Name: a system to create stable nanoparticle aerosols from nanopowders
Uploaded: 2016-07-26T15:00:00.000+00:00
Duration: 12 min 59 s
Description: Watch this Scientific Journal Video about A System to Create Stable Nanoparticle Aerosols from Nanopowders at JoVE.com

The authors are grateful for the financial support given to this study by EU FP7 project ``Managing Risks of Nanomaterials`` (MARINA) (grant agreement no: 263215).

1.系统准备<ol><li>确保使用新的或很好地清洗粒子输运管道和接头装配该系统。确保室壁清洁和无颗粒（参照该清洁方法在协议结束时）。 </li><li>以除去潜在的背景颗粒，连接一个过滤干燥空气流（5-10升/分钟）直接到混合室（没有安装位置a和b之间的漏斗中图1），在至少30分钟。 </li><li>测量根据制造商的协议使用SMPS在测量室中的粒子个数浓度。如果浓度低于10＃/ cm 3的后三扫描，然后再考虑环境的清洁。请注意，使用的SMPS测量当流量可能会减缓。 </li><li>停止空气流，并在FIGUR用塑料或橡胶塞关闭取样管出口和出口管的出口（位置Cë1），以防止进入系统环境颗粒。 </li><li>准备和热身测量仪器（SMPS和OPC）和微粒采样器进行微观分析。 </li></ol> 2.材料准备<ol><li>存储测试材料相对于温度和湿度的良好控制的环境。这是确保在后续实验重复的结果非常重要。 </li><li>小心使用分析天平或高精度的平衡，在一个通风良好的空间称量粉末（ 例如 ，实验室罩）。 注: 二氧化钛，SiO 2的250-500毫克重量，ZnO和的CeO 2纳米粒子粉状体进行了测试，这些通常被证明为稳定雾化的至少30分钟是足够的。然而，适量的强烈依赖于粉末的类型，并且可以为散装材料，水泥或有机粉末显著变化。 </li><li>固定垂直气溶胶发生器LY，并从用适当清洁实验室漏斗气溶胶发生器的顶部开口进料粉末。在实验前，用清水冲洗漏斗和过滤的空气干燥，除去内壁上的灰尘沉积。轻轻敲击漏斗以确保所有的粉末颗粒被送入该过程。不以避免该材料的显著损失早期气雾硬摇动漏斗。 <ol><li>确保大多数粉粒到达发电机的底部，而不是落入周围倾斜壁上。轻轻敲击产生的侧壁移动敷粉末颗粒跌到了谷底。 </li><li>可替代地，使用长漏斗直接沉积在发电机底部的粉末颗粒。为安全起见，在一个通风橱或负压室内部进行这些操作。 </li></ol></li><li>如不粘材料可以滑动通过在底部的开口发电机，用直径2毫米的针在送粉前暂时封闭开口。 </li><li>取下漏斗，并关闭发生器的顶部和底部开口，以避免传输期间粒子发射。 </li></ol> 3.气雾<ol><li>安装气溶胶发生器，卸下入口和出口管连接到所述漏斗的块，其底部连接到过滤空气供应和其顶部的出口到混合室（分别为图1中的位置a和b），并与一垂直连接它金属支架。 </li><li>卸下设置退出（ 图1位置C）的块。 </li><li>交换机上的雾化流。使用流调谐器从0到0.3-0.5升/分钟慢慢提高速度。不移动到高流速过快-目的是要达到的流速可以为至少30分钟提供稳定的气溶胶生成。 <ol><li>为了实现这一目标，在此期间，稳定的雾化的不消耗显著粉末量。作为一个经验法则，使用约1厘米，用于产生一个强大的气雾流，同时维持稳定的浓度在相对 ​​长期间的流化床高度（用H在图1中表示）。如果进入雾化过程中的能量过强则材料将迅速用完，否则该实验的其余部分期间，以维持一个稳定的气溶胶生成。注意，流速范围可以针对不同的粉末变化;上述的值被用于测试上述纳米粉末。 </li></ol></li><li>交换机上的稀释气流。慢慢地从0到2升/分钟增加的速率。所需的总稀释流被采样设备来确定。开关电源，OPC和在这里介绍的系统中使用的微型采样要求的1.6-1.8升/分钟的总流量。 </li></ol> 4.表征<ol><li>启动在线测量仪器同时（这里，SMPS和OPC），一旦雾化和稀释流被引入。 注意:如果雾化的稳定状态下实现的，气溶胶粒子数浓度和大小分布应后约30分钟，成为稳定的。使用来自不同的条件（ 例如 ，湿度），并使用不同的粉末下气溶胶特性的比较这时间点开始测量。分析来自10个连续SMPS扫描结果来计算平均浓度和粒径分布。 </li><li>一旦雾化是稳定的，打开连接于TEM采样开始采样气载粒子的泵。使用通过涂覆有多孔碳膜的TEM网格的0.3升/分钟的流速。如果流速太高网格上的薄膜可能被损坏。对使用采样的详细信息，可21。通常情况下，在采样过程持续从头出3分。 <ol><li>根据不同的颗粒浓度变化的取样持续时间，并且通过粒子沉积（ 例如 ，50％）考虑TEM网格的一个适中的表面覆盖近似。厚厚的沉积可能会修改粒子形态，由于现场集聚。 </li></ol></li></ol> 5.后取样操作和清理<ol><li>在完成测量后，关闭稀释流，然后将雾化流。 </li><li>断开系统的气溶胶发生器，阻断其顶部和底部开口，并将其转移到清洁的空间。清洗在通风良好的清洗设备或一封闭空间，特别是如果危险材料已被处理。 </li><li>分散粉末残基与水或有机溶剂，这取决于粒子表面的亲水性。将溶液倾入关安全回收化学品的容器。长期实验，测试粉末往往STIC坚决ķ到玻璃墙，并且不容易溶解。如果发生这种情况，用酸或碱连同超声波清洗，以溶解粘材料。 </li><li>为了去除留在壁和彻底干燥发电机的内部的任何水分，穿过它的干燥空气为至少1小时。确保不存在明火或与有机溶剂工作时的火源，保证了空间良好的通风。 </li><li>断开粒子输运管道和连接器。与水或溶剂冲洗。擦拭的混合和测量室的内壁，用湿纸巾或布。干他们在一个开放的空间，至少一天或与下次试验之前1小时的干燥空气流。 </li><li>定期清洁SMPS冲击（如果使用）。 </li></ol>

