CN117244096A - Borosilicate-based bioactive glass-modified bacterial cellulose functional dressing and preparation method thereof - Google Patents

Abstract

The invention discloses a boron-silicon-based bioactive glass modified bacterial cellulose functional dressing and a preparation method thereof, belonging to the field of biomedical materials. The preparation method of the boron-silicon-based bioactive glass modified bacterial cellulose functional dressing comprises the following steps: preparing borosilicate-based bioactive glass sol and bacterial cellulose aerogel; soaking the bacterial cellulose aerogel in the borosilicate-based bioactive glass sol, polycondensing and drying to obtain the borosilicate-based bioactive glass modified bacterial cellulose functional dressing. The invention adopts a sol-gel method to deposit ion components in the boron silicon based bioactive glass sol on the surface of bacterial cellulose nanofiber, and utilizes the boron silicon based bioactive glass to carry out functional modification on bacterial cellulose, thereby endowing the bacterial cellulose-based dressing with the functions of antibiosis, anti-inflammation, antioxidation, angiogenesis promotion, wound healing promotion and the like.

Description

Borosilicate-based bioactive glass-modified bacterial cellulose functional dressing and preparation method thereof

Technical field

The invention relates to the field of biomedical materials, and in particular to a borosilicate-based bioactive glass-modified bacterial cellulose functional dressing and a preparation method thereof.

Background technique

Since bacterial cellulose (BC) has a three-dimensional fiber network structure similar to the extracellular matrix of skin tissue, it can imitate the morphology of the extracellular matrix in the skin to a large extent. The bacterial cellulose nanofiber scaffold can simulate skin functions, prevent the invasion of external pathogenic bacteria, and has good water absorption, water retention, breathability, anti-adhesion, biocompatibility and immunogenicity, and can maintain a moist environment on the wound surface. , promotes granulation growth and is one of the ideal dressing base materials (Khalid, et al. International Journal of Biological Macromolecules, 203 (2022) 256-267). However, bacterial cellulose does not have biological properties and cannot treat complex chronic wounds, including diabetic foot. Therefore, introducing active ingredients into the three-dimensional network structure of bacterial cellulose scaffolds to prepare BC-based composite materials is an effective way to improve the biological properties of BC-based dressings.

Bioactive glass contains a variety of bioactive inorganic ions, which is not only widely used in the field of hard tissue engineering repair (Pang, et al. Materials Science & Engineering C, 105 (2019) 110076), but also has good resistance to soft tissue injuries such as skin ulcers. Healing effect (Yang, et al. Chemical Engineering Journal, 419 (2021) 129437). At present, the common method for compounding bioactive glass and BC is the in-situ compounding method, that is, mixing the bioactive glass precursor and BC culture medium, and using the mixed solution to culture BC. However, using the bioactive glass-modified BC obtained by this method, the bioactive glass is filled in the BC network structure, blocking the BC nanopore network structure, thus affecting the dressing properties of BC, and is not suitable for skin wound repair. Therefore, how to develop a new preparation method to weaken the impact of bioactive glass on the bacterial cellulose nanopore network structure is an urgent technical problem that needs to be solved by those skilled in the art.

Contents of the invention

The object of the present invention is to provide a borosilicate-based bioactive glass-modified bacterial cellulose functional dressing and a preparation method thereof. The present invention uses a sol-gel method to deposit the ionic components in the borosilicate-based bioactive glass sol on the surface of bacterial cellulose nanofibers, and uses the borosilicate-based bioactive glass to functionally modify the bacterial cellulose, thereby endowing the bacterial fibers with Plain-based dressings have antibacterial, anti-inflammatory, antioxidant, pro-angiogenic and wound-healing functions.

In order to achieve the above objects, the present invention provides the following technical solutions:

One of the technical solutions of the present invention is to provide a method for preparing a borosilicate-based bioactive glass-modified bacterial cellulose functional dressing, which includes the following steps:

Preparation of borosilicate-based bioactive glass sol and bacterial cellulose aerogel;

The bacterial cellulose aerogel is soaked in the borosilicate-based bioactive glass sol, condensed, and dried to obtain the borosilicate-based bioactive glass-modified bacterial cellulose functional dressing.

