We have recently heard many classmates around us complaining about their poor hair quality. After asking them, we realized that this so-called poor hair quality is not a simple issue, but a complex one encompassing various problems, including hair breakage, loss of elasticity, dryness, and fragility. A brief online search revealed that this is caused by many factors, such as frequent hair dyeing and perming, increasingly severe environmental pollution, and unhealthy eating habits (such as overeating junk food). Additionally, the stress and anxiety of modern life also have negative impacts on hair quality.
 
We conducted further research and surveys on this issue, trying to determine the universality of hair quality problems. We designed and distributed a detailed questionnaire, inviting participants to self-assess their hair quality. The questionnaire included various related questions, such as whether the hair is dry, fragile, has split ends, or other damages. Not only did the participants have to answer these questions, but they also had to give an overall evaluation of their hair quality. We found that regardless of gender, there was a great deal of dissatisfaction with their hair quality. Although the condition of the hair varies from person to person, it is clear that people of all ages, genders, and socio-economic status share the common need to focus on and improve hair quality. Overall, the survey results were surprising, with more than two-thirds of people feeling that there are problems with their hair quality that need to be improved. We began to realize the ubiquity of hair quality problems, and the biggest issue perceived by everyone is split ends and lack of smoothness.
Upon further investigation, we found that many people have tried to take action to improve their hair quality, but often did not get satisfactory results. Some people tried to change their lifestyles, such as improving their diet and reducing stress, but these methods often require a lot of time and effort, and the results are not easily noticeable; some people tried to use various hair care products, but the quality of their hair did not fundamentally improve. After further street interviews,

 we found that the most common, universally accepted method to improve hair quality is the use of conditioners, as this method does not require much effort (for example, improving one's routine requires changing many planzs).
 
We followed up with the interviewees who filled out the previous hair quality self-assessment questionnaire and found that they were all using various types of conditioners, but evidently, the conditioners on the market currently could not meet their needs.

 
So we started thinking about whether we could develop a conditioner ourselves that could alleviate split ends and overall lack of smoothness, thereby improving hair quality.
 

Some team members first communicated with their hairdressers. The hairdresser told us that they recently used a product in their store. This product is applied to the user's hair during the perm process, and compared to traditional perm solutions, its effect is more natural, and the hair is smoother. We asked the hairdresser for this product and carefully examined its ingredient list. We found it contained an amino acid called cysteine. After researching the function of cysteine, we found that it can form and repair disulfide bonds in the hair. The disulfide bond is an important component of keratin in the hair and is a crucial factor in determining whether the hair splits and its smoothness. However, upon further testing, we found that the effectiveness of this product was not very good, which is to say, its level of hair repair was far below our expectations.

We contacted Dr. Zhou and told her that this product contained cysteine and asked why this product did not adequately repair our disulfide bonds. Dr. Zhou raises the possibility that this amino acid is very, very small and has a hard time staying in the hair—and will likely be washed out quickly. If we could increase the volume or adhesion of cysteine to hair while retaining its functionality, we might be able to produce the product we want.

So we designed a longer peptide. It contains more amino acids, which can better bind and adhere to the hair, and it should also contain a large amount of cysteine to repair the disulfide bonds. After designing the relevant peptides, we used E. coli as an engineered bacterium to attempt to produce it. After a period of research and experimentation, we produced the required polypeptides (proteins) and conducted preliminary performance tests. We found that compared to the product provided by the hairdresser, it indeed had a better function of repairing disulfide bonds and thereby improving hair quality.

R1:
After completing our initial research, the students pondered whether it could be used as a product to help everyone mitigate their hair damage. We first went to a nearby mall and found a shop selling hair care products. We described the product we had made to the clerk and asked her, based on her experience, if such a product could potentially enter the market. She explained to us that today's hair care products typically have multiple functions, and our product that simply improves hair damage and enhances hair smoothness may not be competitive enough.

After learning this information, we discussed it within the team. To ensure rigor, we decided to ask Mr. Li for some professional advice on our conditioner. After understanding the purpose of our research, she affirmed us and provided an important direction for our research - hair also needs antioxidant properties.

