The technology could help create a new generation of dermocosmetics designed to support the restoration of the natural skin microbiome, including in people with atopic dermatitis or acne.

Keeping live bacteria alive in finished cosmetic products has been one of the greatest challenges in developing probiotic cosmetics. Preservatives are essential for ensuring the microbiological safety of cosmetics, but while they inhibit the growth of unwanted microorganisms, they also destroy probiotic bacteria added to the formulation.

For this reason, most currently available probiotic cosmetic products contain dead bacteria or their fragments (lysates), rather than live cultures.

Researchers from the Faculty of Chemical Engineering and Technology at the Cracow University of Technology have developed and patented a technology for encapsulating live probiotic bacterial cultures in alginate microcapsules measuring less than 100 micrometers in diameter.

According to Małgorzata Syrda-Śliwa, spokesperson for the Cracow University of Technology, the shell of the capsules, made of alginates — natural polymers derived from brown algae — protects the bacteria from preservatives during cosmetic storage and enables their gradual release after the product is applied to the skin.

"Microcapsules protect the bacteria from preservatives during cosmetic storage and release them only after the product is applied to the skin. This allows the probiotics to retain their activity," explains Anna Łętocha, PhD, from the Cracow University of Technology.

The key result of the study was the durability of the live bacterial cultures. According to Łętocha, bacteria encapsulated in microcapsules remained viable in the cosmetic formulation for more than 12 months.

By comparison, non-encapsulated bacteria in a cosmetic containing preservatives survived for no longer than seven days.

The researchers say the technology could be used in a new generation of cosmetics and dermocosmetics that support the restoration of the skin's natural microbiome.

The skin microbiome consists of billions of bacteria, fungi and other microorganisms that naturally inhabit the surface of the skin. A growing body of research indicates that disruption of this balance can contribute to inflammation and dermatological conditions.

"The use of probiotics in topical preparations is particularly important in the care of dry, sensitive skin, and especially for people struggling with chronic skin conditions such as atopic dermatitis or acne," emphasises Elżbieta Sikora, PhD, a professor at the Cracow University of Technology.

According to the researchers, the solution could also be useful for people whose skin is frequently exposed to disinfectants, including healthcare workers, laboratory workers and food service workers.

One of the most important features of the new technology is the very small size of the microcapsules — less than 100 micrometers. According to the Cracow University of Technology, the cosmetics industry has not yet had technology to obtain such small carriers of live probiotic bacteria.

This allows the microcapsules to be added to standard cosmetic formulations, such as creams, gels and emulsions, without compromising their performance.

The research was conducted in collaboration with the Łukasiewicz Institute of Industrial Organic Chemistry, where bacterial survival during storage was assessed, and with the Małopolska Centre of Biotechnology of the Jagiellonian University, where researchers analysed the safety of the solution for skin cells, its effect on cell proliferation and regenerative properties.

According to Sikora, the effectiveness of the solution was first assessed in laboratory studies on human skin cells and then in dermatological studies involving volunteers.

These studies confirmed colonisation of the skin by probiotic bacteria after using cosmetics containing the microcapsules.

The results were published in five peer-reviewed scientific publications, including papers in the journals ACS Applied Materials & Interfaces, Polymers and Applied Sciences.

The technology has received patent protection from the Polish Patent Office. The next step will be finding an industrial partner and adapting the process for large-scale production.

"The technology is ready for commercialisation. From an industrial perspective, it is important that our microcapsules are compatible with typical cosmetic bases. This means that manufacturers do not need to invest in new production lines, but can utilize existing ones instead. We also have extensive experience implementing similar solutions in collaboration with cosmetic companies," Elżbieta Sikora said.

PAP - Science in Poland

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