Preferably, the bacterial cellulose in the bacterial cellulose aerogel is selected from cellulose synthesized by microorganisms of the genus Acetobacter.

Preferably, the drying is freeze drying.

The freeze-dried bacterial cellulose aerogel can better maintain the nanopore structure, so that the active ions in the borosilicate-based bioactive glass sol can smoothly enter the bacterial cellulose network structure.

Preferably, the polycondensation is carried out in an aqueous ethanol solution with a volume percentage of 90%.

Preferably, the polycondensation temperature is 20-35°C and the time is 18-30 h.

Preferably, in the borosilicate-based bioactive glass-modified bacterial cellulose functional dressing, the mass ratio of borosilicate-based bioactive glass and bacterial cellulose is 1:1-5:1.

Preferably, the preparation method of the borosilicate-based bioactive glass sol includes the following steps:

A silicon source, a calcium source, a phosphorus source and a boron source are mixed in a dispersant to obtain the borosilicate-based bioactive glass sol.

More preferably, the dispersant is ethanol.

Preferably, the silicon source is ethyl orthosilicate; the calcium source is calcium nitrate; the phosphorus source is triethyl phosphate; and the boron source is boric acid.

Preferably, in the borosilicate-based bioactive glass sol, the volume concentration of ethyl orthosilicate is 20-21%, the concentration of calcium nitrate is 60-65 mg/mL, and the volume concentration of triethyl phosphate is 1.8-2.5 %, the concentration of boric acid is 5-10mg/mL.

Preferably, the mixing process further includes the step of adding an antibacterial agent, and the antibacterial agent is an antibacterial agent containing one or more elements among silver, zinc, copper and gallium.

The second technical solution of the present invention is to provide a borosilicate-based bioactive glass-modified bacterial cellulose functional dressing obtained according to the above preparation method.

The third technical solution of the present invention is to provide an application of the above-mentioned borosilicate-based bioactive glass-modified bacterial cellulose functional dressing in the preparation of wound dressings.

The beneficial technical effects of the present invention are as follows:

The present invention uses a sol-gel method to deposit the ionic components in the borosilicate-based bioactive glass sol on the surface of bacterial cellulose nanofibers, and uses the borosilicate-based bioactive glass to functionally modify the bacterial cellulose, thereby endowing the bacterial fibers with The plain-based dressing has antibacterial, anti-inflammatory, antioxidant, pro-angiogenic and wound-healing functions, and can meet the clinical needs for the treatment of chronic ulcers with complex microenvironments, including diabetic foot ulcers.

While adding bioactive glass to introduce bioactive ions, the present invention allows the bioactive glass to only adhere to the surface of BC nanofibers, forming an obvious coating structure, thus retaining the nanopore network structure and dressing properties of bacterial cellulose. , and has strong biological properties, thus expanding the application environment of the product.

Description of drawings

Figure 1 is the SEM image and fiber diameter distribution diagram of BC aerogel and BBG/BC in Example 1. Among them, (a) and (c) are SEM images of BC aerogel at different scales, (b) and (d) are SEM images of BBG/BC, and (e) is the fiber diameter distribution of BC aerogel. , (f) is the fiber diameter distribution diagram of BBG/BC.

Figure 2 is the SEM image and fiber diameter distribution chart of the product in Example 2-4. Among them, (a) and (d) are SEM images of the product of Example 2 at different scales, (b) and (e) are SEM images of the product of Example 3, (c) and (f) are the products of Example 3. SEM image, (g) is the fiber diameter distribution diagram of the product of Example 2, (h) is the fiber diameter distribution diagram of the product of Example 3, (i) is the fiber diameter distribution diagram of the product of Example 4.

Figure 3 shows the XPS full spectrum, tensile test results and water absorption performance of BC aerogel and the products of Examples 1-4. Among them, (a) is the XPS full spectrum chart, (b) is the tensile test result chart, and (c) is the water absorption rate chart.

Figure 4 is a SEM image and fiber diameter distribution chart of the product of Example 5. Among them, (a) and (b) are SEM images at different scales, and (c) is the fiber diameter distribution map.

Figure 5 is a graph showing the antibacterial properties of BC aerogel and the products of Examples 1-4.

