Supersaturated silicium solution and uses thereof

Abstract

The present invention relates to the field of cosmetic formulations and, more specifically, to a novel supersaturated silicium solution. The supersaturated silicium solution exhibits enhanced solubility of silica in a specific solvent system, thereby offering unique advantages in cosmetic applications. The invention further encompasses methods of preparation, characterization, and utilization of the supersaturated silicium solution in various cosmetic formulations.

Description

[0001] SUPERSATURATED SILICIUM SOLUTION AND USES THEREOF

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of cosmetic formulations and, more specifically, to a novel supersaturated silicium solution. The supersaturated silicium solution exhibits enhanced solubility of silica in a specific solvent system, thereby offering unique advantages in cosmetic applications. The invention further encompasses methods of preparation, characterization, and utilization of the supersaturated silicium solution in various cosmetic formulations.

[0004] BACKGROUND

[0005] Cosmetic formulations play a significant role in enhancing beauty, improving skin health, and providing desired aesthetic effects. The quest for innovative and high- performance cosmetic products has driven extensive research and development efforts in the field. Silicium-based materials have gained considerable attention due to their versatile properties and beneficial effects in cosmetic formulations. Silica, a form of silicium dioxide (SiO?), is particularly noteworthy for its oil-absorbing capabilities, soft focus effects, and texture enhancement properties.

[0006] Silica has been traditionally incorporated into cosmetic formulations in various forms such as powders, gels, suspensions, and emulsions. It provides benefits such as matte finishes, reduced shine, optical blurring of fine lines and imperfections, and improved texture and feel. However, the solubility of silica in conventional solvents, especially in aqueous systems, has posed challenges in achieving optimal performance and desired functionalities.

[0007] Silica, in its pure form, is considered insoluble in water. It exhibits low solubility due to the strong bonds between silicium and oxygen atoms in its structure, resulting in minimal dissolution and slow kinetics. These limitations have necessitated the use of modified silica or complex techniques to enhance solubility, such as surface functionalization, substitution with organic groups, or the use of specific solvents. While these methods have shown some efficacy, they often come with drawbacks, such as altered surface properties, increased complexity, compromised compatibility with cosmetic matrices, or limitations in scalability for industrial production.

[0008] Therefore, there remains a need for an innovative and efficient solution that can significantly enhance the solubility of silica in cosmetic formulations without substantial modifications or drawbacks. The present invention addresses this need by introducing a novel supersaturated silicium solution for cosmetic applications. SUMMARY OF THE INVENTION

[0009] The present invention addresses the aforementioned challenges by introducing a novel supersaturated silicium solution for cosmetic applications. The supersaturated silicium solution provides a higher concentration of dissolved silicium than its saturation limit at ambient temperature in a water-based medium. This breakthrough enables the utilization of silicium in cosmetic formulations with enhanced solubility, stability, and performance.

[0010] Supersaturated silicium solutions are of great interest in various scientific and industrial applications besides cosmetic applications. Their unique properties allow for controlled nucleation and precipitation, making them valuable for the synthesis of nanomaterials, development of controlled release systems, and creation of surface coatings with tailored properties. Additionally, supersaturated silicium solutions play a significant role in the fields of chemistry, materials science, and nanotechnology, offering opportunities for the fabrication of advanced materials with specific functionalities and structures.

[0011] In a first aspect, the application provides a supersaturated silicium (Si) solution with an elevated concentration of dissolved Si as measured by ICP-OES.

[0012] ICP-OES measures dissolved silicium, such as silicium in its monomeric and dimeric forms. It does not measure precipitated or gelled silicium, such as in the form of silica.

[0013] In a preferred embodiment of the first aspect, present application provides a supersaturated silicium solution, wherein the concentration of dissolved Si is at least 40 ppm as measured by ICP-OES.

[0014] In a second aspect, a method of producing a supersaturated Si solution is provided, the method comprising the steps of: a. providing a mixture comprising mesoporous silica, preferably said mesoporous silica having a specific surface area of at least 500 m2 / g; b. dissolving said mixture in a range of between 0.05 and 0.3% weight per volume (w / v) to a water-based medium, the medium being at a temperature of between 40 and 90°C; c. filtering the solution at a temperature of between 40 and 90°C using a filter with a mesh size of at most 0.5 pm. In a third aspect, the application provides a cosmetic formulation comprising any of the supersaturated Si solution herein described or obtained by any of the methods herein disclosed, further comprising one or more cosmetic ingredients selected from pigments, emollients, antioxidants, or active compounds. Also provided is a cosmetic formulation obtained by the method comprising the step of mixing any of the supersaturated Si solution herein described or obtained by any of the methods herein disclosed and one or more cosmetic ingredients selected from the list consisting of pigments, emollients, antioxidants and active compounds. Also the use of any of the herein disclosed supersaturated Si solutions is provided for producing a cosmetic formulation.

[0015] BRIEF DESCRIPTION OF THE FIGURES

[0016] Figure 1 shows the concentration of dissolved Si in ppm as determined by ICP-OES from IPM in PBS as function of the incubation time at 23.6°C (black solid line), 40.5°C (grey solid line), 59°C (grey dashed line) and 76°C (black dashed line).

[0017] Figure 2 shows the concentration of dissolved Si in ppm as determined by ICP-OES from 1 g IPM in 500 ml PBS as a function of the incubation time at 77.5°C in three repeats.

[0018] Figure 3 shows that decreasing the temperature of a 160 ppm Si solution from 77.4°C to 39.5°C resulted in a drop of the dissolved Si content to 121.2 ppm. Upon filtering the solution at 39.5°C a further decrease in dissolved Si due to cooling to room temperature (RT) could be overcome.

[0019] Figure 4 reveals that a supersaturated Si solution was obtained by filtering a saturated Si solution before cooling down. RT = room temperature. Timing of the filtering step is shown by the vertical dashed line.

[0020] Figure 5 shows the evolution of a supersaturated Si solution (example 6) and a Si solution below the saturation point (comparative example 7) after the introduction of a large amount of mesoporous silica particles at room temperature. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention concerns a supersaturated silicium solution, methods of producing the supersaturated solution and uses thereof.

[0022] The supersaturated silicium solution is a specialized solution in which the concentration of dissolved silicium exceeds its equilibrium solubility at a given temperature and under specific conditions. In such a solution, the dissolved silicium content surpasses the saturation point, making it thermodynamically unstable and prone to spontaneous precipitation or crystallization. One of the unique aspects of the supersaturated silicium solution of current invention is that the solution is stable even in the absence of stabilizers or crystallization inhibitors.

[0023] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0024] As used herein, the following terms have the following meanings:

[0025] "Silicium", "Silicon" or "Si" as used herein refers to the chemical element with the symbol Si and atomic number 14. "Silica" or "silicium dioxide" refers to the molecule SiO? and is one of the most abundant minerals on Earth. Silica can be found in various forms such as quartz, sand, and glass. Silica is also a significant component of many rocks and minerals.

[0026] "Unmodified" or "not substituted" silicium as used herein refers to silicium in its natural state solely consisting of silicium atoms, without any other elements mixed in or substituted for some of the silicium atoms.

