WO2011092368A1

WO2011092368A1 - Photoprotective composition against uv/vis/ir radiation with silicon microspheres as an active compound

Info

Publication number: WO2011092368A1
Application number: PCT/ES2011/070063
Authority: WO
Inventors: Roberto Fenollosa Esteve; Francisco Javier Meseguer Rico; Alberto Gonzalo PÉREZ-ROLDÁN TACUMI; Marie-Isabelle RODRÍGUEZ
Original assignee: Consejo Superior De Investigaciones Científicas (Csic); Universidad Politécnica De Valencia (Upv); Ona Investigación, S. L.
Priority date: 2010-02-01
Filing date: 2011-02-01
Publication date: 2011-08-04
Also published as: ES2363678A1; ES2363678B1

Abstract

The invention relates to the use of silicon microspheres having diameters of between 0.2 and 50 µm as a filter and/or thermoregulator of electromagnetic radiation with a wavelength of between 280 nm and 180 µm, specifically UVA, UVB by absorption and IR by reflection. The invention also relates to compositions, which may be pharmaceutical or cosmetic, that include said silicon microspheres and to the methods for obtaining same.

Description

UV / VIS / IR RADIATION PHOTOPROTECTOR COMPOSITION WITH SILICON MICROSPHERAS AS ACTIVE COMPOUND

The present invention relates to the use of silicon microspheres as a sunscreen of UVA, UVB absorption and IR reflection radiation. The invention also relates to pharmaceutical and cosmetic compositions comprising said silicon microspheres and their methods of production. STATE OF THE PREVIOUS TECHNIQUE

Nowadays it is well known that the skin is sensitive to sunlight, which can cause different alterations depending on the radiation it receives. The electromagnetic spectrum of solar radiation is broken down into 3 types of light: ultraviolet (UV), visible (VIS) and Infrared (IR).

By convention, UV solar radiation is divided into 3 zones called:

- UVC, corresponding to rays with wavelengths lower than 290 nm, which are absorbed by the ozone of the atmospheric layer without reaching the earth's crust.

- UVB, corresponding to wavelengths between 290 and 320 nm, causing erythema, and burns of varying degrees on the skin.

- UVA, corresponding to wavelengths between 320 and 400 nm, which are responsible for premature skin aging processes, and to promote cancers and numerous phototoxic and photoallergic reactions.

Since the first sun creams appeared at the end of the 60s, the field of sun protection has evolved towards products capable of not only shielding UVB rays but also UVA. Typically sunscreen agents are usually organic chromophores compounds (chemical filters) that absorb UVB very well and to a lesser extent UVA, or particulate inorganic compounds (physical filters) which are very effective for blocking UVAs by reflection and light scattering. Thus, a hybrid formulation of the sunscreen with chemical and physical filters may be suitable for shielding a wide area of solar spectrum radiation.

The physical filters are usually metal oxides and compared to the organic molecules of the filters cause few irritations and are physiologically inert, which are present in most sunscreen formulations. The most common are particles of ΤΊΟ2 (titanium dioxide) or ZnO (zinc oxide) whose size depends on the radiation they block, interacting strongly with wavelengths of approximately twice the diameter of the particle. The great drawback, from the aesthetic point of view, is the whitish effect produced by large-sized particle preparations (the most effective against visible light) on the skin due to the fact that ,2, and to a lesser extent ZnO , have a strong diffusing effect of visible light. This problem has been solved with the increasingly widespread use of nanometric particles that give the product transparency (10-100 nm for T1O2 and 30-200 nm for ZnO) and shifts its activity to the UV zone. However, due to the size of these particles, some reports warn of their possible penetration into the body. Other studies, on the other hand, minimize this effect especially when compared to the toxicity of some organic compounds present in sunscreens (A. Nel et al. Critical reviews in toxicology, 37, 521-277, 2007; X. Deng et al. Nanotechnoloqy, 20, 1 15101, 2009).

In addition, certain studies have shown that metal oxide nanoparticles produce allergic reactions in certain individuals and their photocatalytic nature is well known to chemists, particularly those of ΤΊΟ2 that could generate free radicals by UV light. To minimize this problem, several studies have focused on coating the outer layer of particles with another material such as polymers or manganese dioxide (Mn0 ₂ ) (Eusolex T-PRO®, Merck Chemicals) active with free radical sequestrant. Other ΤΊΟ2 particles have been coated with layers of S1O2 or AI2O3, which form hydrated oxides that can capture hydroxyl radicals, and therefore reduce surface reactions. However, some preparations of ΤΊΟ2 / ΑΙ2Ο3 and TIO2 / S1O2 have shown an increase in photocatalytic activity.