Figure 6 is a cytocompatibility diagram of BC aerogel and the products of Examples 1-4.

Figure 7 is a graph showing the anti-inflammatory properties of BC aerogel and the products of Examples 1-4. Among them, (a) is a graph of the anti-inflammatory properties of the inflammatory factor TNF-α, and (b) is a graph of the anti-inflammatory properties of the inflammatory factor IL-1β.

Figure 8 is a graph showing the healing properties of BC airgel and the product of Example 3.

Figure 9 is a graph of antibacterial performance and cytocompatibility of BC aerogel and the products of Examples 1 and 5. Among them, (a) is the antibacterial performance diagram, and (b) is the cytocompatibility diagram.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention. It should be understood that the terms used in the present invention are only used to describe particular embodiments and are not intended to limit the present invention.

In addition, for numerical ranges in the present invention, it should be understood that every intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or value intermediate within a stated range, and any other stated value or value intermediate within a stated range, is also included within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention.

The words "include", "includes", "have", "contains", etc. used in the present invention are all open terms, which mean including but not limited to.

The bacterial cellulose used in the following examples and comparative examples of the present invention is obtained by culture medium. The preparation and culture method of the medium is: weigh 25g of glucose, 7.5g of yeast powder, 10g of peptone and 10g of Na ₂ PO ₄ , Dissolve in 1L deionized water, stir until completely dissolved; use glacial acetic acid to adjust the pH value of the mixed solution to between 4 and 5, then sterilize at 115°C for 30 minutes and then take it out to use as a bacterial cellulose growth medium.

The preparation method of bacterial cellulose aerogel (BC aerogel) used in the following examples and comparative examples of the present invention is: Mix Acetobacter xylinum seed liquid and culture liquid at a volume ratio of 1:9, and incubate at 30°C. After 3 days, purification and freeze-drying, bacterial cellulose aerogel was obtained.

All raw materials used in the following examples and comparative examples of the present invention are commercially available products.

Example 1

Preparation of borosilicate-based bioactive glass-modified bacterial cellulose functional dressing:

(1) Preparation of borosilicate-based bioactive glass sol: Pour 40 mL of absolute ethanol into a reagent bottle, add 10.2 mL of tetraethyl orthosilicate drop by drop under stirring, stir for 30 min, then add 3.1 g of calcium nitrate tetrahydrate, and stir until When the solution is clear, add 1.1 mL triethyl phosphate (TEP) solution drop by drop and set aside; add 0.4 g boric acid to 10 mL absolute ethanol, heat and stir at 60°C until the boric acid dissolves, then add it to the above reagent bottle, and then use Stir with a magnetic stirrer for 3 hours to obtain borosilicate-based bioactive glass sol.

(2) Condensation polymerization reaction: Immerse 0.5g of BC aerogel into the above 50mL borosilicate-based bioactive glass sol, soak it at 37°C for 24 hours under shaking conditions, take it out and rinse the surface of the material twice with absolute ethanol to obtain the precursor Then prepare an ethanol aqueous solution with a volume percentage of 90%, put in the precursor, take it out after hydrolysis and polycondensation for 24 hours, clean it and then freeze-dry it with a freeze dryer at -50°C for 12 hours to obtain a borosilicate-based bioactive glass-modified bacterial cellulose functional dressing ( BBG/BC).

Figure 1 is the SEM image and fiber diameter distribution diagram of BC aerogel and BBG/BC in Example 1. Among them, (a) and (c) are SEM images of BC aerogel at different scales, (b) and (d) are SEM images of BBG/BC, and (e) is the fiber diameter distribution of BC aerogel. , (f) is the fiber diameter distribution diagram of BBG/BC. As can be seen from Figure 1 (a) and (c), BC has a natural nanofiber porous network structure; as can be seen from (b) and (d), after the borosilicate-based bioactive glass wraps the BC fiber, it forms a coating and remains The porous network structure of BC airgel was discovered; through fiber diameter statistics, it was found that the fiber diameter of BC airgel was 45.7±13.1nm, and the fiber diameter of BBG/BC increased slightly, to 57±22nm.

