Composition for use in the treatment of caries and / or gingivitis

Abstract

The invention relates to a method for producing microparticles loaded with at least one flavonoid and / or flavonoid derivative, having the following steps which are carried out one after the other: a) mixing a water component in the form of an aqueous solution comprising the at least one flavonoid and / or flavonoid derivative with an oil component in order to form a solution of polylactic acid-co-glycolide in an organic solvent in order to form a water-oil emulsion; b) mixing the water-oil emulsion from step a) with another water component in the form of an aqueous solution comprising at least one stabilizer in order to form a water-oil-water emulsion; c) mixing the water-oil-water emulsion with an aqueous salt solution; d) removing the organic solvent in the water-oil-water emulsion in order to form a suspension which comprises the microparticles loaded at least with the flavonoid and / or flavonoid derivative; and e) separating the loaded microparticles from the liquid of the suspension. The invention also relates to microparticles, to the use thereof for producing a medicament, to a dispersion containing the microparticles for use in the treatment and / or prophylaxis of oral infections, and to the non-medical use thereof in cosmetics.

Description

[0001] 21.11.2025 MR / NL

[0002] Composition for use in the treatment of caries and / or gingivitis

[0003] The invention relates to a process for producing microparticles loaded with at least one flavonoid and / or flavonoid derivative. The invention further relates to microparticles whose use in the manufacture of a pharmaceutical product, a dispersion containing the microparticles for use in the treatment and / or prophylaxis of oral infections, as well as non-medicinal use in cosmetics.

[0004] Tooth decay and gingivitis regularly arise from a persistent dental plaque adhering to the teeth, containing, among other things, the bacterial species Streptococcus mutans and Porphyromonas gingivalis, whose increased presence is primarily associated with tooth decay and gingivitis. Streptococcus mutans, in particular, produces glucosyltransferases (GTFs), which catalyze the synthesis of water-insoluble polysaccharides (EPS). These EPS contribute significantly to the stability of the biofilm on the tooth, allowing the bacterial species to continue multiplying.

[0005] It is known that flavonoids and flavonoid derivatives inhibit the glucosyltransferase activity of Streptococcus mutans and can thus counteract biofilm that promotes caries and inflammation. This is particularly true when oral hygiene is restricted due to other (dental) medical treatment. An example is the treatment of marginal periodontitis. Treatment for marginal periodontitis may include the application of a gel to promote wound healing (at least closure), for example, after dental subgingival curettage. Intensive tooth cleaning, such as with dental floss and similar effective cleaning agents, is then temporarily restricted, which can lead to the formation of initial caries or the worsening of existing caries.

[0006] However, the clinical benefit of flavonoids and flavonoid derivatives is limited by their rapid metabolism and restricted bioavailability. Their solubility and structural instability due to autoxidation can further limit their applicability if they significantly reduce bioavailability at the target site.

[0007] Various methods for reducing the decomposition of flavonoids or flavonoid derivatives are known from the prior art. These include, for example, encapsulation or coating with a protective layer in the form of a polymer matrix to obtain a microparticle loaded with the flavonoid or flavonoid derivative. The polymer matrix is ​​designed to allow controlled permeation or release into the surrounding medium. Permeation or release pathways arise, for example, from diffusion through water-filled pores of the polymer matrix, diffusion through the polymer matrix itself, osmotic pumping, and erosion of the polymer matrix. However, known methods for producing loaded microparticles yield microparticles that exhibit a strong release of the flavonoid or flavonoid derivative at the beginning of their use.Flavonoid derivatives show, but this decreases rapidly and thus falls below a desired effective concentration after a short time.

[0008] Advantageously, the at least one flavonoid or flavonoid derivative should be surrounded by the polymer matrix in such a way that a constant release of the at least one flavonoid or flavonoid derivative from the microparticle occurs over a sufficiently long period of several days or weeks. The released concentration of the at least one flavonoid or flavonoid derivative is specifically designed to be toxic to prokaryotic cells. Conversely, the released concentration should be low enough to be non-cytotoxic to the surrounding eukaryotic cells.

[0009] The present invention is therefore based on the objective of providing a method for producing microparticles loaded with at least one flavonoid and / or flavonoid derivative, which overcome the disadvantages of the prior art listed above. In particular, it is an objective of the present invention to provide a method that makes it possible to produce such microparticles in a simple manner and with high purity. Furthermore, it should be possible to provide microparticles which enable a constant release of the at least one flavonoid and / or flavonoid derivative from the microparticles over a period of several days.

[0010] The invention solves this problem by a process for producing microparticles loaded with at least one flavonoid and / or flavonoid derivative, comprising the following successive steps: a) mixing a water component in the form of an aqueous solution comprising the at least one flavonoid and / or flavonoid derivative with an oil component to form a solution of polylactide-co-glycolide in an organic solvent, to form a water-oil emulsion; b) mixing the water-oil emulsion with a further

[0011] Water component in the form of an aqueous solution comprising at least one stabilizer, to a

[0012] Water-oil-water emulsion, c) Mixing the water-oil-water emulsion with an aqueous salt solution, wherein the salt of the salt solution is selected from alkali halides, alkali phosphates, alkali hydrogen phosphates, alkali sulphides, alkaline earth halides, alkaline earth phosphates, alkaline earth hydrogen phosphates, alkaline earth sulphides and mixtures thereof, preferably from sodium chloride, potassium chloride, calcium chloride or magnesium chloride, particularly preferably sodium chloride; d) Removing the organic solvent from the water-oil-water emulsion to form a suspension comprising the microparticles loaded with at least the flavonoid and / or flavonoid derivative; e) Separating the loaded microparticles from the liquid of the suspension.

[0013] Preferred embodiments are found in the dependent claims.

[0014] First, some terms used in connection with the invention will be explained.

[0015] A microparticle is defined as a particle made of a polymer matrix with a maximum diameter between 1 and 1000 micrometers. Approximately spherical and globular particles, such as those produced during manufacturing, particularly during polymerization as an emulsion or suspension, are preferred. A loaded microparticle is defined as a microparticle comprising a polymer matrix in which the at least one flavonoid and / or flavonoid derivative is preferably uniformly distributed within the polymer matrix, and the polymer matrix at least partially surrounds and thus at least partially encapsulates the at least one flavonoid and / or flavonoid derivative.The term microparticles encompasses not only microparticles that completely encapsulate the at least one flavonoid and / or flavonoid derivative, but also microparticles that only partially encapsulate the flavonoid and / or flavonoid derivative and / or may have pores or holes in the polymer matrix. Furthermore, the at least one flavonoid and / or flavonoid derivative may be contained within the pores of the microparticles.

[0016] A stabilizer is understood to be a compound which positively influences the production of a microparticle through a stabilizing effect.

