Silver ion-nucleoside supramolecular hydrogel and preparation method and use thereof

Abstract

The application provides a silver ion-nucleoside supramolecular hydrogel and a preparation method and application thereof, and belongs to the field of biological materials. The nucleoside supramolecular hydrogel with a three-dimensional spatial structure is prepared by using 2-amino adenosine and silver ions. The hydrogel has good biocompatibility, stability, biodegradability, injectability and antibacterial property, and can be used for intrapocket injection administration. The hydrogel is further used for loading a photothermal reagent to obtain a composite hydrogel. The composite hydrogel can play a role of chemotherapy-photothermal synergistic treatment, has excellent antibacterial and antibiofilm capacity, and has a good application prospect in periodontitis treatment.

Description

Technical Field

[0001] This invention belongs to the field of materials processing, specifically relating to a silver ion-nucleoside supramolecular hydrogel, its preparation method, and its uses. Background Technology

[0002] Periodontitis is one of the most common chronic non-communicable diseases worldwide, primarily characterized by swollen and bleeding gums, periodontal pocket formation, alveolar bone resorption, loose teeth, and even tooth loss. It is a leading cause of tooth loss in adults. Periodontitis also affects normal physiological functions such as chewing, speech, and eating. Furthermore, periodontitis is a risk factor for various systemic diseases; patients with periodontitis have a significantly increased chance of developing cardiovascular disease, Alzheimer's disease, and diabetes. Therefore, due to its high incidence and significant impact on both local and systemic systems, periodontitis has become a global health problem.

[0003] Currently, the main clinical treatment for periodontitis involves mechanical methods such as scaling and root planing to remove plaque biofilm and control infection. However, due to the irregular shape of periodontal pockets, mechanical methods alone are insufficient to completely eliminate bacteria deep within the pockets. Therefore, local or systemic drug therapy is a common adjunctive treatment for periodontitis. However, systemic drug therapy delivers very little medication to the lesion area within the periodontal pocket and is prone to causing systemic adverse reactions. Local drug therapy, with its advantages of high local drug concentration within the periodontal pocket and low systemic adverse reactions, is a primary choice for periodontitis drug treatment. Currently, commonly used local drug therapy methods include mouthwash, local irrigation, and periodontal pocket administration. These local administration methods mainly face two problems: ① the drug has difficulty penetrating deep into the periodontal pocket and the local retention time is short; ② traditional antibiotics have limited bactericidal effect on bacteria within the plaque biofilm. Therefore, to overcome the shortcomings of the aforementioned local drug treatments for periodontitis, the development of novel local treatment strategies is imperative. Summary of the Invention

[0004] The purpose of this invention is to provide a silver ion-nucleoside supramolecular hydrogel, its preparation method, and its uses.

[0005] This invention provides a nucleoside supramolecular hydrogel, which is prepared from 2-aminoadenosine, silver ion compound, boron-containing acid, base and water as raw materials; the mass molar ratio of 2-aminoadenosine, silver ion compound, boron-containing acid and base is 20-40 mg: 0.02-0.2 mmol: 0.02-0.2 mmol: 0.02-0.2 mmol.

[0006] Further, the silver ion compound is silver nitrate; the boron-containing acid is boric acid; the base is cesium hydroxide; and the molar ratio of 2-aminoadenosine, the silver ion compound, the boron-containing acid, and the base is 28.3 mg: 0.05 mmol: 0.05 mmol: 0.05 mmol.

[0007] The present invention also provides a method for preparing the above-mentioned nucleoside supramolecular hydrogel, the method comprising the following steps: dissolving 2-aminoadenosine in water, adding silver ion compound, boron-containing acid and base, mixing and reacting, cooling, and thus obtaining the hydrogel.

[0008] Furthermore, the heating reaction temperature is 80–140°C and the time is 1–10 min; preferably, the heating reaction temperature is 100–120°C and the time is 5 min.

[0009] The present invention also provides a composite hydrogel, which is obtained by encapsulating a photothermal reagent in the above-mentioned nucleoside supramolecular hydrogel; wherein the mass ratio of 2-aminoadenosine to the photothermal reagent is 20-35 mg: 1-100 μg.

