该项目已根据第720952号赠款协议（ACEnano）获得了欧盟地平线2020计划（H2020）的资助。作者要感谢Sigrid Benemann的SEM测量，Markus Schneider的ToF-SIMS测量和PCA，以及Philipp Reichardt的拍摄协助。

注意:纳米颗粒的毒理学性质仍在研究中;由于它们的大小，即使它们由本质上无害的材料组成，它们也会在人类和环境中产生独特的危害。在对纳米颗粒进行任何工作之前，应完成适当的风险评估，并根据要研究的材料的危险水平，适当的工程控制，实验室程序和PPE（个人防护设备）到位29，30，31，32。
1. 硅晶圆的制备
注意:这些步骤对于去除不需要的（有机）污染物并增加表面润湿性是必要的。所有使用的溶剂应至少为ACS级。标准超声处理浴（35 kH 和 120 瓦）是合适的。
<ol><li>硅晶圆的湿化学清洗<ol>
<li>将Si晶片放入装有异丙醇的烧杯中，并超声处理5分钟。</li>
		<li>将Si晶圆转移到带有碱玻璃清洁溶液的烧杯中，并超声处理10分钟。</li>
		<li>将威化片放入装有超纯水的烧杯中。通过倒出水并重新填充烧杯来更换水10次;由于毛细管效应，Si晶圆将保持在底部。</li>
		<li>用干净的N2 气体干燥晶圆。 注意:用N2 干燥可防止水干燥形成"咖啡环"和其他伪影。</li>
		<li>将晶圆放入第二个烧杯中，用异丙醇和超声波灭菌10分钟。</li>
		<li>用干净的N2 气体干燥晶圆。</li>
		<li>将晶圆放入装有乙醇的烧杯中，并超声处理10分钟。</li>
		<li>用干净的N2 气体干燥晶圆。该协议可以在此处暂停。</li>
	</ol>
</li>
	<li>硅晶圆的等离子或紫外线/臭氧清洗<ol>
<li>将硅晶圆引入等离子体或紫外线/臭氧清洁剂中，然后打开30分钟。 注:晶圆在使用前应立即进行等离子或紫外线/臭氧清洗。</li>
	</ol>
</li>
</ol>2. 悬浮液沉积纳米颗粒
注意:纳米颗粒最常见的暴露途径是吸入。使用悬架可以最大限度地减少暴露危险。
<ol><li>粉末纳米颗粒悬浮液的制备 注:此处描述的所有数量均为示例。该方法应针对每种情况下使用的特定纳米颗粒进行优化。<ol>
<li>将15mg纳米颗粒粉末（±10%）准确地称量到10mL管中。</li>
		<li>在约 8 mL 超纯水中准确称量。</li>
		<li>关闭管，用纸巾包装在50 mL离心管中，以3，000rpm的速度放入涡旋器中15分钟。</li>
	</ol>
</li>
	<li>从水悬浮液中滴铸导电纳米颗粒<ol>
<li>将晶圆放入紫外线/臭氧清洁剂中30分钟。</li>
		<li>将晶圆置于晶圆支架的一半中，并在环的中心放置3μL纳米颗粒悬浮液。</li>
		<li>将直径为6.07 mm的Viton O形圈安装在液滴周围的晶圆上。注意戒指不要接触液滴。</li>
		<li>将晶圆置于真空干燥器中，在4 mbar的真空下干燥15分钟以干燥晶圆。</li>
		<li>从干燥器中取出晶片，并使用光学显微镜和XPS进行检查，以确定颗粒层是均匀和封闭的。重复步骤 2.2.1 和 2.2.2，直到分析显示一个封闭且均匀的层。该协议可以在此处暂停。</li>
	</ol>
</li>
	<li>水悬浮液中电非导电纳米颗粒的旋涂<ol>
<li>将晶圆放入紫外线/臭氧清洁剂中30分钟。 注意:通过使用相同的方案对不同浓度的悬浮液进行旋涂，可以实现不同水平的表面覆盖。</li>
		<li>对旋转涂布机进行编程。一个合适的示例程序是:步骤1:500 rpm / s斜坡到1，000 rpm（5 s）;第 2 步:1，000 转/秒斜坡至 2，000 转/分（3 分钟）;第 3 步:以 2，000 rpm/s 至 0 rpm 的速度减速。</li>
