L'Oréal scientists are probing certain properties of afro hair by investigating the biological processes involved in the spread of hair breakage caused by tensile stresses.
Why is afro hair more fragile than other types of hair ?
The chemical properties and molecular structure of keratin in the hair fibre of afro hair are no different from European and Asian hair but the recent findings of L'Oréal research teams provide an initial answer to this question. By reconstituting the specific fibre geometry of afro hair using an optical system, L'Oréal laboratories have observed that afro hair is not only helicoidal but also contains many crushed areas. Other experiments have shown that this type of hair swells slightly in water and that the lipids it contains are not distributed in the same way as in European hair. These findings would seem to explain the mechanical weakness of afro hair.
What biological structures in afro hair cause this brittleness ?
One way to answer this question is to subject a strand of afro hair to mechanical stresses and dynamically monitor breaks along its fibre. The Environmental Scanning Electron Microscope (ESEM) is designed to observe these breaks and to track their propagation under natural conditions (fig. 1). Scientists then deploy a more specialised devise - the Transmission Electron Microscopy (TEM) - to detect the biological structures involved in such fractures. By using a TEM fitted with an electrons filter (EFTEM), biophysicists at L'Oréal research laboratories have demonstrated that the breaks which occur in the cuticle and cortex spread via the cytoplasmic residue of the cells (fig. 2). Following breakage, the hair may be observed through an Scanning Electron Microscopy (SEM) (fig. 3).
This research reflects L'Oréal's commitment to probing the diverse hair types among different sections of the population and will pave the way for developing improved care products for Afro hair.