[0010] Furthermore, the mass ratio of the 2-aminoadenosine to the photothermal reagent is 28.3 mg: 30 μg;

[0011] The photothermal reagent is gold nanoparticles.

[0012] The present invention also provides a method for preparing the above-mentioned composite hydrogel, the method comprising the following steps: dissolving 2-aminoadenosine in water, adding silver ion compound, boron-containing acid and base, mixing and heating to react, adding photothermal reagent and mixing, cooling, and thus obtaining the product.

[0013] Furthermore, the heating reaction temperature is 80–140°C and the time is 1–10 min; preferably, the heating reaction temperature is 100–120°C and the time is 5 min.

[0014] The present invention also provides the use of the above-mentioned nucleoside supramolecular hydrogels and composite hydrogels in the preparation of antibacterial agents or drugs for the prevention and / or treatment of periodontitis;

[0015] Preferably, the antibacterial agent is an anti-streptococcus mutans or anti-porphyria gingivalis preparation, and the antibacterial agent is an antimicrobial biofilm disruptor.

[0016] The present invention also provides the use of the above-mentioned nucleoside supramolecular hydrogel and photothermal therapy device in the preparation of antibacterial equipment;

[0017] And / or, the use of the above-mentioned composite hydrogel and photothermal therapy device in combination in the preparation of antibacterial devices.

[0018] The present invention also provides the use of the above-mentioned nucleoside supramolecular hydrogel and photothermal therapy device in the preparation of a device for the prevention and / or treatment of periodontitis;

[0019] And / or, the use of the above-mentioned composite hydrogel and photothermal therapy device in combination in the preparation of devices for the prevention and / or treatment of periodontitis.

[0020] This invention utilizes 2-aminoadenosine and silver ions to prepare a nucleoside supramolecular hydrogel with a three-dimensional spatial structure. This hydrogel exhibits good biocompatibility, stability, biodegradability, injectability, and antibacterial properties, making it suitable for intra-pocket injection administration in periodontal diseases. Furthermore, this invention encapsulates the hydrogel with a photothermal reagent to obtain a composite hydrogel. This composite hydrogel can exert a synergistic effect of chemotherapy and photothermal therapy, possessing excellent antibacterial and anti-biofilm capabilities, and shows promising application prospects in the treatment of periodontitis.

[0021] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0022] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0023] Figure 1 Characterization of the NA hydrogel structure: (A) NA hydrogel; (B) AFM image of NA hydrogel; (C) TEM image of NA hydrogel; (D) SEM image of NA hydrogel at a scale bar of 5 μm; (E) SEM image of NA hydrogel at a scale bar of 0.5 μm.

[0024] Figure 2 Characterization of the gelation mechanism of NA hydrogel: (A) NA hydrogel 11 B NMR spectrum; (B)NA hydrogel 1 (C) 1H NMR spectrum; (D) NA hydrogel IR spectrum; (E) NA hydrogel PXRD spectrum.

[0025] Figure 3Rheological results for NA hydrogel and NA@Au-NPs hydrogel: (A) Frequency scan of NA hydrogel; (B) Strain scan of NA hydrogel; (C) Shear thinning of NA hydrogel; (D) Self-healing of NA hydrogel; (E) Frequency scan of NA@Au-NPs hydrogel; (F) Strain scan of NA@Au-NPs hydrogel; (G) Shear thinning of NA@Au-NPs hydrogel; (H) Self-healing of NA@Au-NPs hydrogel.

[0026] Figure 4 It is cytotoxic to hydrogels.

[0027] Figure 5 The results of bacterial colony counting on agar plates after co-culturing S. mutans with hydrogel.

[0028] Figure 6 The results of bacterial colony counting on agar plates after co-culturing P. gingivalis with hydrogel.

[0029] Figure 7 The results of colony counting on plate after co-culturing S. mutans biofilm and hydrogel.