[0027] Modifications are frequently performed or substitutions introduced to for example increase the solubility of silica. In its pure form, silica is considered insoluble in water. One approach to increase its solubility is the modification of silica by substituting the surface with organic functional groups such as methyl (CH3) groups. By attaching methyl groups to the surface of silica, the overall hydrophobic character of the material increases, which can enhance its solubility in non-polar solvents or organic media.

[0028] "Mesoporous silica" as used herein refers to silica with a specific pore size diameter. Pore diameter is defined as the average distance between pore walls. According to the IUPAC recommendations for characterization of porous solids, porous materials are classified as mesoporous when the pore diameter is between 2 and 50 nm (Loni 2014 Springer International Publishing Switzerland). This classification does not contain any information of pore morphology e.g. geometry, orientation, interconnectivity of pores, etc.

[0029] "Supersaturation" or "supersaturated solution" as used herein refers to a state in which a solution contains a higher concentration of a solute (for example silicium or silicic acid) than it can typically hold in equilibrium at a given temperature and pressure.

[0030] Because the solute is present in a greater amount than it would normally dissolve in the solvent under specific conditions, a supersaturated solution is not in its lowest energy state. Supersaturated solutions are considered metastable as they can spontaneously return to the stable state by precipitating the excess solute. Any disturbance (such as agitation or temperature or pH change) or introduction of nucleation sites can trigger the precipitation process, causing the solute to come out of the solution until the equilibrium concentration is reached.

[0031] Managing the supersaturated state requires thus careful control and manipulation of several factors, including the nature of the solvent system, temperature, pH, and the presence of stabilizing or inhibiting agents, to maintain the solution in its metastable condition, preventing premature precipitation and maximizing the potential for desired applications.

[0032] "Scaling" in the context of a supersaturated silicium solution, refers to the process of solid silica particles precipitating out of the solution and depositing onto surfaces (such as container walls, equipment surfaces or any other available nucleation sites) or forming aggregates. Scaling occurs when the concentration of dissolved silica in the solution exceeds its saturation limit at a given temperature and pH, leading to the spontaneous formation of solid silica particles. The scaling process can be detrimental in various applications, particularly in industrial settings, where the deposition of solid silica particles on equipment surfaces can lead to fouling, reduced efficiency, and increased maintenance costs.

[0033] "Nucleation" as used herein is the initial stage of crystallization or precipitation in a supersaturated solution. It refers to the formation of tiny solid clusters (nuclei) that act as the starting point for the growth of larger solid particles. In the context of an unstable supersaturated silicium solution, nucleation occurs when the concentration of dissolved silica exceeds its saturation limit, but the solution is unable to maintain its supersaturation state.

[0034] Nucleation is a critical step in the scaling process. Once nucleation occurs, solid silica particles start to form and grow, consuming the excess dissolved silica in the solution. This results in a reduction in the concentration of dissolved silica, eventually leading to the solution returning to its equilibrium state or becoming undersaturated.

[0035] "PBS" or "phosphate buffered saline" is a buffer solution commonly used in biological and chemical applications due to its ability to maintain a stable pH. The pH of PBS is typically adjusted to around 7.4 at room temperature.

[0036] "A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

[0037] "About" as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of + / - 20% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -1% or less, and still more preferably + / -0.1% or less of and from the specified value, in so far such variations are appropriate to perform in the disclosed invention. However, it is to be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

[0038] "Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g. component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

[0039] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0040] The expression "% by weight", "weight percent", "w%", "%w", "%wt" or "wt%", here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation.

[0041] Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

[0042] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0043] Silicium solution

[0044] In a preferred embodiment of the first aspect, present application provides a supersaturated silicium solution, wherein the concentration of dissolved Si is at least 40 ppm as measured by ICP-OES.

[0045] In a first aspect, the invention relates to a supersaturated silicium solution. More particularly a man-made or non-natural solution. In one embodiment, the supersaturated silicium solution comprises silicic acid in water. In another embodiment, at least 25%, 35%, 45%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, or 95% of the dissolved silicium present in the supersaturated silicium solution is silicic acid. In one embodiment, said solution is characterized in that the silicium or the silicic acid concentration in the supersaturated silicium solution is at least 100 ppm, 110 ppm, 120 ppm, 130 ppm, 140 ppm or 150 ppm as measured by Inductively Coupled Plasma Optical Emission Spectroscopy or ICP-OES. In another embodiment, the supersaturated silicium solution comprises between 120 and 200 ppm silicium or between 130 and 190 ppm, or between 140 and 180 ppm or between 150 and 175 ppm or between 160 and 170 ppm silicium as measured by ICP-OES.

[0046] More preferably, the concentration of dissolved Si as measured by ICP-OES decreases by at least 5% after a time period of 24 hours at 15 to 25°C, after introducing 100 mg mesoporous silica particles I 100 ml supersaturated silicium solution, wherein the mesoporous silica particles have a specific surface area of at least 400 m2 / g. More preferably, the temperature during the period after introduction and prior to ICP-OES measurement is between 18 and 22°C and the pH of the solution is between 4 and 7, more preferably between 4.5 and 6.5, more preferably between 5 and 6. In another preferred embodiment, the pH of the solution is adjusted to 7 prior to the ICP-OES measurements, and prior to inclusion of mesoporous silica particles thereto. The introduction of particles, and particularly silica particles with a large and accessible surface area, leads to a relatively fast precipitation of supersaturated silicium monomers and dimers from the solution. Consequently, this destructive test acts as a means to measure the supersaturation of the silicium solution provided. The pH has little impact when close to neutral, but can influence the stability measures at very low (i.e. acidic) pH, particularly below 4. More preferably, the concentration of Si at these conditions or their preferred embodiments decreases by at least 10% after a time period of 24 hours; more preferably the concentration of Si decreases by at least 15%; more preferably the concentration of Si decreases by at least 20%; more preferably the concentration of Si decreases by at least 30%; more preferably the concentration of Si decreases by at least 40%; more preferably the concentration of Si decreases by at least 50%.

[0047] In another or further preferred embodiment, the concentration of dissolved Si as measured by ICP-OES decreases by at least 5% after a time period of 24 hours at 15 to 25°C, after introducing 4.0 g mesoporous silica particles I 100 ml supersaturated silicium solution, wherein the mesoporous silica particles have a specific surface area of at least 400 m2 / g. More preferably, the temperature during the period after introduction and prior to ICP-OES measurement is between 18 and 22°C and the pH of the solution is between 4 and 7, more preferably between 4.5 and 6.5, more preferably between 5 and 6. In another preferred embodiment, the pH of the solution is adjusted to 7 prior to the ICP-OES measurements, and prior to inclusion of mesoporous silica particles thereto. More preferably, the concentration of Si at these conditions or their preferred embodiments decreases by at least 10% after a time period of 24 hours; more preferably the concentration of Si decreases by at least 15%; more preferably the concentration of Si decreases by at least 20%; more preferably the concentration of Si decreases by at least 30%; more preferably the concentration of Si decreases by at least 40%; more preferably the concentration of Si decreases by at least 50%; more preferably the concentration of Si decreases by at least 60%; more preferably the concentration of Si decreases by at least 70%; more preferably the concentration of Si decreases by at least 80%; more preferably the concentration of Si decreases by at least 90%; more preferably the concentration of Si decreases by at least 100%. The addition of a large amount of particles (in this case 4g per 100 ml) with a large and accessible surface area leads to a fast precipitation of supersaturated silicium monomers and dimers from the solution. The opposite is noticeable for solutions below their saturation point, even when these are stabilized with compounds promoting the stabilization of Si. There silicium dissolves from the surface of the introduced mesoporous silica, thereby increasing the silicium concentration. Consequently, this destructive testing method provides a clear distinction between stabilized and supersaturated silicium solutions.

