谱特性是吸收峰的肩膀。最大本肩的波长与吸光度值用于分别计算的大小和量子点的浓度。该反应通常产生大约5微摩尔量子点的带在600nm的发射峰。以合成的不同颜色的量子点，反应的持续时间和/或温度可以被改变。较长的反应时间和/或该溶液的结果红移发射峰较高的温度。例如，10分钟提高反应温度到240℃，并维持反应时间将导致具有680纳米的最大发射峰量子点。同样地，减少的反应时间为2分钟，并加倍使用将导致在具有470nm的最大发射峰量子点氯化锌。这些的InP / ZnS量子点可稳定至少一个月，在4℃下在惰性气体下的黑暗。 </li></ol></li></ol> 2.水使用的两亲聚合物的InP /硫化锌量子点的增溶<ol><li> 水增溶 <ol><li>从步骤1.2.10使用的InP / ZnS量子点，淡化量子点的一部分用己烷，得到1毫升1μM的量子点。 <ol><li>在离心管中，转移0.25毫升的InP / ZnS量子点到每个管中。加入1毫升丙酮或甲醇至离心管中并离心分离（3000×g离心10分钟）。小心取出上清，在1毫升四氢呋喃（THF）溶解沉淀的每个。 </li><li>转移溶解在THF中的InP / ZnS量子点的100毫升圆底烧瓶中，并以16毫升THF稀释。为了减少溶液中的聚集体的数量，超声处理的量子点5-10分钟。 </li></ol></li><li>在10ml分子级水溶解30毫克聚（马来andhydride- 中高音 -1-十八碳烯），3-（二甲基氨基）-1-丙胺（PMAL-d）中。水浴超声处理或温和搅拌直至溶液是半透明的足以完全溶解聚合物。该使用涡或剧烈搅拌可产生许多气泡，阻碍与QD聚合物的相互作用。 10毫升聚合物溶液加入100毫升圆底含有的InP / ZnS量子点在THF圆底烧瓶中。 </li><li>从使用旋转蒸发器对QD /聚合物溶液蒸发THF中。放置烧瓶在冰浴中，同时蒸发，以促进聚合物和QD之间的相互作用。根据真空的强度，最THF中的10分钟后蒸发，溶液出现混浊。 <ol><li>一旦溶液被蒸发至10ml，从旋转蒸发器除去该烧瓶，并添加30毫升分子级的水。烧瓶返回到旋转蒸发器，并继续蒸发至2ml。这最后蒸发步骤可能需要许多小时;确保冰浴被保持。 </li></ol></li><li>从用吸管圆底烧瓶中除去水溶性的InP / ZnS量子点。使用连接到0.1微米尼龙SY 3毫升的塑料注射器过滤QD溶液RINGE过滤到5ml的离心管中。 </li><li>将量子点到20000 MWCO膜透析机和透析反对的0.05M硼酸盐缓冲液pH 8.5，去除多余的聚合物。 （缓慢加入0.05M的四硼酸钠十水合物，以0.05M的硼酸，在剧烈搅拌下，直到pH为8.5，使这个硼酸盐缓冲溶液。）用真空浓缩，浓缩物中的硼酸盐缓冲的量子点到1ml。 </li><li>用于存储，用Parafilm密封前吹扫用氮气将溶液。水溶性的InP / ZnS量子点是稳定的，在4℃下在黑暗中在至少4个月。 </li></ol></li></ol>

<ol>
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作者什么都没有透露。

该协议细节，可以在许多生物体系中使用高度荧光的InP / ZnS量子点的合成。此处所合成的量子点的产品表现出在600nm与FWHM为73nm（图1），这与其他先前描述合成12为中心的单个荧光发射峰。反应时间和反应温度是由于对QD合成质量和可重复性其深远的影响非常重要的步骤。在水中溶解后，量子点都确定为具有约6％的量子产率。反应时间，温度，或前体浓度的变化允许QD的尺寸和...