		<li>将晶圆插入旋涂机，打开真空进行固定。</li>
		<li>将80μL悬浮液沉积在晶圆上并开始程序。</li>
		<li>从旋涂机中取出晶圆。</li>
		<li>将样品储存在新的、干净的晶圆托盘中。该协议可以在此处暂停。</li>
		<li>使用SEM分析样品，以确认基板的无间隙覆盖。</li>
	</ol>
</li>
</ol>3. 从粉末中沉积纳米颗粒
<ol><li>纳米颗粒沉积在双面胶带上（"粘住就走"）<ol>
<li>将双面胶粘剂固定在样品架上，然后取下衬垫。</li>
		<li>取纳米颗粒粉末的刮刀尖端，并将其浸入粘合剂上。</li>
		<li>将样品铺在粘合剂上，并用刮刀压入粘合剂中，直到尽可能多的粉末粘附。</li>
		<li>通过倒置和敲击样品架，并通过吹过样品架的气体流（例如氮气）来检查粉末是否固定在水龙头上。该协议可以在此处暂停。 注意:或者，可以将少量粉末放在清洁的表面上（铝箔或载玻片），然后用粘合剂和双面样品架从上方压制。</li>
		<li>将粉末的刮刀尖端放在清洁的表面上。将带有粘合剂的样品架从上方压到粉末上。</li>
		<li>通过倒置和敲击样品架，并通过吹过样品架的气体流（例如氮气）来检查粉末是否固定在水龙头上。该协议可以在此处暂停。</li>
	</ol>
</li>
	<li>
压制粉末颗粒的制备
	<ol>
<li>彻底清洁颗粒模具的所有部分，注意不要划伤抛光表面。</li>
		<li>倒置沉淀模具并放在一个小垫片上。</li>
		<li>插入柱塞和一个不锈钢颗粒，抛光面朝上，并将柱塞拉过，直到有足够的空间填充粉末样品。</li>
		<li>用少量样品（1个大铲头）填充模具，然后插入第二个不锈钢沉淀，抛光面朝向样品。</li>
		<li>将底座放在身体上，小心地倒置。如果需要真空并且可用，请将真空泵连接到颗粒模具的底部。</li>
		<li>将模具放入压力机中，确保其居中。</li>
		<li>施加轻负荷（2 kN）约20秒并释放。</li>
		<li>施加较重的负载（6 kN）2分钟并释放。</li>
		<li>释放负载后，释放真空泵。 注意:由于各种纳米颗粒的材料性质不同，制备一系列具有不同载荷和载荷时间的颗粒以确定最佳颗粒压制条件可能是有利的。</li>
		<li>倒置模具，将提取环放置到位，并在柱塞和提取环之间放置轻负载（最大1 kN）。</li>
		<li>从压机上取出模具部件，并用镊子小心地提取样品沉淀。</li>
		<li>使用双面粘合剂将样品轻轻地安装在清洁的Si晶圆上。该协议可以在此处暂停。</li>
	</ol>
</li>
</ol>4. 纳米颗粒悬浮液的冷冻固定
<ol><li>用液氮填充快速冷冻装置的主腔。</li>
	<li>用冷冻剂（丙烷）填充冷却的快冻室。</li>
	<li>让快速冷冻设备冷却至其工作温度。 注:在样品制备之前，快速冷冻装置需要一些时间才能达到工作温度，因此冷冻固定样品需要合理的时间范围（几个小时）。</li>
	<li>用移液器将10-20μLNP悬浮液滴铸到清洁的Si晶圆上。</li>
	<li>用固定镊子握住硅晶圆，将其放入陷入式冷冻装置内。</li>
	<li>将固定镊子移动到切入位置。</li>
	<li>按下按钮将样品放入制冷剂内。</li>
	<li>等待几秒钟，直到样品完全冻结。</li>
	<li>将冷冻样品尽可能快地转移到冷却环境中。</li>
	<li>将冷冻固定的样品（硅晶圆）放入样品架中，并将其转移到仪器内。 注意:对于运输，建议使用干冰，并且可以短期储存样品。样品可以在冷冻状态下使用冷却仪器或在稳定后通过冷冻干燥样品来测量样品。</li>
</ol>

