Silica particles coated with an ultra-thin film of melanin can prevent the sun’s rays from reaching and being absorbed by the DNA in the nucleus of skin cells (photo: Freepik)

Published on 03/20/2024

By Julia Moióli  |  Agência FAPESP – Scientists affiliated with the Center for Research on Redox Processes in Biomedicine (Redoxome) of the University of São Paulo (USP) in Brazil have developed a method to obtain coated silica particles with potential use in the production of more natural, environmentally friendly, safe sunscreens with broader protection.

The process created at Redoxome – a FAPESP Research, Innovation and Dissemination Center (RIDC) – was recently granted an “Invention Patent” by the National Institute of Industrial Property (INPI) as part of the project “Process for obtaining coated nanosilica and its use.”

“The photoprotectants used today work very well against the effects of ultraviolet B [UVB] radiation, which penetrates the most superficial layers of the skin. In other words, they’re effective in preventing redness and other acute inflammatory reactions that occur during sun exposure and in the hours that follow,” explains Mauricio da Silva Baptista, professor at the Institute of Chemistry (IQ-USP) in its Biochemistry Department and coordinator of the work carried out during André José Cardoso de Miranda’s master’s thesis, defended in 2016.

“However, they only partially protect against UVA rays, which cause photoaging, cancer, cataracts and age-related macular degeneration. What’s more, they completely let through visible light, the spectral range that forms the highest levels of free radicals from sun exposure. This is a problem because it’s been proven that all skin cells respond to this radiation and that an excess of it can cause quite serious damage, with chronic consequences such as cellular aging,” adds Baptista.

In the new process, silica particles are synthesized and coated with an ultra-thin film of melanin, which is capable of preventing these rays from reaching and being absorbed by the DNA present in the nucleus of skin cells. “This is the great commercial advantage of the invention,” says Baptista.

Because it involves only natural products (silica particles are basically a derivative of sand, and melanin is a natural polymer derived from the amino acid tyrosine), the process also results in a more environmentally friendly sunscreen. “Many commercial sunscreens are being banned because some of their molecules, such as titanium dioxide, cause significant environmental damage, such as the death of coral,” recalls Baptista.

Another advantage is that there is no risk of systemic damage because the particle does not penetrate the skin like some commercial photoprotectants – which have been associated with effects similar to taking hormones.

Low cost

The patented method has yet another advantage: if developed and scaled up by the cosmetics industry, it could be affordable. This is because the tyrosinase enzyme used to synthesize melanin is not directly bound to the silica particle, which increases its catalytic activity (to accelerate the transformation of tyrosine and melanin) and allows the input to be reused.

“Our expectation is that, with the patent granted, we’ll be able to approach companies to develop the sunscreen at a commercial level, especially since there’s nothing even remotely similar to our process on the market,” says Baptista.

According to the researcher, the closest thing to the technology are tinted BB creams, which are made with iron oxides and have a sun protection factor (SPF) and also protect against visible light. However, according to the researcher, these products can also have unfavorable consequences for the body and the environment.

The patent obtained by the Redoxoma group is valid for 20 years from October 2016. It is available in the INPI and international patent databases.

Image credit: gpointstudio/Freepik 

 

Source: https://agencia.fapesp.br/51174