Example 2 (adding 0.08g copper nitrate antibacterial agent)

Preparation of Cu ²⁺ @BBG-1:

(1) Preparation of borosilicate-based bioactive glass sol: Pour 40 mL of absolute ethanol into a reagent bottle, add 10.2 mL of tetraethyl orthosilicate drop by drop under stirring, stir for 30 min, then add 3.1 g of calcium nitrate tetrahydrate, and stir until When the solution is clear, add 1.1mL triethyl phosphate (TEP) solution dropwise, then add 0.08g copper nitrate and set aside; add 0.4g boric acid to 10mL absolute ethanol, heat and stir at 60°C until the boric acid dissolves, and then add into the above reagent bottle, and then stirred with a magnetic stirrer for 3 hours to obtain a borosilicate-based bioactive glass sol.

(2) Condensation polymerization reaction: Immerse 0.5g of BC aerogel into the above 50mL borosilicate-based bioactive glass sol, soak it at 37°C for 24 hours under shaking conditions, take it out and rinse the surface of the material twice with absolute ethanol to obtain the precursor ; Then prepare an ethanol aqueous solution with a volume percentage of 90%, put in the precursor, take it out after hydrolysis and polycondensation for 24 hours, clean it and freeze-dry it with a freeze dryer at -50°C for 12 hours to obtain Cu ²⁺ @BBG/BC-1.

Example 3

The only difference from Example 2 is that the added amount of copper nitrate is modified to 0.16g, which is recorded as Cu ²⁺ @BBG/BC-2.

Example 4

The only difference from Example 2 is that the added amount of copper nitrate is modified to 0.39g, which is recorded as Cu ²⁺ @BBG/BC-3.

Figure 2 is the SEM image and fiber diameter distribution chart of the product in Example 2-4. Among them, (a) and (d) are SEM images of the product of Example 2 at different scales, (b) and (e) are SEM images of the product of Example 3, (c) and (f) are the products of Example 3. SEM image, (g) is the fiber diameter distribution diagram of the product of Example 2, (h) is the fiber diameter distribution diagram of the product of Example 3, (i) is the fiber diameter distribution diagram of the product of Example 4. As shown in Figure 2, after adding copper ions, a coating can still be formed on the surface of BC fibers, and as the copper ion content increases, the fiber diameter increases, Cu ²⁺ @BBG/BC-1, Cu ²⁺ @ The fiber diameters of BBG/BC-2 and Cu ²⁺ @BBG/BC-3 are 59±15nm, 64±15nm and 66±14nm, respectively.

Figure 3 shows the XPS full spectrum, tensile test results and water absorption performance of BC aerogel and the products of Examples 1-4. Among them, (a) is the XPS full spectrum chart, (b) is the tensile test result chart, and (c) is the water absorption rate chart. The test conditions for the tensile test result chart are: the sample length × width × height is approximately 2 × 1 × 0.5mm, the tensile rate is 5mm/min, each sample is measured three times, and finally the average and standard deviation are calculated.

As shown in the XPS full spectrum in Figure 3, elements C and O exist on the surface of BC airgel; elements such as C, O, B, Si, Ca and P exist on the surface of BBG/BC; three types of Cu ²⁺ @BBG/BC The presence of elements such as C, O, B, Si, Ca, P, and Cu in the sample indicates that the copper-doped bioactive glass is attached to the surface of the BC fiber.

The tensile test results show that the formation of BBG coating improves the mechanical properties of BC-based composites. After doping with copper, the tensile strength and elongation at break of the product decreased, and the Young's modulus increased.

The water absorption performance chart shows that after the introduction of BBG, BBG/BC can still absorb water quickly. The water absorption rate of BBG/BC is lower than that of BC, and the doped copper ions do not affect the water absorption rate of the product. The faster water absorption rate and higher water absorption rate enable the copper-doped borosilicate-based bioactive glass-modified bacterial cellulose functional dressing to effectively remove wound exudate.

Example 5

The only difference from Example 2 is that the addition of copper nitrate is omitted and 1.6 g of gallium nitrate is added, which is recorded as Ga ³⁺ @BBG/BC.