In that sense, recent research by A.O. Rybaltovskii et al, Optics and Spectroscopy, 101, 590-596, 2006; and in US2007 / 0102282, they propose the use of nanoclusters of silicon particles as a UV protector, underlining their respect for the environment due to their ability to hinder the formation of harmful biological compounds during the UV-induced degradation of sunscreen components .

Although research in the field of sunscreens has mainly focused on the development of UVB and UVA radiation protection products, it should be borne in mind that rays with wavelengths located in the area between 400 and 800 nm ( VIS zone) and above (IR) can also penetrate the skin and chronic exposure can cause damage and contribute to skin aging processes or lead to melanomas (HM Bassel et al. Photochemistrv and Photobioloqy, 84, 450-462, 2008; P. Schroederet al. In Skin Aqinq, Eds B. Gilchrest, J. Krutmann, Springer, Berlin, 45-53, 2006).

In the range of visible radiation (VIS), apart from metal oxide particles of adequate size for the reflection of this type of light, such as ZnO and TiO ₂ (Hombitec®, Sachotec®, ...), they have been proposed from dyes that absorb light of different wavelengths (blue, red, yellow ...) and that used alone or in mixture give the skin a natural color, to flavonoids. The biological effects of IR radiation (which is also divided by convention between IR-A (760 - 1400 nm), IR-B (1400 - 3000 nm) and IR-C (3000 nm -1 mm)) are actually still little known and the results of investigations in this regard are full of controversies. IR radiation would enhance the harmful effects of UV acting in synergy. However, other studies point to a protective effect of IR radiation against damage from UV radiation. However, it should be noted that the light with wavelength in the infrared zone is thermal radiation, which causes the redness and heating of the skin that characterize the thermal erythema: they penetrate the epidermis, reach the vascular network activating the microcirculation and produce immediate vasodilation. For these reasons, there is great interest in investigating the effects of IR radiation on the skin and developing products capable of screening it and acting as thermoregulators. Some filters claim protection against infrared radiation. For example, infrared reflective particles such as so-called pearl luster pigments have been used in patents ES2089356 and US6187298. These are particles with layers or flakes structure generally made of mica as a support material coated with ΤΊΟ2 or SnÜ2 of different thicknesses and which can be doped with iron or cerium.

The T1O2 in its rutile-like structure has a high protective power against IR radiation given its reflective property for those wavelengths (this property is absent when its crystalline structure is anatase). This gives the sunscreens that contain it greater anti-erythema properties (L. Violin, et al, International Journal of Cosmetic Science, 16, 1, 13-120, 1994). However, there are still few developments of IR radiation filters. From all of the above, the absence of a single compound capable of covering a wide range of protection from UV radiation to thermal radiation (IR) and which is totally harmless stands out. DESCRIPTION OF THE INVENTION

The present invention provides a new use of silicon microspheres (whose description and synthesis procedure is detailed in patent application ES2331824 and in the publication: Fenollosa R., et al., Adv. Mater., 20, 95-98 , 2008), as protective compositions of sunlight, effective against broad-spectrum radiation (UVA + UVB), as well as IR radiation. These compositions have as an active component or principle silicon microspheres of a size between 0.2 μηι and 50 μηπ, capable of absorbing UV radiation and reflecting IR thermal radiation conferring a thermoregulatory effect.

In this way, the invention provides the use of silicon microspheres as a sunscreen of UVA, UVB by absorption and IR radiation by reflection, while providing pharmaceutical and cosmetic compositions comprising said silicon microspheres and their methods of obtaining. These compositions can act as sunscreens in a wide range of electromagnetic radiation and as thermoregulators. That is, they offer protection against the harmful effects of the sun, both in the UV zone and in the area of longer wavelengths (VIS and IR) of the solar spectrum and in turn allow, by reflection of the infrared radiation, to maintain a constant temperature on the skin or other surfaces where the preparations of the present invention are applied. Therefore, a first aspect of the present invention relates to the use of silicon microspheres with a diameter between 0.2 and 50 μηι as a solar filter and / or as a thermoregulator, with the capacity to filter electromagnetic radiation of wavelength between 280 nm and 180 μηπ. Preferably these radiations belong to the wavelength range of UVA, UVB, VIS and IR, and more preferably UVA, UVB and IR. By "sunscreen" in the present invention is meant a substance that reflects or absorbs solar radiation preventing it from entering the surface to be protected and / or acting by reflecting or absorbing solar radiation and transforming it into another type of energy that is not harmful for that surface.