[0048] In a preferred embodiment, the concentration of dissolved Si is at least 40 ppm, more preferably at least 50 ppm, more preferably at least 60 ppm, more preferably at least 60 ppm, more preferably at least at least 70 ppm, more preferably at least 80 ppm, more preferably at least 90 ppm, more preferably at least 100 ppm, more preferably at least 110 ppm, more preferably at least 120 ppm, more preferably at least 130 ppm, more preferably at least 140 ppm, more preferably at least 150 ppm, more preferably at least 160 ppm, more preferably at least 170 ppm, more preferably at least 180 ppm, more preferably at least 190 ppm, more preferably at least 200 ppm, more preferably at least 210 ppm, more preferably at least 220 ppm, more preferably at least 230 ppm, most preferably at least 240 ppm, as measured by ICP-OES.

[0049] In a preferred embodiment, the concentration of dissolved Si is at least 60 ppm, more preferably at least at least 70 ppm, more preferably at least 80 ppm, more preferably at least 90 ppm, more preferably at least 100 ppm, more preferably at least 110 ppm, more preferably at least 120 ppm, more preferably at least 130 ppm, more preferably at least 140 ppm, more preferably at least 150 ppm, more preferably at least 160 ppm, more preferably at least 170 ppm, more preferably at least 180 ppm, more preferably at least 190 ppm, more preferably at least 200 ppm at 20°C, as measured by ICP-OES.

[0050] In another or further embodiment, the supersaturated Si solution further comprises a calcium or magnesium salt. The inclusion of calcium or magnesium salts drastically increases the production speed of supersaturated silicium solutions, but have relatively little impact on their stability. Calcium and magnesium salts are thus considered processing aids, which improve the speed at which supersaturated solutions are produced. They do not impact the stability and thus are not considered surfactants, emulsifiers or stabilizers.

[0051] In a further embodiment, the supersaturated Si solution is free of stabilizers, preferably free of stabilizers for silicium compounds. In another or further embodiment, the supersaturated Si solution is free of phenols and polyphenols. In yet another or further embodiment, the supersaturated Si solution is free of quaternary ammonium salts, particularly choline salts. Phenols and quaternary ammonium salts are often used to stabilize silicium compounds, particularly monomeric and dimeric silicium acids as well as organosilicium compounds. Present application aims to provide increased dissolved silicium, assumed to be primarily in its monomeric and dimeric forms, without the need for stabilizers.

[0052] In a preferred embodiment, the supersaturated Si solution has a pH of at least 4.0, more preferably at least 4.5, more preferably at least 5.0, more preferably at least 5.5, more preferably at least 6.0, more preferably at least 6.5, more preferably at least 7.0. In a further preferred embodiment, the supersaturated Si solution has a pH between 4 and 8, more preferably between 5 and 7, more preferably between 5.5 and 6.5. In a further preferred embodiment, the supersaturated Si solution may be buffered. In another preferred embodiment, the supersaturated Si solution may be a phosphate buffered saline (PBS) solution. Dissolved silicium is known to be most stable at low pHs. Advantageously, the method according to present application allows provision of elevated dissolved silicium with low or no stabilizers at neutral and elevated pHs. As a further advantage, the neutral and elevated pHs may be buffered. A particularly interesting case is that of phosphate buffered saline solutions. Neutral pH is easier and safer to work with and preferable or necessary for many applications, particularly in cosmetics and pharmaceuticals.

[0053] ICP-OES is an analytical technique well-known by the skilled person in the art and used to determine the elemental composition of a wide range of samples. It is widely employed in various fields such as environmental analysis, metallurgy, pharmaceuticals, agriculture, and more. Briefly, ICP-OES a sample in liquid form in introduced into a high-temperature plasma in the ICP-OES instrument. The plasma is formed by ionizing an inert gas (usually argon) at extremely high temperatures (around 10,000 degrees Celsius). This results in the creation of a high-energy plasma gas consisting of positively charged ions and free electrons. The intense heat of the plasma causes the atoms and ions in the sample to become ionized (i.e. losing one or more electrons) and excited (i.e. electrons move to higher energy levels). As the excited ions and atoms in the plasma return to their ground state (lower energy levels), they emit light in the form of characteristic wavelengths or colors unique to each element. Each element emits light at specific wavelengths, forming a unique emission spectrum or "fingerprint" for that element. The emitted light is collected and passed through a spectrometer, which disperses the light into its constituent wavelengths. The spectrometer then measures the intensity of the emitted light at specific wavelengths. The intensity of the emitted light is directly proportional to the concentration of the corresponding element in the sample. By comparing the intensity of the emitted light at specific wavelengths with calibration standards of known elemental concentrations, the concentration of various elements in the sample can be determined accurately.

[0054] In another embodiment, the supersaturated silicium solution is characterized in that the concentration of particles present in said solution with a size of 0.50 pm or higher is at most 1 ppm, at most 0.8 ppm, at most 0.5 ppm, at most 0.4 ppm, at most 0.3 ppm, at most 0.2 ppm or at most 0.1 ppm relative to the supersaturated silicium solution.

[0055] In a more particular embodiment, said particles have a size of 0.45 pm or higher, 0.40 pm or higher, 0.35 pm or higher, 0.30 pm or higher, 0.25 pm or higher, 0.20 pm or higher or 0.1 pm or higher.

[0056] In another embodiment, the supersaturated silicium solution is characterized in that the concentration of particles present in said solution with a size of 0.20 pm or higher is at most 1 ppm, at most 0.8 ppm, at most 0.5 ppm, at most 0.4 ppm, at most 0.3 ppm, at most 0.2 ppm or at most 0.1 ppm relative to the supersaturated silicium solution.

[0057] While pure silica is considered insoluble in water, its solubility can be influenced by several factors. For example, the solubility of silica increases with decreasing pH (acidic conditions) and / or higher temperatures. Also the presence of certain compounds or ions in water can affect the solubility of silica. For example, the presence of strong acids or bases, as well as certain metal ions like aluminum or iron, can complex with silica and increase its solubility.

[0058] The inventors of current invention surprisingly developed a method to obtain a supersaturated silicium solution that is stable - hence, in which no scaling or crystallization or nucleation occurs - at room temperature, in neutral pH conditions, in a water-based medium and in the absence of nucleation inhibitors or other stabilizers.