作者没有竞争利益可披露。

已经提出了许多使用XPS和ToF-SIMS制备用于表面分析的纳米颗粒的方法。我们在 表2中总结了这些方法的优缺点，以及误差的可能来源和不同材料的适用性。如代表性结果所示，纳米颗粒的制备可以强烈影响所得表面分析的成功。此外，由于信号干扰基板或安装材料，非导电厚膜中的充电效应，纳米颗粒作为粉末或悬浮液的状态，敏感外层的潜在损坏，生物结构的破坏以及聚集和界面上的信息，或敏感的超高真空仪器对自由纳米颗粒的脆弱性等因素，并非所有方法都适用于所有颗粒类型。
由于XPS和ToF-SIMS测量在一个区域内是平均的，而不是测量单个颗粒，因此只能从均匀的层中获得可重复的结果;因此，应避免颗粒在基板上聚集或团聚。此外，太厚的非导电材料层在分析过程中会引起充电效应，这可能导致光谱中出现不需要的伪影，特别是无法用泛光枪补偿的部分电荷。另一方面，不完整的薄膜显示来自基板或安装材料（例如粘合剂）的强信号，这可能会干扰来自颗粒表面的敏感峰。薄膜的理想厚度取决于材料，应通过对不同厚度薄膜的分析通过实验确定。特别是，使用旋涂制备的样品应使用SEM进行分析，以确保涂层的完整性。
与使用NP粉末相比，使用NP悬浮液的暴露危险和安全要求更少。液滴铸是一种相对简单的方法，设备要求较低，特别适用于不考虑薄膜厚度的悬浮液中的导电纳米颗粒。虽然样品可以在大气条件下轻松干燥，但真空干燥器用于减少液滴的干燥时间，并保护晶圆免受污染。氟橡胶环用于改变液滴的蒸发模式，从而最大限度地减少咖啡环的形成。蒸发模式也可能受到使用清洁方案改变基材亲水性或通过应用替代涂层51，52，在溶剂气氛中蒸发53，甚至通过加热基质54的影响。对于悬浮液中非导电纳米颗粒的悬浮液，建议使用旋涂，因为它能够产生足够薄的均匀颗粒层以避免充电效应，但仍然足够厚以防止Si衬底对XPS和ToF-SIMS光谱做出贡献。对于每个单独的NP系统和浓度，离心机和旋涂参数都必须进行优化，但即使在不同的仪器上也可以非常可靠地再现。由于旋涂液滴始终位于晶圆的中间，因此旋转半径无关紧要，可以使用"每分钟转数"（rpm）单位。启动程序后，悬浮液也可以沉积在晶圆上;然而，这将需要不同的旋涂参数和更多的悬浮液来获得更厚的涂层。
由于其极小的尺寸，纳米颗粒可能从基板上脱落，并在受到离子或X射线束撞击时在超高真空室内自由移动。对于用粉末制备的样品来说，这是一个特殊的问题。在某些情况下，纳米颗粒可以渗透到仪器的敏感组件中，需要昂贵且耗时的维护。由于施加了加速电压，使用ToF-SIMS损坏敏感部件的危险比使用XPS更大。粉末状样品，特别是使用"粘即走"方法制备的粉末样品，应仔细检查，以确保粉末足够牢固地固定，特别是对于ToF-SIMS分析。例如，可以通过将样品倒置并吹过其上的气体流（例如N2）来证实这一点。在分析之前，样品也可以在仪器的气闸或其他初始样品进入室中过夜，其中稳定的真空可以表明样品中没有松散的颗粒。然而，作为颗粒制备的纳米颗粒甚至可以溅射（在低加速度电压下）而不会损坏仪器;这种方法可以消除从压机引入的污染物，特别是碳氢化合物，还可以对颗粒进行批量分析。
在样品架存根中制备NP粉末可以制备具有定义几何形状和宏观平坦表面的样品。关键点是压制样品的工具的清洁度，以及使用低压以避免由于该过程而导致纳米颗粒表面的变化。它的缺点是需要相对大量的材料，以及高真空仪器中材料损失的潜在问题。我们不建议将此方法用于ToF-SIMS分析，因为颗粒不会以任何方式压缩或固定。
关于NP材料，样品制备的首要考虑因素是消除或尽量减少NP与类似材料的基板之间的干扰;例如，硅晶圆不适合使用XPS和ToF-SIMS分析SiO2 NPs，即使有足够的样品覆盖率。由于纳米颗粒和双面粘合剂之间缺乏信号干扰，金属或无机纳米颗粒可以很容易地分析为粘合剂上的粉末（假设它们不包含有机层或涂层），这种制备方法不适合聚合物NP。 并且可能是用相对较少的设备进行直接铸造的;然而，它们可能含有来自其合成的大量杂质和稳定剂，必须小心地去除而不损坏颗粒。聚合物纳米颗粒可能更容易被模压损坏，但也可能更容易在颗粒中保持在一起，这取决于所使用的压力。NP表面上的颗粒或柔软的有机涂层也可能对损伤敏感。溶液中的直接沉积有可能通过悬浮液或干燥过程损坏敏感涂层，但对于分析悬浮液中已经存在的NP是有利的。冷冻固定是分析悬浮液中化学结构、表面或界面的合适方法，这些结构、表面或界面会被各种其他样品制备技术损坏或破坏，但需要XPS和ToF-SIMS46'47的专用冷冻设备。
虽然本文描述了几种可用于样品制备的示例性方法，但在每种情况下，都应使用替代分析方法对该方法进行优化和验证。最近发表了不同因素影响的详细概述22。除了开发和验证合适的制备方法外，这些步骤的记录也至关重要40。本出版物介绍了一些易于处理的方法，并指导您根据特定任务的要求修改或开发新方法。

