How scanning electron microscopy is used for cosmetics research and development

By Karl Kersten - March 29, 2018

Since ancient Egyptian times, cosmetic products have been used to enhance the human appearance. Research around cosmetics therefore deals not only with the development of new substances and the analysis and enhancement of existing ones, but also with the interaction of components with tissue. In this short blog, we introduce you to three examples that show the link between research within the cosmetic industry and scanning electron microscopy (SEM).


Investigating the toxicity of copper oxide nanomaterials on different epithelial cells

The use of nanoparticles in cosmetics is quite widely discussed as potential toxicity discussions are ongoing. In a study of Ude et al., the toxicity of copper oxide nanomaterials on different epithelial cells is investigated.[1] 

A huge variety of nanomaterials are available that vary in size, composition, surface area, charge, shape, and solubility. All these factors influence the biological response to the nanomaterials.

Metallic nanomaterials such as copper oxide (CuO) particles can be soluble and due to this might be toxic via particle effects or ion-mediated effects. Ingestion of copper oxide nanomaterials by humans is most likely to occur accidentally and very little is known so far about the potential risks.

Ude et al. choose the Caco-2 cell line to investigate the potential effect of these nanomaterials in addition to using SEM on cell culture material. Their study clearly demonstrates that the impact of CuO nanomaterials is comparable to studies already performed on copper sulfate (CuSO4) nanomaterials.

SEM imaging confirmed a toxicity of CuO and CuSO4 nanomaterials on Caco-2 cell monolayer integrity. This is an indication that due to tight junction dysfunction, substances such as chemicals and pathogens could potentially be transported across the intestinal barrier. 

Fig 1: SEM image of deodorant. Cosmetics consist of very complex components and often contain particles.

Researching the impact of titanium dioxide nanoparticles on E. coli

Still on the topic of nanoparticles, but with a different model system, Planchon et al. carried out a study. [2] The research was focused on the impact of titanium dioxide nanoparticles on Escherichia coli (E. coli). As reported previously, E. coli shows a toxic reaction from 10ppm onwards, but it was also stated that parts of the bacterial population are able to adapt and survive.

SEM studies show some bacteria being fully covered in titanium dioxide particles, while the major part remains free from nanoparticles. This heterogeneity leads to differences in proteome and metabolome. To be able to deal with biological variety, the study therefore suggests analyzing large samples to minimize the impact of unwanted variance. 

The Planchon et al. study revealed that exposing E. coli to titanium dioxide nanoparticles resulted in heterogeneous bacterial responses. One part of the population is able to adapt to the stress and temporarily survives, while the other part cannot adapt and dies. The study’s attempt at combining proteomics and metabolomics might offer a breakthrough in studying the effect of the nanoparticles as it offers a more precise evaluation of toxicity.


Examining the characterization of dentifrices

A very different study by Pinto et al. aimed to characterize dentifrices, as they are a good source for fluorides.[3] This is because formulations have been improved to enhance therapeutic properties by incorporating, for example, triclosan, potassium nitrate or strontium chloride.

The goal of the research team was to characterize 12 dentifrices via SEM and EDX analysis. To enable a SEM analysis the dentifrices were reduced to ashes at 650°C and then imaged and analyzed by EDX. The study concluded that due to the many components included in dentifrices, each patient should have an individual evaluation to best understand their needs.


Stepping outside the cosmetics industry


Fig. 2 a & b: SEM images of human hair. The left image shows a healthy hair and the right image a damaged one.

With these three examples we hope to have offered you a glimpse into how SEM is an invaluable research tool for the cosmetic industry. But the spectrum of research applications for SEM broadens even further when we step outside of the cosmetic domain. This becomes clear with the variety of SEM images presented in our latest quiz: Guess the size!

In this short but fun SEM images quiz, you will be challenged to guess the size of objects magnified by a SEM beyond your imagination.

Are you Magnification Moderate, Master or Magnificent? Guess the sizes of 12 magnified objects and go for giant glory! Take the quiz now!

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1) Impact of copper nanomaterials on differentiated and undifferentiated Caco-2 intestinal epithelial cells; assessment of cytotoxicity, barrier integrity, cytokine production and nanomaterial penetration, Ude et al, Particle and Fibre Toxicology (2017), 14:31.

2) Metabolomic and proteomic investigations of impacts of titanium dioxide nanoparticles on Escherichia coli, Planchon et al., PLOS ONE, Juni 1 (2017)

3) Characterization of Dentifrices Containing Desensitizing Agents, Triclosan or Whitening Agents: EDX and SEM Analysis, Pinto et al., Brazilian Dental Journal (2014) 25 (2): 153-159

About the author

Karl Kersten is head of the Thermo Scientific Phenom Desktop SEM Application Team at Thermo Fisher Scientific. He is passionate about the Phenom Desktop SEM product and likes converting customer requirements into product or feature specifications so customers can achieve their goals.

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