Ultrasonic dispersion of nanoparticles for environmental, health and safety assessment – issues and recommendations

Abstract

Studies designed to investigate the environmental or biological interactions of nanoscale materials frequently rely on the use of ultrasound (sonication) to prepare test suspensions. However, the inconsistent application of ultrasonic treatment across laboratories, and the lack of process standardization can lead to significant variability in suspension characteristics. At present, there is widespread recognition that sonication must be applied judiciously and reported in a consistent manner that is quantifiable and reproducible; current reporting practices generally lack these attributes. The objectives of the present work were to: (i) Survey potential sonication effects that can alter the physicochemical or biological properties of dispersed nanomaterials (within the context of toxicity testing) and discuss methods to mitigate these effects, (ii) propose a method for standardizing the measurement of sonication power, and (iii) offer a set of reporting guidelines to facilitate the reproducibility of studies involving engineered nanoparticle suspensions obtained via sonication.

Keywords::

• Environmental assessment
• toxicology
• nanoparticle
• nanomaterial
• ultrasonics
• sonication
• dispersion
• suspension

Acknowledgements

The authors thank Fred Klaessig of Pennsylvania Bio Nano Systems, LLC, for helpful suggestions and for his critical review of the draft manuscript. The authors would also like to thank participants of the International Alliance of NanoEHS Harmonization (IANH) for useful discussions, some of which helped motivate the present work.

Declaration of interest: This work was funded in part by a cooperative research agreement (70NANB9H9166) between NIST and the Center for the Environmental Implications of Nanotechnology (CEINT). The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Notes

1. Certain trade names and company products are mentioned in the text or identified in illustrations in order to specify adequately the experimental procedure and equipment used. In no case does such identification imply recommendation or endorsement by National Institute of Standards and Technology, nor does it imply that the products are necessarily the best available for the purpose.