Recent years have witnessed the existing hairdressing market scale in China burgeoning to over 20 billion yuan, and that of overall beauty salon industry amounts to 380 billion yuan, according to a recent estimation.
Traditional methods of perming and dyeing
Figure 1: 3D structure of hair
Figure 2: principle of perming
Hair is mainly composed of cuticle, cortex and medulla and the cortex is the major part constructed by α-keratin1. Perming involves the use of strong reductant at alkaline pH. Alkaline helps open up cuticles and allows reducing agent to enter the cortex, which can reduce the disulfide bonds to sulfhydryl. Curling the hair around a heated curler, dislocated disulfide bonds will form in the process, which gives the hair the curly shape. Its reverse process of hair relaxing is also popular, involving the use of thioglycolates, sodium or lithium hydroxide, and guanidine2.
Figure 3: principle of perming
Dyeing usually requires bleaching before coloring, especially for people with dark hair. Strong alkaline is needed for the entry of oxidizing agent, which is used to decolorize the hair. What's finally applied is coloring agent to color the hair.
Figure 4: damage of chemical hair products
However glamourous the hair looks after perming and dyeing, the health hazards behind which are daunting and unnegligible due to the harmful chemicals contained in the reagents. Amine chemicals in perming reagent are toxic and allergic. Alkaline chemicals for both perming and dyeing process may cause weakly acidic scalp loose moisture and hydrophobicity. Moreover, frequent contact between those reagents and the scalp may let chemical toxins enter human body, leading to leukemia or lymphoma and liver diseases1.
We sent out thousands of questionnaires to find out how people perceive current perming and dyeing methods and whether they know dangers to both their hair and health brought by perming and dyeing. We discovered that 93.27% of people are concerned about the adverse health consequences perming and dyeing can bring and that 70.73% of them desire better and healthier styling products like natural pigment hair dye, and that's where our aspiration for developing an optimized perming and dyeing device came from. We want to synthesize something that can achieve perming and dyeing while reducing the deleterious health consequences. After consulting numerous dissertations, we laid our eyes on indigo, curcumin and lycopene, standing for the three primary colors-blue, yellow and red respectively, to achieve dyeing345. What we chose for perming are peptide fragments that can change the shape of the hair by interacting with keratin in hair fiber1.
What we want to achieve in our project is utilizing synthetic biology methods to construct engineered yeast that can produce enzymes to catalyze pigment precursors into natural pigments, as well as short peptides. (Please refer to proof of concept to verify the feasibility of our project) Those products, when applied on hair, can change the color and shape of hair, functioning as an effective and healthy alternative to current perming and dyeing methods. (Please refer to design part for detailed information) Moreover, in order to grant our potential customers better using experience, we developed some software and hardware and proved the safety of our products. (Please refer to proposed implementation part for detailed information)
We designed xylose-responding system to realize regulable synthesis of natural pigments and secretion of decolorization enzymes or peptides for perming and straightening hair within the engineered yeast. Using genetic engineering techniques, we assembled basic parts to form systems of full functionality, which were inserted into integrative vector plasmid. Electro-transformation assisting the plasmids to be integrated into the chromosome of the pichia pastoris GS115, they were then cultivated in antibiotic gradient culture media to select engineered yeast strain with multiple copies. The selected engineered yeast fermented in culture media with glucose or xylose as the carbon source, and expression products of three kinds of pigment, three kinds of decolorization enzymes and short peptide for perming or straightening hair. (Please refer to experiment overview part for detailed information) Our products can finally be applied with the hardware we designed.
We have made a lot of innovations in multiple aspects, including software, hardware and experience of wet lab. Numerous basic and composite parts were also constructed, contributing to the proliferation of synthetic biology. (Please refer to contribution for detailed information)
Safety has always been the primary concern for our project. We have considered this issue from many aspects seriously and thoroughly, paying special attention to the choices of chassis organism, promoters to construct regulatory system and the final products. The safety principals in the lab were disseminated and protective measures during Covid-19 were taken by our team members. (Please refer to safety part for detailed information)