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The authors declare that they have no competing financial interests.

基于漏斗气雾化的设置能有效激活在选定的能量输入级粉末颗粒（可通过空气流速雾化过程中量化）。粒子运动和碰撞在产生站点达到平衡状态，分手粉末附聚物并以恒定的速率发射相同尺寸分布的空气中的颗粒。一个稳定的雾化可以持续30分钟至至多2小时，这是足够的时间以高尺寸的分辨率，如SMPS甚至慢测量仪器，以产生统计学上显著的结果。设置只需要少量的测试材料，它可以是一个优点，用于测试贵重材料如纳米颗粒粉末。 然而，该系统的环境和工艺参数能显著影响试验结果。为了产生重复的数据，标准作业程序必须严格遵循整个experi求。在进行使用这个系统雾化测试中，以下几个方面应慎重考虑。 首先，为了获得有意义的结果，这是至关重要的设置的内部部件提供用于测试一个清洁的环境。污染物的潜在来源是环境颗粒和从以前的实验测试材料。环境粒子的影响通常消失比较快，一旦被引入雾化和稀释流。然而，从残留的材料干扰可以在整个实验持续。作为生成的气雾颗粒流动通过该系统，可以在输送管，弯曲点和连接器的窄的通道，并且该混合的内表面和测量室的内壁上沉积。如果这些部件不正常之前，新实验清洗，先前沉积的材料可以被不断地重新悬浮于主流气溶胶流的，从而干扰测试结果。 其次，粉末灌装过程应该非常仔细地进行。这里最显著的问题是供入设置的粉末的量，特别是当使用的材料的极少量。在给定的气雾流率，较少量的粉末的产生降低气溶胶浓度，并且可能具有较小尺寸的颗粒，由于每粉末的单位重量更高能量输入。此外，已经示出了测试材料（ 如 ，相对湿度和温度）的储存条件以影响粉末雾化行为和含尘22的水平。因此，原料粉末应始终保持在相同的大气条件下，在可能的情况。 第三，调整在实验开始时的气雾流大大影响检测结果。在流动急剧增加吹大的粉末颗粒ū峰值到空气和传播他们遍布漏斗状表面，显着降低了材料的可用于实验的其余部分的量。其后果可能是一个失败的测试，由于粉不足。 由于这里描述的设置不使用标准化的实验室设备，试图复制这一系统的核心部件时建，应从以下几个方面加以考虑。标准实验室分液漏斗可以用作气溶胶发生器（请注意，它们不应在加压条件下使用）。不同几何形状的分液​​漏斗中的实验进行了测试，并且它们的定制漏斗提供类似的功能。具有嵌入输送管的橡胶密封块可用作漏斗盖。 不同的几何形状，但类似的卷混合和测量室可以使用。请注意，车厢太大的将显著拖延时间NEEDED达到稳定的气溶胶条件（浓度）。所需的时间可以通过考虑的总空气流率和隔室的体积来估计。虽然该方法可以通过使用大量的稀释流被加速，应该记住的是，最终粒子个数浓度，可显着降低由于稀释，这可能会影响气溶胶的粒度分布，以及测量仪器的性能（取决于在他们的检测限）。电被推荐的导电材料。 运输管道的长度可以根据一般实验室设置而改变。然而，长度应，以便其在运输过程中，以避免显著粒子损失保持尽可能短。微粒穿透性效率可以通过考虑粒径，空气流速，管的直径和长度，并考虑两种重力沉积轴承或计算扩散损失，或两者。 不同的表征方法可以采用。然而，空气供应（稀释流）应调节以匹配总采样流速。不足的空气供应量将导致在测量室的负压，在室温粒子从而导致在结论中的错误绘图。不同的空气供应源可以使用，但确保它们无颗粒或预治疗与高效率过滤器的空气。 这种雾化方法的一个主要的限制是，它需要的测试粉末的良好的流动性，以便在相对长的时期内保持稳定的颗粒的产生。粘的材料，如具有高水分含量的亲水性粉末，通常停止在雾化过程的早期阶段中流动，并产生非常低的粒子浓度。解决这一问题的可能方式可以包括一个预处理原料粉末，如烘干-S的O作为改善其流动性。用途后的原料的贮存条件应保持良好， 例如 ，保持在干燥的环境中和适当的温度下。在实验中，更高的气雾流动速度（0.5-1升/分钟）和较大量的原材料（ 例如 ，500毫克）的可使用。此外，降低了稀释流量可以增加在测量室的颗粒浓度。 这种方法的另一个限制是尘埃粒子的生成速率（因此粒子个数浓度在测量室）的可重复性。变化一定程度依然存在。改进的可能途径是更好的界定喂养过程中减少材料损耗，并控制良好的气雾流量。 该系统和这里描述的方案可用于各种应用。使用相对少量的试料，使潜在诉方法aluable作为测试含尘粉的替代工具。由我们的系统的一些常见的材料产生的空气中的颗粒的水平的排名是类似于在现有雾化系统19，旋转鼓15,17，连续滴23和涡旋振荡器的方法24，如观察到的。此外，可调节的能量输入（空气流量），也可以用于研究纳米粒子粉末附聚物的稳定性。最后，稳定气溶胶的产生可以作为在体内或体外毒理学研究空降工程纳米颗粒的可靠来源。可控粒子浓度将允许的剂量依赖的生物反应的分析。相比，使用液体悬浮其他雾化方法，该方法避免了诸如材料悬浮性和悬浮颗粒的物理-化学性质修饰（潜在的问题例如 ，一个gglomeration，表面特性）。