[0017] The synthesis of microparticles loaded with at least one flavonoid and / or flavonoid derivative is advantageously carried out using a double emulsion technique. In this technique, the at least one flavonoid and / or flavonoid derivative is dissolved in the aqueous solution of the water component and subsequently emulsified in the oil component, which contains the polylactide-co-glycolide (PLGA) in an organic solvent. This water-oil emulsion is then transferred to another water component in the form of an aqueous solution comprising at least one stabilizer and is mixed with an aqueous salt solution, from which the organic solvent is removed, for example, by evaporation. The result is microparticles loaded with the at least one flavonoid and / or flavonoid derivative from a PLGA matrix, which at least partially encapsulate the at least one flavonoid and / or flavonoid derivative.The resulting loaded microparticles can then be separated from the supernatant liquid and thus isolated.

[0018] This method enables the simple and technically efficient production of microparticles loaded with at least one flavonoid and / or flavonoid derivative. The method according to the invention eliminates the need for special apparatus for production, which is required, for example, in known methods using microfluidic systems or spray drying.

[0019] Compared to known single-emulsion techniques, the double-emulsion process offers the advantage that water-soluble compounds such as flavonoids and / or flavonoid derivatives can be encapsulated with high efficiency, i.e., in large quantities, thus producing loaded microparticles. Simple emulsions can be achieved by directly adding the at least one flavonoid and / or flavonoid derivative to the oil component contained in the PLGA and subsequently emulsifying the mixture in an aqueous solution. However, water-soluble flavonoids and / or flavonoid derivatives can migrate from the oil component into the surrounding water component during the manufacturing process, which generally leads, among other things, to a reduced encapsulation efficiency, as observed for the double-emulsion process according to the invention.

[0020] The present method enables the simple and efficient production of microparticles loaded with at least one flavonoid and / or flavonoid derivative. Furthermore, this method allows for a narrower particle size distribution and no or only negligible aggregation or agglomeration.

[0021] Preferably, the PLGA is dissolved in a suitable organic solvent. Suitable organic solvents are sparingly or immiscible with water and can be selected, for example, using miscibility tables. Suitable organic solvents include, for example, dichloromethane (DCM) and / or ethyl acetate (EtAc). The use of DCM is preferred because DCM is particularly sparingly soluble in the water component. Suitable organic solvents are more volatile than water. Thus, DCM, in particular, can be easily removed, for example, by evaporation. Furthermore, the use of DCM also promotes the separation of the resulting microparticles and prevents agglomeration, which allows, in particular, the obtaining of spherical microparticles with a smooth surface.

[0022] The stabilizer enables the stabilization of the microparticles. Additionally, the addition of a stabilizer can reduce the diffusion-based release of the at least one flavonoid and / or flavonoid derivative. Preferably, the at least one stabilizer is selected from alcohols, polysorbates, oleates, stearates, poloxamers, and mixtures thereof; more preferably from polyvinyl alcohol, sorbitan monooleate, or sorbitan monostearate; polyvinyl alcohol (PVP) is particularly preferred as a stabilizer. In a preferred embodiment of the invention, the aqueous solution additionally contains only the stabilizer.

[0023] By mixing the water-oil-water emulsion with the aqueous salt solution, the osmotic pressure during the production of the microparticles can be reduced, thereby achieving better loading efficiency.

[0024] In one embodiment of the invention, the water component comprises only at least one flavonoid and / or flavonoid derivative. The addition of the at least one stabilizer and the aqueous salt solution can be sequential or simultaneous.

[0025] Preferably, the at least one flavonoid and / or flavonoid derivative is selected from the group of catechins, preferably from epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin gallate, and is further preferably epigallocatechin gallate (EGCG). Flavonoids and / or flavonoid derivatives are used in a variety of ways due to their characteristic effects. Generally, these effects are based on an antioxidant action. For example, EGCG, a carboxylic acid ester of gallic acid with the alcohol and catechin epigallocatechin, exhibits antioxidant, anti-inflammatory, anticancer, and antibiotic properties. Furthermore, EGCG, alone or in synergy with conventional antibiotics, shows antibacterial activity even against drug-resistant strains of bacteria. Advantageously, two or more flavonoids and / or flavonoid derivatives can also be used according to the invention.

[0026] The polymer matrix of the microparticles preferably comprises PLGA. PLGA is a polyester composed of D,L-lactic acid and glycolic acid. This polyester is generally hydrophilic, so the matrix of the microparticles erodes over time. This erosion occurs particularly with water through hydrolysis. The erosion process degrades PLGA into its monomers, releasing lactic acid and glycolic acid. By appropriately selecting the ratio of D,L-lactic acid to glycolic acid (L:G), the durability of the microparticles can be tailored to specific requirements. The PLGA is preferably formed from D,L-lactic acid and glycolic acid in a ratio of 2:1 to 1:2, preferably 1:1 (50:50). Surprisingly, it turned out that a ratio of 50:50 of D,L-lactic acid to glycolic acid in particular is associated with a desirable slower release from the microparticles.In addition to PLGA, the polymer matrix may also contain other components, including in particular other polymers or copolymers.

[0027] The release mechanism of the at least one flavonoid and / or flavonoid derivative from the microparticle is based, firstly, on the diffusion of the at least one flavonoid and / or flavonoid derivative through the PLGA matrix of the microparticle into the surrounding medium, and secondly, on the erosion of the PLGA matrix itself, which releases the at least one flavonoid and / or flavonoid derivative. Improved diffusion of the flavonoid and / or flavonoid derivative, as well as faster decomposition of the microparticle itself, thus promotes the rapid release of the at least one flavonoid and / or flavonoid derivative. Rapid and / or uncontrolled release results in a shortened time during which a desired concentration of the at least one flavonoid and / or flavonoid derivative can be maintained, for example, in the oral cavity of a patient.In particular, microparticles of PLGA containing D,L-lactic acid and glycolic acid in a 1:1 ratio exhibit a nearly constant release of the at least one flavonoid and / or flavonoid derivative, whereas microparticles with a higher lactic acid content exhibit a biphasic release profile with a strong release surge in the first two days, followed by a low, constant release over two weeks. According to the invention, therefore, by optimizing the ratio of D,L-lactic acid to glycolic acid, an even longer-lasting active ingredient release and a slower, more controlled release of the at least one flavonoid and / or flavonoid derivative can be achieved.

[0028] Preferably, the microparticles contain 0.1 to 20% by weight of the at least one flavonoid and / or flavonoid derivative, more preferably 0.2 to 15% by weight, further preferably 1 to 10% by weight, and more preferably 1 to 5% by weight, based on the total weight of the microparticles. In this way, the release of the at least one flavonoid and / or flavonoid derivative from the microparticles can be achieved at the desired effective concentration.

[0029] Preferably, the microparticles have a particle size between 1 pm and 500 pm, more preferably between 1 pm and 100 pm, and more preferably between 1 pm and 80 pm, as measured by laser scattering. This ensures good bioavailability. Furthermore, it prevents the immune responses that would be expected with larger particles.

[0030] Preferably, the microparticles have a mean particle size D50 between 5 pm and 200 pm, more preferably between 5 pm and 100 pm, more preferably between 10 pm and 90 pm, and most preferably between 20 pm and 80 pm, as measured by laser scattering. A mean particle size D50 is defined as a particle size with a pass-through value of 50%. Thus, 50% of the particle sizes in the sample are smaller and 50% are larger than this value. Accordingly, for example, a value of D90 is understood to represent a pass-through value of 90%, and D10 a pass-through value of 10%.

