Our daily lives are hectic, and we're looking for long-lasting solutions that simplify our lives. On the other hand, we're paying increasingly closer attention to our health and appearance. The combination of these two needs has led to the success of UV-cured nail polishes, known as hybrid polishes, on the cosmetics market. Their application is simple, and the effect lasts significantly longer than traditional nail polish. So, what do hybrid polishes have to do with our health, and especially the health of our nails?
Thanks to research conducted at the Department of Environmental Chemistry, Faculty of Chemistry, University of Lodz by Dr Kamila Borowczyk, it turns out that a lot!
Our nails are composed of keratin, which is responsible for, among other things, their hardness. The two basic components necessary for the proper synthesis of this building block are cysteine and methionine. Dr Kamila Borowczyk, from the team of Prof. dr hab. Rafał Głowacki from the Department of Environmental Chemistry, Faculty of Chemistry, University of Lodz, focused her research on the changes in their content in women's nail plates resulting from the use of UV-cured hybrid nail polish.
The idea for research to assess the key components of the nail plate stemmed from personal observations. Encouraged by the opinions of friends who use hybrid polishes, I began using them. It turned out to be a very convenient solution – hybrid polish didn't peel off the nail plate or wear off as quickly as traditional polishes. Traditional polish lasted an average of three days when worn daily and while wearing protective gloves, while hybrid polishes looked good even after two weeks, so my nails didn't require as much maintenance. The problem arose after about two months of regular hybrid polish use. I noticed that after removing each layer of hybrid polish, my nails became different – delicate, bending, paper-thin and very dry, even cracking. The weakening of the nail plate in such a short time gave me pause. What could be happening to the nail plate chemically as a result of using UV-cured hybrid polish? This is how the idea was born to conduct research on the assessment of the content of cysteine and methionine, the most important amino acids that make up the nail plate.
The researcher, from Prof. dr hab. R. Głowacki's team, conducted the first stage of the experiments using her own fingernails as the research material. Nail samples, cut using properly sterilised clippers, were stored in sealed polypropylene tubes at room temperature until they were examined. This procedure ensured that the samples retained their properties and could be used as research subjects. During sample preparation, the nails, which constituted the solid sample, were liquefied. During this stage, the experimenter dissolved 2 mg of the nails in hydrochloric acid at the appropriate concentration. The "liquefied nail," in the form of an acid hydrolysate, was further processed until it achieved properties that allowed for its examination and the determination of cysteine and methionine content, components essential for the proper synthesis of nail keratin.
I started my research with my own nails, as I first needed to verify whether the tools I actually had in the laboratory would allow me to assess the content of the substances I was interested in. I used samples from my own nails for preliminary experiments. I conducted the research within a week of collecting the nails to avoid additional drying, which could affect the sample weight. The study required a nail sample the size of a tulip's stamen. The small amount of material tested also allowed for a reduction in the number of chemical reagents used during the study. Furthermore, I wanted the entire procedure to be short, repeatable, and not too complicated, so that it could be easily replicated in other laboratories
– says the University of Lodz researcher.
The research method could not have been random either – the scientist used high-performance liquid chromatography, and although the name is complicated, the analytical technique itself is one of the most commonly used in the analysis of plant, animal and human samples. It is a versatile technique used to test food, medicines and even car paints. The use of high-performance liquid chromatography was important for Dr Kamila Borowczyk because the advantage of this analytical technique is that only a sample the size of a teardrop is needed to perform the analysis. This was extremely important because the scientist conducted preliminary experiments on her own sample and then expanded her research to include 14 volunteers who regularly applied hybrid varnish and provided the necessary samples:
In the experiments that were conducted, the amount of test material was crucial. I couldn't assume that I would always have a lot of samples, a lot of nails. I wanted to expand this research, and we know that everyone's nails grow at different rates. Minimising the amount of test material, i.e. the number of nail samples needed for the research, increased the possibility of verifying uncertain results and made the research more comfortable to conduct. I managed to find people willing to participate in the research among my friends who had never used UV-cured hybrid nail polishes before and had not used tips or gel extensions. In a questionnaire prepared for the purposes of the study, the participants confirmed that they were not taking any medication and that they were in good health.
Before applying the hybrid nail polish for the first time, the nails of the participants were photographed, measured for thickness, and then trimmed in order to collect samples. The thickness of the nails was measured using a tool that is rarely found in beauty salons, namely a sterilized calliper.
The scientist wanted the steps of measuring nail thickness, applying base coat, colour coat, top coat and removing the old coat to be performed in a sterile and uniform manner. Therefore, the procedure was performed by a single person who had completed the necessary training.
This was particularly important because the test subjects had to have exactly the same products applied to their nails, using the same techniques. A cosmetic drill of the same thickness was used to remove the old styling, and acetone was not used to avoid additional drying of the nail plate. This procedure was repeated every two weeks for six months for each of the subjects.
The nail polish application and removal procedures using a nail file were repeated systematically every two weeks for a period of six months. During this entire period, the nail plate, "insulated" by the polish layer, had limited access to air, water, light and moisturising cosmetics. These conditions can cause the nail to become compromised—thin, soft, and dry. Consequently, it ceases to fulfil its protective function and becomes more sensitive, rough and cracked
– explained the scientist.
Research conducted by a team at the Department of Environmental Chemistry has demonstrated that the use of hybrid nail polishes has a negative impact on the nail plate. This impact is visible during normal functioning through increased brittleness, splitting and crumbling of the nail. The observed damage can be explained by the results obtained in the study. From a chemical perspective, we observe that after six months of nail styling using UV radiation, the amount of the amino acids that constitute the nail plate – the building blocks mentioned earlier – cysteine and methionine – significantly decreases.
In the case of the first compound, i.e. cysteine, the amount of this amino acid in the plates after six months of using hybrid varnishes decreased by 22%, and in the case of methionine by over 30%!
Hybrid nail polishes can certainly be a beautiful decoration for our nails, but we should remember that underneath this beautiful layer, chemical processes take place which, as research by Dr Kamila Borowczyk from the Department of Environmental Chemistry, Faculty of Chemistry, University of Lodz has proven, affect the composition of our nails.
After a hard day, we need rest, and the same applies to our nails, which with the regular use of hybrid nail polishes should be given a moment of rest and regeneration.
Source: dr hab. Kamila Borowczyk, Department of Environmental Chemistry, Faculty of Chemistry, University of Lodz
Detailed information on the experiments conducted by the University of Lodz team has been published in a scientific journal with global reach: Borowczyk K., Głowacki R., The influence of UV varnishes on the content of cysteine and methionine in women nail plates - chromatographic studies, International Journal of Molecular Sciences, 21(3),1049 (2021).