[0030] Figure 8 Study on the treatment of periodontitis in rats using hydrogel in vivo: (A) Micro-CT three-dimensional images and sagittal tomographic images of representative maxillae in each group; (B) CEJ-ABC distance of maxillae in each group. Detailed Implementation

[0031] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0032] Example 1: Preparation of NA hydrogel

[0033] 28.3 mg of 2-aminoadenosine (NA) was added to 1700 μL of deionized water and heated to dissolve. Then, 100 μL of 0.5 M boric acid (H3BO3) solution and 100 μL of 0.5 M CsOH solution were added and mixed well. The mixture was then heated at 100-120 °C for 5 minutes. Finally, 100 μL of 0.5 M AgNO3 solution was added and mixed well. The mixture was cooled to room temperature to obtain the NA hydrogel.

[0034] Example 2: Preparation of NA@Au-NPs photothermal gel

[0035] 28.3 mg of 2-aminoadenosine (NA) was added to 1700 μL of deionized water and heated to dissolve. Then, 100 μL of 0.5 M boric acid (H3BO3) solution and 100 μL of 0.5 M CsOH solution were added, mixed, and heating continued for 5 minutes. Next, 100 μL of 0.5 M AgNO3 solution was added and mixed. Finally, 100 μL of gold nanoparticles (Au-NPs) (300 μg / mL) were added and mixed. The mixture was cooled to room temperature to obtain the NA@Au-NPs hydrogel loaded with the photothermal reagent (final concentration of photothermal nanoparticles: 15 μg / mL).

[0036] The following experimental examples demonstrate the beneficial effects of the present invention.

[0037] Experimental Example 1: Structural Characterization of Hydrogels

[0038] 1. Experimental Methods

[0039] The formation of the nanogel was confirmed by inverting the vial, and observations and photographs were taken for recording. The nanogel was then subjected to atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). 1 H NMR, 11 Characterized by B NMR, infrared spectroscopy (IR), and X-ray powder diffraction (PXRD).

[0040] 2. Experimental Results

[0041] Depend on Figure 1 As can be seen from A, the NA hydrogel remains stable even after the vial is inverted. Figure 1 A) indicates that the NA hydrogel was successfully prepared. AFM, TEM, and SEM results show that the NA hydrogel has a loose, porous structure composed of fibers. Figure 1 B-1E). 11 B NMR results indicate the presence of borate diester bonds in the NA hydrogel. Figure 2 A), 1 H NMR further confirmed the above results. Figure 2 B); IR analysis revealed that the hydroxyl peak ν(-OH, 3500 cm⁻¹) of the NA hydrogel was present. -1 The signal was significantly weaker than that of NA, suggesting that the hydroxyl groups at the 2' and 3' positions of the NA molecule may have participated in the formation of the borate diester bond. Figure 2 C). PXRD results showed that the lyophilized sample of the NA hydrogel was at 2θ≈26.68°. There is a peak ( Figure 2 D) indicates that the NA hydrogel is formed by π-π stacking.

[0042] Experimental Example 2: Characterization of the mechanical properties of hydrogels

[0043] 1. Experimental Methods

[0044] Rheological tests were performed using an Anton Paar modular intelligent rotational rheometer (MCR302). The rheological properties of the NA hydrogel were analyzed at 25°C using frequency scanning, strain scanning, shear rate testing, and self-healing tests.

[0045] 2. Experimental Results

[0046] Frequency scanning results show that the storage modulus G′ of the NA hydrogel is much greater than the loss modulus G″, indicating that the sample is in a gel state and has good solid-like mechanical properties. Figure 3 A). Figure 3 As shown in Figure B, when the strain is less than 15%, G′ is greater than G″, and the NA hydrogel is in a gel state; when the strain is greater than 40%, G′ is less than G″, and the NA hydrogel is in a sol state. The samples were subjected to alternating high-strain and low-strain conditions, and the results showed that G′ and G″ of the samples could basically recover to their initial states, indicating that the NA hydrogel has good self-healing properties. Figure 3 C). Shear rate experiments show that the viscosity of the NA hydrogel gradually decreases with increasing shear rate. Figure 3 D) indicates that NA hydrogels have shear-thinning properties. Figure 3 EH results showed that the NA@Au-NPs hydrogel loaded with photothermal reagents maintained good mechanical properties.