[0031] The particle size and mean particle size were determined using laser scattering (LA-900 laser scattering particle size analyzer, Horiba, Japan).

[0032] Preferably, the size of the microparticles is unimodally distributed.

[0033] Preferably, the loaded microparticles are dispersed in a flowable hydrogel, preferably an agarose hydrogel, to achieve dispersion within the hydrogel. This dispersion of the microparticles distributes or disperses the PLGA particles within the hydrogel, thus preventing or significantly reducing agglomeration between the individual microparticles. By suppressing agglomeration, a more consistent and therefore more predictable release of the at least one flavonoid and / or flavonoid derivative can be achieved.

[0034] The use of an agarose hydrogel, in particular, further prevents or reduces the swelling capacity of the microparticles, resulting in less decomposition of the microparticles and thus a lower release of the at least one flavonoid and / or flavonoid derivative. Other advantageous free-flowing hydrogels include K-carrageenan, sodium alginates, as well as non-ionic surfactants and surfactant polyols, including, for example, Pluronic F-127®.

[0035] Preferably, the hydrogel is sufficiently fluid at 23°C to be dispensed from cannulas commonly used in dentistry. The flowability of the composition according to the invention is important for the safe and easy application of the composition in the oral cavity, particularly for injecting the composition between the neck of the tooth and the gingiva using a thin cannula and a syringe, i.e., directly filling the gingival sulcus with the composition. It is particularly advantageous if the user has to exert little force to extrude the composition from the cannula. This extrusion force, for example, to actuate the plunger of a syringe, is preferably less than 200 Newtons, more preferably less than 150 Newtons, more preferably less than 100 Newtons, more preferably less than 50 Newtons, and more preferably less than 30 Newtons.This extrusion force, for example to actuate the piston of a syringe, is preferably greater than 0.01 Newtons, and more preferably greater than 0.1 Newtons.

[0036] Preferably, the manufactured microparticles are formed by a hydrogel containing PLGA as a polymer, wherein the microparticles have a hydrogel content of 80 to 99.9% by weight, based on the total weight of the microparticles. The addition of a hydrogel matrix ensures that the PLGA particles are well distributed or dispersed in the sample and prevents agglomeration. This results in a more consistent release of the at least one flavonoid and / or flavonoid derivative.

[0037] Preferably, the polymer contains 50 to 100 wt% PLGA, preferably 90 to 100 wt% PLGA.

[0038] Preferably, the microparticles have a PLGA concentration between 8 and 20 wt%, based on the total weight of the microparticles. In the range between 8 and 20 wt% PLGA, the particle size increases with the PLGA content. A linear relationship between particle size and PLGA concentration can be observed in this range. Within this concentration range, the average particle diameter D50 increases. Furthermore, the size distribution does not change significantly within this concentration range. PLGA concentrations above 17 wt% resulted in only a negligible increase in encapsulation efficiency. Thus, the loss of the at least one flavonoid and / or flavonoid derivative can be minimized by maximizing the loading efficiency of the microparticles.

[0039] At the same time, maximum loading of the microparticle can thus be achieved.

[0040] Preferably, the process comprises one or more of the following features: the water-oil emulsion from step a) is mixed by ultrasound; the water-oil-water emulsion from step c) is mixed by mechanical means; the microparticles obtained in step d) are separated in step e) by centrifugation; the microparticles obtained in step d) or the separated microparticles from step e) are dried by freeze-drying.

[0041] Preferably, the water-oil emulsion from step a) is mixed using ultrasound, while the water-oil-water emulsion from step c) is mixed using mechanical means, such as a magnetic stirrer. This approach offers the advantage that the resulting microparticles exhibit a narrower distribution and reduced aggregation, which is usually caused by an unstable emulsion that can lead to the precipitation of PLGA.

[0042] Furthermore, the invention relates to loaded microparticles, which are loaded with at least one flavonoid and / or flavonoid derivative and comprise polylactide-co-glycolide, produced according to the inventive method. Preferably, the microparticles release the flavonoid and / or flavonoid derivative from the microparticles over a period of at least 7 days at a release rate between 0.05 and 0.08 mg / ml per 24 hours.

[0043] In one embodiment of the invention, the polymer of the microparticles consists only of polylactide-co-glycolide.

[0044] Furthermore, the invention relates to loaded microparticles, wherein the microparticles are loaded with at least one flavonoid and / or flavonoid derivative and the microparticles comprise polylactide-co-glycolide, wherein the microparticles

[0045] Release flavonoid and / or flavonoid derivative from the microparticles over a period of at least 7 days at a release rate between 0.05 and 0.08 mg / ml per 24 hours.

[0046] To be effective against bacteria, the at least one flavonoid and / or flavonoid derivative must be released daily in an amount corresponding to an effective concentration. This concentration is between 100 and 300 ppm per day. This minimum concentration of 100 ppm corresponds to a release rate of the at least one flavonoid and / or flavonoid derivative of 0.05 to 0.08 mg / ml per 24 hours. Preferably, this effective concentration or release rate can be maintained for a period of two weeks. The microparticles according to the invention thus make it possible to provide an effective minimum amount of the at least one flavonoid and / or flavonoid derivative over a period of days, for example, to suppress a biofilm, particularly one containing Porphyromonas gingivalis and / or Streptococcus mutans.

[0047] The at least one flavonoid and / or flavonoid derivative preferably has a solubility in water and / or in a mixture of water and a completely miscible organic solvent of at least 0.01 mg / ml, preferably at least 0.1 mg / ml, and more preferably at least 1 mg / ml at 23 °C. Preferably, the at least one flavonoid and / or flavonoid derivative is selected from the group of catechins, more preferably from epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin gallate, and is more preferably epigallocatechin gallate.

[0048] Preferably, the PLGA is formed from D,L-lactic acid and glycolic acid in a ratio of 2:1 to 1:2, more preferably 1:1 (50:50). Preferably, the microparticles contain 0.1 to 20% by weight of the at least one flavonoid and / or flavonoid derivative, more preferably 0.2 to 15% by weight, more preferably 1 to 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the microparticles.

[0049] Preferably the microparticles have a particle size between 1 pm and 500 pm, more preferably between 1 pm and 100 pm, and more preferably between 1 pm and 80 pm, measured by laser scattering.

[0050] Preferably the microparticles have a mean particle size D50 between 5 pm and 200 pm, more preferably between 5 pm and 100 pm, more preferably between 10 pm and 90 pm, more preferably between 20 pm and 80 pm, measured by laser scattering.

[0051] Preferably, the loaded microparticles are dispersed in a flowable hydrogel, preferably in an agarose hydrogel, to obtain a dispersion of the microparticles in the flowable hydrogel.

[0052] Preferably, the microparticles are formed by a hydrogel containing the polylactide-co-glycolide as a polymer, wherein the microparticles have 80 to 99.9 wt% hydrogel, based on the total weight of the microparticles.