[0059] Therefore, in particular embodiments, the supersaturated silicium solution of the invention is provided at a temperature of less than 60°C, 50°C, 40°C, 30°C or 20°C. At these temperatures the supersaturated silicium solution is stable, which means that no crystallization or scaling occurs.

[0060] In another embodiment, the supersaturated silicium solution is stable at a temperature between 10 and 70°C, between 15° and 65°C, between 18°C and 62°C, between 20°C and 55°C, between 22°C and 50°C, between 25°C and 45°C, between 28°C and 42°C or between 32°C and 40°C.

[0061] In another particular embodiment, the supersaturated silicium solution of the invention is provided at a pH of between 5 and 8, of between 5.5 and 7.8, of between 6 and 7.6 of between 6.5 and 7.5, of between 6.8 and 7.4, of between 7 and 7.2 or of between 7.2 and 7.4. At these pH the supersaturated silicium solution is stable, which means that no crystallization or scaling occurs.

[0062] In another embodiment, the supersaturated silicium solution of the invention further comprises a salt, more particularly a salt comprising a divalent cation, even more particularly a calcium salt or magnesium salt. Said calcium salt can be selected from the list consisting of calcium acetate, calcium citrate, calcium lactate, calcium carbonate, calcium chloride, calcium gluconate, calcium hydroxide, calcium pantothenate, calcium phosphate, calcium stearate, calcium propionate, calcium butyrate, calcium formate, calcium sorbate and calcium benzoate. In a particular embodiment, the calcium salt is calcium acetate. Said magnesium salt can be selected from the list consisting of magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium citrate and magnesium phosphate.

[0063] Other non-limiting salts that can be part of the supersaturated silicium solution of the invention are sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, ammonium sulfate and lithium chloride.

[0064] In another embodiment, the supersaturated silicium solution comprises dissolved silicium, at least one calcium salt and a water-based medium. In a particular embodiment, said water-based medium is PBS. In another particular embodiment, said water-based medium is water.

[0065] As mentioned above, supersaturated silicium solutions can be obtained by adding stabilizers or chemical compounds that increase the solubility of silicium in water and stabilize silicium in the dissolved status. One of the inventive aspects of current invention is that a supersaturated silicium solution is provided in the absence of said compounds.

[0066] Therefore, in another particular embodiment, the supersaturated silicium solution according to the invention is free of phenols and polyphenols. Phenol and other phenolic compounds can form soluble complexes with silicium species. Phenols, with their hydroxyl (-OH) groups, can coordinate with silicium, leading to the formation of stable phenol-silicium complexes.

[0067] Also amines, such as ammonia and organic amines, can form soluble complexes with silicium, increasing its solubility in various solvents. Therefore, in another particular embodiment, the supersaturated silicium solution according to the invention is free of quaternary ammonium salts, particularly choline salts.

[0068] Dissolved silicium can also be stabilized by adding chelating agents like EDTA (ethylenediaminetetraacetic acid), and oxalic acid. In another particular embodiment, the supersaturated silicium solution according to the invention is free of chelating agents, more particularly free of EDTA (ethylenediaminetetraacetic acid) and / or and oxalic acid.

[0069] Some polymers or surfactants can stabilize silicium species in solution by forming micelles or providing a protective coating around the silicium particles, preventing their agglomeration or precipitation. In another particular embodiment, the supersaturated silicium solution according to the invention is free of polymers or surfactants that stabilize silicium species in solution.

[0070] Because the supersaturated Si solution of the invention is free from compounds that stabilize Si in the dissolved status, adding one or more scaling nuclei to the supersaturated Si solution of the invention will initiate Si precipitation and thus a decrease of the dissolved Si content.

[0071] Hence, in one embodiment, the application provides a supersaturated Si solution with a set concentration of dissolved Si as measured by ICP-OES, characterized in that said concentration of dissolved Si decreases with at least 5% when a plurality of particles with a size of least 0.50 pm are added to said solution at a temperature of 20°C and at a pH between 5 and 8.

[0072] In a particular embodiment, said set concentration is at least 90 ppm, 100 ppm, 110 ppm, 120 ppm, 130 ppm, 140 ppm, 150 ppm, 160 ppm, 170 ppm, 180 ppm, 190 ppm or at least 200 ppm.

[0073] In another or further particular embodiment, the supersaturated silicium solution comprises silicic acid in water. In another or further particular embodiment, at least 25%, 35%, 45%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, or 95% of the dissolved Si present in the supersaturated silicium solution is silicic acid.

[0074] In another or further particular embodiment, said at least 5% decrease in dissolved Si is an at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least

[0075] 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 16%, at least

[0076] 17%, at least 18%, at least 19%, at least 20%, at least 21%, at least 22%, at least

[0077] 23%, at least 24%, at least 25%, at least 26%, at least 27%, at least 28%, at least

[0078] 29%, at least 30%, at least 35%, at least 40%, at least 45% or an at least 50% decrease in dissolved Si as measured by ICP-OES.

[0079] In another or further particular embodiment, said decrease in dissolved Si concentration is determined at at least 0.5h, Ih, 1.5, 2h, 3h, 6h, 12h or 24h after adding the plurality of particles. In another or further particular embodiment, said size of said plurality of particles is 0.45 pm or higher, 0.40 pm or higher, 0.35 pm or higher, 0.30 pm or higher, 0.25 pm or higher, 0.20 pm or higher or 0.1 pm or higher.

[0080] In another or further particular embodiment, said particles are added to the supersaturated Si solution at a temperature of between 20 and 40°C, between 15 and 30°C or between 18 and 25°C and at a pH of the Si solution between 5 and 8, between 5.5 and 7.5, between 6.5 and 7.2 or about 7.

[0081] In another or further particular embodiment, said plurality of particles is a concentration of said particles that is added to the supersaturated Si solution of at least 0.1 ppm, 0.2 ppm, 0.3 ppm, 0.4 ppm, 0.5 ppm, 0.6 ppm, 0.7 ppm, 0.8 ppm, 0.9 ppm or at least 1 ppm.

[0082] In another embodiment, the supersaturated Si solution has a Si concentration of at least 50 ppm, more preferably at least 70 ppm, more preferably at least 80 ppm, more preferably at least 100 ppm, more preferably at least 120 ppm, more preferably at least 150 ppm as measured by ICP-OES, throughout a period of at least 1 week, more preferably 2 weeks, more preferably at least 4 weeks, more preferably at least 2 months, more preferably at least 3 months, more preferably at least 6 months, more preferably at least 12 months, more preferably at least 18 months, most preferably at least 24 months when stored at a temperature between 0 and 40°C, more preferably a temperature between 5 and 25°C, more preferably a temperature between 15 and 25°C, more preferably a temperature between 18 and 22 °C.