The term "thermoregulator" means substances that keep the temperature constant on a surface where it is applied, by means of the reflection of the infrared radiation.

The silicon microspheres used in the present invention are spherical microparticles with a very regular and smooth surface. These microspheres may have undergone surface modification treatments, for example an increase in hydrophilic character.

A preferred embodiment of the present invention comprises silicon microspheres for use as a pharmaceutical composition. More preferably, silicon microspheres are used as a pharmaceutical composition for the prevention of sunburn or damage. Even more preferably when sunburn or damage occurs on skin and / or hair.

By "sun damage" refers to pathologies caused by exposure to the sun, for example they can be selected from actinic keratosis or skin cancer. Different types of skin cancer can occur, for example basal cell carcinoma (also called basal cell epithelioma), squamous cell carcinoma (also called spinocellular epithelioma) or melanoma. In a preferred embodiment, this pharmaceutical composition is in the form suitable for topical administration. Such compositions and / or their formulations can be administered to an animal, including a mammal and, therefore, to man, by solutions, hydroalcoholic solutions, emulsions, lotions, ointments, gels, creams that can be lipophilic or hydrophilic, pastes or any other. suitable form known to any expert in the field. Preferably it is a lotion or a cream, which can be lipophilic or hydrophilic.

"Lotion" in the present invention is understood as a preparation made with an aqueous or low-alcohol vehicle containing dissolved or suspended substances.

By "cream" is meant in the present invention a multiphase preparation consisting of a lipophilic phase and an aqueous phase. Creams are classified in turn into:

- Lipophilic creams: the continuous phase is lipophilic, these emulsions are known by W / O (water in oil)

Hydrophilic creams: the continuous phase is aqueous, these emulsions are known O / W (oil in water) The dosage to obtain a therapeutically effective amount depends on a variety of factors, such as age, skin type, tolerance, etc. .. In the sense used in this description, the term "therapeutically effective amount" refers to the amount of the composition of the invention that produces the desired effect and, in general, will be determined, inter alia, by the characteristics of said composition and the therapeutic effect to be achieved. It is contemplated that the compositions of the present invention may be pharmaceutical compositions, which comprise a therapeutically effective amount of the silicon microspheres, together with, a therapeutically effective amount of a pharmaceutical carrier.

By "pharmaceutical composition" is meant in the present invention a compound that contains at least one high purity chemical used in the prevention of a disease, or to prevent the appearance of an unwanted physiological process.

In another preferred embodiment, the silicon microspheres are used for the preparation of a cosmetic composition. In a more preferred embodiment the cosmetic composition is used for the prevention of spots and premature aging of the skin / or hair and other adverse effects, on the skin and / or hair, of solar radiation. Like the pharmaceutical composition, the cosmetic composition is in the form suitable for topical administration.

By "cosmetic composition" is meant in the present invention a product used for body hygiene or for the purpose of improving beauty, especially of the face, body, lips, etc.

Another preferred use of silicon microspheres is for the manufacture of a protective composition of all types of materials. These materials being protected selected from natural, synthetic or any combination thereof. The materials may be wood, plastics, metals or alloys, etc., their combinations, or any other type of material known to any person skilled in the art. These compositions act as a protective barrier against aging and deterioration of these materials, due to the electromagnetic radiation that could be affecting them.

In the above-mentioned uses, the use of these microspheres is as an active component, since it acts as a sunscreen and other electromagnetic radiation, absorbing, above all, UVA, UVB radiation and reflecting IR radiation.

In the present invention, being microspheres a physical filter, they have the advantage of not causing irritation and of being physiologically inert. And being Small particles of micrometer size will also have the additional advantage of preventing the composition from looking whitish when applied. In turn, being micrometric they do not cause allergies such as the nanometric particles of ΤΊΟ2 or ZnO.

