Particles of cross-linked proteins and polysaccharides with hydroxamic groups for chelating metals and their uses notably in cosmetics

OF THE INVENTION

Variants Of Preparation Of The Chelating Microspheres

1) The aqueous solution prepared in Example Ia can contain from 5 to 25 g / kg of atelocollagen, it being possible for this collagen to be of mammalian origin or of fish origin, from 10 to 100 g / kg of anhydrous sodium carbonate and from 1 to 100 g / kg of polysaccharide.

2) It is possible to use a buffer other than the carbonate buffer (phosphate, borate, ammonia, succinate, etc. . . . ), it being possible for the pH adjusted in Ib to be between 7.5 and 12 for the proteins other than plant proteins, and between 4.5 and 8, for plant proteins.

3) It is possible to lead the whole of the operation at temperatures between 4.degree. C. and 40.degree. C., and preferably at temperatures between 6 and 25.degree. C.

4) The polysaccharide used- is preferably selected from the polysaccharides described in Example I, and is more preferably chitosan, but various other polysaccharides can be used in the invention: chitosan and its de

OF THE INVENTION

Currently Preferred Method Of Preparation Of Small-Sized Chelating Particles

First step

a) 2 kg of an aqueous solution comprising 18 g / kg of atelocollagen of marine origin is prepared, for example obtained from non-pigmented fish skins such as described in the preceding document by the Applicant U.S. Pat. No. 5,420,248, and 48 g / kg of anhydrous sodium carbonate.

A solution of chitosan prepared beforehand is added into this solution so as to obtain a final concentration of 3 g / kg of chitosan in this aqueous solution.

This addition is carried out with mechanical stirring which is kept up until a perfectly homogeneous solution is obtained.

b) The pH of this solution is adjusted to 9 with 6N hydrochloric acid and 6N sodium hydroxide;

c) 400 g of terephthalic acid dichloride are dispersed in 8 liters of a fatty acid ester, for example Dragoxat.RTM. (Dragoco, Germany);

d) In a vessel refrigerated at 6.degree. C., 300 ml of sorbitan trioleate, for example Span 85.RTM. (ICI, Uni

OF THE INVENTION

Variants Of Preparation Of The Chelating Microspheres

The chelating microspheres can equally encapsulate hydrosoluble substances (e.g.: flavonoids, vitamin C, plant extracts, etc . . . ), insoluble substances (e.g.: insoluble particles, pigments, etc . . . ), or liposoluble substances (vitamin A or E and derivatives thereof, essential oils, etc . . . ). In this case, these solutions are added to the solution described in Ia with very strong mechanical stirring (Ultra-Turax type, 10,000 rpm for 5 minutes), so as to ensure a good dispersion of the whole.