Free radicals are unstable molecules that can destroy cellular structure, affect metabolic functions, leading to worse hair quality, and even hair loss. Therefore, we need to use antioxidants to neutralize these free radicals, preventing oxidative damage to hair cells. In addition, antioxidants can prevent melanin oxidation, delay the formation of white hair, and maintain the natural color of the hair. Through extensive discussions with experts and searching for articles online, we found a substance called glutathione. Glutathione is an antioxidant that can meet our current needs. At the same time, glutathione also contains cysteine, which promotes the formation of disulfide bonds while enhancing scalp health, making the hair smooth and less prone to split ends, and has some effects on hair strength and elasticity.

Based on this, we once again designed a corresponding engineered bacterium to produce glutathione synthetase, a bifunctional enzyme that can directly convert raw materials into glutathione in two steps. At the same time, we ensured that the conditioner contains enough glycine, cysteine, and glutamic acid supply. After fine-tuning and adjusting the proportion of the previous polypeptides, a new product was generated.

 

R2:
After updating the product, we tried to hit the streets again to conduct interviews, introduce our product to users, and see if anyone would like to buy it. During the introduction process, we discovered new information. When we talked about the role of glutathione in delaying the appearance of white hair, many users in their thirties and forties showed strong interest. They mentioned that they often have sporadic white hair and that it was not necessary to dye their hair for this reason. If there was such a conditioner that could alleviate the appearance of white hair, it would be very helpful.

Based on this, we wondered if we could introduce other ingredients to further enhance the hair dyeing function of our conditioner. A classmate first found a shampoo on the market labeled with a hair dyeing function online. By contacting the seller online, they told us that their product contains black sesame extract, which promotes the formation of melanin. However, they couldn't explain to us in detail how this function is achieved. We contacted experts in related fields once again. One of them proposed a feasible plan: the precursor of melanin, dopaquinone, can be obtained by converting dopa. He suggested that we could try to synthesize dopa. Following our previous thoughts, we tried to find commonly found substances in biology to help us synthesize dopa. After a period of inquiry, we finally determined that we could use tyrosinase to catalyze tyrosine to become dopa, thereby producing melanin.
Once again, we produced this enzyme with engineered bacteria and improved our product.

After completing this part of the research, we wanted to try to make it into a product. The first problem to solve was how our product could be used by customers. We proposed several feasible solutions: directly applying the bacteria to the head; selling the bacteria to the users, so that after a reasonable design, they can cultivate the bacteria at home and add their metabolic products to the conditioner; producing the bacteria in a factory, letting them metabolize to produce the ingredients we need, and adding them to the shampoo to directly sell the finished product to customers.

Faced with the above three solutions, we conducted a team discussion. Applying bacteria directly to the head may cause safety issues, such as gene leakage, environmental pollution, infection, etc.Allowing customers to cultivate E. coli at home could also pose a variety of problems. First of all, at home, there is a lack of precision instruments for continuous cultivation of this bacterium. If we can provide a large amount of cultivated bacteria to the buyer, we still cannot overcome the operation of directly applying the bacteria to the hair, and we can't avoid leakage, which can occur during transportation and also at home. They recommend that we ferment and cultivate the bacterial strains in a factory, then break the bacterial strain using ultrasound, releasing related substances. Subsequently, this substance is purified in the factory and made into a conditioner product. In this way, the problem of gene leakage is solved at the root when the bacterial strain is broken by ultrasound, and it is directly rich in required substances rather than bacterial strains, which makes it more acceptable to consumers.

At the same time, the startup group also wanted to know what kind of products in the market are more popular with the public. They conducted an online survey on everyone's preferences. They found that the vast majority of users cannot accept direct contact with E. coli, nor can they accept cultivating E. coli at home. Therefore, they also recommend that we produce the product directly and sell the finished product without bacteria to the customers.

So, in the end, we decided to produce the required substances in the factory using engineered bacteria and then add them to the conditioner for users.