A second aspect of the present invention relates to a pharmaceutical composition comprising silicon microspheres with diameters between 0.2 and 50 μηπ, in addition to a pharmaceutically effective vehicle. In a more preferred embodiment the silicon microspheres have diameters between 0.2 and 5 μηπ.

The percentage by weight of the silicon microspheres is preferably between 0.5 and 5%, more preferably between 0.8 and 2% with respect to the weight of the final composition.

The dosage to obtain a therapeutically effective amount depends on a variety of factors, such as age, skin type, tolerance, etc. In the sense used in this description, the expression "therapeutically effective amount" refers to the amount of the composition of the invention that produces the desired effect and, in general, will be determined, among other things, by the characteristics of said composition and the therapeutic effect to be achieved. It is contemplated that the compositions of the present invention may be pharmaceutical compositions, which comprise a therapeutically effective amount of the silicon microspheres, together with, a therapeutically effective amount of a pharmaceutical carrier.

The pharmaceutical composition in a preferred embodiment is characterized by further comprising at least one other component selected from thickener, emulsifier, moisturizer, colorant or any combination thereof. This pharmaceutical composition in a preferred embodiment is in a form suitable for topical administration, as described above. Being in another more preferred embodiment characterized by being a lotion, or a lipophilic or hydrophilic cream.

A third aspect of the present invention refers to a cosmetic composition comprising silicon microspheres with diameters between 0.2 and 50 μηπ. In a preferred embodiment the silicon microspheres have diameters between 0.5 and 5 μηπ.

The percentage by weight of the silicon microspheres is preferably between 0.5 and 5%. And more preferably between 0.8 and 2% with respect to the final cosmetic composition.

The cosmetic composition of the present invention may further comprise at least one additive that is selected from thickeners, emulsifiers, moisturizers, dyes or any combination thereof.

The cosmetic composition is preferably in a form suitable for topical administration, as defined above. More preferably said form suitable for topical administration is a lotion, or a lipophilic or hydrophilic cream.

These pharmaceutical and cosmetic compositions may contain only silicon microspheres as active component against solar radiation or also contain other protective ingredients such as chemical UV filters and / or known physical filters. It is understood by chemical filters, chromophore compounds that absorb light of a certain wavelength, and physical filters, inorganic compounds that reflect and scatter the light. These cosmetic compositions, like pharmaceuticals, can also be used as thermoregulatory creams.

The silicon microspheres used for the elaboration of the different pharmaceutical or cosmetic compositions can be subjected to surface modification treatments, such as an increase in the hydrophilic character.

Thus, a fourth aspect of the present invention relates to a process for the manufacture of a pharmaceutical or cosmetic composition as described above, where silicon microspheres are pretreated by grinding.

In a preferred embodiment of the process of the present invention, silicon microspheres are added over an aqueous solution. In this case it would be possible to make a lotion, or a hydrophilic cream, to which an oil will be added later.

In a preferred embodiment the silicon microspheres are added to the aqueous phase at a concentration between 0.5 and 5% by weight.

Also the silicon microspheres can preferably be added on an aqueous solution to subsequently form an emulsion with oil, thereby achieving a lipophilic cream.

Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and drawings are provided by way of illustration, and are not intended to be limiting of the present invention. DESCRIPTION OF THE FIGURES

Figure 1: Diameter distribution of silicon colloids used in the development of sunscreen creams. The distribution is centered around 1, 8 microns and has a width (σ) of 0.5 microns.

Figure 2: Effective Wed scattering section averaged according to the distribution of colloid diameters in Figure 1. Figure 3: Optical transmission spectra obtained, in the IR range, of the samples prepared in the form of an O / W emulsion, with silicon microspheres (0.8% by weight and with the size distribution of Figure 1) object of the present invention (solid line), and of the samples prepared according to the same procedure with 0.8% by weight of ΤΊΟ2 particles (P-25 Degussa) (broken line), with different amounts on the glass substrates (1 1 mg / cm ² ) and PMMA-HD6® (2 mg / cm ² ).

Figure 4: Optical transmission spectra obtained, in the UV range, of the samples prepared in the form of O / W emulsions, with silicon microspheres (0.8% by weight and with the size distribution of Figure 1) object of the present invention, and with the samples prepared according to the same procedure with ΤΊΟ2 particles (P-25 Degussa), with the substrates PMMA-HD6® (solid line) and PMMA-HD2® (dashed line). With quantities on substrates of 2mg / cm ² .