纳米材料的粉末被广泛用于不同的工业部门，作为用于生产新产品，或作为添加剂用于他们的功能性应用1-4的原料。然而，对于工人暴露于纳米粉末气溶胶的潜力已在各种职业搬运活动5-8所指出的，并且在体内 和体外毒理学研究9-12相关联的健康风险已研究英寸为了方便有效的发展战略，以保护处理纳米材料的工人，职业卫生专业人员需要更好地了解纳米颗粒气溶胶如何从受到外部能源投入粉状物料产生的。 不同实验室系统已被开发，以模拟在实际条件粉末雾化行为。其中，两个标准程序建立的参考方法<su用于测试粉末含尘，其被定义为粉末的趋势，进行给定的能量输入，对&gt; 13释放空气中的颗粒。第一种方法使用一个旋转鼓，作为能量输入的介质和粉末颗粒14,15的雾化。第二种方法通过一个垂直圆柱体滴以恒定速率的粉末和通过的上升空气流16的装置aerosolizes粉末颗粒。然而，这些方法需要相对大量的试验材料（35 毫升或500克），并且这可以是由于它们的高成本和潜在的暴露风险与纳米材料的粉末的问题。按比例缩小的测试系统相结合的单点和转鼓工艺的开发，允许使用少量的试验粉末（6克样品）17。基于涡流激振器最近开发的雾化系统也被用于纳米粉体，使测试向下原材料1厘米3 <suP&gt; 18。 在这里，我们提出了基于实验室纳米粉体漏斗测试一种新型的气雾化和去聚集系统。它提供了使用小于1g试验粉末的稳定气溶胶生成过程。稳定雾化可维持足够长的持续时间为强大的气溶胶特征。系统的性能进行了详细两个以前的出版物19,20进行了描述。 测试设置由气雾剂发生器，混合和计量室，和表征仪器， 如图1。粒子输送管道和连接器的连接这些不同的元件。的流调谐器和两个流量计控制和监视系统中的空气流的条件。压力计和一个温度和湿度的传感器监测测量室内部的环境。干燥的压缩空气是使用hyperfilter在进入系统之前过滤。一个细长的V形，玻璃气雾剂发生器用于粉末雾化。这种几何形状便于健壮雾化过程和光滑颗粒输送到随后的隔室。在漏斗的底部的流动状态是湍流由于与粉末颗粒的交互作用，而它是层中的上部（重新编号&lt;15）。发电机壁的厚度是专门设计用来抵御需要使用临界孔解凝集试验的高压（高达400千帕△P）。一个高精度流量控制调谐器在0.01升/分钟为单位的流量。导电管（6外径，厚度为1毫米）被用来避免由于在运输过程中的静电沉积粒子的损失。管长是气溶胶发生器和混合室，20厘米混合室和测量室之间，和100厘米为取样管之间约50cm。向1L的金属瓶被用作混合湛误码率，和一个12升的金属鼓被用作测量室。颗粒样品从测量室的顶部绘制。一个出口引导额外流入过滤系统。混合和测量室电接地，以防止颗粒的静电损耗。测量仪器包括一个扫描移动粒度仪（SMPS）和颗粒数浓度和粒度分布的光学粒子计数器（OPC），以及用于颗粒形态分析的透射电子显微镜（TEM）采样器（MPS）。 安装的雾化过程类似于流化床工艺。空气流从底部开口成漏斗（2毫米直径）进入并aerosolizes的粉末。粉末颗粒以类似的方式移动到水在一个喷泉。生成的气雾剂满足在混合腔室中的稀释液的流动。稀释空气流量可被调节为，如果效果不同水平的湿度的此参数的需要的分析。腔室的空气兼作缓冲容积根据采样需要用干燥稀释空气平滑地混合所述气雾剂。气溶胶流然后经由正常管出口（用于气雾化测试）或临界孔（为解凝聚测试）引入到测量室。孔可以提供不同的压力降的条件下，施加剪切力，以通过它的颗粒。这种机制允许其解聚势（机械稳定性）的研究。 <img alt="图1" src="/files/ftp_upload/54414/54414fig1.jpg" /> 图1.雾化和解聚体系的示意图。缺省情况下，一个管连接与所述测量室中的混合室中。中所示的小孔是一个可选的附加 ​​（在本协议中没有说明）。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig1large.jpg" target="_blank">请点击此处Ť</a>Ø查看此图的放大版本。