[0053] Preferably, the polymer contains 50 to 100 wt% polylactide-co-glycolide, preferably 90 to 100 wt% polylactide-co-glycolide.

[0054] Preferably, the microparticles contain a stabilizer, preferably polyvinyl alcohol (PVA). The stabilizer enables the stabilization of the microparticles. Additionally, the addition of a stabilizer can reduce the diffusion-based release of the at least one flavonoid and / or flavonoid derivative.

[0055] Furthermore, the microparticles according to the invention can be further developed with additional features, which are described in connection with the process according to the invention, in particular in connection with its further and additional components and properties. Likewise, the process according to the invention can be further developed with additional features, which are described in connection with the microparticles according to the invention, in particular in connection with its further and additional components and properties.

[0056] Furthermore, the invention relates to the use of the microparticles for the manufacture of a pharmaceutical product, wherein the loaded microparticles preferably release the at least one flavonoid and / or flavonoid derivative from the microparticles over a period of at least 7 days with a release rate between 0.05 and 0.08 mg / ml per 24 hours. According to the invention, the pharmaceutical product can be used, for example, for the treatment of gingivitis and periodontitis.

[0057] Furthermore, the invention also relates to the use of a dispersion containing the microparticles in the treatment and / or prophylaxis of oral infections, in particular gingivitis, including the treatment and / or prophylaxis of caries. In addition to the microparticles according to the invention, the dispersion can also comprise further microparticles with different loadings.

[0058] The loaded microparticles according to the invention, for example, enable the reduction of bacteria-specific biofilms when applied in a patient's oral cavity. The release of at least one flavonoid or flavonoid derivative can counteract biofilms that promote caries and inflammation. This is particularly relevant when oral hygiene is restricted (due to other dental treatments). An example of this is the treatment of marginal periodontitis. Treatment of marginal periodontitis can include the application of the microparticles to promote wound healing (at least closure), for example, after dental subgingival curettage. Intensive cleaning of the teeth, for example with dental floss and similarly effective cleaning agents, is then temporarily restricted, which can lead to the formation of initial caries or the worsening of existing caries.

[0059] Preferably, the dispersion can be used in the treatment and / or prophylaxis of oral infections, with between 100 and 300 ppm of the at least one flavonoid and / or flavonoid derivative being administered per day.

[0060] Furthermore, the invention also relates to the non-medicinal use of the microparticles in cosmetics, including the prevention of tooth discoloration. The microparticles according to the invention can significantly inhibit the growth of bacteria, particularly those that typically form the persistent dental plaque adhering to the tooth. Plaque is one of the main causes leading to the formation of caries and / or gingivitis. The microparticles according to the invention make it possible to inhibit these responsible bacterial strains and thus prevent or at least significantly reduce resulting damage to the gums and, in particular, to the teeth. Cosmetic damage caused by caries and / or gingivitis includes, among other things, redness, swelling, bleeding and receding gums, exposed tooth necks, as well as discoloration and chalky stains on the teeth.The present invention is described in more detail with reference to the following examples 1-10 and figures 1-17. It shows.

[0061] Fig. 1: Schematic representation of the synthesis of PLGA microparticles loaded with at least one flavonoid and / or flavonoid derivative using double emulsion technology.

[0062] Fig. 2: 1 H-NMR of PLGA (bottom), EGCG (middle) and EGCG-loaded PLGA microparticles (top), showing a successful loading of PLGA microparticles with EGCG.

[0063] Fig. 3: Characterization of PLGA microparticles with different EGCG loadings, (A) scanning electron microscopy (SEM) images of PLGA microparticles with 17 wt% PLGA and different drug loadings, (B) size distribution of PLGA microparticles with different theoretical drug loadings, (C) experimentally measured drug loading and encapsulation efficiency of PLGA microparticles with experimental drug loadings of 2 to 15 wt% (data presented as mean ± SD, n = 3).

[0064] Fig. 4: Influence of PLGA concentration on the properties of PLGA microparticles, (A) SEM images of EGCG-loaded microparticles with different concentrations of PLGA (scale: 200 pm), (B) Plot of the mean diameters of the PLGA microparticles against the PLGA concentration, (C) With increasing PLGA concentration, an increasing encapsulation efficiency is observed (data presented as mean ± SD, n = 3). Fig. 5: Schematic representation of the synthesis of a gel starting from EGCG-loaded PLGA microparticles with agarose.

[0065] Fig. 6: SEM images of PLGA microparticles after different incubation times at 37°C in an electrolyte solution (ES). Particles without a hydrogel matrix agglomerated, while PLGA microparticles in an agarose hydrogel remained separated.

[0066] Fig. 7: EGCG release from PLGA microparticles in a

[0067] Electrolyte solution (ES), (A) Cumulative release of EGCG, (B) Total mass of released EGCG per mg of microparticles used, (C) Daily dose of released EGCG per mg of particles. (D) EGCG release from PLGA microparticles dispersed in various hydrogels.

[0068] Fig. 8: EGCG release from PLGA microparticles with 6.98%

[0069] Active ingredient loading DL at constant pH and at changing pH values ​​between 3 and 6.

[0070] Fig. 9: Release of EGCG from different amounts of

[0071] PLGA microparticles with the same drug loading, (A) Mass of EGCG released per mg of PLGA microparticles with the same profile for each mass of PLGA microparticles used, (B) Total mass of EGCG released, (C) Cumulative release, (D) Daily EGCG dose per mg of PLGA microparticles over 14 days.

[0072] Fig. 10: SEM images of PLGA microparticles in an agarose hydrogel incubated in ES.

[0073] Fig. 11: Characterization of PLGA microparticles coated with

[0074] PLGA were produced in a ratio of D,L-lactic acid to glycolic acid (L:G) of 75:25, (A) SEM images show the morphology of the PLGA microparticles.

[0075] (B) Size distribution of PLGA microparticles compared to PLGA microparticles produced with an L : G ratio of 50:50.

[0076] Fig. 12: Release profiles of EGCG from PLGA microparticles with L:G ratios of 75:25 and 50:50 in simulated saliva with 3% and 7% drug loading, DL.

[0077] Fig. 13: L : G ratio of 50:50 and 75:25. (A) NMR spectra. (B) Calculation of the L : G ratio from the NMR results. (C) TGA analysis and (B) GPC trace.

[0078] Fig. 14: Cytotoxicity of EGCG at different concentrations for human gingival fibroblasts (A) and for THP-1 macrophages (B) .

[0079] Fig. 15: EGCG in 100 pL release medium over a period of two weeks compared to the minimum and maximum concentrations for EGCG.

[0080] Fig. 16: Effect of EGCG released from PLGA microparticles with 3% DL on the biofilm formation of P. gingivalis, (A) EGCG-loaded microparticles prepared with 50:50 PLGA and (B) EGCG-loaded microparticles prepared with 75:25 PLGA. * Extraction for 72 hours.