Figure 5: Distribution of diameters (Φ) of silicon colloids used to calculate the average effective section of Figure 6. The distribution is centered around 2.5 microns and has a width (or) of 0.75 microns. Figure 6: Emitting power of the human body (curve below) as a function of the wavelength calculated from Planck's law, considering that it is a black body that is at a temperature of 37 ° C. Top curve It corresponds to a calculation of the effective Wed scattering section averaged according to the distribution of colloid diameters in Figure 5. In both curves the maximum is centered around 9.3 microns. EXAMPLES

The invention will now be illustrated by tests carried out by the inventors, which shows the specificity and effectiveness of silicon microspheres as a sunscreen, and the corresponding optical measurements. By way of comparison, the results obtained with the same type of preparation are also presented but replacing the Silicon microparticles with ΤΊΟ2 (P25 Degussa).

Through the following examples, the optical properties of various sunscreen preparations object of the present invention are presented. Optical transmittance measurements have been performed both in the Infrared, by Fourier transform Infrared Spectroscopy (FTIR), and in the ultraviolet range. (UV) The optical measurements presented in this document have been made on thin layers of the different sunscreen preparations, of the same thickness on glass substrates and PMMA substrates (Helioplate® HD6 (roughness of 6 microns), Helioplate HD2 (roughness 2 microns) - Helioscreen), which simulate the skin. The amounts of preparation applied on the substrates vary between 2 mg / cm ² (on PMMA) and 1 1 mg / cm ² (on glass).

The silicon microspheres, with size distribution according to the curve of Figure 1 were synthesized according to the procedure detailed in patent application ES2331824 and in the publication: "Fenollosa R., et al., Adv. Mater. 20, 95 -98,2008 ", and they were subjected to a grinding in order to obtain microparticles as loose as possible and without the presence of aggregates. These microspheres give rise to an average Wed scattering section in the Near infrared illustrated in Figure 2. This scattering is responsible for shielding solar infrared radiation.

Example 1

This example describes the preparation of an oil-in-water (O / W) emulsion with silicon microparticles as an active compound and its optical properties in the Infrared range between 850 nm and 2.2 microns and the UV of 280nm at 450 nm. The results of the optical transmissions of the preparations in glass plates and in roughness 6 and 2 micron PMMA plates are shown.

Preparation of an oil-in-water emulsion (O / W):

0.3% by weight of methylcellulose is dissolved in water at 70 ° C, with stirring. Once a homogeneous solution is obtained, 4% self-emulsifiable glyceride monostearate is added while stirring.

Before use, the silicon microparticles synthesized according to the method described in patent application ES2331824 and in the publication: "Fenollosa R., et al., Adv. Mater. 20, 95-98,2008", with distribution of sizes according to the curve of Figure 1, they were subjected to grinding to obtain individual microspheres and avoid aggregates of several particles.

The silicon microparticles are added to the aqueous solution (between 0.8 and 1% by weight with respect to the total weight of the emulsion) under strong mechanical agitation (3000 rpm).

After 10-15 minutes, mineral oil is added gradually (between 20-30% by weight with respect to the total weight) while stirring vigorously for another 10-15 minutes.

The preparation obtained has a creamy and smooth touch due to the regular geometry of the silicon microspheres. Sample preparation for optical measurements.

Evenly, 1 1 mg / cm ² and ² mg / cm ² of preparation are spread on a glass object holder and PMMA plates (Helioplate®. HD) respectively marketed by Helioscreen. PMMA plates are internationally accepted as a measuring substrate for solar preparations. PMMA plates of 6 μηι roughness (HD6) and 2 μηι roughness (HD2) were used

Optical measurements

Measurements in the Infrared range

Samples prepared in the form of emulsion (O / W), containing silicon microspheres of the present invention, were analyzed optically by infrared spectroscopy in the range between 0.85μηι and 2.2 μηι considering the substrates (glass or PMMA- HD) as a reference, and varying the amounts of emulsion distributed by area (1 1 mg / cm ² and ² mg / cm ² respectively).