<table><tbody><tr><td>titanium dioxide nanopowder</td><td>JRC</td><td>NM-103/104</td><td>Reference materials provided within EU FP7 MARINA project</td></tr><tr><td>silicon dioxide nanopowder</td><td>AEROSIL</td><td>R974</td><td></td></tr><tr><td>silicon dioxide nanopowder</td><td>JRC</td><td>NM-200</td><td>Reference materials provided within EU FP7 MARINA project</td></tr><tr><td>zinc oxide nanopowder</td><td>JRC</td><td>NM-110/111</td><td>Reference materials provided within EU FP7 MARINA project</td></tr><tr><td>cerium dioxide nanopowder</td><td>JRC</td><td>NM-211/212</td><td>Reference materials provided within EU FP7 MARINA project</td></tr><tr><td>The V-shaped aerosol generator</td><td>Souffleur de verre S.A.</td><td></td><td>Specially made based on conditions required in the experiments (e.g., geometry, thickness)</td></tr><tr><td>scanning mobility particler sizer (SMPS)</td><td>GRIMM</td><td>Model N&amp;deg; 5.403</td><td>Size range: 11.1&amp;ndash;1083.3&amp;nbsp;nm (impactor: d50=1,082&amp;nbsp;nm); composed of a condensation particle counter (CPC) and a dynamic mobility analyzer (DMA); sampling flow ate: 0.3&amp;nbsp;L/min; sheath flow rate: 3.0&amp;nbsp;L/min; with standard multiple charge correction and diffusion loss correction.</td></tr><tr><td>optical particle counter (OPC)</td><td>GRIMM</td><td>Model N&amp;deg; 5.403</td><td>Size range: 0.25-32 &amp;micro;m</td></tr><tr><td>mini-particle sampler (MPS)</td><td>ECOMESURE</td><td></td><td></td></tr><tr><td>transport tubes</td><td>Milian S.A.</td><td>8 mm-conductive</td><td>6 mm inner diameter</td></tr></tbody></table>

a system to create stable nanoparticle aerosols from nanopowders

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring minimal amounts of test materials (min. 200 mg), for studying powder aerosolization behavior and aerosol properties. The aerosolization procedure follows the concept of the fluidized-bed process, but occurs in the modified volume of a V-shaped aerosol generator. The airborne particle number concentration is adjustable by controlling the air flow rate. The system supplied stable aerosol generation rates and particle size distributions over long periods (0.5-2 hr and possibly longer), which are important, for example, to study aerosol behavior, but also for toxicological studies. Strict adherence to the operating procedures during the aerosolization experiments ensures the generation of reproducible test results. The critical steps in the standard protocol are the preparation of the material and setup, and the aerosolization operations themselves. The system can be used for experiments requiring stable aerosol concentrations and may also be an alternative method for testing dustiness. The controlled aerosolization made possible with this setup occurs using energy inputs (may be characterized by aerosolization air velocity) that are within the ranges commonly found in occupational environments where nanomaterial powders are handled. This setup and its operating protocol are thus helpful for human exposure and risk assessment.

