Kenneth Olesen PhD May 21, ’19 < 5 min

How is the protein-surface interaction influenced by the presence of surfactant?

Proteins tend to interact with surfaces and doing so they can unfold and aggregate. The behavior of therapeutic proteins in solution is generally well characterized, but the adsorption to, and interaction with, various surface material is often not studied. Studying protein interaction with various surface materials and at different solution conditions, the material compatibility can be evaluated and conditions that minimize adsorption can be identified. Here we show you one way to do this assessment.

Proteins tend to adsorb to surfaces

Aggregation originating from protein-surface interaction could arise throughout all stages of drug manufacturing, storages and distribution. Typical materials the protein would meet could be glass, metals, plastic polymers and oils. The protein stability can however be enhanced by the addition of an excipient, such as a surfactant. So how does the addition of a surfactant affect the protein adsorption to a surface? Will the adsorption be prevented or just reduced? And would it be possible to identify a set of conditions that minimizes the amount of protein that adsorbs to the surface?

Analysis of protein adsorption, with and without excipient, using QCM-D

The nature of the protein adsorption depends on the specific combination of protein, surface, ambient conditions and surfactant used. In the study here presented, the adsorption of two different monoclonal antibodies to four different surface materials was analyzed with QSense® QCM-D [1]. The adsorption was analyzed both with and without the presence of surfactant.

The questions to be answered were:

  • How much antibody will adsorb to the respective surface material?
  • How will the addition of surfactant affect the adsorption?
  • Is there any combination of protein, surface material and excipient that prevents the adsorption?

Protein adsorption conditions analyzed

The protein-surface interaction varies with the surface and solution conditions

The QCM-D results, Fig. 1, show significant differences in the adsorbed amount, depending on which of the two antibodies that were measured, which surface material that was used and whether excipient was present or not.

Antibody: The amount of protein adsorbed varies with the antibody used. mAb2 shows a larger surface uptake than mAb1 on all the four surface materials studied.

Surface material: The results show that the surface material significantly impacts the amount of protein adsorbed. The highest amount of adsorption is found on Au, and the lowest is found on PS.

Excipient: The presence of surfactant in the solution significantly reduces the amount adsorbed for both antibodies. For certain combinations of antibody and material, the adsorption is essentially prevented when the surfactant is added. The effect is most pronounced for mAb1 on PS.

Protein adsorption to different surfaces with and without surfactant

Figure 1. Mass of irreversibly adsorbed antibody to four different surface materials. + and – represent the presence (+) or absence (-) of surfactant [1].

Concluding remarks

Protein-surface interaction may trigger protein unfolding and aggregation and can result in loss of therapeutic properties as well as in immunogenic reactions.  The extent of the protein-surface interaction depends on numerous factors, such as the nature of the protein itself, the surface material, pH, protein concentration, ionic strength, and presence of excipient etc. In this study, the conditions that minimize protein-surface interaction within a defined context, were identified via QCM-D analysis of mass-uptake at the surface.

Download the application note to read more about the study.

Application note  QCM-D in drug formulation and storage  Download


  1. Oom, A., et al., J. Pharm. Sci., 101(2), 2012, 519-529


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