Using enzymes towards the development of a milder, more sustainable permanent hair straightening method

Lead Research Organisation: University of Nottingham
Department Name: Faculty of Engineering


Permanent hair straightening stands amongst the most popular capillary treatments within the $90 billion hair care market (Statistica & Gosreports). It involves the breaking of disulfide bonds between keratin filaments followed by crosslinking reinstatement. Current commercialised methods rely on the use of harsh chemicals, associated with both health and environmental issues.

Alkaline hydroxides, such as sodium hydroxide, are the harshest and fastest relaxing agents for the breaking of keratin disulfide bonds, with poor selectivity and permanent fission. Hydroxyl ions disrupt the disulfide bonds of the hair keratins, enabling the formation of monosulfide thioethers, referred to as lanthionines. Serious health concerns have been associated with chemical hair straightening, both for the users and the professionals applying the products. These include scalp irritation, skin burn, hair loss, as well as inflammatory scalp disorders, especially amongst people of African descent. Despite their effectiveness, such chemical agents are toxic, carcinogenic, erosive, and flammable. Furthermore, as disulfide bonds are broken, hydrogen disulfide is formed as a by-product. Not only is it deadly to humans, animals and vegetation, hydrogen disulfide is also highly flammable and a groundwater pollutant. Formaldehyde, another chemical relaxer, is also very toxic to animals, especially in aquatic environments.

In this way, the number of health and environmental issues associated with chemical hair straightening calls for tougher legislation on these chemicals as well as an emphasis on safer and greener methods. An alternative permanent hair straightening treatment could stem from biotechnologically derived compounds, such as enzymes, commonly used in the cosmetic industry.

Since the chemistry involved in hair straightening treatments is prevalent in the natural plasticity of proteins and their turnover, the development of an enzymatic route for hair straightening may be a fertile area of interest. The associated catalytic steps are predicted to be similar to the classical chemical route to lanthionisation. This research project thus aims at exploring the feasibility of incorporating enzymes into permanent hair straightening treatments.

An initial study of available literature and a baseline project at Croda have enabled the identification of possible enzyme candidates. These enzyme candidates will be used in order to develop reliable assays allowing for the detection of activities of interest, including the breaking of keratin disulfide bonds and the reinstatement of crosslinking. The sequences of such enzymes will be used to search the genome database in order to find novel enzymes with structural and functional homology to the known enzyme candidates. The selected novel enzymes will be expressed and improved. Work will then be conducted towards their integration into an appropriate formulation, with sufficient shelf-life and suitable concentrations yielding the desired straightening effect in an appropriate time at a reasonable cost.

In this way, we will be introducing permanent enzymatic hair straightening as a milder and more sustainable alternative to the harsh chemicals currently used on the market.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S515528/1 01/10/2018 30/09/2022
2114841 Studentship EP/S515528/1 01/10/2018 30/09/2022 Candice Ford