A correction was made to: <a href="http://www.jove.com/video/53684/synthesis-cd-free-inpzns-quantum-dots-suitable-for-biomedical" target="_blank">Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications</a>. There was an error with an author's given name. The author's name was corrected to:
Katye M. Fichter
from:
Kathryn M. Fichter

A correction was made to: <a href="http://www.jove.com/video/53684/synthesis-cd-free-inpzns-quantum-dots-suitable-for-biomedical" target="_blank">Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications</a>.

Erratum: Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

量子点（QDs）是 ​​半导体时与光1照射表现出荧光性质的纳米晶体。由于它们的小尺寸（2-5纳米），其类似于许多较大的生物分子，和易于biofunctionalization的，量子点是用于生物医学应用的非常有吸引力的工具。他们已经发现在生物标记的使用，单分子的活细胞成像，药物递送， 体内成像 ，病原体检测，和细胞的跟踪，许多其他用途2-8之间。 基于CD的量子点已经在生物医学领域最常用的，因为他们强烈的荧光，窄的发射峰宽9。然而，关注已经提出，由于镉的潜在毒性2+离子 10可通过纳米颗粒的降解被释放。近年来，基于InP基量子点已探索作为一种替代基于镉量子点，因为他们认为许多荧光特性的镉量子点的基础和可能更生物相容性11。基于CD的量子点已被发现比在浓度低至10 分在体外试验基于InP基量子点更毒显著，只有48小时11后。 量子点的荧光发射颜色是尺寸可调的1。也就是说，随着量子点尺寸的增加，荧光发射是红移。量子点的产品的大小和尺寸分散度可以通过在反应12期间改变温度，反应持续时间，或前体浓度的条件进行修改。虽然磷化铟量子点的发射峰通常是更广泛，比基于镉量子点不太激烈，磷化铟量子点可以在种类繁多的设计，以避免光谱重叠的颜色进行，并且是大多数生物医学应用12足够强。在本协议中详述的合成产生与600纳米为中心的红色发射峰量子点。 几个步骤采取自动对焦在QD核之三合成，保持量子点的光学完整性，使其成为生物应用程序兼容。 QD核的表面必须防止可能导致淬火氧化或表面缺陷;因此，一的ZnS壳涂覆在核心产生的InP /硫化锌（核/壳）量子点13。这种涂层已显示保护QD产物的光致发光。锌离子中的InP量子点的合成的存在已经显示出，以限制表面缺陷，以及减少尺寸分布12。甚至用Zn 2+在反应介质存在下，InZnP的合成是非常不可能12。涂布后，所得的InP / ZnS量子点被涂覆在疏水性配体诸如三辛基氧化膦（TOPO）或油胺12,14。两亲聚合物可以与量子点表面上的疏水性配位体以及本体水分子相互作用以赋予水溶性15。与鸬鹚两亲聚合物xylate化学基团可以被用作"化学柄"，进一步官能化的量子点。 该协议细节的合成和水溶性的InP / ZnS量子点的官能具有非常强烈的荧光发射和相对小的尺寸的分散性。这些量子点都可能比常用的CdSe / ZnS量子点毒性较低。在这里，磷化铟/ ZnS量子点的合成提供了基于光盘的量子点生物医学领域的实用替代。