纳米材料被定义为具有1 nm至100 nm之间的任何外部尺寸或在此尺度上具有内部或表面结构的材料1。由于其小规模和相应大表面积（以及其他因素）所产生的独特性能，它们在农业，化学，汽车制造，化妆品，环境，医药，印刷，能源和纺织等广泛领域中得到越来越多的应用。这种使用的增加意味着人类和环境都将以前所未有的规模暴露于这些材料，这些材料的毒理学性质尚不完全清楚，其尺寸使其能够轻松集成到生物或环境系统中2。
在表面积和粒径/粒径分布的基本性质之后，表面化学和涂层被确定为纳米材料最关键的特性3;较小的颗粒具有更高的单位质量表面积，因此表面与体积原子的比例更高。实际上，对于1nm大小的纳米颗粒，可以在角落或边缘找到超过70%的原子;这强烈影响了表面性质，例如化学吸附，其高度依赖于原子尺度的表面形态4。涉及纳米材料的法规要求有关物理化学性质的准确数据以及对这些材料的毒理学性质的可靠估计。为了从纳米材料的物理和化学性质中有效地估计毒理学性质，纳米材料界需要可靠，标准化和经过验证的分析程序。ACEnano5等项目旨在收集和关联来自纳米颗粒的准确和可验证的物理数据，以便更好地调节和表征纳米材料。ACS Nano的编辑们也支持这种对标准化分析程序的推动，希望"巩固并商定表征方法和材料的最低分析水平6"。此外，XPS和ToF-SIMS为阐明核壳纳米粒子的粒子结构提供了新的可能性7，8。
与表1中比较的X射线光电子能谱（XPS）和飞行时间二次离子质谱（ToF-SIMS）是研究表面原子的成熟方法。在XPS中，样品被能量在1到2 keV之间的X射线照射，由于光电效应导致电子发射。这些发射的电子具有相同范围内的动能，与固体中电子的结合能相关;因此，在这些定义的结合能和可测量的强度下，光电子的外观允许对成分进行定量分析。由于这些光电子的平均游离途径低于10 nm，因此XPS是一种用于定量分析的高表面敏感技术。此外，对高分辨光谱中结合能的详细分析使得能够定量测定这些电子的价态。
在ToF-SIMS中，表面用聚焦离子束（初级离子）溅射，从材料中喷射的离子（二次离子）在飞行时间质谱仪中收集和分析。获得的质量/电荷图允许测定元素，同位素或分子组成。由于二次离子的平均自由通路，该技术也具有高度的表面敏感性，并且具有1-2nm的信息深度，但由于基质效应，二次离子的电离概率（因此产量）受到其周围基质的强烈影响，因此充其量是半定量的。ToF-SIMS可以在静态或动态模式下运行;两者之间的区别在于影响表面的主要离子通量。静态SIMS将初级离子通量保持在影响（即碎片）最多1%-10%表面的水平;表面保持相对不受干扰，这允许分析材料的顶层原子层。由于即使是静态SIMS也会对表面造成一些破坏，因此这两种方法被认为"非破坏性"较小。
这些表面敏感技术允许分析材料的前几纳米，包括有意或无意的涂层，对于纳米材料，这些涂层可以显着影响材料性能。有意涂层的例子包括:在量子点上封顶层以提高光致发光量子产率并降低环境反应性9，氧化铝或二氧化硅涂层用于防止防晒剂中二氧化钛纳米颗粒的光催化活性10，表面功能化以实现生物结合和随后的生物活性11，用于诊断和药物递送应用的涂层12和碳氟化合物涂层在磁性颗粒上，用于铁磁流体和核壳金属体系，以提高催化剂性能13。生物系统中的无意涂层，如氧化，表面污染或蛋白质电晕对纳米颗粒性质具有同样强烈的影响，并且至关重要的是，实验制备程序确保涂层以及更普遍的纳米材料的表面化学不被破坏或转化。评估纳米颗粒的性质也至关重要，因为它们是原位的，因为它们的性质可以通过变化而发生巨大变化2，14，15。此外，纳米颗粒悬浮液中稳定剂的浓度可以显着影响纳米颗粒的分析和结构完整性;稳定剂的存在可能导致分析中出现大的不需要的信号（例如，C，H，O和Na），而其去除可能导致纳米颗粒的损坏或团聚。
