WO2017153888 – Physical solar filters consisting of substituted hydroxyapatite in an organic matrix

RIF.: 102016000023614
Inventors: Sandri Monica, Sprio Simone, Tampieri Anna
Owner: Consiglio Nazionale delle Ricerche
Priority Data: 07/03/2016
Pub. No.: (WO/2017/153888)
International Application No.: PCT/IB2017/051290
International Filing Date: 06.03.2017 Publication Date: 14.09.2017

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The present invention relates to a composition for the protection against solar radiation, consisting of an organic matrix, preferably a gelatin, and hydroxyapatite nanoparticles modified by the substitution of part of the phosphorus with titanium, and part of the calcium with iron.

1.Composition for the preparation of physical solar filters, comprising an organic matrix formed by polymer molecules, onto which are linked nanoparticles of hydroxyapatite substituted with titanium and/or iron ions, in which phosphorus is partially replaced by titanium in an amount between 8 and 50% atomic with respect to phosphorus, and/or in which calcium is partially replaced by iron in an amount between 2 and 40% atomic with respect to calcium, and wherein the amount of the organic matrix is between 5 and 60% by weight and the amount of substituted hydroxyapatite is between 35 and 90% by weight, the remaining part being constituted by water.
2.Composition according to claim 1 , wherein the compound constituting the organic matrix is selected from polylactic acid, collagen, sodium alginate, polyethylene glycols (PEGs), chitosan, solid lipid particles (SLPs) and gelatins.
3.Composition according to any one of claims 1 or 2 wherein said hydroxyapatite particles have a size between 10 and 200 nm.
4.Process for the preparation of a composition according to any one of claims 1 to 3, which comprises the steps of:
a) preparing an aqueous solution containing a precursor of calcium and of at least one salt of iron (II) and at least one salt of iron (III);
b) preparing a hydroalcoholic solution of a titanium precursor;
c) preparing an aqueous solution, containing the constituent of the organic matrix, of a water soluble phosphorus compound;
d) adding simultaneously and slowly the solutions of the precursors of titanium and of phosphorus compound/organic matrix to the solution containing the precursor of calcium;
e) allowing the system to react at a temperature between room temperature and 70 °C for a time between 1 and 5 hours;
and f) subjecting to freeze-drying treatment the product obtained as a result of step e), in which the nanoparticles of hydroxyapatite substituted by titanium and/or iron ions are generated directly on the polymer molecules of the organic matrix during the process.
5.Process according to claim 4 wherein, in the solution of step a) are used, as a precursor of calcium, a salt thereof or the hydroxide (Ca(OH)2), and in which the calcium ion has a concentration of between 50 and 150 mg/mL, and the iron precursors are employed in molar ratio 1:1 with an overall concentration of iron ions between 10 and 45 mg/mL.
6.Process according to claim 5, wherein the precursor of calcium is Ca(OH)2 and in which the precursors of iron (II) and iron (III) are the chlorides thereof, respectively FeCl2-4H2O and FeCl3-6H2O.
7.Process according to any one of claims 4 to 6 wherein, in the solution of step b) , as precursor of titanium it is employed the isopropoxide (Ti(-O-CH(CH3)2)4) and the solution has a concentration between 12 and 100 mg/mL of titanium.
8.Process according to any one of claims 4 to 7 wherein, in the solution of step c) , as precursor of phosphorus it is used a salt thereof or a phosphoric acid, and the solution has a concentration between 75 and 1 10 mg/mL of phosphorus.
9.Use of a composition according to any one of claims 1 to 3 for the preparation of a solar filter of physical type.

Contact: Monica Sandri