Diamond-containing composition and method for the production thereof

Abstract

The present invention pertains to a diamond-containing composition (1), comprising – diamond particles (101) whose surface is oxidized and comprises oxygen-containing functional groups such as hydroxyl groups, carboxyl groups, keto groups, aldehyde groups, epoxy groups and / or lactone groups, – a hydrophilic biopolymer (103) which envelops each individual diamond particle (101), where the hydrophilic biopolymer (103) is held on the surface of the diamond particles (101) by way of a multiplicity of hydrogen bonds per molecule. The present invention further relates to a method for producing the diamond-containing composition (1) and also to a cosmetic product and its use.

Description

[0001] Diamond-containing composition and process for its preparation

[0002] The present invention relates to a diamond-containing composition and a process for its preparation as well as to a cosmetic product containing the diamond-containing composition.

[0003] Diamonds are not only used in the jewelry and watchmaking industries, but also have a wide range of applications in medicine. For example, diamonds are used as contrast agents. Diamonds can also be used to transport medications into the body. In these applications, diamond grain sizes are exclusively in the nanoscale, i.e., in the range of 100 nm and smaller.

[0004] For example, in "Noninvasive Nanodiamond Skin Permeation Profiling Using a Phase Analysis Method: Ex Vivo Experiments" (ACS Nano (2022)), Channa Shapira et al. describe the production of nanodiamonds capable of delivering medicinal agents through the skin. The nanodiamonds used must be no larger than 100 nm.

[0005] The use of diamonds in cosmetics has so far been limited to mixing diamond powder into cosmetics and then marketing it as a "diamond-based beauty product." The diamonds used here have grain sizes in the range of several micrometers and primarily exert an optical effect on the skin, particularly through light refraction and scattering. Alternatively, diamond powder can be used as an exfoliating agent. No other cosmetic uses for diamonds are known.

[0006] However, in cosmetics, there is a need to not only create superficial effects with diamonds, but also to introduce cosmetically effective preparations into the skin without penetrating the deepest layers of the skin, as is the case with nanodiamonds in medical applications.

[0007] The present invention is therefore based on the object of overcoming the disadvantages of the prior art and of providing a diamond-containing composition and a method for its preparation which is designed to penetrate the epidermis almost completely, but does not penetrate into deeper skin layers lying beneath the epidermis.

[0008] This object is achieved in a first aspect of the present invention by a diamond-containing composition (1) comprising

[0009] - diamond particles (101 ) whose surface is oxidized and has oxygen-containing functional groups such as hydroxyl groups, carboxy groups, keto groups, aldehyde groups, epoxy groups and / or lactone groups,

[0010] - a hydrophilic biopolymer (103) which surrounds each individual diamond particle (101), wherein the hydrophilic biopolymer (103) is held on the surface of the diamond particles (101) via a plurality of hydrogen bonds per molecule.

[0011] For the purposes of the present invention, “diamond particle” is understood to mean a particle in the cubic modification of carbon, the surface of which is oxidized so that it has the above-mentioned groups.

[0012] "Hydrophilic biopolymers" are polymers that originate naturally, biologically, or occur in plants and / or animals, and whose solubility and polarity allow them to dissolve in aqueous media. The opposite of the hydrophilic biopolymer of the invention would be fat-soluble, physiological substances.

[0013] A characteristic of these hydrophilic biopolymers (103) is that the solubility is not primarily achieved via salt-like or ionic groups, but via a high polarity based on hydrophilic, organic, functional groups.

[0014] The reason for the choice of hydrophilic groups according to the invention lies in their ability to form strong hydrogen bonds with other hydrophilic substances, namely the hydrophilic surface characteristics of the diamond particles (101). The individual hydrogen bonds are weak, but due to the large number of hydrogen bonds and the density at the surface of the diamond particles, the hydrophilic biopolymer (103) remains "reliably" bound to the surface of the diamond particles (101). A hydrophilic biopolymer (103) is typically a macromolecule whose "weight" or chemical weight is expressed in units of daltons (Da) or kilodaltons (kDa).

[0015] Particularly important for the present invention is the high degree of purity of the diamond, or rather the diamond surface, so that it contains as many oxygen-containing functional groups of the aforementioned type as possible. These oxygen-containing functional groups, in turn, form the basis for the hydrophilic biopolymer (103) to "bind" to the diamond particles (101) via hydrogen bonds.

[0016] The present invention, for the first time, makes it possible to bond a hydrophilic biopolymer (103) to diamond particles (101) in a sufficiently strong manner. Specifically, each individual diamond particle (101) can be coated by one or more molecules of the hydrophilic biopolymer (103). This makes it possible to introduce hydrophilic biopolymers (103) into deeper layers of the epidermis, into which they would not readily penetrate without the diamond particles (101) as a carrier.