<table><tbody><tr><td>Oleylamine</td><td>Acros</td><td>129540010</td><td></td></tr><tr><td>Zinc(II) chloride</td><td>Sigma</td><td>030-003-00-2</td><td></td></tr><tr><td>Indium(III) chloride</td><td>Chem-Impex</td><td>24560</td><td></td></tr><tr><td>Tris(dimethylamino)phosphine</td><td>Encompass</td><td>50-901-10500</td><td></td></tr><tr><td>1-dodecanethiol</td><td>Acros</td><td>117625000</td><td></td></tr><tr><td>Hexanes</td><td>Fisher Sci</td><td>H292-4</td><td></td></tr><tr><td>Acetone</td><td>TransChemical</td><td>UN 1090</td><td></td></tr><tr><td>Zinc Stearate</td><td>Aldrich Chem</td><td>307564-1KG</td><td></td></tr><tr><td>Tetrahydrofuran</td><td>Acros</td><td>34845-0010</td><td></td></tr><tr><td>Molecular Water</td><td>Fisher Sci</td><td>BP2470-1</td><td></td></tr><tr><td>Poly(maleic anhyrdride-&lt;em&gt;alt&lt;/em&gt;-1-tetradecene), 3-(dimethylamino)-1-propylamine derivative</td><td>Sigma</td><td>90771-1G</td><td></td></tr><tr><td>Boric acid</td><td>Fisher Sci</td><td>BP168-500</td><td></td></tr><tr><td>Sodium Tetraborate Decahydrate</td><td>Fisher Sci</td><td>BP175-500</td><td></td></tr><tr><td>Rhodamine B</td><td>Aldrich Chem</td><td>R95-3</td><td></td></tr><tr><td>Nitrogen gas</td><td>Airgas</td><td>UN1066</td><td></td></tr><tr><td>Trypan blue</td><td>Thermo Sci</td><td>SV30084.01</td><td></td></tr><tr><td>3 ml plastic Luer-lock syringe</td><td>BD</td><td>309657</td><td></td></tr><tr><td>Luer-lock Needle</td><td>Air-Tite</td><td>8300014471</td><td>4 inch, 22 gauge</td></tr><tr><td>50 ml polypropyene centrifuge tube</td><td>Falcon</td><td>352098</td><td></td></tr><tr><td>250 ml centrifuge bottle</td><td>Thermo Sci</td><td>05-562-23</td><td>Nalgene PPCO</td></tr><tr><td>5 ml centrifuge tubes</td><td>Argos-Tech</td><td>T2076</td><td></td></tr><tr><td>1.5 ml microcentrifuge tubes</td><td>Bio Plas</td><td>4150</td><td></td></tr><tr><td>0.1 &amp;mu;m Syringe filter</td><td>Whatman</td><td>6786-1301</td><td>Puradisc 13 mm nylon filter</td></tr><tr><td>Slide-A-Lyzer MINI Dialysis Unit</td><td>Thermo Sci</td><td>69590</td><td>20,000 MWCO</td></tr><tr><td>Rotary Evaporator</td><td>Heidolph</td><td></td><td></td></tr><tr><td>Centrifuge 5072</td><td>Eppendorf</td><td></td><td>Swinging Bucket with 50&amp;nbsp;ml tube adapters</td></tr><tr><td>Lambda 650 UV/VIS Spectrometer</td><td>Perkin Elmer</td><td></td><td>UV-Vis Spectrophotometer</td></tr><tr><td>LS 55 Fluorescence Spectrometer</td><td>Perkin Elmer</td><td></td><td>Fluorometer</td></tr><tr><td>Axio Observer.A1</td><td>Zeiss</td><td></td><td>epifluorescence microscope</td></tr><tr><td>AxioCam MRm</td><td>Zeiss</td><td></td><td>CCD Camera</td></tr><tr><td>Tecnai TF20 Microscope</td><td>FEI</td><td></td><td>Transmisison Electron Miscroscope</td></tr><tr><td>TEM Eagle CCD</td><td>FEI</td><td></td><td>TEM CCD Camera</td></tr><tr><td>NanoBrook Omni DLS</td><td>Brookhaven</td><td></td><td>Dynamic Light Scattering Instrument</td></tr></tbody></table>