[0047] Experimental Example 3: Cytotoxicity Test of Hydrogel

[0048] 1. Experimental Methods

[0049] Add 10 mg of hydrogel to 10 mL of DMEM and culture for 24 hours to obtain the stock solution for the leachate. Collect well-grown L929 cells and adjust the cell density to 1*102. 4 Cells were seeded at a density of 100 μl / ml into 96-well plates. After cell adhesion, 100 μl of hydrogel extract was added. The light-treated group underwent photothermal therapy (680 nm, 1 W / cm²). 2 (5 min). After incubating at 37℃ for 24 h, add 10% CCK8 reagent and incubate for 1 h. Detect the absorbance value at a wavelength of 450 nm.

[0050] 2. Experimental Results

[0051] The results showed that cell viability in the NA hydrogel and NA@Au-NPs hydrogel groups was almost different from that in the control group. Figure 4 This indicates that the NA hydrogel and the NA@Au-NPs hydrogel light-irradiated group have good cell biocompatibility.

[0052] Experiment Example 4: Using hydrogels to simulate the in vitro antibacterial properties of photothermal therapy

[0053] 1. Experimental Methods

[0054] (1) Hydrogel combined with photothermal therapy for in vitro anti-mutant streptococcus (S. mutans)

[0055] Thaw the frozen S. mutans solution rapidly in a 37°C water bath. Add 10 mL of BHI medium to a 15 mL sterile centrifuge tube, followed by 100 μL of thawed S. mutans inoculum. Incubate overnight at 37°C. Then, drop 10 μL of the bacterial culture onto a BHI agar plate using the streaking method with a sterile inoculating loop. Incubate anaerobicly at 37°C for 1-3 days. Pick single colonies and add them to BHI medium. Incubate at 37°C until the logarithmic growth phase, then adjust the bacterial concentration to 10-1. 6 CFU / ml. Take 1 mL of bacterial culture and add less than 50 mg of the following substances to each group: PBS, Ag. + Solution, Au-NPs, NA hydrogel, NA@Au-NPs hydrogel. Au-NPs and NA@Au-NPs hydrogel groups underwent photothermal therapy (680nm, 1W / cm²). 2 (5 min). After 24 h of incubation, the bacteria were diluted with PBS, plated, and colony counted.

[0056] (2) Hydrogel combined with photothermal therapy for in vitro anti-porphyrinoma gingivalis

[0057] Thaw the frozen solution of *P. gingivalis* rapidly in a 37°C water bath. Add 10 mL of BHI medium (containing 5 μg / mL heme and 1 μg / mL vitamin K) to a 15 mL sterile centrifuge tube, then add 100 μL of thawed *P. gingivalis* inoculum. Incubate anaerobicly at 37°C (10% H2, 10% CO2, and 80% N2) for 1-2 days. Then, drop 10 μL of the bacterial culture onto a blood agar plate and streak using a sterile inoculating loop. Incubate anaerobicly at 37°C for 3-5 days. Pick single colonies and add them to BHI medium (containing 5 μg / mL heme and 1 μg / mL vitamin K). Incubate anaerobicly at 37°C until the logarithmic growth phase, then adjust the bacterial concentration to 10-1. 6 CFU / ml. Take 1 mL of bacterial culture and add less than 50 mg of the following substances to each group: PBS, Ag. + Solution, Au-NPs, NA hydrogel, NA@Au-NPs hydrogel. Au-NPs and NA@Au-NPs hydrogel groups underwent photothermal therapy (680nm, 1W / cm²). 2 (5 min). After 24 h of incubation, the bacteria were diluted with PBS, plated, and colony counted.

[0058] 2. Experimental Results

[0059] (1) Hydrogel combined with photothermal therapy for in vitro anti-mutant streptococcus (S. mutans)

[0060] S. mutans bacterial plate count results showed Ag + The number of colonies in the NA hydrogel and Au-NPs (NIR+) groups decreased by 2 to 3 orders of magnitude. Figure 5 This indicates that both photothermal therapy and the silver ion-containing NA hydrogel group possess certain antibacterial properties. The number of bacterial colonies in the NA@Au-NPs(NIR+) group decreased by approximately four orders of magnitude, demonstrating superior antibacterial activity compared to the Au-NPs(NIR+), NA hydrogel, and minocycline groups. In other words, the antibacterial effect of the same dose of NA@Au-NPs(NIR+) is superior to that of Au-NPs(NIR+) and also superior to that of NA hydrogel, indicating that the combined use of the NA@Au-NPs hydrogel and the photothermal therapy device in this invention achieves a synergistic antibacterial effect.