由于它们的尺寸和表面积，纳米颗粒的储存条件也会影响它们的行为，无论是作为储存的粉末/悬浮液还是作为制备的样品。各种研究表明，次优储存条件的影响，特别是室温储存和暴露在光下，会导致纳米颗粒降解，这已被证明会改变颗粒的物理，化学和/或毒理学性质14，15，16，17，18.较小的纳米颗粒已被证明比较大的纳米颗粒氧化更快，其氧化/降解速率取决于储存条件15以及表面化学14。储存过程中纳米颗粒降解的影响已被证明会显着影响物理化学性质，包括毒性14，而氧化生长可以以牺牲核心为代价向内进行15。
因此，仔细储存和制备纳米材料对于准确的表面分析至关重要，并且应仔细考虑可能影响样品表面和/或测量质量的任何因素。应该注意的是，由于XPS（在μm范围内）和ToF-SIMS（几百nm）的空间分辨率相对较低，因此只能研究纳米颗粒的一小部分;这些方法在一个区域内平均，并且不具备像电子显微镜等技术那样对单个粒子进行成像的能力。因此，任何分析都需要将纳米颗粒沉积在连续层中，以确保没有来自基板的干扰。因此，电子显微镜和XPS / ToF-SIMS通常一起用作纳米材料分析的补充方法。
除了表面化学的变化之外，制备用于XPS和ToF-SIMS分析的纳米颗粒样品的主要挑战是制备一层:均匀的，以提高可重复性;无间隙，以尽量减少基板对光谱的贡献;足够薄以避免充电效应（对于非导电样品）;并牢固地固定在基板上，以避免自由纳米颗粒进入并损坏超高真空仪器
纳米颗粒可以从悬浮液或粉末沉积到基板上。首先，我们将讨论从悬浮液中沉积纳米颗粒的不同方法。硅晶片是悬浮沉积常用的衬底，因为它们相对便宜，很容易作为由纯硅或掺杂硅组成的高纯度产品（掺杂避免充电效应），并且对于大多数纳米颗粒，光谱峰不与纳米颗粒的典型峰重叠。这最后一点是重要的。在分析之前，应确保衬底峰与纳米颗粒的预期峰值很好地分离，否则光谱的解释是复杂或不可能的，并且无法验证纳米颗粒对衬底的连续覆盖。在使用硅晶圆之前，需要广泛的清洁程序（如本出版物所述）以去除（有机）污染物并提高表面润湿性。其他合适的基材，如金膜，高序热解石墨（HOPG）或铟箔已被成功使用，但关于其制备的讨论超出了本工作的范围19，20，21，22。
其次，我们提出了在基板上沉积纳米颗粒粉末的方法，用于XPS和ToF-SIMS分析，并介绍了每种方法的优缺点，使该技术的研究人员能够找到适合其目的的最佳制备方法。第三，我们讨论了冷冻固定，这是一种合适的制备方法，可以保存诸如团聚行为，有机电晕，固体/水界面23，24 或NPs生物介质25 中的分布等特征。该过程不会导致冰晶形成，但会形成无定形冰，使膜以及细胞和组织结构保持其天然生物状态，避免水结晶过程造成的损害，并使所有细胞代谢物和细胞膜化合物的精确化学分布得以维持26，27，28.该制备方法对于呈现实际NP附聚物或杂凝聚物的精确化学图谱，在悬浮液中直接在纳米颗粒附近可视化精确化学空间，或关联NP附聚物或杂聚物内的细胞组织特异性特征或细胞内区室可能特别感兴趣。
通过本工作中呈现的结果所示，在特定情况下最合适的程序取决于各种参数，例如纳米颗粒的亲水性，稳定性，导电性，状态（例如，粉末或悬浮液）和手头的分析问题（例如，尺寸，体积性质或表面涂层）。这里介绍了可用于制备用于表面分析的NP的各种方法，以及其优缺点的比较。