[0017] In a preferred embodiment, the diamond particles (101) have a size of 0.1 pm to 5.0 pm, preferably 0.25 pm to 1.5 pm, in particular 0.5 pm to 1.0 pm.

[0018] The size determination of the diamond particles (101) was carried out depending on the grain size range for particles from 1 pm to 5 pm by means of particle size measurement using the Coulter counter principle with the device “Multisizer 3” from the manufacturer Beckman-Coulter, and for particles from 0.1 pm to 1 pm with a CPS disc centrifuge from the manufacturer of the same name.

[0019] The Coulter counter method uses capillaries with a defined potential, whereby a change in resistance is detected individually for each particle as the particles to be measured flow through them. The disc centrifuge is based on a retention principle analogous to chromatography, i.e., the temporal measurement of the particle penetration through a liquid gradient allows direct conclusions to be drawn about the particle size. This method is the most precise method for measuring particles in the submicro- and nano-range.

[0020] The particle size selected according to the invention ensures, on the one hand, that the diamond-containing composition (1) can penetrate the epidermis. On the other hand, however, it largely prevents the diamond-containing composition (1) from penetrating deeper skin layers below the epidermis. The selection of diamond as the base material also guarantees physiological compatibility and safety.

[0021] The diamond particles (101) used in the present invention are explicitly not nanoparticles. According to an EU-wide definition (see https: / / single-market-economy.ec.europa.eu / sectors / cosmetics / cosmetic-products-specific-topics / nanomaterials_en), these are defined, at least with regard to cosmetics, as particles in a range of 1 nm to 100 nm.

[0022] For the purposes of the present invention, it has been found advantageous if the diamond particles (101) have a spherical morphology with a length-to-width ratio of 1.0 to 2.0, preferably 1.3 to 1.5, in particular 1.4. The spherical morphology facilitates the penetration of the diamond-containing composition (1) into the epidermis.

[0023] The aspect ratio indicates the ratio between the minimum and maximum diameter of a particle. It is essentially a measure of how "round" a particle is. The aspect ratio was measured using image analysis. Depending on the particle size, microscope images are taken at magnifications of up to 100x. The finely dispersed, isolated, and individual particles are photographically captured, separated, and identified by software. The software then measures the isolated, circled particles based on the magnification used and determines the aspect ratio.

[0024] In the practice of the present invention, a ratio of 1.4 has been found to be optimal in order to allow the particles of the diamond-containing composition (1) to penetrate the skin as easily as possible, but on the other hand also to avoid damaging the skin, as might be the case with sharp-edged diamond particles.

[0025] In a further development of the invention, the hydrophilic biopolymer (103) is selected from hydrophilic polysaccharides, hydrophilic peptides, hydrophilic amino acids, hydrophilic polyamides, hydrophilic polyamines, hydrophilic polysulfones or polysulfonates, hydrophilic polyphosphones or phosphonates, hydrophilic polyelectrolytes, or mixtures thereof. Most preferably, the hydrophilic biopolymer (103) is hyaluronic acid.

[0026] The benefits and effects of hyaluronic acid are generally known. With the present invention, it is possible to allow the hyaluronic acid bound to the diamond particles (101) to penetrate into the deeper layers of the epidermis, down to approximately the basal cell layer. There, the hyaluronic acid can plump and smooth the skin by binding water. The diamond particles (101) also exert a physical effect on the skin, stimulating intensive skin renewal. This allows the hyaluronic acid to deliver its effect precisely where desired.

[0027] Hyaluronic acid, in particular, with its glucose-like structure, has countless hydroxy functions and thus offers opportunities to "dock" onto the hydrophilic diamond surface. Thus, the macromolecular hyaluronic acid envelops the diamond particles (101). The same applies to other hydrophilic biopolymers or polyelectrolytes.

[0028] Particularly preferably, for a further development of the invention, the diamond-containing composition (1) is present in a complete dispersion of the diamond particles (101) in the biopolymer (103).

[0029] In a specific embodiment, the diamond-containing composition (1) according to the invention is characterized in that it has a transmission of 0% in UV / Vis spectroscopy in the wavelength range from 200 nm to 1,100 nm.

[0030] This specific embodiment has the advantage that the diamond-containing composition (1) according to the invention, in addition to the advantageous effects described above, also offers effective sun protection. A specific embodiment is described below. [Further aspects?]