synthesis of cd-free inp/zns quantum dots suitable for biomedical applications

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, quantum dots should be highly fluorescent and small/monodisperse in size. While commonly used cadmium-based quantum dots possess these qualities, they are potentially toxic due to the possible release of Cd2+ ions through nanoparticle degradation. Indium-based quantum dots, specifically InP/ZnS, have recently been explored as a viable alternative to cadmium-based quantum dots due to their relatively similar fluorescence characteristics and size. The synthesis presented here uses standard hot-injection techniques for effective nanoparticle growth; however, nanoparticle properties such as size, emission wavelength, and emission intensity can drastically change due to small changes in the reaction conditions. Therefore, reaction conditions such temperature, reaction duration, and precursor concentration should be maintained precisely to yield reproducible products. Because quantum dots are not inherently soluble in aqueous solutions, they must also undergo surface modification to impart solubility in water. In this protocol, an amphiphilic polymer is used to interact with both hydrophobic ligands on the quantum dot surface and bulk solvent water molecules. Here, a detailed protocol is provided for the synthesis of highly fluorescent InP/ZnS quantum dots that are suitable for use in biomedical applications.

未涂层的InP核心不要被眼睛表现出实质性的可见荧光。然而，磷化铟/硫化锌（核/壳）量子点似乎是由眼睛的紫外线照射下明亮荧光。使用荧光光谱的InP / ZnS量子点的荧光的特点。量子点的在己烷中的荧光光谱在533激发（图1）处展示在600nm与半最大值（FWHM）的73纳米的全宽为中心的一个主要的峰。 而在图1的偏移吸光度（0.2）可能意味...

Watch this Scientific Journal Video about Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications at JoVE.com

Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

In this protocol, the synthesis of Cd-free InP/ZnS quantum dots (QDs) is detailed. InP-based QDs are gaining popularity due to the toxicity of Cd2+ ions that may be released through nanoparticle degradation. After synthesis, QDs are solubilized in water using an amphiphilic polymer for use in biomedical applications.

镉免费的InP /硫化锌量子点的合成适合生物医学应用

Fluorescent nanocrystals, specifically quantum dots, have been a useful tool for many biomedical applications. For successful use in biological systems, ...

synthesis-cd-free-inpzns-quantum-dots-suitable-for-biomedical

Research

JoVE Journal

Chemistry

13.6K 次观看.  Missouri State University. In this protocol, the synthesis of Cd-free InP/ZnS quantum dots (QDs) is detailed. InP-based QDs are gaining popularity due to the toxicity of Cd2+ ions that may be released through nanoparticle degradation. After synthesis, QDs are solubilized in water using an amphiphilic polymer for use in biomedical applications.

视频: Synthesis of Cd-free InP/ZnS Quantum Dots Suitable for Biomedical Applications

Compact Quantum Dots for Single-molecule Imaging

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study.
Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7.
Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm).

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

紧凑型量子点的单分子成像

Single-molecule imaging is an important tool for  understanding the mechanisms of biomolecular function and for visualizing the  spatial and temporal ...

科研

工程学

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

硒化镉/硫化镉棒和纳米四脚合成种子

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

化学

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

合成，表征和混合金/硫化镉和Au / ZnS核/壳纳米颗粒功能化

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Solubilization and Bio-conjugation of Quantum Dots and Bacterial Toxicity Assays by Growth Curve and Plate Count

Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. QDs have attracted a lot of interest for imaging, diagnostics, and therapy due to their bright, stable fluorescence1,2 3,4,5. QDs can be conjugated to a variety of bio-active molecules for binding to bacteria and mammalian cells6.
QDs are also being widely investigated as cytotoxic agents for targeted killing of bacteria. The emergence of multiply-resistant bacterial strains is rapidly becoming a public health crisis, particularly in the case of Gram negative pathogens 7. Because of the well-known antimicrobial effect of certain nanomaterials, especially Ag, there are hundreds of studies examining the toxicity of nanoparticles to bacteria 8. Bacterial studies have been performed with other types of semiconductor nanoparticles as well, especially TiO2 9,10-11, but also ZnO12 and others including CuO 13. Some comparisons of bacterial strains have been performed in these studies, usually comparing a Gram negative strain with a Gram positive. With all of these particles, mechanisms of toxicity are attributed to oxidation: either the photogeneration of reactive oxygen species (ROS) by the particles or the direct release of metal ions that can cause oxidative toxicity. Even with these materials, results of different studies vary greatly. In some studies the Gram positive test strain is reportedly more sensitive than the Gram negative 10; in others it is the opposite 14. These studies have been well reviewed 15.
In all nanoparticle studies, particle composition, size, surface chemistry, sample aging/breakdown, and wavelength, power, and duration of light exposure can all dramatically affect the results. In addition, synthesis byproducts and solvents must be considered16 17. High-throughput screening techniques are needed to be able to develop effective new nanomedicine agents.
CdTe QDs have anti-microbial effects alone18 or in combination with antibiotics. In a previous study, we showed that coupling of antibiotics to CdTe can increase toxicity to bacteria but decrease toxicity to mammalian cells, due to decreased production of reactive oxygen species from the conjugates19. Although it is unlikely that cadmium-containing compounds will be approved for use in humans, such preparations could be used for disinfection of surfaces or sterilization of water.
In this protocol, we give a straightforward approach to solubilizing CdTe QDs with mercaptopropionic acid (MPA). The QDs are ready to use within an hour. We then demonstrate coupling to an antimicrobial agent.
The second part of the protocol demonstrates a 96-well bacterial inhibition assay using the conjugated and unconjugated QDs. The optical density is read over many hours, permitting the effects of QD addition and light exposure to be evaluated immediately as well as after a recovery period. We also illustrate a colony count for quantifying bacterial survival.

Nanoparticles such as semiconductor quantum dots (QDs) can be used to create photoactivatable agents for anti-microbial or anti-cancer applications. This technique shows how to water-solubilize cadmium telluride (CdTe) QDs, conjugate them to an antibiotic, and perform a bacterial inhibition assay based upon growth curves and plate count.

量子点的生长曲线和平皿计数的细菌毒性检测的增溶作用和生物共轭

Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. ...

生物工程

Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired.

Herein we present a method to synthesize ligand-free cadmium sulfide (CdS) nanoparticles based on a unique sulfur copolymer. The sulfur copolymer operates as a high temperature solvent and a sulfur source during the nanoparticle synthesis and stabilizes the nanoparticles after the reaction.

a硫磺共聚物基质内的免费配体硫化镉纳米粒子的合成

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature ...

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m-2, and a maximum current efficiency of 1.15 cd A-1. The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

A protocol is presented for fabricating high-performance, pure blue ZnCdS/ZnS-based quantum dots light-emitting diodes by employing an autoxidized aluminum cathode.

采用部分氧化铝阴极增强电子注入和激子约束的纯蓝色量子点发光二极管

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation ...

Production and Targeting of Monovalent Quantum Dots

The multivalent nature of commercial quantum dots (QDs) and the difficulties associated with producing monovalent dots have limited their applications in biology, where clustering and the spatial organization of biomolecules is often the object of study. We describe here a protocol to produce monovalent quantum dots (mQDs) that can be accomplished in most biological research laboratories via a simple mixing of CdSe/ZnS core/shell QDs with phosphorothioate DNA (ptDNA) of defined length. After a single ptDNA strand has wrapped the QD, additional strands are excluded from the surface. Production of mQDs in this manner can be accomplished at small and large scale, with commercial reagents, and in minimal steps. These mQDs can be specifically directed to biological targets by hybridization to a complementary single stranded targeting DNA. We demonstrate the use of these mQDs as imaging probes by labeling SNAP-tagged Notch receptors on live mammalian cells, targeted by mQDs bearing a benzylguanine moiety.

We provide detailed instructions for the preparation of monovalent targeted quantum dots (mQDs) from phosphorothioate DNA of defined length. DNA wrapping occurs in high yield, and therefore, products do not require purification. We demonstrate the use of the SNAP tag to target mQDs to cell-surface receptors for live-cell imaging applications.

生产和目标单价量子点

The multivalent nature of commercial quantum dots (QDs) and the difficulties associated with producing monovalent dots have limited their applications in ...