[0083] In a particular embodiment, the supersaturated Si solution is :

[0084] - a water-based solution, preferably a phosphate buffer solution (PBS) solution, preferably with a pH between 6 and 8, more preferably with a pH between 7 and 8,

[0085] - with a Si concentration of at least 65 ppm, more preferably at least 70 ppm, more preferably at least 80 ppm, more preferably at least 90 ppm, most preferably at least 100 ppm Si; as measured by ICP-OES,

[0086] - at a temperature below 25°C, more preferably at a temperature between 1°C and 25°C, most preferably at a temperature between 15°C and 25°C; preferably devoid of stabilizers, more preferably devoid of phenols, polyphenols, tertiary amine salts, quaternary amine salts and alkali or earth alkaline hydroxides. In another or further particular embodiment, the supersaturated Si solution of the invention is a water-based solution. A "water-based solution" refers to a solution or homogeneous mixture wherein water serves as the solvent. In a water-based solution, organic solvents such as acetone or benzene are not present as the primary solvent.

[0087] Method of producing a supersaturated Si solution

[0088] In a second aspect, a method of producing a supersaturated Si solution is provided, the method comprising the steps of: a. providing a mixture comprising mesoporous silica, preferably said mesoporous silica having a specific surface area of at least 500 m2 / g; b. dissolving said mixture in a range of between 0.05 and 0.3% weight per volume (w / v) to a water-based medium, the medium being at a temperature of between 40 and 95°C; c. filtering the solution at a temperature of between 40 and 90°C using a filter with a mesh size of at most 0.5 pm.

[0089] A particularly preferred embodiment of the method comprises the steps of : a. providing a mixture of between 20 and 40 w% mesoporous silica, preferably with a specific surface area of at least 500 m2 / g; and between 80 and 60 w% of a calcium or magnesium salt; b. dissolving said mixture in a range of between 0.05 and 0.3% weight per volume (w / v) to a water-based medium, the medium being at a temperature of between 70 and 90°C; c. filtering the solution at a temperature of between 70 and 90°C using a filter with a mesh size of at most 0.5 pm.

[0090] In one embodiment, the method further comprises an incubation step before the filtering step, wherein the incubation step comprises incubating the obtained solution from step b) for at least 0.5 h at an elevated temperature of between 40 and 90°C. Preferably the incubation step may comprise mixing or stirring.

[0091] Preferably the incubation step comprises maintaining the elevated temperature for at least 1 hour, more preferably at least 2 hours, more preferably at least 3 hours, more preferably at least 4 hours, more preferably at least 6 hours, more preferably at least 12 hours, most preferably at least 24 hours. The incubation step allows the mesoporous silica to break down to its monomeric and dimeric components and dissolve as completely as possible. The solution gradually reaches its equilibrium, having a longer incubation period allows for higher concentrations of silicium for any given temperature.

[0092] In a preferred embodiment, the dissolution temperature in step b) is at least 40°C, more preferably at least 50°C, more preferably at least 60°C, more preferably at least 65°C, more preferably at least 70°C, more preferably at least 75°C, more preferably at least 80°C, more preferably at least 85°C, most preferably at least 90°C. A higher temperature increases the equilibrium concentration. In other words, higher temperatures in dissolution step b), or in the incubation step between dissolution b) but prior to filtering c), result in a higher silicium concentration of the supersaturated Si solution. The maximum temperature should be below the boiling point of the solution, preferably at most 95°C.

[0093] In another embodiment, the solution temperature may be gradually increased during the incubation. Advantageously, this allows a gradual increase of the dissolved Si concentration without the need to operate at the highest temperature throughout the full incubation period. Compared to operating at the maximum temperature obtained, this approach requires a longer incubation period but often lower overall energy and heating requirements.

[0094] In step c), the solution should always be filtered at about the maximum temperature reached during dissolution step b) and the optional incubation step. Allowing the solution to cool prior to filtering all particles that can act as a nucleus from the solution results in precipitation, which is removed upon filtration, and thus lower final silicium concentrations in the resulting supersaturated Si solution.

[0095] In another or further embodiment, the method further comprises a cooling step after the filtering step, wherein the cooling step comprises the cooling of the filtered solution to ambient temperature. Preferably, no precipitation of silicium to silica occurs during the cooling of the filtered solution. In another preferred embodiment, the process may comprise a second filtering step after cooling of the solution. More preferably, the method further comprises the steps of : d. cooling the solution to a temperature lower than 30°C, and e. filtering the solution with a mesh size of at most 0.5 pm, at a temperature lower than 30°C. In a further preferred embodiment, the second filtering step e) may utilize a smaller mesh size compared to the first filtering step c). The second filtering step can benefit the long term stability of the solution by removing residual particles.

[0096] In another further preferred embodiment, step d. may comprise at least one, preferably multiple cooling cycles to temperatures just above the freezing point. This improved the long term stability of the supersaturated silicium solution. Without wishing to be bound by theory, by first reducing the temperature and promoting silicium precipitation, oligomeric silica with a particle size lower than the mesh size is allowed to grow and subsequently filtered from the solution effectively. This results in a method which removes particles just under the mesh size effectively, without the exponential increase in energy requirements by reducing the mesh size. This does come at the expense of a minor reduction in the final silicium concentration.

[0097] In another or further embodiment, the method further comprises a step of determining the concentration of dissolved Si.

[0098] In a preferred embodiment, step a) of the method consists of providing a mixture comprising 20 to 40 wt.% mesoporous silica, preferably said mesoporous silica having a specific surface area of at least 500 m2 / g; and 60 to 80 wt.% of a soluble salt chosen from calcium salts, magnesium salts or mixtures thereof. More preferably, the mixture consists essentially of, most preferably consists of, mesoporous silica and soluble divalent salts. The divalent salts increase the rate at which the mesoporous silica is broken down, in other words the dissolution rate. As a direct consequence, they reduce the process time or incubation time needed to obtain a certain silicium concentration; or increase the silicium concentration obtained at a set temperature and dissolution profile.

[0099] In yet another or further embodiment, said calcium salt is selected from the list consisting of calcium acetate, calcium citrate, calcium chloride and calcium carbonate. In yet another or further embodiment, said filter is a hydrophobic filter, particularly a polytetrafluoroethylene (PTFE) membrane filter. In yet another or further embodiment, said filter is a hydrophilic filter, particularly a cellulose filter. In yet another or further embodiment, said filter is intermediate hydrophilic and hydrophobic properties, particularly a polyethersulfone (PES) or a polyvinylidene difluoride (PVDF) filter.

[0100] In one embodiment, the mixture of unmodified mesoporous silica and a divalent cation salt is a blend composed of between 20 and 40 w% unmodified mesoporous silica and between 80 and 60 w% of a divalent cation salt, wherein the mesoporous silica and divalent cation salt together form 100 w%. In another embodiment, the mixture of unmodified mesoporous silica and a divalent cation salt is composed of unmodified mesoporous silica and a divalent cation salt in a ratio of between 20:80, 25:75, 30:70, 35:65 or 40:60.

[0101] In a particular embodiment, said divalent cation salt is a calcium salt or a magnesium salt. In a further particular embodiment, the calcium salt is selected from the list consisting of calcium acetate, calcium citrate, calcium chloride and calcium carbonate.