With the sample containing 0.8% by weight of silicon microspheres and prepared with emulsion amounts of 11 mg / cm ² (on glass), optical transmission values are obtained between 5% (1 μηπ) and 10% (2.2 μηπ).

With the sample containing 0.8% by weight of silicon microspheres and prepared with emulsion quantities of 2mg / cm ² (on HD6), optical transmission values between 48% (1 μηπ) and 65% (2.2 μηπ) are obtained ).

Measures in the UV range

Samples prepared in the form of emulsion (O / W), containing silicon microspheres and object of the present invention, were analyzed optically by UV spectroscopy, with integrating sphere, in the range between 280 nm and 450 nm considering air as reference , and on 2 PMMA-HD substrates of different roughness (6μηι (HD6) and 2μηι (HD2)). Emulsion amounts of 2mg / cm ^{2 were used} . With the sample containing 1% by weight of silicon microspheres and prepared on a substrate of PMMA-HD® (HD6) of roughness 6μηι, optical transmission values between 41% (280 nm) and 65% (450nm) are obtained With the sample containing 1% by weight of silicon microspheres and prepared on a substrate of PMMA-HD® (HD2) of roughness 2μηι, optical transmission values between 40% (280 nm) and 64% (450nm) are obtained.

For comparison, a sample was prepared according to the same preparation and characterization procedure as detailed in example 1, but replacing the silicon microspheres with Titania microparticles (P25-Degussa), that is to say with the same weight percentage as the of silicon microspheres. Figures 3 and 4 show the experimental results of optical transmission obtained. In Figure 3 the results of optical transmission in the IR range are compared with emulsions of the present invention prepared with silicon microparticles (example 1) and with emulsions prepared with ΤΊΟ ₂ particles (P25 Degussa) with the same weight percentage than that of silicon microspheres, on glass substrates and PMMA-HD6® by varying the amounts of emulsion distributed by area (1 1 mg / cm2 and 2mg / cm2 respectively). It is observed how emulsions with silicon microspheres produce a greater attenuation of infrared radiation than emulsions with microparticles of Titania. Figure 4 compares the results of optical transmission in the UV range, with integrating sphere, obtained with 2mg / cm2 of the preparations containing the silicon microparticles of the present invention and of the preparations containing the Ti0 ₂ particles (P25 Degussa ) with the same weight percentage as silicon microparticles, on PMMA-HD6® substrates (6 μΐη roughness) (continuous line) and PMMA-HD2 (2 μΐη roughness) (dashed line). Similar transmission values are observed for both types of emulsion, titania and silicon, however in the wavelength range from 350 nm to 440 nm the emulsion with silicon microparticles produces 10% more screening than the emulsion with titania microparticles. Example 2

This example describes the preparation of an aqueous base cream with silicon microparticles as an active compound, and its optical properties in the range of Infrared between 850 nm and 2.2 microns and UV 280nm at 450 nm. The results of the optical transmissions with different quantities (1 1 mg / cm ² and ² mg / cm ² ) distributed on glass and PMMA-HD® plates are shown respectively

Preparation of a cream:

0.3% by weight of methylcellulose is dissolved in water at 70 ° C, with stirring (2000 rpm). Once a homogeneous solution is obtained, 4% of self-emulsifiable glyceride monostearate is added while stirring.

The silicon microparticles are added to the aqueous solution (between 0.8 and 1% by weight with respect to the total weight) under strong mechanical agitation (3000 rpm).

Sample preparation for optical measurements.

Evenly, 1 1 mg / cm ² and ² mg / cm ² of preparation are spread on a glass object holder and PMMA plates respectively (Helioplate®.HD marketed by Helioscreen) Optical measurements

Infrared range measurements

Samples prepared in the form of an aqueous cream, containing silicon microspheres and object of the present invention, were analyzed optically by infrared spectroscopy in the range between 0.85μηι and 2.2 μηι considering the substrates (glass or PMMA-HD) as a reference, and varying the amounts of cream spread by area (11 mg / cm ² and ² mg / cm ² respectively). With the sample containing 0.8% by weight of silicon microspheres and with amounts of cream of 1 1 mg / cm ² (on glass), optical transmission values are obtained between 33% (1 μηπ) and 27% (2.2 μηπ).