Figure 4 is a SEM image and fiber diameter distribution chart of the product of Example 5. Among them, (a) and (b) are SEM images at different scales, and (c) is the fiber diameter distribution map. It can be seen from the figure that the introduction of gallium-doped borosilicate-based bioactive glass does not destroy the unique three-dimensional network structure of BC, but the fiber diameter changes significantly, indicating that the gallium-doped borosilicate-based bioactive glass wraps around the fiber surface to form a coating.

Effect verification

(1) Carry out antibacterial performance test. The specific test conditions are: co-culture Staphylococcus aureus (S. aureus, ATCC 25923) and methicillin-resistant Staphylococcus aureus (MRSA, ATCC 43300) with the material for 24 hours, and use 2.5% amyl The samples were fixed in dialdehyde solution, dehydrated through graded alcohol, and observed using scanning electron microscopy. The results are shown in Figure 5.

Figure 5 is a graph showing the antibacterial properties of BC aerogel and the products of Examples 1-4. As can be seen from the figure, S. aureus and MRSA bacteria formed biofilms on BC aerogels and BBG/BC, and the number of bacteria on the surface of Examples 2-4 was significantly reduced, proving that copper-doped materials are effective against common types of bacteria. Exhibits good antibacterial properties.

(2) Conduct a cytocompatibility test. The specific test conditions are: co-culture mouse embryonic fibroblasts (NIH-3T3) with the material for 1, 3 and 5 days, and use CCK-8 to detect cell proliferation. The results are shown in Figure 6.

Figure 6 is a cytocompatibility diagram of BC aerogel and the products of Examples 1-4. It can be seen from the figure that the number of cells on the surface of BBG/BC, Cu ²⁺ @BBG/BC-1, and Cu ²⁺ @BBG/BC-2 is significantly more than that of BC, indicating that BBG/BC, Cu ²⁺ @BBG/BC- 1. Both Cu ²⁺ @BBG/BC-2 can promote cell proliferation; on the contrary, the number of cells on the surface of Cu ²⁺ @BBG/BC-3 material was significantly reduced, and it was less than that in the BC group, and dead cells were found. The results It shows that Cu ²⁺ @BBG/BC-3 has greater cytotoxicity, which is consistent with the trend of experimental results of cell proliferation.

(3) Carry out anti-inflammatory performance test. The specific test conditions are: culture with THP-1 special medium for 3-5 days, then add PMA (Phorbol-12-myristate-13-acetate) for 1 day of induction as a source of macrophages, and collect adherent cells. The cells were then added with 100ng/mL concentration of LPS (Lipopolysaccharide) to induce cellular inflammation model. Co-culture the material with the above-mentioned 5×10 ⁴ cells/mL induced inflammation model macrophages, incubate it in a 37°C incubator for 24 hours, take the culture supernatant from each well, and use enzyme labeling according to the instructions of the inflammatory factor kit. The instrument detects the secretion of inflammatory factors TNF-α and IL-1β. The results are shown in Figure 7.

Figure 7 is a graph showing the anti-inflammatory properties of BC aerogel and the products of Examples 1-4. Among them, (a) is a graph of the anti-inflammatory properties of the inflammatory factor TNF-α, and (b) is a graph of the anti-inflammatory properties of the inflammatory factor IL-1β. It can be seen from the figure that after co-culture, the BC group showed higher amounts of inflammatory factors, while BBG/BC, Cu ²⁺ @BBG/BC-1, Cu ²⁺ @BBG/BC-2, Cu ²⁺ @BBG/ The measured data of BC-3 material shows that inflammatory factors are reduced. The results showed that the inflammatory factors measured after the composite material was co-cultured for 24 hours were less than those of BC, indicating that the material has a certain anti-inflammatory ability.

(4) Test the chronic wound healing performance. The specific test conditions are as follows: establish a diabetic mouse wound model to examine the wound healing ability of the copper-doped borosilicate-based bioactive glass-modified bacterial cellulose functional dressing. The results are shown in Figure 8.