[0031] If process features are mentioned in the description of the diamond-containing composition (1) according to the invention, these refer to the process according to the invention. Likewise, material features mentioned in the description of the process according to the invention refer to the diamond-containing composition (1) according to the invention.The above-mentioned object is achieved in a second aspect of the present invention by a process for producing a diamond-containing composition (1) as described above, comprising the steps of a) providing a diamond powder having a particle size of 0.1 pm to 5.0 pm, b) chemically oxidizing the particle surfaces of the diamond powder at 450 °C to 550 °C in a strongly oxidizing melt, c) obtaining diamond particles (101) whose surface has oxygen-containing functional groups such as hydroxyl groups, carboxy groups, keto groups, aldehyde groups, epoxy groups and / or lactone groups, d) applying a hydrophilic biopolymer (103) to the diamond particles (101).

[0032] The diamond powders provided in step a) are preferably monocrystalline diamonds, which can be produced, for example, by conventional high-pressure, high-temperature (HPHT) syntheses. These diamond powders are further conditioned according to the invention, for example, by milling and thus shaping them, i.e., the edges are broken, thus slightly rounding the particles.

[0033] According to the invention, the extreme and intensive surface cleaning of the provided diamond powder by means of chemical oxidation in step b) is very important. Without this treatment, the diamond would essentially have only non-polar CH bonds on its surface, to which no hydrogen bonds can bond.

[0034] By chemical oxidation, preferably in liquid (anhydrous) alkali, in the specified temperature range, especially at about 480 °C, and addition of strong, literature-known, inorganic oxidizing agents, the otherwise inert diamond surface can be broken up in order to implement the oxygen-containing functional groups.

[0035] During this intense oxidation process, a significant amount of diamond weight is also lost in the form of carbon dioxide. The resulting new surface of the diamond particles consists of carbon atoms that were previously within the crystal lattice. This makes the surface chemically extremely pure, and the color of the diamond particles is very light or colorless (white). The chemical purity of the surfaces can be quantified by the residual ion content. Normal metal ions such as Fe, Cr, Cu, and Ni are present at most in the single-digit ppm range, while alkali and alkaline earth ions are present only in the single-digit ppb range.

[0036] The method according to the invention basically has the advantages already described above that a diamond-containing composition (1) can be produced which combines a hydrophilic biopolymer (103) with diamond particles (101) in a sufficiently strong manner, so that each individual diamond particle (101) can be coated by one or more molecules or macromolecules of the hydrophilic biopolymer (103).

[0037] The application of the hydrophilic biopolymer (103) in step d) is carried out by a type of incubation in which the hydrophilic biopolymer (103) is given time to attach to the surface of the diamond particles (101) according to the invention, which surface is special with regard to the polarity present.

[0038] The highly complete dispersion of the diamond particles (101) and the resulting complete dissolution of the macromolecules of the hydrophilic biopolymer (103) can take many hours until the corresponding swelling and dissolution is complete. It is also important to completely dissolve the only sparingly water-soluble hydrophilic biopolymer (103) without the formation of gel clumps.

[0039] In a further development of the method according to the invention, in or after step d) the diamond particles (101) are completely dispersed in the biopolymer (103).

[0040] For a material with the particle size of the diamond-containing composition (1) according to the invention, it is not trivial to produce a stable dispersion. Comparative tests with conventional diamond powder in a similar particle size range have shown that residual "lumps" always remain and the material quickly flocculates and / or sediments.

[0041] In contrast, the chemically very pure surface of the diamond particles (101) according to the invention ensures very good health compatibility. Due to the strong chemical oxidation, the diamond particles (101) also acquire a hydrophilic and partially negatively charged surface characteristic. The mixtures dispersed in water therefore typically have a zeta potential of -46 mV ± 2 mV. This uniform surface charge enables or guarantees complete dispersion. This specific zeta potential of the diamond particles (101) according to the invention could also be used to characterize them. Untreated or unoxidized diamond has a lower zeta potential than the diamond particles (101) according to the invention.

[0042] In a third aspect, the present invention relates to a cosmetic agent comprising

[0043] - the diamond-containing composition (1 ) as described above,

[0044] - a fluid carrier material.

[0045] The fluid carrier material is preferably purified water. Further additives are not necessary according to the invention.

[0046] Depending on requirements, other additives can be added to thicken the mixture; these would then be present, for example, in a kind of oil-in-water system.

[0047] The cosmetic agent according to the invention basically has the advantages already described above, namely that the diamond-containing composition (1) contained therein has a hydrophilic biopolymer (103) bonded to diamond particles (101) in a sufficiently strong manner, so that each individual diamond particle (101) can be coated by one or more molecules of the hydrophilic biopolymer (103).