With the sample containing 0.8% by weight of silicon microspheres and with cream amounts of 2mg / cm ² (over PMMA-HD® (HD6) roughness 6 μηπ), optical transmission values between 79% (1 μηπ) are obtained ) and 84% (2.2 μηπ)

Measures in the UV range

The prepared samples object of the present invention were optically analyzed by UV spectroscopy, with integrating sphere, in the range between 280 nm and 450 nm considering air as reference. Preparation amounts of 2mg / cm ^{2 were used} .

With the sample containing 1% by weight of silicon microspheres and prepared on a substrate of PMMA-HD6® (HD6) of roughness 6 μηι, optical transmission values between 41% (280 nm) and 67% (450 nm) are obtained.

With the sample containing 1% by weight of silicon microspheres and prepared on a substrate of PMMA-HD® (HD2) of roughness 2 μηι, optical transmission values between 46% (280 nm) and 79% (450 nm) are obtained. For comparison, a sample was prepared according to the same preparation and characterization procedure as detailed in example 2 (aqueous base cream), but replacing the silicon microspheres with Titania microparticles (P25-Degussa), that is, with the same weight percentage as that of silicon microspheres.

Measurements in the Infrared range

Table 1 summarizes and compares the results of optical transmission in the IR range obtained with the creams prepared with silicon microparticles of the present invention and Ti02 particles (P25 Degussa), on glass substrates and PMMA-HD6® varying the amounts of emulsion distributed by area (1 1 mg / cm ² and 2 mg / cm ² respectively).

TABLE 1: Optical transmission results in the IR range Measures in the UV range

Table 2 summarizes and compares the results of optical transmission in the UV range, with integrating sphere, obtained with 2 mg / cm ² of the preparations containing the silicon microparticles of the present invention and 2mg / cm ² of the preparations containing Ti0 ₂ particles (P25 Degussa) on PMMA-HD6® substrates (6 μηι roughness) and PMMA-HD2 (2 μηι roughness).

TABLE 2: Optical transmission result in the IR range

Example 3

This example describes the preparation of an oil with silicon microparticles as an active compound and the optical properties of this same preparation in the range of Infrared between 850 nm and 2.2 microns and UV 280nm at 450 nm. The results of the optical transmissions of the preparations with different quantities per area on glass plates and roughness PMMA of 6 microns are shown.

Oil preparation

Before use, silicon microparticles synthesized according to the method described in patent application ES2331824 and in the publication: "Phenolose R., et al., Adv. Mater., 20, 95-98,2008 ", with size distribution according to the curve of Figure 1, were subjected to grinding to obtain individual microspheres and avoid aggregates of several particles. Silicon microparticles are added to a mineral oil (between 0.8% and 1% by weight with respect to the total weight) under strong mechanical agitation (3000 rpm).

Sample preparation for optical measurements.

Evenly, 1 1 mg / cm ² and ² mg / cm ² of preparation are spread on a glass object holder and PMMA plates respectively (Helioplate®. HD6).

Optical measurements

Measurements in the Infrared range

The oil samples prepared with silicon microspheres and object of the present invention were analyzed optically by infrared spectroscopy in the range between 0.85 μηι and 2.2 μηι considering the substrate (glass or PMMA-HD) as a reference. With the oil sample containing 0.8% by weight of silicon microspheres and prepared with 1 1 mg / cm2 on glass, optical transmission values of 78-79% are obtained.

With the oil sample containing 0.8% by weight of silicon microspheres and prepared with 2mg / cm ² on HD6, optical transmission values of 47-50% are obtained.

Measures in the UV range

The oil samples prepared with silicon microspheres and object of the present invention were analyzed optically by UV spectroscopy, with integrating sphere, in the range between 280 nm and 450 nm considering the Air as a reference. Two types of substrates with roughness of 6 (HD6) and 2 microns (HD2), and preparation amounts of 2 mg / cm ^{2 were used} .

With the oil sample containing 1% by weight of silicon microspheres and prepared on a substrate of PMMA-HD® (HD6) of roughness 6μ (η, optical transmission values are obtained between 43% (280 nm) and 76% (450nm )

With the oil sample containing 1% by weight of silicon microspheres and prepared on a substrate of PMMA-HD® (HD2) of roughness 2 μηι, optical transmission values are obtained between 48% (280 nm) and 76% (450nm) .

