Nanoneedle technique paves way for skin disease study
UK researchers have developed a way to build a 3D model of people’s skin that could improve the study of skin diseases and ageing.
A team from Bath University used a technique developed for carrying out surgical procedures on individual cells to map not only the surface of the skin but also the structure and properties of the cells below it.
This involves combining an atomic force microscopy (AFM) probe, which effectively feels the shape of a surface and translates that information into a computer map, with a nanoneedle between 20nm and 70nm in diameter that penetrates cells without significantly damaging them.
By using the technique to perform a mechanical scan or “tomography” of the skin surface, scientists could detect structural and biomechanical changes caused by environmental factors, ageing or skin disease.
Dr Sergey Gordeev, a senior lecturer in Bath’s physics department and one of the authors of a paper on the work published in the Journal of Investigative Dermatology, said the pyramidal shape of the AFM probe meant it couldn’t collect information about the structure below the surface.
‘The more you press it, the more you have information not only about what happens at the apex but also what happens at the side of the probe,’ he told The Engineer.
‘But if you make a very high aspect ratio nanoneedle [i.e. long and thin] with high resolution you can find a lot of structure under your skin.’
He said, ‘AFM probes measure the force of interaction between the probe and the surface. With a nanoneedle you can insert it inside skin cells and measure forces experienced by the nanoneedle.’
The researchers had to develop a way to turn the force readings from the probe and nanoneedle into a computer model.
This also included information about properties of the cells such as their elasticity, which were measured by assessing the plastic deformation of the cells – how much they changed shape – as the needle was withdrawn.
Gordeev said, ‘When you insert the needle the walls of the cell interact with the hole, and if this interaction is very strong then you get information not just at the apex but from the rest of the needle. So we had to prove that the force we were measuring came mostly from the apex.
‘Also, the deformation isn’t just one parameter. It’s described by elasticity, plasticity and viscosity so we had to understand all these contributed to our measurements.’
The technique could be particularly useful for studying the thin top layer of the skin known as the stratum corneum, which forms the barrier that keeps water inside our bodies and microbes out but maintains remarkably strength and elasticity.
Using the nanoneedle the researchers have been able to demonstrate there is a clear difference between the softer, external layer of the corneocyte and more a rigid, internal structure.