图2示出的随时间的总气溶胶粒子数浓度和大小的变化，使用上述的协议中的雾化实验疏水SiO 2的一个典型的例子。颗粒浓度开始就引入了雾化气流上升。颗粒的几何平均大小逐渐增加了。后大约10 SMPS扫描（3.5分钟/扫描），气溶胶开始进入稳定状态，其中，颗粒浓度和平均直径不再由任何显著量变化。这种状态持续了30分钟以上，这是足以完成10个3分钟的SMPS扫描。 图3示出了在个人尺寸分布的形式在粒子浓度的变化（基于相同的数据在图2中）。高峰缓慢上升一段时间，并且一旦该气溶胶变得稳定，它仍然在整个第相同尺寸范围内测试电子休息。 在实验开始时示出的非常小的平均直径是不是由于不稳定粉末雾化。相反，它是通过将粉末填充过程之后漏斗内的残留周围空气造成的。空气的这种体积是第一流入测量室，并在它的初始扫描（ 图4）是由SMPS采样。这可以通过，如果这是需要通过手边的科学问题在一个干净的房间进行所有的实验来避免。事实上，在第一次扫描的尺寸分布非常类似于环境空气。作为粉末气雾颗粒继续从迅速减少环境粒子流中的干扰，以及之后的效果几SMPS扫描几乎已经消失。 <img alt="图2" src="/files/ftp_upload/54414/54414fig2.jpg" /> 图2. 更改总粒子数浓度和平均气雾实验直径（241毫克疏水的SiO 2;气雾流量0.3升/分钟）。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/54414/54414fig3.jpg" /> 图3. 在气雾实验粒度分布变化。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图4" src="/files/ftp_upload/54414/54414fig4.jpg" /> 图4. 气雾剂的粒度分布在雾化试验开始。粒子浓度上呈现的相对比例（归一吨Ø为了频谱从一个非常低的浓度后浓度较高的扫描，光谱扫描先比较总人数）。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 在颗粒浓度的变化并不总是遵循同样的模式。四种可能性通常可以在雾化测试可以看出。在图5A中 ，浓度缓慢升 ​​至一个"高原"区域，则仍然是实验的其余部分几乎不变。在图5B中 ，浓度先上升至最高点，逐渐下降到一个较低的水平，然后超过1.5小时保持稳定。在图5C中 ，浓度继续降低到零。在图5D中 ，浓度增加至最大值，仍然保持，ð有一段时间，然后再次下降。 当标准操作程序之后方案（一）通常看到。雾化气流慢慢引入和最后的适当的范围内稳定。原料的量足以相对于所述雾化水平，并以恒定的气溶胶发生速率可维持相当长的时间周期。方案（b）是最有可能是由于在整个实验过大的雾化流，与粉末的数量不足组合。粉末被迅速消耗，不能够维持稳定的悬浮微粒产生。方案（c）示出在粒子个数浓度，只是一个很短的时间后，空气流速被重新调整到一个适当的范围内，并在整个试验的其余保持恒定的类似下降到场景（b）中。这使粒子浓度逐渐达到一个稳定范围内。方案（D）一当使用原料的量不足ppears。在实验的后期阶段，不再有足够的测试粉末以恒定的速率来产生气溶胶粒子，如在雾化的早期阶段是可能的。因此，在系统中的微粒浓度降低。 <img alt="图5" src="/files/ftp_upload/54414/54414fig5.jpg" /> 图 5. 在气雾实验改变总颗粒物浓度典型模式:（A）慢慢增加，直至达到一个平台; （B）逐渐减小至零; （ 三 ）迅速达到高峰，然后下降到一个稳定的水平; （ 四 ）提高到一个稳定的状态，并保持一定的时间周期，然后下降。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> </p&gt; 不同的雾化流速，以研究其对气溶胶的产生的影响进行了测试。从0.3-1.1，流量率/分钟被使用，并且将所得的粒径分布如图6所示。在光谱的峰上升作为流增加。在最高流速（1.1升/分钟），微米级的空气中的颗粒开始进入系统（二次峰）。气溶胶粒子的模态尺寸停留相似时相同的雾化气流下，但是，它们逐渐降低时的空气流通过的范围内增加从0.3-0.7升/分钟（ 图7）。日益增加的颗粒产生速率及减少平均粒径为流速增加表明更为动态雾化处理（与显著粒子运动和碰撞）促进粉末颗粒的解聚，从而导致该气溶胶的变形大小分布产生的颗粒。 <img alt="图6" src="/files/ftp_upload/54414/54414fig6.jpg" /> 图6. 改变粒度分布随空气流量（0.3〜1.1 L /分钟）。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig6large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图7" src="/files/ftp_upload/54414/54414fig7.jpg" /> 图7. 在不同的流量粒度分布的比较。光谱变成了相对规模相似的高度（归总粒子数），它具有更好的高峰期转变。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig7large.jpg" target="_blank">请点击此处查看这个大版本数字。</a> 图8示出了从使用相同的材料四个重复试验中的粒度分布的变化的一个例子。标准偏差为总颗粒浓度为39.7％，为几何平均大小为6.6％。数量浓度的变化可能是由于以下几个原因:1）的不同的原料的状态（ 例如 ，附聚水平）; 2）在灌粉过程中的人为因素（影响沉积在漏斗底部的粉量，从而可用于气雾化的量）;或3）在雾化的开始空气流量调节。 <img alt="图8" src="/files/ftp_upload/54414/54414fig8.jpg" /> <strong&gt;的图8. 变异的重复实验雾化测试结果的疏水性二氧化硅 。误差条表示在个体大小渠道粒子数浓度的标准偏差。 <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54414/54414fig8large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about A System to Create Stable Nanoparticle Aerosols from Nanopowders at JoVE.com

A System to Create Stable Nanoparticle Aerosols from Nanopowders

We designed and developed an effective nanopowder aerosolization setup and operating protocol. The system generated nanoparticle aerosols with stable number concentrations and size distributions for long durations, requiring only small quantities of test material (min. 200 mg).

系统创建从纳米粉体纳米稳定气溶胶

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring ...

a-system-to-create-stable-nanoparticle-aerosols-from-nanopowders

Universidad San Sebastian

Research

JoVE Journal

Engineering

9.5K 次观看.  Universities of Lausanne and Geneva. We designed and developed an effective nanopowder aerosolization setup and operating protocol. The system generated nanoparticle aerosols with stable number concentrations and size distributions for long durations, requiring only small quantities of test material (min. 200 mg). 

视频: A System to Create Stable Nanoparticle Aerosols from Nanopowders

Generation of Zerovalent Metal Core Nanoparticles Using n-(2-aminoethyl)-3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of n-(2-aminoethyl)-3-aminosilanetriol is presented. This compound can be used to effectively reduce and complex metal salts into metal core nanoparticles coated with the compound. By controlling the concentrations of salt and silane one is able to control reaction rates, particle size, and nanoparticle coating. The effects of these changes were characterized through transmission electron microscopy (TEM), UV-Vis spectrometry (UV-Vis), Nuclear Magnetic Resonance spectroscopy (NMR) and Fourier Transform Infrared spectroscopy (FTIR). A unique aspect to this reaction is that usually silanes hydrolyze and cross-link in water; however, in this system the silane is water-soluble and stable. It is known that silicon and amino moieties can form complexes with metal salts. The silicon is known to extend its coordination sphere to form penta- or hexa-coordinated species. Furthermore, the silanol group can undergo hydrolysis to form a Si-O-Si silica network, thereby transforming the metal nanoparticles into a functionalized nanocomposites.

Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol

A novel method for metal core nanoparticle synthesis using a water stable silanol is described.

使用N-零价金属芯纳米粒子的生成（2-氨基乙基）-3- aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of ...

科研

化学

Experimental Protocol to Investigate Particle Aerosolization of a Product Under Abrasion and Under Environmental Weathering

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering, which is a fundamental element to the approach of nanosafety-by-design of nanostructured products for their durable development. This approach is basically a preemptive one in which the focus is put on minimizing the emission of engineered nanomaterials' aerosols during the usage phase of the product's life cycle. This can be attained by altering its material properties during its design phase without compromising with any of its added benefits. In this article, an experimental protocol is presented to investigate the nanosafety-by-design of three commercial nanostructured products with respect to their mechanical solicitation and environmental weathering. The means chosen for applying the mechanical solicitation is an abrasion process and for the environmental weathering, it is an accelerated UV exposure in the presence of humidity and heat. The eventual emission of engineered nanomaterials is studied in terms of their number concentration, size distribution, morphology and chemical composition. The purpose of the protocol is to study the emission for test samples and experimental conditions which are corresponding to real life situations. It was found that the application of the mechanical stresses alone emits the engineered nanomaterials' aerosols in which the engineered nanomaterial is always embedded inside the product matrix, thus, a representative product element. In such a case, the emitted aerosols comprise of both nanoparticles as well as microparticles. But if the mechanical stresses are coupled with the environmental weathering, the experimental protocol reveals then the eventual deterioration of the product, after a certain weathering duration, may lead to the emission of the free engineered nanomaterial aerosols too.

In this article, an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental weathering is presented. Results on the emission of engineered nanomaterials, in the form of aerosols are presented. The specific experimental set-up is described in detail.

实验协议来调查产品的粒子雾化在耐磨和环境下风化

The present article presents an experimental protocol to investigate particle aerosolization of a product under abrasion and under environmental ...

工程学

Fabrication of Spherical and Worm-shaped Micellar Nanocrystals by Combining Electrospray, Self-assembly, and Solvent-based Structure Control

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of fabricating micellar nanocrystals based on combining top-down electrospray, bottom-up self-assembly, and solvent-based structure control. This method involves first using electrospray to generate uniform ultrafine liquid droplets, each of which functions as a micro-reactor in which self-assembly reaction occurs forming micellar nanocrystals, with the structures (micelle shape and nanocrystal encapsulation) controlled by the organic solvent used. This method is largely continuous and produces high quality micellar nanocrystal products with an inexpensive structure control approach. By using a water-miscible organic solvent tetrahydrofuran (THF), worm-shaped micellar nanocrystals can be produced due to solvent-induced/facilitated micelle fusion. Compared with the common spherical micellar nanocrystals, worm-shaped micellar nanocrystals can offer minimized non-specific cellular uptake, thus enhancing biological targeting. By co-encapsulating multiple nanocrystals into each micelle, multifunctional or synergistic effects can be achieved. Current limitations of this fabrication method, which will be part of the future work, primarily include imperfect encapsulation in the micellar nanocrystal product and the incompletely continuous nature of the process.

The present work describes a method to fabricate micellar nanocrystals, an emerging major class of nanobiomaterials. This method combines top-down electrospray, bottom-up self-assembly, and solvent-based structure control. The fabrication method is largely continuous, can produce high quality products, and possesses an inexpensive means of structure control.

结合电喷雾、自组装和溶剂型结构控制制备球形和蜗杆状胶束纳米晶

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of ...

A Continuous-flow Photocatalytic Reactor for the Precisely Controlled Deposition of Metallic Nanoparticles

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic nanoparticles is developed. Guidelines for the replication of the reactor and its operation are provided in detail. Three different composite systems (Pt/graphene, Pt/TiO2, and Au/TiO2) with monodisperse and uniformly distributed particles are produced by this reactor, and the photodeposition mechanism, as well as the synthesis optimization strategy, are discussed. The synthesis methods and their technical aspects are described comprehensively. The role of the ultraviolet (UV) dose (in each excitation pulse) on the photodeposition process is investigated and the optimum values for each composite system are provided.

For a continuous and scalable synthesis of noble-metal-based nanocomposites, a novel photocatalytic reactor is developed and its structure, operation principles, and product quality optimization strategies are described.

一种用于金属纳米粒子精确控制沉积的连续流动光催化反应器

In this work, a novel photocatalytic reactor for the pulsed and controlled excitation of the photocatalyst and the precise deposition of metallic ...

Development of a Nose-only Inhalation Toxicity Test Chamber That Provides Four Exposure Concentrations of Nano-sized Particles

Using a numerical analysis based on computerized fluid dynamics, a nose-only inhalation toxicity chamber with four different exposure concentrations is designed and validated for flow field uniformity and cross-contamination among the exposure ports for each concentration. The designed flow field values are compared with the measured values from exposure ports located horizontally and vertically. For this purpose, nanoscale sodium chloride particles are generated as test particles and introduced to the inhalation chamber to evaluate the cross-contamination and concentration maintenance among the chambers, for each concentration group. The results indicate that the designed multiconcentration inhalation chamber can be used in animal inhalation toxicity testing without cross-contamination among concentration groups. Moreover, the designed multiconcentration inhalation toxicity chamber can also be converted to a single-concentration inhalation chamber. Further testing with gas, organic vapor, or non-nanoscale particles will ensure the use of the chamber in the inhalation testing of other test articles.