Example 4

Example of a cream to maintain body heat. Examples of sunscreen creams made above are based on a distribution of colloid diameters centered around 1.8 microns and with a size dispersion of 30% (see figure 1). This size distribution shields infrared light from solar radiation with near-infrared wavelengths. If a different size distribution is chosen, for example a distribution like that of Figure 5, with an average size of about 2.5 microns and with a 30% dispersion, a cream developed from these colloids would resemble infrared radiation with a wavelength of 9.5 microns, which is precisely the radiation emitted by the human body. Therefore this cream can be used to maintain body heat. Figure 6 illustrates these reasonings: the curve below shows the radiation of the human body (at 37 ° C) calculated from Planck's law assuming it is a black body and the curve above shows the effective scattering section Average Wed which gives rise to the size distribution of Figure 5. It is observed that the radiation and scattering maximums respectively coincide and are located around 9.5 microns.

Claims

1. Use of silicon microspheres with diameters between 0.2 and 50 μηι as a filter and / or thermoregulator of electromagnetic radiation of wavelength between 280nm and 180 μηπ.

2. Use according to claim 1, wherein the radiations are UVA, UVB and IR.

3. Use of the microspheres according to any of claims 1 or 2, for the preparation of a pharmaceutical composition.

4. Use according to claim 3, for the prevention of sunburn or damage.

5. Use according to claim 4, wherein sunburn or damage occurs on skin and / or hair.

6. Use according to any of claims 3 or 4, wherein the pharmaceutical composition is in the form suitable for topical administration.

7. Use according to claims 4 to 6 wherein the sun damage can be selected from actinic keratosis or skin cancer.

8. Use of the microspheres according to any of claims 1 or 2, for the preparation of a cosmetic composition.

9. Use according to claim 8, for the prevention of spots and premature aging of the skin / or hair.

10. Use according to any of claims 8 or 9, wherein the cosmetic composition is in the form suitable for topical administration.

eleven . Use according to any of claims 1 or 2, for the manufacture of a protective composition of materials.

12. Use according to claim 1, wherein the materials to be protected are selected from natural, synthetic or any combination thereof.

13. Pharmaceutical composition comprising silicon microspheres with diameters between 0.2 and 50 μηι and a pharmaceutically acceptable carrier.

14. Pharmaceutical composition according to claim 13, wherein the silicon microspheres have diameters between 0.2 and 5 μηπ.

15. Pharmaceutical composition according to any of claims 13 or 14, wherein the percentage by weight of the silicon microspheres is between 0.5 and 5% with respect to the final composition.

16. Pharmaceutical composition according to any of claims 13 to 15, wherein the percentage by weight of the silicon microspheres is between 0.8 and 2% with respect to the final composition.

17. Pharmaceutical composition according to any of claims 13 to 16, further comprising at least one component that is selected from the list comprising thickener, emulsifier, moisturizer, colorant or any combination thereof.

18. Pharmaceutical composition according to any of claims 13 to 17, in a form suitable for topical administration.

19. Pharmaceutical composition according to any of claims 13 to 18, characterized in that it is a lotion, a lipophilic or hydrophilic cream.

20. Cosmetic composition comprising silicon microspheres with diameters between 0.2 and 50 μηπ.

twenty-one . Cosmetic composition according to claim 20, wherein the silicon microspheres have diameters between 0.5 and 5 μηπ.

22. Cosmetic composition according to any of claims 20 or 21, wherein the percentage by weight of the silicon microspheres is between 0.5 and 5%.

23. Cosmetic composition according to any of claims 20 to 22, wherein the percentage by weight of the silicon microspheres is between 0.8 and 2%.

24. Cosmetic composition according to any of claims 20 to 23, further comprising at least one additive that is selected from thickeners, emulsifiers, moisturizers, colorants or any combination thereof.

25. Cosmetic composition according to any of claims 20 to 24, in a form suitable for topical administration.

26. Cosmetic composition according to claim 25, wherein the suitable form for topical administration is a lotion, a lipophilic or hydrophilic cream.

27. Process for the manufacture of a pharmaceutical composition according to any of claims 13 to 19 or a cosmetic composition according to any of claims 20 to 26, wherein the silicon microspheres are pretreated by grinding.

28. A method according to claim 27, wherein the silicon microspheres are added over an aqueous solution.

29. Method according to any of claims 27 or 28, wherein the silicon microspheres are added onto an aqueous solution to subsequently form an oil emulsion.