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News article14 December 2018

How and why to measure the hydrophobicity of nanoparticles

Hydrophobicity of nanoparticles
© EU,2018

JRC scientists developed a quantitative method for measuring the surface energy and hydrophobicity of nanomaterials, as the knowledge about hydrophobicity is important when assessing potential risks of chemicals.

Hydrophobicity is an important parameter to determine for the risk assessment of chemicals and in particular of nanomaterials.


Because hydrophobicity plays a critical role in various biological processes such as:

  • protein adsorption
  • interaction with biological membranes
  • cellular uptake
  • immune response
  • hemolytic effects.

It is also recognized as key quality attribute for nanomedicines.

The hydrophobicity is an important parameter that contributes in determining the biological and environmental fate of nanoparticles as well as their potential toxicity.

Only a few methods are currently available for characterising the hydrophobicity of nanomaterials, and none of them enables, for all nanomaterial types, a full characterisation and quantification of this key parameter. In addition, most of these techniques are based on expensive and time-consuming analytical techniques. The development of a fast and reliable general method for nanomaterials hydrophobicity characterisation is therefore of great interest.

With this research, the JRC has extended its previous method in order to quantitatively determine the surface energy components of nanomaterials by measuring their binding affinity to the collectors’ surfaces, via analysis of their adsorption kinetics.

The adsorption kinetics is calculated by measuring the number of nanoparticles binding to the different collector as a function of time, by using Dark-Field microscopy. The method has been tested with Au and SiO2 nanoparticles with different degrees of hydrophobicity to assess the validity of the method.

The study shows a clear advantage of the method in the capability to quantitatively determine the hydrophobicity degree over of a wide range of the surface energy by using only one set of collectors.

This method is a good candidate to support the development of an international test guideline to address the safety of nanomaterials.

Read more in: Valsesia A., et al., Direct quantification of nanoparticle surface hydrophobicity, Communications Chemistry, 1, Article number: 53 (2018),

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Direct quantification of nanoparticle surface hydrophobicity


Publication date
14 December 2018