[0048] The hydrophilic biopolymer (103) itself only has an indirect effect. Rather, the hydrophilic biopolymer (103), particularly the highly hydrophilic hyaluronic acid, attracts and binds water or water molecules. The attracted or bound water then supplies the skin with moisture from within, i.e., the hydrophilic biopolymer (103), particularly the hyaluronic acid, creates a water reservoir for the skin.

[0049] Finally, a fourth aspect of the present invention relates to the use of the above-mentioned cosmetic agent for application to the skin, wherein the diamond-containing composition (1) penetrates into deeper skin layers down to the basal cell layer and binds water there to the hydrophilic biopolymer (103).

[0050] Further objects, features, advantages, and possible applications will become apparent from the following description of non-limiting embodiments of the invention, taken in conjunction with the figures. All described and / or illustrated features, individually or in any combination, constitute the subject matter of the invention, regardless of their summary in the claims or their references. They show:

[0051] Fig. 1 : a schematic representation of the crystal lattice of diamond,

[0052] Fig. 2: a schematic representation of a diamond particle 101 according to an embodiment of the invention,

[0053] Fig. 3: a schematic representation of the structural formula of hyaluronic acid,

[0054] Fig. 4: a schematic representation of the diamond-containing composition 1 according to an embodiment of the invention,

[0055] Fig. 5: an IR spectrum of diamond, untreated and oxidized,

[0056] Fig. 6: an IR spectrum of hyaluronic acid,

[0057] Fig. 7: an IR spectrum of the diamond-containing composition 1 according to the invention in comparison with oxidized diamond and hyaluronic acid and

[0058] Fig. 8 a UV / Vis spectrum of a sample according to the invention against a control sample (placebo).

[0059] Figure 1 shows a schematic representation of the known structure of diamond with its cubic modification of carbon.

[0060] Figure 2 represents the crystal lattice of the diamond from Figure 1, where the structure has been chemically oxidized so that oxygen-containing functional groups are anchored on the surface, in this particular representation hydroxyl groups and carboxy groups.

[0061] Figure 3 shows a schematic representation of the known structural formula of hyaluronic acid.

[0062] Figure 4 shows schematically how the hyaluronic acid, as a particularly preferred case of the hydrophilic biopolymer 103, is attached or bound to the surface of the oxidized diamond particle 101 according to the invention via a plurality of hydrogen bonds.

[0063] Figure 5 first shows the spectrum of diamond, with the curve labeled (II) showing the untreated diamond and the curve labeled (III) showing the oxidized diamond. In comparison, the band for COC can be clearly seen for the oxidized diamond at a wavenumber of approximately 1150 / cm, whereas it is not noticeably present for the untreated diamond. This clearly shows that the surface of the diamond has been massively altered. Also very pronounced and prominent is the stretching vibration of the carbonyl band at a wavenumber of approximately 1700 / cm; this band is only present in the diamond particles 101 oxidized according to the invention and is absent in conventional non-oxidized diamond.

[0064] The IR spectrum of hyaluronic acid is shown in Figure 6 as curve (I), showing the known bands for this substance. The glucose-based structure is clearly visible with the bands for COC, C=O, CH, and OH.

[0065] Figure 7 shows the IR spectrum of the diamond-containing composition 1 according to the invention as curve (IV), which also includes the spectra of the untreated diamond in curve (II), the oxidized diamond in curve (III), and the hyaluronic acid in curve (I) for comparison. The prominent band for COC at a wavenumber of approximately 1150 / cm is still clearly visible, and in curve (IV) also appears the band for OH at a wavenumber of approximately 3400 / cm. This is considered evidence that the hyaluronic acid is bound to the diamond surface via a large number of hydrogen bonds. The pronounced valence vibration at a wavenumber of approximately 1700 / cm in curve (IV) for the sample of hyaluronic acid on diamond confirms the successful combination of the two substances, since this band is not pronounced for pure hyaluronic acid.

[0066] Further studies have shown that the hydrogen bonds are relatively stable over time. Thus, the effect exerted by the diamond-containing composition 1 according to the invention on the skin is also long-lasting. This allows the cosmetic product according to the invention to have a much more intensive effect.

[0067] Figure 8 shows a UV / Vis spectrum of a sample of diamond-containing composition 1 according to the invention, represented as a dashed curve. The measurements were performed on a "Specord 200 plus" spectrometer from Analytik Jena in the wavelength range between 200 nm and 1,100 nm. The measurement conditions were standard (room temperature, ambient pressure) throughout the entire UV / Vis spectrum.