[0081] Fig. 17: Representation of bovine tooth samples to visualize potential damage caused by increased acidity during the PLGA degradation process. Black arrows indicate areas where the samples show enamel damage. I. Measurements and Methods

[0082] 1. Chemicals used

[0083] The following chemicals were used in the subsequent examples: Polylactide-co-glycolide (Resomer® RG 503 H, L:G = 50:50, 24-38 kDa), urea, sodium bicarbonate (NaHCOa), and sodium chloride (NaCl) were sourced from Sigma-Aldrich (Germany). Polylactide-co-glycolide (L:G = 75:25, 24-38 kDa) was sourced from BLD Pharmatech Ltd. (China). Dichloromethane (DCM), potassium thiocyanate (KSCN), and dimethyl sulfoxide (DMSO) were sourced from Fisher-Scientific (USA). Agarose (NEEO ultra grade), kappa-carrageenan, sodium sulfate (Na₂SO₄), potassium dihydrogen phosphate (KH₂PO₄), and potassium chloride (KCl) were purchased from Carl Roth (Germany). Sodium alginate (10-600 kDa), ammonium chloride (NH4Cl), and calcium chloride dihydrate (CaCl2·2H2O) were obtained from PanReac AppliChem (USA). (2R,3R)2 (3,4,5-trihydrohydroxyphenyl)-3,4-dihydro-1(2H)benzopyran-3,5,7-triol-3-

[0084] (3,4,5-trihydroxybenzoate) (EGCG) was purchased from BLD-Pharmatech Ltd. (China). Poly(vinyl alcohol) (PVA) was acquired from VWR International (Germany), and deuterated dimethyl sulfoxide (DMSO-d6) was purchased from Deutero GmbH (Germany). All chemicals were used as purchased without further purification.

[0085] 2. Particle size distribution

[0086] The mean diameter and particle size distribution were determined using an LA-900 laser scattering particle size analyzer (Horiba, Japan). EGCG-loaded PLGA microparticles (5 mg) were weighed into a 2 mL reaction vessel and dispersed in 1 mL of deionized water. Approximately 400 pL of the PLGA particle dispersion was then added to the quartz cuvette of the instrument and measured at a refractive index of 1.46. The mean diameter of the particles was determined from three separate batches prepared under identical conditions.

[0087] 3. Drug loading, DL and encapsulation efficiency, EE

[0088] The encapsulation efficiency (EE) and the actual drug loading (DL) of the microparticles were evaluated by UV-Vis measurements using a NanoDrop 2000c spectrophotometer (Thermo Fisher Scientific, USA). PLGA microparticles loaded with EGCG (5 mg for low DL, 2 mg for high DL) were accurately weighed into a 2 mL reaction vessel and dissolved in DMSO (0.8 mL). The amount of EGCG was then determined by comparing the absorbance at 280 nm with a previously generated calibration curve and used to calculate the experimental drug loading.

[0089] The encapsulation efficiency EE was then calculated by comparing the experimental drug loading with the theoretical loading.

[0090] 4. Visual characterization

[0091] Morphology and homogeneity of the PLGA microparticles were evaluated using electron microscopy. To investigate agglomeration and degradation behavior, PLGA microparticles were retained in release buffer (deionized water or simulated saliva (ES)) for up to 7 days and analyzed at regular intervals using a Quanta 250 FEG electron microscope (FEI, USA). The particles were freeze-dried by rapid freezing in liquid nitrogen using a Beta 2-8 LD plus freeze dryer (Christ, Germany), and the water was sublimed for 24 hours at room temperature under reduced pressure (< 2 mbar). The dried microparticles were uniformly distributed on an SEM sample holder coated with double-sided adhesive tape. The particles were gold-coated and imaged at various magnifications.

[0092] The simulated saliva (ES) was produced from:

[0093] Sodium chloride (NaCl): 125.6 mg / L, Potassium chloride (KCl): 963.9 mg / L, Calcium chloride dihydrate (CaC12 • 2H2O): 227.8 mg / L, Ammonium chloride (NH4C1): 178.0 mg / L, Potassium thiocyanate (KSCN): 189.2 mg / L, Sodium sulfate (Na2SO4): 336.5 mg / mL, Urea: 200 mg / L, Sodium bicarbonate (NaHCO2): 630.8 mg / L and Potassium dihydrogen phosphate (KH2PC>4): 654.5 mg / L.

[0094] 5. Suitability for tooth surfaces

[0095] A model experiment was conducted to determine whether the acids released by PLGA microparticles could damage teeth. Bovine teeth were washed, dried, and coated with a protective layer of nail polish. A 5x5 mm window was left exposed on the enamel surface to apply the PLGA microparticles. The exposed surface was then coated with 20 pL of a PLGA microparticle dispersion (2 mg / pL) in water and allowed to dry. The PLGA microparticle layer was then covered with 20 pL of an agarose solution (0.8 wt%) to prevent the particles from being washed off. The teeth were then placed in individual glass vials and surrounded with 4 mL of an agarose solution (0.8 wt%) to limit their movement. The hydrogel was coated with 4 mL of deionized water and incubated for 4 weeks at 37 °C without changing the supernatant.After the respective incubation period of 1, 2, 3 or 4 weeks, the teeth were removed, washed, dried and examined for erosion, which is clearly recognizable by a white, chalky appearance of the surface.

[0096] 6. Microbiological activity

[0097] The microbiological effect of released EGCG was investigated in an in vitro experiment. From the obtained release protocols in simulated saliva, the quantity of EGCG-loaded PLGA microparticles required to achieve the minimum effective concentration was calculated from the mean daily dose of the first 7 days. The corresponding particle mass was weighed and dispersed in a sterile 0.6 wt% agarose gel. The microparticle-loaded hydrogel was then incubated in a bacterial culture medium to release the EGCG. Each day, the medium was separated, and the hydrogel was suspended in a fresh medium. The effect of EGCG on the bacterial strain was validated by analyzing its ability to reduce biofilm formation by cultivating the separated medium with Porphyromonas gingivalis.

[0098] 7. NMR studies

[0099] Freeze-dried PLGA microparticles loaded with EGCG were dissolved in deuterated DMSO (20 mg / ml) and transferred to an NMR tube. Spectra were recorded using an Avance 300 MHz NMR spectrometer (Bruker, USA) at 25°C. The resulting spectra were analyzed using Topspi n software version 4.2.0 (Bruker, USA) with the residual DMSO peak at 2.5 ppm as an internal reference.

[0100] 8. In vitro release profiles: EGCG-loaded PLGA microparticles (10 mg) were weighed into 2 mL light-protected reaction vials (ambered reaction vials). The microparticles were then either dispersed in a hydrogel matrix (0.7 wt%, 200 pL) or stored as pure microparticles and then dispersed in 1 mL of the respective release buffer. The samples were subsequently incubated at 37 °C for two weeks. At regular intervals (days 1–7, 10, and 14), 450 pL of the release medium was withdrawn from the reaction vials using a QIAgility pipetting robot (Qiagen, Netherlands) and evenly distributed into three wells of a half-surface UV-Star UV-transparent 96-well plate (Grainer, Austria). The withdrawn buffer was then replaced with fresh medium to maintain a constant volume and ensure sink conditions."Sink conditions" refers to a state in which the medium can dissolve at least 3 times as much active ingredient as is contained in the sample, in order to minimize any influence on the release profile.