<table><tbody><tr><td>4-figure Laboratory balance</td><td>Kern &amp;amp; Sohn GmbH</td><td>ADB200-4A</td><td></td></tr><tr><td>5 mm Pellet die</td><td>Specac</td><td>GS03060</td><td></td></tr><tr><td>Alkali glass cleaning solution</td><td>Sigma-Aldrich</td><td>Hellmanex&amp;trade; III Z805939</td><td>Special cleaning solution for cuvettes</td></tr><tr><td>Carbon adhesive tabs</td><td>Plano</td><td>&quot;Leit-Tabs&quot; G3347</td><td></td></tr><tr><td>Clean laboratory beakers</td><td>any</td><td></td><td>e.g. 300 mL</td></tr><tr><td>Cryo-freezer</td><td>Electron Microscopy Sciences</td><td>EMS-002 Cryo Workstation</td><td></td></tr><tr><td>Dialysis tube with fasteners</td><td>Medicell Membranees Ltd</td><td>DTV12000.06.30</td><td>Molecular weight cut-off (MWCO) 12-14 kDa</td></tr><tr><td>Die press</td><td>any</td><td></td><td>Capable of 2 kN force</td></tr><tr><td>Disposable syringe, 1 mL, Luer-slip</td><td>TH Geyer</td><td>Labsolute 7657545</td><td>Any appropriate volume can be used</td></tr><tr><td>Double-sided adhesive</td><td>3M</td><td>Removable Repositionable Tape 665</td><td></td></tr><tr><td>Dry ice</td><td>Linde AG</td><td>ICEBITZZZ&lt;sup&gt;&amp;reg;&lt;/sup&gt;</td><td>For short term storage/cooling</td></tr><tr><td>Eppendorf transfer pipette and tips</td><td>Eppendorf</td><td>various</td><td>Check correct size for planned pipetting volume</td></tr><tr><td>Ethanol, ACS grade</td><td>Merck KGaA</td><td>1009832500</td><td></td></tr><tr><td>FFP2 or FFP3 mask</td><td>various</td><td></td><td>For working with nanoparticles from non-hazardous materials, when not in a fume hood or glove box</td></tr><tr><td>Isopropanol, ACS grade</td><td>Merck KGaA</td><td>1096342500</td><td></td></tr><tr><td>Lab coat, gloves and goggles</td><td>any</td><td></td><td></td></tr><tr><td>Laboratory centrifuge</td><td>Eppendorf</td><td>Centrifuge 5430</td><td></td></tr><tr><td>Laboratory fume hood</td><td>any</td><td></td><td>necessary for working with nanoparticles</td></tr><tr><td>Laboratory stirrer &amp;amp; stirrer bar</td><td>NeoLab</td><td>D-6010</td><td></td></tr><tr><td>Lint-free wipes</td><td>Kimberley Clark Professional</td><td>Kimtech Science Precision wipes</td><td>Recommended for working with Si wafers</td></tr><tr><td>Liquid Nitrogen</td><td>Linde AG</td><td>Stickstoff fl&amp;uuml;ssig 5.0</td><td>Only for cooling of the cryogen.</td></tr><tr><td>Microtube/centrifuge tube 1,5 mL</td><td>T.H. Geyer GmbH &amp;amp; Co. KG</td><td>Labsolute 7696751</td><td></td></tr><tr><td>Nitrogen 5.0</td><td>any</td><td></td><td>99.999% purity</td></tr><tr><td>Pasteur pipette, PE, plastic 3 mL</td><td>TH Geyer</td><td>Labsolute 7 691 203</td><td></td></tr><tr><td>Pasteur pipette, PE, plastic 3 mL</td><td>TH Geyer</td><td>Labsolute 7 691 203</td><td></td></tr><tr><td>Powder sample holder</td><td>BAM workshop</td><td></td><td>&quot;Home-made&quot; sample holder</td></tr><tr><td>Propane</td><td>Sigma-Aldrich</td><td>769037</td><td>The cryogen should be of highest possible purity.</td></tr><tr><td>Sample vial or centrifuge tube 1 mL</td><td>Greiner Bio-One GmbH</td><td>Cellstar 188 261</td><td>Should be capable of being fixed in the Vortexer</td></tr><tr><td>Silicon wafers</td><td>any</td><td></td><td>ideally 1cm&lt;sup&gt;2&lt;/sup&gt; pre-cut</td></tr><tr><td>Spin-coater</td><td>SPS Europe</td><td>SPIN150i-NPP</td><td></td></tr><tr><td>Syringe filter 0,45 &amp;micro;m</td><td>Th Geyer</td><td>Labsolute 7699803</td><td>For smaller samples; larger versions exist for larger sample volumes</td></tr><tr><td>ToF-SIMS</td><td>IONTOF GmbH</td><td>ToF-SIMS IV or V, equipped with Bi LMIG and flood gun</td><td></td></tr><tr><td>Tweezers for handling Si wafers</td><td>any</td><td></td><td></td></tr><tr><td>ultrapure water</td><td>TKA</td><td>MicroPure 08.1202</td><td></td></tr><tr><td>Ultrasonicator</td><td>Bandelin</td><td>Sonorex Super</td><td></td></tr><tr><td>UV/Ozone cleaner</td><td>NanoBioAnalytics</td><td>UVC-1014</td><td></td></tr><tr><td>Vacuum dessicator</td><td>any</td><td></td><td></td></tr><tr><td>Vacuum pump (membrane/diaphragm)</td><td>Vacuubrand GmbH</td><td>Type MD-4T</td><td></td></tr><tr><td>Viton O-ring 6.07 x 1.78 mm</td><td>Betech GmbH</td><td>2-010, FKM 80</td><td></td></tr><tr><td>Vortexer</td><td>Heathrow Scientific</td><td>Vortexer HS120212</td><td></td></tr><tr><td>Wafer Holder 25mm coin style</td><td>Semiconductor Production Systems Europe</td><td>eWB0091-ASSY-1</td><td></td></tr><tr><td>XPS</td><td>Kratos</td><td>Kratos Axis Ultra DLD</td><td></td></tr></tbody></table>