A nose-only inhalation toxicity chamber capable of testing inhalation toxicity at four different exposure concentrations was designed and validated for flow field uniformity and cross-contamination between the exposure ports for each concentration. Here, we present a protocol to confirm that the designed chamber is effective for inhalation toxicity testing.

提供纳米颗粒四种曝光浓度的单鼻子吸入毒性试验室的研制

Using a numerical analysis based on computerized fluid dynamics, a nose-only inhalation toxicity chamber with four different exposure concentrations is ...

Preparation of Nanoparticles for ToF-SIMS and XPS Analysis

Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, chemistry, and their potential to enable advanced materials. To effectively understand and regulate the physico-chemical properties and potential adverse effects of nanoparticles, validated measurement procedures for the various properties of nanoparticles need to be developed. While procedures for measuring nanoparticle size and size distribution are already established, standardized methods for analysis of their surface chemistry are not yet in place, although the influence of the surface chemistry on nanoparticle properties is undisputed. In particular, storage and preparation of nanoparticles for surface analysis strongly influences the analytical results from various methods, and in order to obtain consistent results, sample preparation must be both optimized and standardized. In this contribution, we present, in detail, some standard procedures for preparing nanoparticles for surface analytics. In principle, nanoparticles can be deposited on a suitable substrate from suspension or as a powder. Silicon (Si) wafers are commonly used as substrate, however, their cleaning is critical to the process. For sample preparation from suspension, we will discuss drop-casting and spin-coating, where not only the cleanliness of the substrate and purity of the suspension but also its concentration play important roles for the success of the preparation methodology. For nanoparticles with sensitive ligand shells or coatings, deposition as powders is more suitable, although this method requires particular care in fixing the sample.

A number of different procedures for preparing nanoparticles for surface analysis are presented (drop casting, spin coating, deposition from powders, and cryofixation). We discuss the challenges, opportunities, and possible applications of each method, particularly regarding the changes in the surface properties caused by the different preparation methods.

用于ToF-SIMS和XPS分析的纳米颗粒的制备

Nanoparticles have gained increasing attention in recent years due to their potential and application in different fields including medicine, cosmetics, ...

Rapid, Scalable Assembly and Loading of Bioactive Proteins and Immunostimulants into Diverse Synthetic Nanocarriers Via Flash Nanoprecipitation

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging applications. This increased specificity can have significant clinical implications, including decreased side effects and lower dosages with higher potency. Furthermore, the in situ targeting and controlled modulation of specific cell subsets can enhance in vitro and in vivo investigations of basic biological phenomena and probe cell function. Unfortunately, the required expertise in nanoscale science, chemistry and engineering often prohibit laboratories without experience in these fields from fabricating and customizing nanomaterials as tools for their investigations or vehicles for their therapeutic strategies. Here, we provide protocols for the synthesis and scalable assembly of a versatile non-toxic block copolymer system amenable to the facile formation and loading of nanoscale vehicles for biomedical applications. Flash nanoprecipitation is presented as a methodology for rapid fabrication of diverse nanocarriers from poly(ethylene glycol)-bl-poly(propylene sulfide) copolymers. These protocols will allow laboratories with a wide range of expertise and resources to easily and reproducibly fabricate advanced nanocarrier delivery systems for their applications. The design and construction of an automated instrument that employs a high-speed syringe pump to facilitate the flash nanoprecipitation process and to allow enhanced control over the homogeneity, size, morphology and loading of polymersome nanocarriers is described.

Nanomaterials provide versatile mechanisms of controlled therapeutic delivery for both basic science and translational applications, but their fabrication often requires expertise that is unavailable in most biomedical laboratories. Here, we present protocols for the scalable fabrication and therapeutic loading of diverse self-assembled nanocarriers using flash nanoprecipitation.

快速, 可伸缩的组装和负载的生物活性蛋白和免疫增强剂到不同的合成 Nanocarriers 通过闪光 Nanoprecipitation

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging ...

生物工程

Flash NanoPrecipitation for the Encapsulation of Hydrophobic and Hydrophilic Compounds in Polymeric Nanoparticles

The formulation of a therapeutic compound into nanoparticles (NPs) can impart unique properties. For poorly water-soluble drugs, NP formulations can improve bioavailability and modify drug distribution within the body. For hydrophilic drugs like peptides or proteins, encapsulation within NPs can also provide protection from natural clearance mechanisms. There are few techniques for the production of polymeric NPs that are scalable. Flash NanoPrecipitation (FNP) is a process that uses engineered mixing geometries to produce NPs with narrow size distributions and tunable sizes between 30 and 400 nm. This protocol provides instructions on the laboratory-scale production of core-shell polymeric nanoparticles of a target size using FNP. The protocol can be implemented to encapsulate either hydrophilic or hydrophobic compounds with only minor modifications. The technique can be readily employed in the laboratory at milligram scale to screen formulations. Lead hits can directly be scaled up to gram- and kilogram-scale. As a continuous process, scale-up involves longer mixing process run time rather than translation to new process vessels. NPs produced by FNP are highly loaded with therapeutic, feature a dense stabilizing polymer brush, and have a size reproducibility of &#177; 6%.

