Day 2 of the 9th International Conference on Applied Hair Science focused on the complex microstructure of the hair fiber, and how this affects hair properties and hair’s response to cosmetic treatments.
Amusingly, one key presentation proposed that the hair matrix structure was comparable with the filling in sausages…read-on to find-out more!
Presentations on Day 2 described the exciting advances made in the analysis of the structure and composition of the hair and its sub-compartments, and the building of new models linking these microstructures to the physical properties of the hair. The Plenary talk was given by Evelyne Mayes (Ag Research), entitled “Untangling a Hairy Mess with Molecular-Level Insights From Mass Spectrometry”. In her presentation Evelyne talked about the very detailed proteomic studies that can now be performed on hair samples. Evelyne showed how mass spectrometry techniques can measure various protein crosslinks in the hair fiber and how these new techniques will bring new insights into the damaging effects of cosmetic treatments on hair.
Following this we had presentation by Paul Carpenter (Unilever) titled “High-Strain Stress Relaxation: Probing the Main Structural Components in the Cortex of Human Hair”. Most readers will be familiar with the traditional stress-strain experiments routinely performed in hair research. In his presentation, Paul demonstrated that additional information can be drawn from alternative, stress relaxation experiments, where hair fibers are stretched a little bit, held at this extended length and the tensile forces measured over time. His work showed that new information about the internal structure and physical properties of the hair can be obtained with this unique approach.
Next presentation was given by Trefor Evans (TRI) and Crisan Popescu and was entitled “The Matrix Revisited.” The hair matrix is the filling material that surrounds all the keratin filaments in the fiber cortex. Hence, the analogy with the filling in sausages (or wurst)….the matrix is the stuffing in the hair sausage. Just like the stuffing in a sausage, the hair matrix has no tightly organized structure, but it has a key role in hair physical properties, and, particularly, in hair’s response to moisture and chemical treatments. In their presentation, Trefor and Crisan argued that the matrix is a complex and vital component of the hair. More work is required in the future, they claimed, to design the ideal sausage filling!
Paul Pudney (Unilever) talked about “Nano Scale Chemical Characterization of Human Hair Using AFM-IR”. His presentation showed that it was possible, using AFM-IR, to chemically distinguish features within the cells that make-up the hair fiber. Using this new tool, Paul was able to characterize all sorts of interesting microstructural features of the hair. For example, the changes in protein structure and composition across the sub-compartments of cuticle cells and cortical cells. A very interesting finding was the discovery of two types of matrix types in cortical cells, which Paul called the intra-macrofibrilar matrix and the inter-microfibrilar matrix. These showed differences in chemical composition and structure, suggesting, for the first time, that the sausage filling, is more ordered than we first thought!
Manuel Gamez-Garcia (Ashland) spoke about “Moisture in the Cuticle Sheath: Effects on Hair Mechanical and Cosmetic Properties”. In his presentation, Manuel presented the hypothesis that it is the imbalances in water content across the fiber sub-compartments created by different heat styling processes that drive physical damage to the cuticle. He showed, for example, that rapid evaporation of water from treatment with straightening irons, causes mismatches in the water content in different cuticle cell sublayers, and the contraction, buckling and cracking of cuticle cells. It is interesting to speculate on what treatments could reduce and control these water imbalances and protect hair from heat styling damage!
In the final talk of the day, Ernesta Malinauskyte (TRI) talked about “The Impact on Physical Properties of Hair After Extracting Lipids with Shampoo Surfactants”. In her presentation, Ernesta showed that loss of hair lipids can cause an increase in fiber breakage, illustrating the important role lipids play in the mechanical strength of the hair fiber. Her work also showed that repeated washing with surfactants extracted hair lipids and increased breakage. This raises interesting questions; how much damage do routine surfactants do to the hair fiber? and, how can we protect hair from lipid loss during washing?
All these great talks showed us new techniques used to evaluate hair structure and gave us a new perspective of the complexity of hair fiber components.
Hair Structure is definitely a very interesting and important topic of research, and we look forward to more insights in future talks!
For more content about hair science, you can go to https://library.triprinceton.org