Synthesis and characterization of isotopically labeled silver nanoparticles for tracing studies
Synthesis and characterization of isotopically labeled silver nanoparticles for tracing studies
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DOI：
10.1039/c3en00100h
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发表时间：
2014-05
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通讯作者：
Adam Laycock;B. Stolpe;I. Römer;A. Dybowska;E. Valsami-Jones;J. Lead;M. Rehkämper
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文献类型：
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作者：
Adam Laycock;B. Stolpe;I. Römer;A. Dybowska;E. Valsami-Jones;J. Lead;M. Rehkämper
银纳米颗粒（AgNPs）越来越多地用于工业过程和消费产品中，导致向自然环境的排放增加。为了了解银纳米颗粒的行为和环境命运，至关重要的是，它们可以在高灵敏度的暴露中在复杂的天然样品中被追踪。稳定同位素标记技术非常适合这一目的。为了支持这样的应用程序，我们提出了一个详细的评估技术的稳定同位素标记的银纳米粒子的制备和证明，同位素修饰的颗粒是唯一的区别与天然同位素组成的颗粒，其强大的同位素签名。通过用硼氢化钠还原硝酸银溶液，合成了目标尺寸为17、20和30 nm的柠檬酸盐稳定的AgNPs的单分散悬浮液。AgNP悬浮液是使用天然Ag和107Ag富集到99.2%的Ag制备的，天然Ag由两种稳定同位素107Ag（52%）和109Ag（48%）组成。在两个实验室中，合成在三个不同的场合可靠地再现。在合成后不久和储存长达12个月后，使用动态光散射（DLS）对AgNP进行表征。还使用透射电子显微镜（TEM）和不对称流场流分级（FlFFF）对一些批次进行了表征。粒度分布在实验室之间显示出良好的重现性，并在12个月的储存期内保持稳定性。重要的是，富含107 Ag的颗粒在尺寸和形状上与具有天然同位素组成的颗粒难以区分。可靠性、对颗粒尺寸的控制以及约80%的高产率表明该合成技术非常适合于同位素标记的AgNP的小规模生产。同位素质量平衡计算进一步表明，标记的应用使得能够追踪灵敏度为AgNP的至少40倍，并且可能高达4000倍，高于用本体Ag浓度测量和接近预测的环境水平的暴露浓度的实验可实现的灵敏度，如果采用最精确的同位素测量技术。
Silver nanoparticles (AgNPs) are ever more being used in industrial processes and consumer products, resulting in increasing emissions to the natural environment. To understand the behavior and environmental fate of AgNPs, it is paramount that they can be traced in complex natural samples from exposures at high sensitivity. The technique of stable isotope labeling is ideally suited for this purpose. To support such applications, we present a detailed evaluation of techniques for the preparation of stable isotope labeled AgNPs and demonstrate that isotopically modified particles are only distinguishable from particles with a natural isotope composition by their strong isotopic signature. Monodisperse suspensions of citrate-stabilized AgNPs with target sizes of 17, 20 and 30 nm were synthesized by reduction of silver nitrate solutions with sodium borohydride. The AgNP suspensions were produced using both natural Ag, which is comprised of the two stable isotopes 107Ag (52%) and 109Ag (48%), and Ag enriched to 99.2% in 107Ag. Synthesis was reliably reproduced on three separate occasions in two laboratories. The AgNPs were characterized using dynamic light scattering (DLS) shortly after synthesis and after up to 12 months storage. Some of the batches were also characterized using transmission electron microscopy (TEM) and asymmetric flow field-flow fractionation (FlFFF). The particle size distributions showed good reproducibility between the laboratories and stability over 12 months of storage. Importantly, the 107Ag-enriched particles were indistinguishable in size and shape from particles with a natural isotope composition. The reliability, control on particle size, and high yield of about 80%, demonstrate that the synthesis technique is well suited for small-scale production of isotopically labeled AgNPs. Isotope mass balance calculations furthermore show that the application of labeling enables tracing sensitivities for AgNPs that are at least 40 times, and possibly up to 4000 times, higher than those achievable with bulk Ag concentration measurements and experiments with exposure concentrations that approach predicted environmental levels are possible, if the most precise isotopic measurement techniques are employed.