Flash NanoPrecipitation (FNP) is a scalable approach to produce polymeric core-shell nanoparticles. Lab-scale formulations for the encapsulation of hydrophobic or hydrophilic therapeutics are described.

闪速纳米沉淀法包聚物纳米粒子中疏水亲水化合物的作用

The formulation of a therapeutic compound into nanoparticles (NPs) can impart unique properties. For poorly water-soluble drugs, NP formulations can ...

Dry Powder and Nebulized Aerosol Inhalation of Pharmaceuticals Delivered to Mice Using a Nose-only Exposure System

Obstructive respiratory diseases like asthma and chronic obstructive pulmonary disease (COPD) are currently treated by inhaled anti-inflammatory and bronchodilator drugs. Despite the availability of multiple treatments, both diseases are growing public health concerns. The majority of asthma patients are well controlled on current inhaled therapies but a substantial number of patients with severe asthma are not. Asthma affects an estimated 300 million people worldwide and approximately 20 percent have a severe form of the disease. In contrast to asthma, there are few effective therapies for COPD. An estimated 10% of the population has COPD and the trend in death rates is increasing for COPD while decreasing for other major diseases. Although developing drugs for inhaled delivery is challenging, the nose-only inhalation unit enables direct delivery of novel drugs to the lung of rodents for pre-clinical efficacy and safety/toxicology studies. Inhaled drug delivery has multiple advantages for respiratory diseases, where high concentration in the lung improves efficacy and minimizes systemic side effects. Inhaled corticosteroids and bronchodilators benefit from these advantages and inhaled delivery may also hold potential for future biologic therapies. The inhalation unit described herein can generate, sample for characterization, and uniformly deposit a drug aerosol in the lungs of rodents. This enables the pre-clinical determination of the efficacy and safety of drug doses deposited in the lungs of rodents, key data required before initiating clinical development.

The inhalation unit described herein can generate, sample for characterization, and uniformly deposit a drug aerosol in the lungs of rodents. This enables the pre-clinical determination of the efficacy and safety of drug doses deposited in the lungs; key data enabling clinical inhaled drug development.

干粉和药品的雾化吸入气雾剂递送小鼠使用鼻只曝光系统

Obstructive respiratory diseases like asthma and chronic obstructive pulmonary disease (COPD) are currently treated by inhaled anti-inflammatory and ...

医学

Whole-Body Nanoparticle Aerosol Inhalation Exposures

Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle inhalation toxicology studies, the aerosols in a chamber housing the experimental animals must have: 1) a steady concentration maintained at a desired level for the entire exposure period; 2) a homogenous composition free of contaminants; and 3) a stable size distribution with a geometric mean diameter &lt; 200 nm and a geometric standard deviation &sigma;g &lt; 2.5 5. The generation of aerosols containing nanoparticles is quite challenging because nanoparticles easily agglomerate. This is largely due to very strong inter-particle forces and the formation of large fractal structures in tens or hundreds of microns in size 6, which are difficult to be broken up. Several common aerosol generators, including nebulizers, fluidized beds, Venturi aspirators and the Wright dust feed, were tested; however, none were able to produce nanoparticle aerosols which satisfy all criteria 5.
A whole-body nanoparticle aerosol inhalation exposure system was fabricated, validated and utilized for nano-TiO2 inhalation toxicology studies. Critical components: 1) novel nano-TiO2 aerosol generator; 2) 0.5 m3 whole-body inhalation exposure chamber; and 3) monitor and control system. Nano-TiO2 aerosols generated from bulk dry nano-TiO2 powders (primary diameter of 21 nm, bulk density of 3.8 g/cm3) were delivered into the exposure chamber at a flow rate of 90 LPM (10.8 air changes/hr). Particle size distribution and mass concentration profiles were measured continuously with a scanning mobility particle sizer (SMPS), and an electric low pressure impactor (ELPI). The aerosol mass concentration (C) was verified gravimetrically (mg/m3). The mass (M) of the collected particles was determined as M = (Mpost-Mpre), where Mpre and Mpost are masses of the filter before and after sampling (mg). The mass concentration was calculated as C = M/(Q*t), where Q is sampling flowrate (m3/min), and t is the sampling time (minute). The chamber pressure, temperature, relative humidity (RH), O2 and CO2 concentrations were monitored and controlled continuously. Nano-TiO2 aerosols collected on Nuclepore filters were analyzed with a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis.
In summary, we report that the nano-particle aerosols generated and delivered to our exposure chamber have: 1) steady mass concentration; 2) homogenous composition free of contaminants; 3) stable particle size distributions with a count-median aerodynamic diameter of 157 nm during aerosol generation. This system reliably and repeatedly creates test atmospheres that simulate occupational, environmental or domestic ENM aerosol exposures.

A whole-body nanoparticle aerosol inhalation exposure facility was constructed for nano-sized titanium dioxide (TiO2) inhalation toxicology studies. This system provides nano-TiO2 aerosol test atmospheres that have: 1) a steady mass concentration; 2) a homogenous composition free of contaminants; and 3) a stable particle size distribution during aerosol generation.

全身纳米气溶胶吸入暴露

Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle ...