Particles comprising a biopolymer which is degradable under the effect of an electromagnetic wave as emitted by a solar radiation

Abstract

The invention relates mainly to a particle comprising at least one biopolymer which is degradable under the effect of an electromagnetic wavelength, notably the wavelength of which is in the spectrum of the wavelengths emitted by the sun, this biopolymer comprising nucleosides. The invention also relates to compositions containing such particles with the aim of delivering an active principle. These particles can be used mainly in cosmetics, in dermatology, in pharmacy, in agri-food or en agro-industrials.

Description

[0001] The invention relates mainly to a particle comprising at least one biopolymer which is degradable under the effect of an electromagnetic wave, notably the wavelength of which is in the spectrum of the wavelengths emitted by the sun, this biopolymer comprising nucleosides.[0002] More particularly, the invention finds cosmetic, dermatological, pharmaceutical, agri-food or agro-industrial use, in releasing an active principle contained by this particle when it is subjected to an electromagnetic wave.STATE OF THE ART[0003] With the aim of better mastering the bioavailability and the release of a microencapsulated active, many studies have been made so as to develop microcapsules or microspheres which release their actives under the influence of physical factors such as pH or temperature.[0004] For pharmaceutical applications, the use of pH-dependent polymers such as Eudragit.RTM. S and L (Bayer), cellulose acetate phthalate, cellulose acetate trimellitate and hydroxypropyl methyl...

AI Technical Summary

Problems solved by technology

However, these compounds are highly toxic and this limits their uses in cosmetics (Vyas et al., 1985, Neurotoxicology, 6, 3, 123-132; Hayashi et al., 1989, Arch. Toxicol., 63, 4, 308-313).

However, the doses of solar energy which are necessary for the degradation of the film are very significant (500,000 kJ / m.sup.2), doses which correspond to more than 15 days of exposure in full Summer (Getlichermann et al., 1994, Polym. Deg. Stab., 43, 343-352) and which are therefore incompatible with the rapid degradation expected during a daily solar exposure (as an indication, the daily solar energy received varies from 5,000 to 10,000 kJ / m.sup.2).

The ultra-violet light first of all creates an ionization reaction in the gel formed from this polymer, and this leads to an increase in the internal osmotic pressure and a swelling of the gel.

As the gels obtained are also heat-sensitive, the increase in the temperature thus leads to a contraction of the gel.

However, a high toxicity of the molecules formed from the isopropylacrylamide does not facilitate the use of this technique in cosmetics (Vyas et al., 1985, Neurotoxicology, 6, 3, 123-132; Hayashi et al., 1989, Arch. Toxicol., 63, 4, 308-313).

The experimental conditions selected are thus quite far from the realistic conditions of use in the case of a cosmetic application.

Moreover, the toxicity of all the photoreactive polymers obtained by organic synthesis hitherto remains a brake for their cosmetic use.

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