[0101] The concentration of EGCG in the release medium was measured by measuring the absorbance at 274 nm using a BioTek Synergy HTX wellplate reader (Agilent Technologies, USA) and compared to a previously recorded calibration curve. Each release profile was generated from three different batches of EGCG-loaded PLGA microparticles with the same drug loading.

[0102] 9. Achieving effective concentration

[0103] To demonstrate that the manufactured PLGA microparticles could maintain the effective concentration of EGCG over a two-week period, a model experiment was designed. The obtained EGCG release profiles were used to determine the microparticle content (2.98% DL) required to achieve an EGCG concentration of 45.8 pg / mL in 100 pL. Slightly more microparticles (4 mg) than required were dispersed in an agarose matrix (0.6%, 50 pL) by mixing on a vortex shaker and incubating in simulated saliva (100 pL) after gelation. The gel was transferred to fresh medium daily, and the EGCG concentration in the release buffer was determined by measuring the absorbance at 274 nm.

[0104] 10. Determination of flowability

[0105] To determine the flowability of a composition (hydrogel, dispersion), the extrusion force was measured when the composition was extruded through a fine standard cannula. The extrusion force was determined using a universal testing machine (50 N load cell, EZ-SX texture analyzer, Shimadzu, Japan). A syringe with a 1 ml filling volume and a 20 G cannula (outer / inner diameter 0.9 / 0.6 mm, length 33 mm) was mounted in the force cell of the universal testing machine. The composition was then extruded through the cannula at a constant speed of 1 mm / s at 23°C ± 3°C. The force curves were plotted in triplicate for each composition. The maximum, mean, and deviation from the mean extrusion force during extrusion were determined.

[0106] For the agarose hydrogels made from 2 wt% agarose in distilled water, a maximum force of 15.8010.15 Newtons was achieved. The relative deviation from the mean extrusion force of the individual agarose gels was 25.56 ± 5.93%. A maximum extrusion force of 15.8010.15 Newtons was not exceeded.

[0107] 11. Examples

[0108] 1. Presentation of EGCG-loaded PLGA microparticles Example 1

[0109] 19 mg of EGCG were dissolved in 0.6 ml of water. 170 mg of PLGA (50:50) were dissolved in 1 ml of DCM. The EGCG solution was added to the PLGA solution, and ultrasound was applied for 30 seconds (amplitude 30%, Vibra-Cell™ VCX 130, Sonics & Materials Inc., USA) to create a water-in-oil (W / O) emulsion.

[0110] The emulsion was added dropwise to 6 ml of an aqueous solution containing 40 mg / ml PVA and 9 mg / ml NaCl using a vortex shaker, while continuously mixing. Mixing continued for 1 minute. An additional 10 ml of the PVA / NaCl solution was added and mixed again for 2 minutes using a vortex shaker to produce a water-oil-water (W1 / O / W2) emulsion. The emulsions were then added to 40 ml of an aqueous solution containing 9 mg / ml NaCl while being mixed using a magnetic stirrer (400 rpm). Stirring continued for 3 hours to allow the solvent DCM to evaporate and to obtain a suspension.

[0111] The suspension was centrifuged for 5 min at 1900 rpm and the supernatant was decanted. The sediment was resuspended with 50 ml of ice-cold water and centrifuged again. This process was repeated twice more. The resulting sediment was shock-frozen in liquid nitrogen and freeze-dried for 24 hours at <2 mbar (Beta 2-8 LD plus, Martin Christ Freeze-Drying Systems GmbH, Germany). Figure 1 schematically shows the representation of the loaded microparticles using the inventive method.

[0112] The yield was 65 wt% microparticles. The microparticles contained 2.98 ± 0.14 wt% EGCG. The encapsulation efficiency (EE) and EGCG loading efficiency (DL) were therefore very good. The particles were spherical and did not form aggregates or agglomerates. The mean particle size D50 was 50.7312.91 micrometers. The DIO and D90 values ​​were 27.0512.36 and 75.7414.70 micrometers, respectively. The particles exhibited a unimodal size distribution. Figure 2 shows an NMR image of the successful encapsulation of EGCG in PLGA. Examples 2 to 6

[0113] Further EGCG-loaded PLGA microparticles according to the invention were produced using the method described above. The PLGA content in Examples 2 to 6 was 17% by weight. Particles with different theoretical drug loadings of 2, 4, 5, 6.5, and 15% by weight were produced using a constant PLGA concentration and a constant volume of the water component. The results for Examples 2 to 6 are shown in Table 1 below. Table 1: EGCG-loaded PLGA microparticles with 17% by weight PLGA and EGCG drug loadings of 2, 4, 5, 6.5, and 15% by weight, based on Examples 2 to 6.

[0114] The plotted size distributions of the microparticles with different drug loadings according to Examples 2 to 6 largely overlapped and resulted in similar mean diameters. Figure 3A shows scanning electron microscopy (SEM) images of the particles from Examples 2 to 6, which were prepared with 17 wt% PLGA and various drug concentrations of 2 to 15 wt%. Figure 3B shows the size distribution of the EGCG-loaded PLGA microparticles, and Figure 3C shows their theoretical loading.

[0115] For examples 2 to 6, PLGA concentrations of 17 wt% were selected. PLGA concentrations above 17 wt% resulted in a negligible increase in encapsulation efficiency, as shown in Table 2 below. It was observed that within the range of 8 to 20 wt%, the average particle diameter D50 increases linearly (Figures 4A, 4B and 4G).

[0116] Table 2: Summary for EGCG-loaded PLGA particles prepared with different PLGA concentrations. 2. Production of a gel containing EGCG-loaded PLGA microparticles

[0117] Example 7

[0118] 10 mg of the particles from Example 1 were dispersed in 0.2 ml of an aqueous agarose solution (6 mg / ml, 38 °C) and then cooled to a temperature between 4 and 8 °C. Figure

[0119] Figure 5 schematically shows the reaction of EGCG-loaded PLGA microparticles with agarose.

[0120] 3. Determination of EGCG release in simulated saliva

[0121] Example 8

[0122] 0.05 ml of gel from Example 7 were immersed in 0.1 ml of an electrolyte solution (ES) at 37 °C, simulating human saliva. Microparticles stabilized in this way showed no agglomeration even after various incubation times at 37 °C in the electrolyte solution (Figure 6). Unstabilized particles without agarose hydrogel, however, did show agglomeration.

[0123] The gel was added to fresh 0.1 ml electrolyte solution each time. The supernatant was removed every 24 hours and its mass concentration of EGCG was determined. Figure 7 shows the release of EGCG from PLGA microparticles. Figure 7C shows the EGCG release rate in pg / day per mg of particles from the gel into the surrounding electrolyte solution for different drug loadings (0.47%, 1.12%, 1.62%, 2.98%, 6.98%). In contrast to the release of EGCG into an aqueous solution, the release into the electrolyte solution is more constant and does not exhibit a high burst-release behavior. The determination of the mass concentrations showed that the EGCG was released into the electrolyte solution over 7 days at a rate between 0.05 and 0.08 mg / ml per 24 hours. Figure 7D shows the EGCG release from various hydrogels. The gel from example 7 is therefore particularly well suited for use in (caries-preventive) wound healing in a periodontal pocket.