[0061] (2) Hydrogel combined with photothermal therapy for in vitro anti-porphyrinoma gingivalis

[0062] Bacterial plate count results showed Ag + NA hydrogel and NA@Au-NPs group can kill 100% of P. gingivalis ( Figure 6 ).

[0063] Experimental Example 5: Anti-biofilm effect of hydrogel combined with photothermal therapy

[0064] 1. Experimental Methods

[0065] Adjust the bacterial concentration of S. mutans culture to 1*10-1 5 Cells / ml. Place a sterile glass slide (18 mm diameter) into a 12-well plate, add 2 mL of bacterial culture, and incubate for 48 hours to form a biofilm. Add less than 50 mg of the following substances to each well of the biofilm-forming plate: PBS, Ag. + Solution, minocycline, Au-NPs, NA hydrogel, NA@Au-NPs hydrogel. Au-NPs and NA@Au-NPs hydrogel groups underwent photothermal therapy (680nm, 1W / cm²). 2 (5 min). After 24 h of incubation, the bacteria on the slide were scraped into PBS, diluted with PBS, plated, and colony counted.

[0066] 2. Experimental Results

[0067] Biofilm removal efficiency directly affects the therapeutic effect of periodontitis. Therefore, we established a biofilm of *S. mutans* to evaluate the anti-biofilm ability of NA@Au-NPs hydrogel. Plate count results showed that Ag... + The number of colonies in both the NA hydrogel and Au-NPs (NIR+) groups decreased by approximately two orders of magnitude. Figure 7 This indicates that both photothermal therapy and the silver ion-containing NA hydrogel group possess certain anti-biofilm properties. The NA@Au-NPs(NIR+) group showed a decrease in bacterial colony count of approximately three orders of magnitude, exhibiting superior antibacterial activity compared to the Au-NPs(NIR+), NA hydrogel, and minocycline groups. In other words, the same dose of NA@Au-NPs(NIR+) demonstrates better antibacterial efficacy than Au-NPs(NIR+) and also superior to NA hydrogel, indicating that the combined use of the NA@Au-NPs hydrogel and the photothermal therapy device in this invention achieves a synergistic antibacterial effect. This suggests that the synergistic effect of photothermal therapy and silver ion chemotherapy enhances the anti-biofilm effect.

[0068] Experimental Example 6: Evaluation of the efficacy of in vivo periodontitis treatment

[0069] 1. Experimental Methods

[0070] A rat periodontitis model was established using the ligation method: A 3-0 silk suture (pre-soaked in *Porphyromonas gingivalis* solution) was used to ligate the neck of the right maxillary second molar in rats. The suture was placed in the gingival sulcus and secured with a knot on the palatal side. After two weeks, redness and swelling of the gingiva around the maxillary second molar were observed, with bleeding on probing, deep periodontal pockets, and a large accumulation of plaque and soft deposits, indicating successful establishment of the periodontitis model. The ligation was removed, and each group received an injection of 20 μL of the following substances into the periodontal pocket: PBS, Ag... + Solution (25 mM AgNO3 solution), minocycline hydrochloride ointment (2%), NA hydrogel (containing 25 mM AgNO3 solution) + ), NA@Au-NPs (containing 25mM Ag) + And 15 μg / mL Au-NPs hydrogel. The NA@Au-NPs hydrogel group received photothermal therapy (680nm, 1W / cm²) every two days. 2 (5 min). On day 14 of treatment, rats were sacrificed, and the maxillae were harvested. Part of the maxillae were fixed with 4% paraformaldehyde, and the rest were stored at -80℃ for later use. The maxillae were scanned using a Micro CT system to perform imaging analysis of the alveolar bone.

[0071] 2. Experimental Results

[0072] Micro CT analysis showed that after suture ligation, significant alveolar bone resorption was observed on both the buccal and palatal sides of the maxillary second molar. Partial alveolar bone recovery was observed in the NA@Au-NPs hydrogel group after photothermal treatment. Figure 8A). The corresponding alveolar bone resorption is represented by the distance from the cementoenamel junction to the alveolar ridge crest (CEJ-ABC). Results showed that the NA@Au-NPs photothermal therapy group had the shortest CEJ-ABC distance, and compared to other groups (PBS, Ag...). + Significant differences were observed in the solution, minocycline, and NA hydrogel groups. Figure 8 B) suggests that NA@Au-NPs photothermal therapy has a good therapeutic effect on periodontitis.

