HOW TO ALLEVIATE THE IMPACT OF METAL IONS HAIR MECHANICAL PROPERTIES ? A NEW SPECIFIC COMBINATION OF ACIDS FOR HAIR CARE
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Presented by: Adrien Kaeser
Hair is providing a medium to express personality and group ownership, and salon services like color and texture transformation (permanent wave, relaxers) have multiplied the opportunities for all to dare expressing themselves.
Poorly controlled, these treatments can eventually lead to fragilization of the hair hierarchical structure and integrity. Its repeated exposure to water, washing and grooming routine may bring an important impact upon its mechanical properties and beauty. Moreover, daily mechanical stresses such as combing, brushing or heat drying can even increase the fragility of the fiber. It is therefore important to reduce the tall of hair damages on the aspect of hair and its manageability.
Among all these external aggressors, the quality of the washing and rinsing water and in particular their content in cations, plays a major role in hair quality. It has been long evidenced that exogenous metal ions will accumulate within the hair fiber, depending principally on the level of damage of the hair. Chemical damages in keratin (oxidative bond cleavage, formation of cysteic acids increasing coulombic interaction) increase binding sites for metal ions, to which copper, zinc and particularly calcium ions tend to accumulate in the structure. While copper ions are particularly deleterious on the hair integrity during oxidative treatment [1], calcium ions have been linked to the overall mechanical properties (increased young modulus [2], less resistance to breakage of the fiber and its appearance and shine [3]), although its clear role remains to be better understood.
In our work to improve the quality of damaged hair, we ambitioned to maximize the creation of reinforcing weak bonds in the protein networks. Hence, a large variety of ingredients from rinse off application was screened, based on their impact on the temperature of denaturation of keratin measured by high pressure DSC (HP-DSC). Polyacids are the main ingredients boosting the resistance of the fiber to temperature (TDEN, temperature of denaturation of the keratin). Screening combinations of ingredients, a specific combination of acids was identified as the most effective to improve the resistance of keratin to temperature.
Isolated from the cosmetic formula, a simplex mixture of the actives applied 5 times on bleached hair, shampooed between treatments, improves the mechanical properties of the fibers and by resilience, to breakage from repetitive tensile stress.
Nano-SIMS analysis allows to observe that a large fraction of metal ions are removed from all over the cross-section of the fiber. Moreover, remaining actives can be imaged in the outer region of the hair fiber, suggesting strong interaction between them and the keratin after wash.
All together, these data suggest the impact of ion removal on the improvement of the hair fiber mechanical properties, and the importance to protect the hair fiber from metal ions. This innovation paves the way for new effective hair care treatment able to prevent hair damages and improve hair quality.
[1] 2021 IFSCC Podium HC74
[2] Evans, A. O.; Marsh, J. M.; Wickett, R. R. The Structural Implications of Water Hardness Metal Uptake by Human Hair: Structural Implications of Water Hardness. International Journal of Cosmetic Science 2011, 33 (5), 477–482.
[3] Marsh, J. M.; Mamak, M.; Wireko, F.; Lebron, A.; Cambron, T.; Huber, D.; Boona, I.; Williams, R. E. A.; McComb, D. W. Multimodal Evidence of Mesostructured Calcium Fatty Acid Deposits in Human Hair and Their Role on Hair Properties. ACS Appl. Bio Mater. 2018, 1 (4), 1174–1183.
Poorly controlled, these treatments can eventually lead to fragilization of the hair hierarchical structure and integrity. Its repeated exposure to water, washing and grooming routine may bring an important impact upon its mechanical properties and beauty. Moreover, daily mechanical stresses such as combing, brushing or heat drying can even increase the fragility of the fiber. It is therefore important to reduce the tall of hair damages on the aspect of hair and its manageability.
Among all these external aggressors, the quality of the washing and rinsing water and in particular their content in cations, plays a major role in hair quality. It has been long evidenced that exogenous metal ions will accumulate within the hair fiber, depending principally on the level of damage of the hair. Chemical damages in keratin (oxidative bond cleavage, formation of cysteic acids increasing coulombic interaction) increase binding sites for metal ions, to which copper, zinc and particularly calcium ions tend to accumulate in the structure. While copper ions are particularly deleterious on the hair integrity during oxidative treatment [1], calcium ions have been linked to the overall mechanical properties (increased young modulus [2], less resistance to breakage of the fiber and its appearance and shine [3]), although its clear role remains to be better understood.
In our work to improve the quality of damaged hair, we ambitioned to maximize the creation of reinforcing weak bonds in the protein networks. Hence, a large variety of ingredients from rinse off application was screened, based on their impact on the temperature of denaturation of keratin measured by high pressure DSC (HP-DSC). Polyacids are the main ingredients boosting the resistance of the fiber to temperature (TDEN, temperature of denaturation of the keratin). Screening combinations of ingredients, a specific combination of acids was identified as the most effective to improve the resistance of keratin to temperature.
Isolated from the cosmetic formula, a simplex mixture of the actives applied 5 times on bleached hair, shampooed between treatments, improves the mechanical properties of the fibers and by resilience, to breakage from repetitive tensile stress.
Nano-SIMS analysis allows to observe that a large fraction of metal ions are removed from all over the cross-section of the fiber. Moreover, remaining actives can be imaged in the outer region of the hair fiber, suggesting strong interaction between them and the keratin after wash.
All together, these data suggest the impact of ion removal on the improvement of the hair fiber mechanical properties, and the importance to protect the hair fiber from metal ions. This innovation paves the way for new effective hair care treatment able to prevent hair damages and improve hair quality.
[1] 2021 IFSCC Podium HC74
[2] Evans, A. O.; Marsh, J. M.; Wickett, R. R. The Structural Implications of Water Hardness Metal Uptake by Human Hair: Structural Implications of Water Hardness. International Journal of Cosmetic Science 2011, 33 (5), 477–482.
[3] Marsh, J. M.; Mamak, M.; Wireko, F.; Lebron, A.; Cambron, T.; Huber, D.; Boona, I.; Williams, R. E. A.; McComb, D. W. Multimodal Evidence of Mesostructured Calcium Fatty Acid Deposits in Human Hair and Their Role on Hair Properties. ACS Appl. Bio Mater. 2018, 1 (4), 1174–1183.