[0102] In a particular embodiment, the total Si content of the mixture is between 10 and 20 w%, between 11 and 19w%, between 12 and 18 w%, between 13 and 16w% or about 14 w%.

[0103] In a particular embodiment, the mesoporous silica of the invention has a specific surface area, calculated from nitrogen sorption isotherms at liquid nitrogen temperature (77K) by the Brunauer, Emmett and Teller (BET) theory, of at least 10 m2 / g, preferably at least 100 m2 / g, more preferably at least 250 m2 / g, more preferably at least 300 m2 / g, more preferably at least 350 m2 / g, more preferably at least 400 m2 / g, more preferably at least 450 m2 / g, even more preferably at least 500 m2 / g. The specific surface is preferably at most 1500 m2 / g, more preferably at most 1250 m2 / g, even more preferably at most 1000 m2 / g, and even more preferably at most 800 m2 / g. In another or further embodiment of the invention, said mesoporous silica has a specific surface area, calculated from nitrogen sorption isotherms at liquid nitrogen temperature (77K) by the Brunauer, Emmett and Teller (BET) theory, of between 10 and 1500 m2 / g, preferably between 100 and 1250 m2 / g, more preferably between 250 and 1000 m2 / g, between 300 m2 / g and 500 m2 / g, between 325 m2 / g and 475 m2 / g, between 350 m2 / g and 450 m2 / g or between 375 m2 / g and 425 m2 / g, even more preferably between 500 and 800 m2 / g. Higher surface area results in faster dissolution rates, and thus lower incubation times required to obtain a set silicium concentration and set temperature, or higher silicium concentration given a set dissolution time and temperature.

[0104] In a particular embodiment, the supersaturated silicium solution further comprises a calcium and / or magnesium salt. Said calcium salt can be selected from the list consisting of calcium acetate, calcium citrate, calcium lactate, calcium carbonate, calcium chloride, calcium gluconate, calcium hydroxide, calcium pantothenate, calcium phosphate, calcium stearate, calcium propionate, calcium butyrate, calcium formate, calcium sorbate and calcium benzoate. In a most particular embodiment, the calcium salt is calcium acetate, calcium citrate, calcium chloride or calcium carbonate. Said magnesium salt can be selected from the list consisting of magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, magnesium citrate and magnesium phosphate.

[0105] In another embodiment, the mixture of the mesoporous silica and the divalent cation salt is dissolved in a water-based medium in a range of between 0.05 and 0.3% weight per volume (w / v). This means that between 0.05 gram and 0.3 gram of said mixture is dissolved in 100 ml of the water-based medium. Before the mixture is added to the water-based medium, said medium is heated to a temperature of between 70 and 90°C, particularly of between 72 and 85°C, more particularly of between 75 and 80°C.

[0106] In one embodiment, the filtering step in the method of the second aspect is performed at a temperature of between 72 and 85°C, more particularly of between 75 and 80°C. In another embodiment, the filter used in the filtering step has a mesh size of at most 0.5 pm, at most 0.45 pm, at most 0.4 pm, at most 0.35 pm, at most 0.3 pm, at most 0.25 pm, at most 0.2 pm, at most 0.15 pm or at most 0.1 pm. In another embodiment, the filter used in the filtering step has a mesh size of between 0.1 and 0.5 pm, 0.2 and 0.45 pm, 0.3 and 0.4 pm, or between 0.15 and 0.3 pm or about 0.2 pm or about 0.45 pm.

[0107] In a particular embodiment, the method further comprises an incubation step before the filtering step, the incubation step comprises incubating the obtained solution from step b) for at least 0.5 h, at least 1 h, at least 1.5 h, at least 2 h, at least 3 h or at least 4 h at a temperature of between 70 and 90°C. In a more particular embodiment, the temperature is between 72 and 85°C, more particularly between 75 and 80°C.

[0108] In another or further particular embodiment, the method further comprises a cooling step after the filtering step, wherein the cooling step comprises the cooling or lowering of the temperature of the filtered solution to ambient temperature, wherein no precipitation of silica occurs. In a more particular embodiment, the ambient temperature is between 10 and 30°C, between 12 and 30°C, between 15 and 30°C, between 18 and 26°C or between 20 and 24°C. In another particular embodiment, the method further comprises a final step of determining the concentration of dissolved Si. In a most particular embodiment, said determining step is performed using ICP-OES.

[0109] In another or further particular embodiment, the filter from step c) has hydrophobic, hydrophilic or intermediate properties. In a more particular embodiment, the filter has hydrophobic properties and is a polytetrafluoroethylene (PTFE) membrane filter. In another more particular embodiment, the filter has hydrophilic properties and is a cellulose filter. In another more particular embodiment, the filter has intermediate properties and is a polyethersulfone (PES) or a polyvinylidene difluoride (PVDF) filter.

[0110] In a third aspect, a cosmetic formulation is provided comprising any of the supersaturated silicium solutions herein described, further comprising one or more cosmetic ingredients selected from pigments, emollients, antioxidants, or active compounds.

[0111] In a particular embodiment, the cosmetic formulation is obtained by the method comprising the step of mixing any of the supersaturated silicium solutions herein described and one or more cosmetic ingredients selected from the list consisting of pigments, emollients, antioxidants and active compounds.

[0112] In a more particular embodiment, the supersaturated silicium solution that is part of said cosmetic formulation is obtained by any of the methods described herein, more particularly under the second aspect.

[0113] In a fourth aspect, the use of any of the supersaturated silicium solutions herein described or obtained by any of the methods herein described is provided for producing a cosmetic formulation.

[0114] Using the supersaturated silicium solution as an intermediate is advantageous. It reduces the amount of silicium solution required to obtain a desired silicium concentration in the final product; thereby reducing transport and storage volumes significantly. The prior art often relies on silicium solutions which are stabilized, such as those including phenols, polyphenols, tertiary amines and the like for these applications. However, the stabilizers are difficult to separate and are thus typically included in the final product. This is exposes the end user to these compounds unnecessarily. As such, the use of a supersaturated solution as an intermediate is beneficial, even if the final product contains silicium (Si) at a concentration at or below its saturation point.

[0115] Analytic method

[0116] ICP-OES was used as an analytic method to obtain the concentration of dissolved silicium in a medium. Characterization of all examples herein was done on an 5110 ICP-OES from Agilent to quantify Si content. The Si calibration curve from 1.56 to 25 ppm in ultra-pure water is performed with the appropriate dilution of the Si standard solution certified by supplier Chem-Lab.

[0117] All samples at room temperature and lower are diluted with ultrapure water at a degree of dilution of 10: 1 prior to analysis by ICP-OES.

[0118] All samples at elevated temperatures are filtrated on a 0.45 pm PTFE filter; subsequently diluted 10: 1 with ultrapure water, and finally analysed by ICP-OES at room temperature, unless otherwise specified. The filtration, prior to dilution, is performed to avoid changes in Si concentration due to precipitation or dissolution of precipitates due to dilution or temperature changes.

[0119] EXAMPLES

[0120] Example 1. An injectable Si composition

[0121] In order to obtain an injectable Si composition, a blend was composed of calcium acetate and mesoporous silica at the following ratio:

[0122] - calcium acetate: 70 w% mesoporous silica (SiO?) : 30 w%

[0123] The Si total content of the blend is 14 w%. The dissolved Si content ranged from 9.8 to 11.2% after 6h in water-based media at 37°C for SiO? concentration inferior to 60mg / l. The blend is from hereon referred to as IPM. The mesoporous silica had a surface area above 700 m2 / g.

[0124] Example 2. Determining the Si kinetic profile of IPM

[0125] An IPM blend in PBS was formed by mixing 833 mg IPM; corresponding to 250 mg silica, in 500 ml PBS. To study the effect of temperature on the solubility of Si starting from the IPM composition, the IPM blend was incubated in PBS at 4 different temperatures. At several time points (0.5h; Ih; 2h; 3h; 3.25h) a 5 ml sample was taken. The samples were filtered on a 0.45 pm PTFE filter, diluted 100 times and the Si dissolved content was determined by ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy). For all temperatures it can be observed that the dissolved Si content is higher at 3.25h compared to the 0.5h sample. However, it can equally be observed that a plateau phase was already reached at 3h and thus that incubating the sample in PBS for more than 3h did not lead to a higher dissolved Si concentration (Figure 1).

[0126] The highest concentration of dissolved Si that was reached was 49.1, 85.2, 122.3 and 155.6 ppm respectively at a temperature of 23.6°C, 40.5°C, 59°C and 76°C.

[0127] Next, 1 gram of IPM was introduced in 500 ml of PBS (i.e. 280 ppm of Si) at a temperature of 77.5°C. The obtained solution was not transparent but had a cloudy or turbid appearance, indicating that not all silica was dissolved.

[0128] After the following time points: 0.5h ; Ih ; 2h and 3h, samples were taken. The samples were filtered on a 0.45 pm PTFE filter and diluted 100 times before their analysis by ICP-OES to determine Si dissolved content. Table 1 and Figure 2 show the amount of dissolved Si at the different time points for 3 repeat trials at identical conditions.

[0129] Table 1. The dissolved Si content from 1 g IPM in 500 ml PBS at different time points.

[0130] Example 3. Supersaturated Si solutions

[0131] To obtain a supersaturated Si solution, a solution of 160 ppm Si was aimed for by dissolving 457.4 mg of IPM in 400 ml of PBS at a temperature of 77.4°C. ICP-OES measurements revealed that the Si dissolved content at 77.4°C was between 152.6 and 160.4 ppm (Figure 3). Again, a cloudy solution was obtained (data not shown).

[0132] After the third hour, it was determined how the Si dissolved concentration was affected by cooling down the Si solution. Between the third and fourth hour, the temperature of the Si solution was decreased to 39.5°C. As can be observed in Figure 3, when the temperature of the Si solution was decreased to 39.5°C, the dissolved Si concentration significantly dropped to 121.2 ppm. This indicates that a certain amount of dissolved Si precipitated to reach a new equilibrium at 39.5°C. After the 4thhour, the solution was filtered using a PTFE filter with a mesh size of 0.45 pm. The solution was allowed to cool to room temperature of 20°C. Surprisingly, it was found that a further decrease in dissolved Si concentration due to a further cooling down of the solution to room temperature could be prevented by filtering the Si solution (Figure 3).

[0133] Based on these insights, it was analysed what the effect is on the dissolved Si concentration when the filtering step was performed at 79.4°C. A Si solution was made by dissolving 572 mg of IPM in 400 ml PBS at a temperature of 79.4°C, that would theoretically lead to a 160 ppm Si solution. After Ih the Si concentration measured by ICP-OES was 133.7 ppm (Figure 4). After 3 hours, the Si concentration stabilized at 133.0 ppm in a cloudy medium. After the three hour mark, the the solution was filtered at 79.4°C using a PTFE filter of 0.45 pm indicated as a dashed line on the figure. Because of the filtering step a transparent solution was obtained (data not shown). The solution was then cooled down to 39.5°C, a temperature which was obtained by the 5.5 hour mark. Surprisingly, the dissolved Si concentration maintained stable at 131.2 ppm and no precipitation of Si could be observed (Figure 4). The solution also remained transparent. The solution was allowed to cool to room temperature of 20°C. The Si concentration was again measured by ICP-OES after 24 hours, at room temperature. Interestingly, even lowering the temperature to room temperature did not lead to a drop in dissolved Si (Figure 4). Hence, a supersaturated transparent Si solution was obtained.

[0134] Next, a saturated Si solution was made by dissolving 833 mg IPM into 500 ml PBS at 76°C (210 ppm Si). Based on the ICP-OES measurements a dissolved Si concentration was obtained of 153 ppm after a period of 3 hours.

[0135] Then, one half of the solution was filtered on a cellulose filter and the other half of the solution was filtered on a polyethersulfone (PES) filter. Both filtering steps were performed at 76°C and using a mesh size of 0.45 pm. In line with the above disclosed findings, the Si solution remained stable and the solution remained transparent when cooling down to room temperature. The Si concentration remained stable for at least 1 week at room temperature, maintaining a Si concentration as measured by ICP- OES above 150 ppm. Overall, these tests indicates that several types of filters can be used to achieve these result.

[0136] Example 4. Stability of a supersaturated Si solution

[0137] A saturated Si solution was made by dissolving 833 mg IPM into 500 ml PBS at 76°C (210 ppm Si). Based on the ICP-OES measurements a dissolved Si concentration was obtained of 150 ppm. Then, one half of the solution was filtered on a polyethersulfone (PES) filter, the filtering step was performed at 76°C and using a mesh size of 0.45 pm and cooled down to room temperature, providing a supersaturated Si solution.

[0138] The supersaturated Si solution was stored at 20°C for a period of 6 months. The Si concentration of the stored supersaturated Si solution was measured every month. The Si concentration deviated less than 10% from 150 ppm at every measurement.

[0139] Example 5. Disruptive trial of a supersaturated Si Solution

[0140] A Si solution was made by dissolving 833 mg IPM into 500 ml PBS at 76°C (210 ppm Si). Based on the ICP-OES measurements a dissolved Si concentration was obtained of 150 ppm. Then, one half of the solution was filtered on a polyethersulfone (PES) filter, the filtering step was performed at 76°C and using a mesh size of 0.45 pm. The Si solution was cooled to 20°C, resulting in a supersaturated Si solution with an Si concentration measured at 147 ppm.

[0141] To 100 ml of this supersaturated Si solution, 100 mg of mesoporous silica with a surface area of 750 m2 / g was added. The mixture was stirred, then stored at 20°C for 20 days. The Si concentration was measured by ICP-OES regularly. After the first 24 hours, the concentration had decreased to 127.6 ppm. By the third day, the concentration decreased to 116.1 ppm. After 15 days, a concentration of 91.4 ppm was observed. After 20 days, a concentration of 71.9 ppm was observed.