[0073] In summary, this invention provides a silver ion-nucleoside supramolecular hydrogel, its preparation method, and its applications. This invention utilizes 2-aminoadenosine and silver ions to prepare a nucleoside supramolecular hydrogel with a three-dimensional spatial structure. This hydrogel exhibits good biocompatibility, stability, biodegradability, injectability, and antibacterial properties, and can be used for intra-periodontal pocket injection. Furthermore, this invention encapsulates the hydrogel with a photothermal reagent to obtain a composite hydrogel. This composite hydrogel can exert a synergistic effect of chemotherapy and photothermal therapy, possessing excellent antibacterial and anti-biofilm capabilities, and shows promising application prospects in the treatment of periodontitis.

Claims

1. A nucleoside supramolecular hydrogel, characterized in that, The nucleoside supramolecular hydrogel is prepared from 2-aminoadenosine, silver ion compounds, boron-containing acids, bases, and water; the molar ratio of 2-aminoadenosine, silver ion compounds, boron-containing acids, and bases is 20~40 mg : 0.02~0.2 mmol : 0.02~0.2 mmol : 0.02~0.2 mmol. The boron-containing acid is boric acid; the base is cesium hydroxide.

2. The nucleoside supramolecular hydrogel according to claim 1, characterized in that, The silver ion compound is silver nitrate; the molar ratio of the 2-aminoadenosine, the silver ion compound, the boron-containing acid, and the base is 28.3 mg : 0.05 mmol : 0.05 mmol : 0.05 mmol.

3. A method for preparing the nucleoside supramolecular hydrogel of claim 1 or 2, characterized in that, The method includes the following steps: dissolving 2-aminoadenosine in water, adding silver ion compound, boron-containing acid and base, mixing and heating to react, cooling, and then obtaining the product.

4. The method according to claim 3, characterized in that, The heating reaction is carried out at a temperature of 80~140℃ for a time of 1~10 min.

5. The method according to claim 4, characterized in that, The heating reaction is carried out at a temperature of 100~120℃ for 5 minutes.

6. A composite hydrogel, characterized in that, The composite hydrogel is obtained by encapsulating a photothermal reagent in the nucleoside supramolecular hydrogel according to claim 1 or 2; wherein the mass ratio of 2-aminoadenosine to the photothermal reagent is 20~35mg : 1~100μg.

7. The composite hydrogel according to claim 6, characterized in that, The mass ratio of 2-aminoadenosine to the photothermal reagent is 28.3 mg : 30 μg; The photothermal reagent is gold nanoparticles.

8. A method for preparing the composite hydrogel of claim 6 or 7, characterized in that, The method includes the following steps: dissolving 2-aminoadenosine in water, adding silver ion compound, boron-containing acid and base, mixing and heating to react, adding photothermal reagent and mixing well, cooling, and then obtaining the product.

9. Use of the nucleoside supramolecular hydrogel of claim 1 or 2, or the composite hydrogel of claim 6 or 7, in the preparation of antibacterial agents or medicaments for the prevention and / or treatment of periodontitis.

10. The use according to claim 9, characterized in that, The antibacterial agent is an anti-streptococcus mutans or anti-porphyria gingivalis preparation, and the antibacterial agent is a preparation that disrupts bacterial biofilms.

11. Use of the nucleoside supramolecular hydrogel of claim 1 or 2 in combination with a photothermal therapy device in the preparation of an antibacterial apparatus; And / or, the use of the composite hydrogel and photothermal therapy device as described in claim 6 or 7 in the preparation of an antibacterial device.

12. Use of the nucleoside supramolecular hydrogel of claim 1 or 2 in combination with a photothermal therapy device in the preparation of a device for the prevention and / or treatment of periodontitis; And / or, the use of the composite hydrogel and photothermal therapy device as described in claim 6 or 7 in the preparation of a device for the prevention and / or treatment of periodontitis.

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