UNLABELLED A novel methodology to detect unlabeled inorganic nanoparticles was experimentally demonstrated using a mixture of nano-sized (70 nm) and submicron (250 nm) silicon dioxide particles added to mammalian tissue. The size and concentration of environmentally relevant inorganic particles in a tissue sample can be determined by a procedure consisting of matrix digestion, particle recovery by centrifugation, size separation by sedimentation field-flow fractionation (SdFFF), and detection by light scattering. BACKGROUND Laboratory nanoparticles that have been labeled by fluorescence, radioactivity, or rare elements have provided important information regarding nanoparticle uptake and translocation, but most nanomaterials that are commercially produced for industrial and consumer applications do not contain a specific label. METHODS Both nitric acid digestion and enzyme digestion were tested with liver and lung tissue as well as with cultured cells. Tissue processing with a mixture of protease enzymes is preferred because it is applicable to a wide range of particle compositions. Samples were visualized via fluorescence microscopy and transmission electron microscopy to validate the SdFFF results. We describe in detail the tissue preparation procedures and discuss method sensitivity compared to reported levels of nanoparticles in vivo. CONCLUSION Tissue digestion and SdFFF complement existing techniques by precisely identifying unlabeled metal oxide nanoparticles and unambiguously distinguishing nanoparticles (diameter<100 nm) from both soluble compounds and from larger particles of the same nominal elemental composition. This is an exciting capability that can facilitate epidemiological and toxicological research on natural and manufactured nanomaterials.

中文翻译：

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一种通过沉降场流分级检测组织中未标记无机纳米颗粒和亚微米颗粒的新方法。

未标记 使用添加到哺乳动物组织中的纳米级 (70 nm) 和亚微米级 (250 nm) 二氧化硅粒子的混合物，通过实验证明了一种检测未标记无机纳米粒子的新方法。组织样品中与环境相关的无机颗粒的大小和浓度可以通过由基质消化、离心回收颗粒、沉降场流分级 (SdFFF) 的尺寸分离和光散射检测组成的程序确定。背景技术已被荧光、放射性或稀有元素标记的实验室纳米粒子提供了关于纳米粒子吸收和易位的重要信息，但为工业和消费应用商业生产的大多数纳米材料不包含特定标签。方法用肝和肺组织以及培养的细胞测试硝酸消化和酶消化。用蛋白酶混合物进行组织处理是优选的，因为它适用于广泛的颗粒组合物。通过荧光显微镜和透射电子显微镜观察样品以验证 SdFFF 结果。我们详细描述了组织制备程序，并讨论了与报告的体内纳米颗粒水平相比的方法敏感性。结论 组织消化和 SdFFF 通过精确识别未标记的金属氧化物纳米颗粒和明确区分纳米颗粒（直径 <100 nm）与可溶性化合物和具有相同标称元素组成的较大颗粒来补充现有技术。