Inkjet Printing All Inorganic Halide Perovskite Inks for Photovoltaic Applications

A method for synthesizing photoactive inorganic&#160;perovskite quantum dot inks and an inkjet printer deposition method, using the synthesized inks, are demonstrated. The ink synthesis is based on a simple wet chemical reaction and the inkjet printing protocol is a facile step by step method. The inkjet printed thin films have been characterized by X-ray diffraction, optical absorption spectroscopy, photoluminescent spectroscopy, and electronic transport measurements. X-ray diffraction of the printed quantum dot films indicates a crystal structure consistent with an orthorhombic room temperature phase with (001) orientation. In conjunction with other characterization methods, the X-ray diffraction&#160;measurements show high quality films can be obtained through the inkjet printing method.

A protocol for synthesizing inorganic-lead-halide hybrid perovskite quantum dot inks for inkjet printing and the protocol for preparing and printing the quantum dot inks in an inkjet printer with post characterization techniques are presented.

用于光伏应用的喷墨打印所有无机舱齐德 perovskite 油墨

A method for synthesizing photoactive inorganic&#160;perovskite quantum dot inks and an inkjet printer deposition method, using the synthesized inks, are ...

Synthesis of In37P20(O2CR)51 Clusters and Their Conversion to InP Quantum Dots

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 clusters have been observed as intermediates in the synthesis of InP quantum dots from molecular precursors (In(O2CR)3, HO2CR, and P(SiMe3)3) and may be isolated as a pure reagent for subsequent study and use as a single-source precursor. These clusters readily convert to crystalline and relatively monodisperse samples of quasi-spherical InP quantum dots when subjected to thermolysis conditions in the absence of additional precursors above 200 &#176;C. The optical properties, morphology, and structure of both the clusters and quantum dots are confirmed using UV-Vis spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and powder X-ray diffraction. The molecular symmetry of the clusters is additionally confirmed by solution-phase 31P NMR spectroscopy. This protocol demonstrates the preparation and isolation of atomically-precise InP clusters, and their reliable and scalable conversion to InP QDs.

Synthesis of In37P20O2CR51 Clusters and Their Conversion to InP Quantum Dots

A protocol for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots is presented.

37p20 (o2cr)51聚类中的合成及其转化为 inp 量子点

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 ...

量子点纳米珠可提高生物标志物检测的灵敏度

Fluorescent Lateral Flow Immunoassay Based on Quantum Dots Nanobeads

Quantum dots, also known as semiconductor nanocrystals, are novel fluorescent labels for biological imaging and sensing. However, quantum dot-antibody conjugates with small dimensions (~10 nm), prepared through laborious purification procedures, exhibit limited sensitivity in detecting certain trace disease markers using lateral flow immunoassay strips. Herein, we present a method for the preparation of quantum dot nanobeads (QDNB) using a one-step emulsion evaporation method. Using the as-prepared QDNB, a fluorescent lateral flow immunoassay was fabricated to detect disease biomarkers using C-reactive protein (CRP) as an example. Unlike single quantum dot nanoparticles, quantum dot nanobead-antibody conjugates are more sensitive as immunoassay labels due to signal amplification by encapsulating hundreds of quantum dots in one polymer composite nanobead. Moreover, the larger size of QDNBs facilitates easier centrifugation separation when conjugating QDNBs with antibodies. The fluorescent lateral flow immunoassay based on QDNBs was fabricated, and the CRP concentration in the sample was measured in 15 min. The test results can be qualitatively assessed under UV light illumination and quantitatively measured using a fluorescent reader within 15 min.

作者聚焦：用于灵敏荧光侧向层析免疫测定的高质量量子点纳米珠

Here, we describe a protocol for the preparation of quantum dot nanobeads (QDNB) and the detection of disease biomarkers using QDNB-based lateral flow immunoassay strips. The test results can be qualitatively assessed under UV light illumination and quantitatively measured using a fluorescent strip reader within 15 min.

基于量子点纳米珠的荧光侧向层析免疫测定

Quantum dots, also known as semiconductor nanocrystals, are novel fluorescent labels for biological imaging and sensing. However, quantum dot-antibody ...