[0068] In accordance with ISO 24444-2019, a reference amount of the diamond-containing composition 1 according to the invention was determined in an amount of 2 mg / cm 2used. For this purpose, the diamond-containing composition 1 according to the invention with the original concentration of 50 mg / ml (or 15 kt / 60 ml) was diluted to the corresponding concentration in one cubic centimeter in a UV / Vis measuring cuvette.

[0069] It was observed that, despite dilution, the high number of diamond particles 101 according to the invention rendered the sample completely opaque during UV / Vis measurements. Visual inspection alone did not allow for a clear view through the sample.

[0070] As can be seen from the UV / Vis spectrum (dashed curve) in Figure 8, no UVA / UVB radiation penetrates the sample in the wavelength range from 280 nm to 380 nm. The spectrum shows a horizontally straight curve at 0% transmission in the wavelength range between 200 nm and 1,100 nm.

[0071] For comparison and to verify the functionality of the measurement, a reference sample made from the pure carrier fluid of the sample according to the invention (i.e., without diamond particles coated with hyaluronic acid) was measured as a placebo. The continuous measurement curve in the UV / Vis spectrum in Figure 8 shows that it exhibits a transmission of 100%, i.e., completely transparent, starting at a wavelength of approximately 350 nm.

[0072] The result of these measurements shows that the diamond-containing composition 1 according to the invention not only offers the possibility for the first time of bonding a hydrophilic biopolymer 103 with diamond particles 101 in a sufficiently strong manner, thus bringing hydrophilic biopolymers 103 into deeper skin layers of the epidermis, but also provides UVA / UVB protection and thus offers the effect of effective sun protection.

[0073] 1 diamond-containing composition

[0074] 101 Diamondpartikel 103 hydrophilic Biopolymer

Claims

Patent claims 1 . Diamond-containing composition (1 ) comprising - diamond particles (101) whose surface is oxidized and has oxygen-containing functional groups such as hydroxyl groups, carboxy groups, keto groups, aldehyde groups, epoxy groups and / or lactone groups, - a hydrophilic biopolymer (103) which surrounds each individual diamond particle (101), wherein the hydrophilic biopolymer (103) is held on the surface of the diamond particles (101) via a plurality of hydrogen bonds per molecule.

2. Diamond-containing composition (1) according to claim 1, wherein the diamond particles (101) have a size of 0.1 pm to 5.0 pm, preferably of 0.25 pm to 1.5 pm, in particular of 0.5 pm to 1.0 pm.

3. Diamond-containing composition (1) according to claim 1 or 2, wherein the diamond particles (101) have a spherical morphology with a length-width ratio of 1.0 to 2.0, preferably of 1.3 to 1.5, in particular of 1.

4.

4. Diamond-containing composition (1) according to one of claims 1 to 3, wherein the hydrophilic biopolymer (103) is selected from hydrophilic polysaccharides, hydrophilic peptides, hydrophilic amino acids, hydrophilic polyamides, hydrophilic polyamines, hydrophilic polysulfones or polysulfonates, hydrophilic polyphosphones or phosphonates, hydrophilic polyelectrolytes or mixtures thereof.

5. Diamond-containing composition (1) according to one of claims 1 to 4, wherein the hydrophilic biopolymer (103) is hyaluronic acid.

6. Diamond-containing composition (1) according to one of claims 1 to 5, wherein the diamond-containing composition (1) is present in a complete dispersion of the diamond particles (101) in the biopolymer (103).

7. Diamond-containing composition (1) according to one of claims 1 to 5, wherein the diamond-containing composition (1) has a transmission of 0% in UV / Vis spectroscopy in the wavelength range from 200 nm to 1,100 nm.

8. A method for producing a diamond-containing composition (1) according to any one of claims 1 to 7, comprising the steps of a) providing a diamond powder having a particle size of 0.1 pm to 5.0 pm, b) chemically oxidizing the particle surfaces of the diamond powder at 450 °C to 550 °C in a strongly oxidizing melt, c) obtaining diamond particles (101) whose surface has oxygen-containing functional groups such as hydroxy groups, carboxy groups, keto groups, aldehyde groups, epoxy groups and / or lactone groups, d) applying a hydrophilic biopolymer (103) to the diamond particles (101).

9. The method according to claim 8, wherein in step d) the diamond particles (101) are completely dispersed in the biopolymer (103).

10. Cosmetic product comprising, - the diamond-containing composition (1) according to any one of claims 1 to 7, - a fluid carrier material.

11. Use of the cosmetic agent according to claim 109 for application to the skin, wherein the diamond-containing composition (1) penetrates into deeper skin layers down to the basal cell layer and binds water there to the hydrophilic biopolymer (103).

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