preparation of nanoparticles for tof-sims and xps analysis

近年来，纳米颗粒由于其在医学，化妆品，化学等不同领域的潜力和应用以及它们使先进材料成为可能而受到越来越多的关注。为了有效地理解和调节纳米颗粒的物理化学性质和潜在的不利影响，需要开发经过验证的纳米颗粒各种性质的测量程序。虽然测量纳米颗粒尺寸和尺寸分布的程序已经建立，但分析其表面化学性质的标准化方法尚未到位，尽管表面化学对纳米颗粒性质的影响是无可争议的。特别是，用于表面分析的纳米颗粒的储存和制备强烈影响各种方法的分析结果，为了获得一致的结果，样品制备必须既优化又标准化。在本文中，我们详细介绍了一些制备用于表面分析的纳米颗粒的标准程序。原则上，纳米颗粒可以从悬浮液或粉末沉积在合适的基板上。硅（Si）晶圆通常用作基板，但是，它们的清洁对工艺至关重要。对于悬浮液的样品制备，我们将讨论滴铸和旋涂，其中不仅基质的清洁度和悬浮液的纯度，而且其浓度对制备方法的成功起着重要作用。对于具有敏感配体壳或涂层的纳米颗粒，沉积为粉末更合适，尽管这种方法在固定样品时需要特别注意。

Watch this Scientific Journal Video about Preparation of Nanoparticles for ToF-SIMS and XPS Analysis at JoVE.com

Preparation of Nanoparticles for ToF-SIMS and XPS Analysis

介绍了制备用于表面分析的纳米颗粒的多种不同程序（滴铸，旋涂，粉末沉积和冷冻固定）。我们讨论了每种方法的挑战，机遇和可能的应用，特别是关于不同制备方法引起的表面性能变化。

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, ...

preparation-of-nanoparticles-for-tof-sims-and-xps-analysis

Research

JoVE Journal

Chemistry

7.9K 次观看.  Federal Institute for Material Research and Testing (BAM). 介绍了制备用于表面分析的纳米颗粒的多种不同程序（滴铸，旋涂，粉末沉积和冷冻固定）。我们讨论了每种方法的挑战，机遇和可能的应用，特别是关于不同制备方法引起的表面性能变化。

视频: Preparation of Nanoparticles for ToF-SIMS and XPS Analysis

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of novel materials. Coupled with analysis by in situ secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS), soft landing provides unprecedented insights into the interactions of well-defined species with surfaces.

在质谱选择离子软着陆准备好定义的表面原位二次离子质谱和红外光谱

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using ...

科研

化学

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

能量色散X射线断层摄影术对个人纳米3D元素映射

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

工程学

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 ...

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

We describe the synthesis and properties of multifunctional Fe2O3-Au nanoparticles produced by a wet chemical approach and investigate their photothermal properties using laser irradiation. The composite Fe2O3-Au nanoparticles retain the properties of both materials, creating a multifunctional structure with excellent magnetic and plasmonic properties.

多功能混合铁<sub&gt; 2</sub&gt; 0<sub&gt; 3</sub&gt; -Au纳米粒子高效的电浆暖气

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to ...

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO&#903;, -H2C&#903;, -O&#903;, -CO&#903; radicals. During the degradation process, CO and CO2 were also produced.

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

表面上的纳米硅聚酯涂料暴露在阳光下的演变

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, ...