[0142] Without wishing to be bound by theory, this decreasing evolution shows that the monomeric and dimeric silicium species dissolved in the supersaturated solution polymerize at the surface of the mesoporous silica. The mesoporous silica particles are nucleation points that initiate and increase the condensation kinetics of the silicium species in solution. It is important to note that the quantification of chemical elements in solid form is not possible using ICP-OES. They must be in their dissolved form in order to be analyzed by this technique.

[0143] Examples 6 - 7 : Comparison of a supersaturated and subsaturated silicium solution.

[0144] A further trial was conducted to determine whether destabilization of the IPM solution occurs exclusively when adding mesoporous silica to a supersaturated silicium solution, or whether this destabilization phenomenon can also be observed in (sub)saturated solutions. This further exemplifies that a supersaturated solution can be formed according to the process described in present application, including formation at elevated temperatures followed by filtration at said elevated temperatures prior to cooling. By comparison, preparations at room temperature are saturated or below saturation.

[0145] Two solutions were prepared. Example 6 comprises a Phosphate Buffer Saline (PBS) solution heated until 79 °C. 833 miligrams of IPM was introduced in 500 ml of PBS at 79°C, which was maintained at this temperature for 3 hours. After 3 hours, the solution is filtered on PES filter 0,45 pm with an ultrafiltration device at 79°C.

[0146] Comparative example 7 comprises 833 miligrams of IPM, introduced in 500 ml of PBS at room temperature. After 3 hours at room temperature, the solution is filtered on PES filter 0,45 pm with a ultrafiltration device.

[0147] For both solutions (example 6 prepared 79°C and comparative example 7 prepared at room temperature) an initial sampling was performed immediately prior to the introduction of the mesoporous silica particles (tO).

[0148] Subsequently, 4 grams of mesoporous silica particles (identical particles to example 5) are introduced in 400 ml of the each filtered solution.

[0149] The silicon (Si) content in both solutions was subsequently measured at various time intervals over a 65-hour trial period, as illustrated in Figure 5, which shows the evolution of Si content in both solutions as a function of time. Example 6 is indicated in solid black, with data points marked as squares (■), with a starting point of 139 ppm. Comparative example 7 is indicated in gray, with the data points marked as large dots (•) and the trendline shown as a dotted line, with a starting point of 40 ppm. The evolution of the dispersion of mesoporous silica in example 6 exhibited a significant decrease in Si content, from 139 ppm at tO to a plateau at approximately 65 ppm after 24 hours. Without wishing to be bound by theory, this decrease is attributed to monomeric and dimeric silicon species undergoing polymerization and thus precipitation at the surface of the introduced mesoporous silica particles.

[0150] Conversely, in the dispersion of mesoporous silica in comparative example 7, the Si content increased from 40 ppm to a plateau at an average of 65 ppm after 24 hours. This increase in Si content is attributed to the dissolution of mesoporous particles introduced at tO. The initial Si content at tO was below the saturation point. In both trials, the equilibrium Si concentration reached was approximately 65 ppm. Far from all mesoporous silica was dissolved. Consequently, this concentration is likely close to the saturation point at the measured conditions.

[0151] In conclusion, a supersaturated silicon solution can be destabilized in less than 24 hours by the introduction of mesoporous particles. Furthermore, such supersaturated silicon solutions can be obtained by a process utilizing elevated temperatures in accordance with present description. Room temperature was about 20°C throughout this trial.

Claims

CLAIMS1. A supersaturated silicium (Si) solution with a concentration of dissolved Si of at least 40 ppm as measured by ICP-OES.

2. The supersaturated silicium (Si) solution according to claim 1, wherein the concentration of dissolved Si as measured by ICP-OES decreases by at least 5% after a time period of 24 hours at 15 to 25°C, after introducing 100 mg mesoporous silica particles / 100 ml supersaturated silicium solution, wherein the mesoporous silica particles have a specific surface area of at least 400 m2 / g.

3. The supersaturated silicium (Si) solution according to claim 1 or 2, wherein said solution has a pH between 4 and 7, preferably between 4.5 and 6.

4. The supersaturated Si solution according to any of claims 1-3, wherein the concentration of dissolved Si is at least 110 ppm as measured by ICP-OES.

5. The supersaturated Si solution according to any of the previous claims further comprising a calcium or magnesium salt.

6. The supersaturated Si solution according to any of the previous claims, wherein said supersaturated Si solution is free of phenols and polyphenols.

7. The supersaturated Si solution according to any of the previous claims, wherein said supersaturated Si solution is free of quaternary ammonium salts, particularly choline salts.

8. A method of producing a supersaturated Si solution, comprising the steps of: a. providing a mixture comprising mesoporous silica, preferably said mesoporous silica having a specific surface area of at least 500 m2 / g; b. dissolving said mixture in a range of between 0.05 and 0.3% weight per volume (w / v) to a water-based medium, the medium being at a temperature of between 40 and 90°C; c. filtering the solution at a temperature of between 40 and 90°C using a filter with a mesh size of at most 0.5 pm.

9. The method according to claim 8 further comprising an incubation step before the filtering step, the incubation step comprises incubating the obtainedsolution from step b) for at least 0.5 h at a temperature of between 70 and 90°C.

10. The method according to any of claims 8 or 9 further comprising a cooling step after the filtering step, wherein the cooling step comprises the cooling of the filtered solution to ambient temperature, wherein no precipitation of silica occurs.

11. The method according to any of claims 8-9, further comprising the steps of: d. cooling the solution to a temperature lower than 30°C, and e. filtering the solution with a mesh size of at most 0.5 pm, at a temperature lower than 30°C.

12. The method of any of claims 8-11, comprising the step of : a. providing a mixture comprising 20 to 40 wt.% mesoporous silica, preferably said mesoporous silica having a specific surface area of at least 500 m2 / g; and 40 to 80 wt.% of a soluble salt chosen from calcium salts, magnesium salts or mixtures thereof.

13. The method of claim 12, wherein the soluble salt is selected from the list consisting of calcium acetate, calcium citrate, calcium chloride and calcium carbonate, preferably calcium acetate, calcium citrate or calcium chloride.

14. The method according to claim 13, wherein step c. comprises filtering with a polytetrafluoroethylene (PTFE) membrane filter.

15. The method according to claim 13, wherein step c. comprises filtering with a cellulose filter.

16. The method according to claim 13, wherein step c. comprises filtering with a polyethersulfone (PES) or a polyvinylidene difluoride (PVDF) filter.

17. A cosmetic formulation comprising the supersaturated Si solution of any of claims 1-7, further comprising one or more cosmetic ingredients selected from pigments, emollients, antioxidants, or active compounds.

18. A cosmetic formulation obtained by the method comprising the step of mixing the supersaturated Si solution according to any of claims 1-7 and one or more cosmetic ingredients selected from the list consisting of pigments, emollients, antioxidants and active compounds.

19. The cosmetic formulation according to any of claims 17-18, wherein the supersaturated Si solution is obtained by the method according to any of claims 8-16.

20. Use of the supersaturated Si solution according to any of claims 1-7 or obtained by the method according to any of claims 8-16 for producing a cosmetic formulation.

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