In realistic exposure scenarios, the detection and quantification of engineered nanoparticles in complex environmental or biological matrixes is a challenge since nanoparticle concentrations are frequently low and have to be discerned from a background that may contain the same elements in various chemical forms in much higher concentrations. The use of radiolabelled nanoparticles may overcome these difficulties offering high detection sensitivity without the necessity of complex sample preparation procedures. However, the labelling procedure must not alter the physicochemical and biological properties of the nanoparticles. In the present work, the radiolabelling of three different types of TiO₂ nanoparticles with primary particle sizes between 5 nm and 26 nm with commercially available ⁴⁴Ti has been investigated applying a simple diffusion heat treatment at 180 °C for 2.5 h on nanoparticles impregnated with a solution containing the ⁴⁴Ti radiolabel. The same treatment has been investigated to radiolabel amorphous SiO₂ nanoparticles with ⁴⁴Ti. The radiolabels are stably integrated in the nanoparticle matrix, and the release is less than 0.1% in aqueous suspension at neutral pH for at least 4 weeks. The method appears to be fast and reliable. By transmission electron microscopy, dynamic light scattering and ζ-potential measurements, only minor alterations of the nanoparticle size could be detected in the range of 1 to 2 nm.

在现实的暴露场景中，在复杂的环境或生物基质中对工程化的纳米颗粒进行检测和定量分析是一个挑战，因为纳米颗粒的浓度通常很低，并且必须与可能以更高的浓度包含各种化学形式的相同元素的背景相区别。放射性标记的纳米粒子的使用可以克服这些困难，从而提供高检测灵敏度，而无需复杂的样品制备程序。但是，标记程序不得改变纳米粒子的物理化学和生物学特性。在目前的工作中，使用市售的⁴⁴标记初级粒径在5 nm至26 nm之间的三种不同类型的TiO ₂纳米粒子已经研究过在含⁴⁴ Ti放射性标记的溶液中浸渍的纳米颗粒上在180°C下简单扩散热处理，对Ti进行了2.5 h的Ti处理。已经研究了相同的处理方法以⁴⁴ Ti放射性标记无定形SiO ₂纳米颗粒。放射性标记物稳定地整合在纳米颗粒基质中，在中性pH值的水性悬浮液中释放至少4周少于0.1％。该方法似乎是快速而可靠的。通过透射电子显微镜，动态光散射和ζ电位测量，只能检测到1至2 nm范围内的纳米颗粒尺寸的微小变化。