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

Micro-analytical techniques based on chemical element imaging enable the localization and quantification of chemical composition at the cellular level. They offer new possibilities for the characterization of living systems and are particularly appropriate for detecting, localizing and quantifying the presence of metal oxide nanoparticles both in biological specimens and the environment. Indeed, these techniques all meet relevant requirements in terms of (i) sensitivity (from 1 up to 10 &#181;g.g-1 of dry mass), (ii) micrometer range spatial resolution, and (iii) multi-element detection. Given these characteristics, microbeam chemical element imaging can powerfully complement routine imaging techniques such as optical and fluorescence microscopy. This protocol describes how to perform a nuclear microprobe analysis on cultured cells (U2OS) exposed to titanium dioxide nanoparticles. Cells must grow on and be exposed directly in a specially designed sample holder used on the optical microscope and in the nuclear microprobe analysis stages. Plunge-freeze cryogenic fixation of the samples preserves both the cellular organization and the chemical element distribution. Simultaneous nuclear microprobe analysis (scanning transmission ion microscopy, Rutherford backscattering spectrometry and particle induced X-ray emission) performed on the sample provides information about the cellular density, the local distribution of the chemical elements, as well as the cellular content of nanoparticles. There is a growing need for such analytical tools within biology, especially in the emerging context of Nanotoxicology and Nanomedicine for which our comprehension of the interactions between nanoparticles and biological samples must be deepened. In particular, as nuclear microprobe analysis does not require nanoparticles to be labelled, nanoparticle abundances are quantifiable down to the individual cell level in a cell population, independently of their surface state.

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

We describe a procedure for the detection of chemical elements present in situ in human cells as well as their in vitro quantification. The method is well-suited to any cell type and is particularly useful for quantitative chemical analyses in single cells following in vitro metal oxide nanoparticles exposure.

原位金属氧化物纳米粒子的核探针检测与单细胞定量研究

Micro-analytical techniques based on chemical element imaging enable the localization and quantification of chemical composition at the cellular level. ...

Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, the focus is on metallic substrates immersed in acidic solutions containing organic corrosion inhibitors, as these systems can be particularly sensitive to oxidation following removal from solution. To minimize the likelihood of such degradation, samples are removed from solution within a glove box purged with inert gas, either N2 or Ar. The glove box is directly attached to the load-lock of the ultra-high vacuum X-ray photoelectron spectroscopy instrument, avoiding any exposure to the ambient laboratory atmosphere, and thus reducing the possibility of post immersion substrate oxidation. On this basis, one can be more certain that the X-ray photoelectron spectroscopy features observed are likely to be representative of the in situ submerged scenario, e.g. the oxidation state of the metal is not modified.

A protocol to avoid the oxidation of metallic substrates during sample transfer from an inhibited acidic solution to an X-ray photoelectron spectrometer is presented.

确定缓蚀剂/金属界面的化学成分与XPS:最小化后浸入氧化

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, ...

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution of capping ligands during the synthesis reaction, their role in regulating the nucleation and growth rates of colloidal nanoparticles is not well understood. In this work, we demonstrate a mechanistic investigation of the role of trioctylphosphine (TOP) in Pd nanoparticles in different solvents (toluene and pyridine) using in situ SAXS and ligand-based kinetic modeling. Our results under different synthetic conditions reveal the overlap of nucleation and growth of Pd nanoparticles during the reaction, which contradicts the LaMer-type nucleation and growth model. The model accounts for the kinetics of Pd-TOP binding for both, the precursor and the particle surface, which is essential to capture the size evolution as well as the concentration of particles in situ. In addition, we illustrate the predictive power of our ligand-based model through designing the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can be applied to other synthesis systems and therefore serves as an effective strategy for predictive synthesis of colloidal nanoparticles.

The main goal of this work is to elucidate the role of capping agents in regulating the size of palladium nanoparticles by combining in situ small angle x-ray scattering (SAXS) and ligand-based kinetic modeling.

配体介导成核与钯金属纳米粒子的生长

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution ...

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 ...

Imaging Corrosion at the Metal-Paint Interface Using Time-of-Flight Secondary Ion Mass Spectrometry

Corrosion developed at the paint and aluminum (Al) metal-paint interface of an aluminum alloy is analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), illustrating that SIMS is a suitable technique to study the chemical distribution at a metal-paint interface. The painted Al alloy coupons are immersed in a salt solution or exposed to air only. SIMS provides chemical mapping and 2D molecular imaging of the interface, allowing direct visualization of the morphology of the corrosion products formed at the metal-paint interface and mapping of the chemical after corrosion occurs. The experimental procedure of this method is presented to provide technical details to facilitate similar research and highlight pitfalls that may be encountered during such experiments.

Time-of-flight secondary ion mass spectrometry is applied to demonstrate the chemical mapping and corrosion morphology at the metal-paint interface of an aluminum alloy after being exposed to a salt solution compared with a specimen exposed to air.