[0124] 4. Decomposition of the microparticles

[0125] Investigation of particle morphology after release using ESEM revealed no particle agglomeration. Figure 6 shows SEM images of PLGA microparticles with an agarose matrix after different incubation times in the 37 °C electrolyte solution (top) compared to particles without such a matrix (bottom). Microparticles in an agarose hydrogel matrix also showed no agglomeration after seven days.

[0126] To investigate the influence of pH on drug release, the above example 8 was repeated with a drug loading of 6.98% and a fluctuating pH. Figure 8 shows the pH dependence. Release profiles were recorded at a constant pH of 6 and at pH values ​​fluctuating between 3 and 6. The pH was set to 3 for 8 hours and then back to 6 for 16 hours. No significant influence of pH on the drug release rate was observed. Therefore, the influence of pH does not lead to a significantly accelerated degradation of the PLGA matrix and thus does not result in faster drug release.

[0127] Therefore, the consumption of acidic drinks or the effects of gastric reflux have no influence on the release of EGCG.

[0128] The gel from Example 7 is therefore particularly well-suited for (caries-preventive) use in wound healing within a periodontal pocket, even for individuals with gastric reflux. Figure 9 shows that different amounts of EGCG are released depending on the mass of particles applied, while the release per mg of particle remains largely unchanged. For this purpose, the formulation containing 1.62 wt% EGCG in varying amounts was dispersed in an agarose hydrogel, and the profiles were plotted. It was found that the cumulative release hardly differs, allowing for precise control of the total amount of EGCG released. The release of EGCG per mg of particle is the same for all different amounts of particles (Figure 9A), while the total amount of EGCG released is highest in the experiment where the most particles were used (Figure 9B).Furthermore, the cumulative release and the measured daily dose are almost the same for all samples (Figure 9C and Figure 9D).

[0129] 5. Ratio of D,L-lactic acid to glycolic acid in PLGA

[0130] PLGA is a polyester composed of D,L-lactic acid and glycolic acid. This polyester is generally hydrophilic, so the matrix of the microparticles erodes over time, particularly through hydrolysis. The degradation process breaks down PLGA into its monomers, releasing lactic acid and glycolic acid. Surprisingly, a ratio of 75:25 of D,L-lactic acid to glycolic acid, in particular, resulted in a longer-lasting drug release and a slower release of EGCG. Figure 10 shows SEM images of PLGA microparticles in an agarose hydrogel. The images show no significant degradation even after seven days.

[0131] The optimized manufacturing protocol using 17 wt% PLGA (72:25) was used to produce microparticles with enhanced hydrophobicity. Particles with two different theoretical drug loadings were synthesized. The obtained particles had a comparable size and experimental drug loading to microparticles with a 50:50 L:G ratio (Figure 11). The microparticles were shown to have the same morphology as the previously prepared samples with 50:50 (L:G) PLGA. The 50:50 PLGA particles exhibit a nearly constant release for both drug loadings, while the particles with a higher lactic acid content show a biphasic release profile with a strong, abrupt release in the first two days, followed by a low, constant release over two weeks (Figure 12).Under both conditions, the final mass of released EGCG is the same for both PLGA types; only the release time varies. Figure 13 shows the characterization of microparticles with different ratios of D,L-lactic acid to glycolic acid.

[0132] 6. Kinetics

[0133] To better understand the release of EGCG from the PLGA microparticles, the data obtained from Figure 12 were adapted to a Korsmeyer-Peppas model.

[0134] Release exponents n > 0.43 were determined for EGCG release from 50:50 PLGA pP, indicating a diffusion- and erosion-based mechanism. In contrast, for release from 75:25 PLGA, exponents less than 0.43 (n = 0.404 for 3% DL, n = 0.329 for 7% DL) were calculated to match 100% of the cumulative release. Therefore, release from 75:25 PLGA is based solely on diffusion and is not affected by polymer matrix degradation.

[0135] Based on these results, it can be assumed that the interactions between hydrophilic EGCG and PLGA are less favorable with increased hydrophobicity due to the higher lactic acid content. This leads to an unfavorable distribution of EGCG within the particles, which could result in high EGCG release even with low water diffusion into the PLGA particles.

[0136] 7. Pharmacological Window

[0137] For a drug to be effective, its concentration must be above the effective concentration (EC), i.e., the minimum concentration of a drug that elicits a biological response at the target site. Below this threshold, no effect of the drug is to be expected, while potential toxicity may occur if this value is significantly exceeded. For EGCG, the EC range was determined by testing its ability to inhibit the biofilm formation of Porphyromonas gingivalis.

[0138] EGCG was tested at concentrations of 100 pM and 300 pM. The 100 pM concentration reduced the biofilm to approximately 80% of the reference value. The 300 pM concentration reduced the biofilm to 40% compared to an untreated sample. Both concentrations are therefore suitable for reducing the Porphyromonas gingivalis biofilm.

[0139] To determine the toxic concentration of EGCG, cytotoxicity tests were performed against human gingival fibroblasts (hGF) and macrophages (THP-1). The EGCG concentration ranged from 1 to 1000 pM. Concentrations of 600 pM and 1000 pM were cytotoxic to fibroblasts and macrophages, respectively. A concentration of 300 pM showed moderate toxicity to fibroblasts, while no toxicity to macrophages was observed (Figure 14).

[0140] Therefore, a concentration range between 100 and 300 pM EGCG should preferably be achieved to demonstrate efficacy against biofilm formation without exhibiting potential cytotoxicity.

[0141] 8. Effective concentration

[0142] To be effective against bacteria, EGCG must be released daily in an amount sufficient to achieve an effective concentration. This concentration lies between 100 and 300 pM. Above this concentration, EGCG exhibits cytotoxicity. A model experiment was designed to demonstrate that the manufactured PLGA particles can release EGCG in the required amount to achieve the target EGCG concentration for at least one week (100 pM, 45.8 pg / mL). The average amount of EGCG released per day and per mg of particle was calculated from previously measured release logs, and the minimum mass of microparticles required to achieve the target concentration in 100 pL of medium was determined to be 3.98 mg. The microparticles were then dispersed in an agarose matrix, and the microparticle-loaded hydrogel was transferred to fresh medium every day.The achieved concentration was then compared with the pharmacological window (Figure 15). The measured concentration showed that the previously determined release profiles could be used as a template for other model experiments. Indeed, the EGCG concentration remained almost constant over 10 days, while the minimum effective concentration was reached after 12 days. The maximum concentration was not exceeded at any time.

[0143] 9. Biological activity against Porphyromonas gingi vali s

[0144] However, even after release from the particles, the EGCG must still be biologically active. To prove that the released EGCG still possesses antibacterial properties, an experiment was conducted to validate its potential for reducing biofilm formation. The release was tested against Porphyromonas gingi vali s in vitro over 7 days.