Figure 8 is a diagram of the healing properties of BC aerogel and the product of Example 3, in which the Control group is an uninfected BC treatment group, the BC group is a MRSA-infected BC treatment group, and the Cu ²⁺ @BBG/BC-2 group is Infected with MRSA, Cu ²⁺ @BBG/BC-2 treatment group. It can be seen from the figure that on the fourth day after surgery, the wounds of the BC group had obvious symptoms of infection and inflammation; while the Cu ²⁺ @BBG/BC-2 group was similar to the Control group, and no infection lesions were found in the wounds, indicating that Cu ²⁺ @BBG/BC- 2 Dressings can eliminate infections caused by MRSA. Despite bacterial invasion, with effective elimination of infection, the healing rate of the Cu ²⁺ @BBG/BC-2 group was significantly higher than that of the uninfected Control group, and complete healing was achieved on day 16. The BC group affected by infection had the slowest healing rate because infection affects wound healing.

(5) Conduct in vitro biological experiments to test the antibacterial performance and cell compatibility of the product of Example 5. Among them, the test conditions for antibacterial performance are: using scanning electron microscopy to observe the material's ability to inhibit the formation of biofilms on the surface of the material by Staphylococcus aureus (S. aureus, ATCC 25923) and Escherichia coli (E.coli, ATCC 25922). The test conditions for cytocompatibility are: co-culture NIH-3T3 with materials for 1, 3 and 5 days, and use CCK-8 to detect cell proliferation. The results are shown in Figure 9.

Figure 9 is a graph of antibacterial performance and cytocompatibility of BC aerogel and the products of Examples 1 and 5. Among them, (a) is the antibacterial performance diagram, and (b) is the cytocompatibility diagram. It can be seen from the figure that the number of S.aureus and E.coli bacteria on BC and BBG/BC is complete and the number of biofilms is formed, while the number of S.aureus and E.coli bacteria on the surface of Ga ³⁺ @BBG/BC material is were significantly reduced, indicating that Ga ³⁺ @BBG/BC has good antibacterial properties. On the other hand, the cell activity of cells on the surface of BBG/BC is significantly better than that of BC, that is, compared with BC, BBG/BC can promote cell proliferation, and the OD value of Ga ³⁺ @BBG/BC composite material is different from that of BBG/BC group. Similar, no obvious cytotoxicity.

The above-described embodiments only describe the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can make various modifications to the technical solutions of the present invention. All deformations and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims (9)

1. The preparation method of the boron-silicon-based bioactive glass modified bacterial cellulose functional dressing is characterized by comprising the following steps of:

preparing borosilicate-based bioactive glass sol and bacterial cellulose aerogel;

soaking the bacterial cellulose aerogel in the borosilicate-based bioactive glass sol, polycondensing and drying to obtain the borosilicate-based bioactive glass modified bacterial cellulose functional dressing.

2. The process according to claim 1, wherein the polycondensation is carried out at a temperature of 20 to 35 ℃ for a time of 18 to 30 hours.

3. The preparation method of claim 1, wherein in the boron-silicon-based bioactive glass modified bacterial cellulose functional dressing, the mass ratio of the boron-silicon-based bioactive glass to the bacterial cellulose is 1:1-5:1.

4. The preparation method of the boron-silicon-based bioactive glass sol according to claim 1, comprising the following steps:

and mixing a silicon source, a calcium source, a phosphorus source and a boron source in a dispersing agent to obtain the boron-silicon-based bioactive glass sol.

5. The method of claim 4, wherein the silicon source is ethyl orthosilicate; the calcium source is calcium nitrate; the phosphorus source is triethyl phosphate; the boron source is boric acid.

6. The preparation method of claim 5, wherein in the borosilicate-based bioactive glass sol, the volume concentration of the tetraethoxysilane is 20-21%, the concentration of the calcium nitrate is 60-65mg/mL, the volume concentration of the triethyl phosphate is 1.8-2.5%, and the concentration of the boric acid is 5-10mg/mL.

7. The method according to claim 4, wherein the mixing process further comprises a step of adding an antimicrobial agent, wherein the antimicrobial agent is an antimicrobial agent containing one or more elements selected from the group consisting of silver, zinc, copper and gallium.

8. A boron-silicon-based bioactive glass-modified bacterial cellulose functional dressing obtainable by the method of any one of claims 1 to 7.

9. Use of a boron-silicon-based bioactive glass modified bacterial cellulose functional dressing as claimed in claim 8 in the manufacture of a wound dressing.