[0145] The required particle mass to achieve an EGCG concentration of 100 pM was calculated from the obtained release profiles of the average daily dose during the first 7 days. The effect of the re-released EGCG from PLGA microparticles with 3% DL was quantified by measuring the reduction in biofilm formation (Figure 16). An agarose hydrogel without microparticles and one with PLGA microparticles without encapsulated EGCG (pure PLGA) were tested as a reference. The particles prepared with 50:50 and 75:25 PLGA were compared with respect to their duration of action. For EGCG-loaded microparticles with 50:50 PLGA, the results showed a significant reduction in biofilm formation after 24 hours under all conditions, with the EGCG-loaded particles exhibiting the highest efficiency (< 20% of normal absorption).

[0146] 10. Suitability for tooth surfaces

[0147] Example 9

[0148] Since PLGA is a polyester, it is slowly degraded by hydrolysis. This degradation process breaks down PLGA into its monomers, releasing lactic acid and glycolic acid. These released acids can be potentially harmful to teeth, as they can cause erosion of the tooth surface.

[0149] The gel from Example 7 was applied to tooth cubes with enamel and dentin surfaces. These were stored in deionized water at 37°C for four weeks and removed at predetermined intervals to take micro-CT images of the previously gel-treated surfaces. The micro-CT images showed no surface erosion (Figure 17). This means that the hydrogel itself does not have a demineralizing effect and protects the tooth surface from demineralization and lesion formation for at least 14 days. Only after three weeks were the first signs of erosion observed. However, this experiment is not comparable to actual application, where the lactic and glycolic acids do not remain on the tooth. In real-world application, the released acid would be diluted by saliva in the mouth, which is exchanged at a rate of 0.3–0.4 ml / min.Therefore, in a real-world application, a longer period of time is expected in which no erosion is observed.

[0150] The gel is therefore particularly well suited as a gel for a periodontal pocket.

[0151] Example 10 (not according to the invention)

[0152] Aqueous suspensions of PLGA microparticles without a stabilizer lead to erosion of the dentin surface. This means that such compositions have a demineralizing effect and are therefore less suitable for use as a gel in periodontal pockets.

Claims

Patent claims 1. A method for producing microparticles loaded with at least one flavonoid and / or flavonoid derivative, comprising the following steps: a) mixing a water component in the form of an aqueous solution comprising the at least one flavonoid and / or flavonoid derivative with an oil component to form a solution of polylactide-co-glycolide in an organic solvent, to form a water-oil emulsion;b) Mixing the water-oil emulsion with another water component in the form of an aqueous solution comprising at least one stabilizer, to form a water-oil-water emulsion; c) Mixing the water-oil-water emulsion with an aqueous salt solution, wherein the salt of the salt solution is selected from alkali halides, alkali phosphates, alkali hydrogen phosphates, alkali sulphides, alkaline earth halides, alkaline earth phosphates, alkaline earth hydrogen phosphates, alkaline earth sulphides and mixtures thereof, preferably sodium chloride, potassium chloride, calcium chloride or magnesium chloride, particularly preferably sodium chloride; d) Removing the organic solvent from the water-oil-water emulsion to form a suspension comprising the microparticles loaded with at least the flavonoid and / or flavonoid derivative; e) Separating the loaded microparticles from the liquid of the suspension.

2. Method according to claim 1, characterized in that the at least one flavonoid and / or flavonoid derivative is selected from the group of catechins, preferably selected from epicatechin, epicatechin gallate, epigallocatechin and epigallocatechin gallate, more preferably epigallocatechin gallate.

3. Method according to one of claims 1 or 2, characterized in that the polylactide-co-glycolide is formed from D,L-lactic acid and glycolic acid in a ratio of 2:1 to 1:2, preferably 1:1 (50:50).

4. Method according to one of the preceding claims, characterized in that the microparticles comprise 0.1 to 20 percent by weight of the at least one flavonoid and / or flavonoid derivative, preferably 0.2 to 15 percent by weight, more preferably 1 to 10 percent by weight, more preferably 1 to 5 percent by weight, based on the total weight of the microparticles.

5. Method according to one of the preceding claims, characterized in that the microparticles have a particle size between 1 pm and 500 pm, preferably between 1 pm and 100 pm, more preferably between 1 pm and 80 pm, measured by laser scattering.

6. Method according to one of the preceding claims, characterized in that the microparticles have a mean particle size D50 between 5 pm and 200 pm, preferably between 5 pm and 100 pm, more preferably between 10 pm and 90 pm, more preferably between 20 pm and 80 pm, measured by laser scattering.

7. Method according to one of the preceding claims, characterized in that the loaded microparticles in a flowable hydrogel, preferably in an agarose hydrogel, to obtain a dispersion of the microparticles in the flowable hydrogel.

8. Method according to one of the preceding claims, characterized in that the microparticles are formed by a hydrogel containing the polylactide-co-glycolide as a polymer, wherein the microparticles have 80 to 99.9 wt% hydrogel, based on the total weight of the microparticles.

9. Method according to claim 8, characterized in that the polymer comprises 50 to 100 wt% polylactide-co-glycolide, preferably 90 to 100 wt% polylactide-co-glycolide.

10. A method according to any of the preceding claims, characterized in that the method comprises one or more of the following features: the water-oil emulsion from step a) is mixed by ultrasound; the water-oil-water emulsion from step c) is mixed by mechanical means; the microparticles obtained in step d) are separated in step e) by centrifugation; the microparticles obtained in step d) or the separated microparticles from step e) are dried by freeze-drying.

11. Loaded microparticles, characterized in that the microparticles are loaded with at least one flavonoid and / or flavonoid derivative and the microparticles comprise polylactide-co-glycolide, produced according to the method according to one of claims 1 to 10.

12. Loaded microparticles, wherein the microparticles are loaded with at least one flavonoid and / or flavonoid derivative and the microparticles comprise polylactide-co-glycolide, wherein the microparticles release the flavonoid and / or flavonoid derivative from the microparticles over a period of at least 7 days at a release rate between 0.05 and 0.08 mg / ml per 24 hours.

13. Loaded microparticles according to claim 11 or claim 12 for use in the manufacture of a medicament, wherein the loaded microparticles preferably release the at least one flavonoid and / or flavonoid derivative from the microparticles over a period of at least 7 days with a release rate between 0.05 and 0.08 mg / ml per 24 hours.

14. Dispersion containing the loaded microparticles according to claim 11 or one of claims 12 to 13 for use in the treatment and / or prophylaxis of oral infections, in particular gingivitis including the treatment and / or prophylaxis of caries.

15. Dispersion according to claim 14 for use in the treatment and / or prophylaxis of oral infections, wherein between 100 and 300 ppm of the at least one flavonoid and / or flavonoid derivative is administered per day.

16. Non-medicinal use of the loaded microparticles according to claim 11 or any of claims 12 to 13 in cosmetics, including the prevention of tooth discoloration.

Images