Apparatus and method for producing a bacterial cellulose composite having a core-shell structure by dynamic fermentation

Abstract

An apparatus and method for producing a bacterial cellulose composite having a core-shell structure by dynamic fermentation are described. The apparatus comprises a fermentation culture container and two rollers and two heating guide plates arranged in the fermentation culture container. The apparatus can realize dynamic fermentation and coating, and can obtain a bacterial cellulose composite material with controllable shape and size, good biocompatibility and safety.

Claims

1. An apparatus for producing a bacterial cellulose composite having a core-shell structure through a dynamic fermentation, comprising: a fermentation culture container, and two rollers and two heating guide plates arranged in the fermentation culture container; both ends of the rotating shafts of the two rollers are respectively movably connected to the inner wall of the fermentation culture container; the two rollers are arranged in parallel in the horizontal direction with a gap therebetween; and the distance between the rotating shafts of the rollers is adjustable; the two heating guide plates are parallel to the rotating shafts of the two rollers, wherein one end of one of the heating guide plates is movably connected to the fermentation culture container, and the other end thereof extends obliquely downward to be above the gap between the two rollers and abuts against one of the rollers; and one end of the other heating guide plate is movably connected to the fermentation culture container, and the other end thereof extends obliquely downward to be above the gap between the two rollers and abuts against the other roller.

2. The apparatus according to claim 1, wherein the apparatus further comprises a driving member for driving the two rollers to rotate.

3. The apparatus according to claim 1, wherein the driving member is used for driving the two rollers to rotate in the same direction.

4. The apparatus according to claim 1, wherein the apparatus further comprises a heating member for heating the two heating guide plates.

5. The apparatus according to claim 1, wherein the two rollers are cylindrical rollers of the same shape and size.

6. The apparatus according to claim 1, wherein each of the two heating guide plates has an angle with the inner side wall of the fermentation culture container of 15-60 degrees.

7. A method for producing a bacterial cellulose composite having a core-shell structure by performing dynamic fermentation using the apparatus according to claim 1, comprising: adjusting the distance between the rollers so that the minimum width of the gap is smaller than the diameter or length of the core material; sterilizing the core material to be coated, and then placing it above the gap between the two rollers to ensure that the core material can abut against each of the two rollers above the gap; setting the rotation speed and rotation direction of the rollers, so that the core material can realize vibration without horizontal displacement according to the rotation of the rollers; setting the length of the heating guide plates and adjusting the angle of the heating guide plates to ensure that one end of the two heating guide plates is at the gap where the core material abuts against the rollers; formulating a bacterial cellulose fermentation culture solution and sterilizing it at high pressure, and then mixing it with strain seed mash to obtain a fermentation mixed solution; pouring the fermentation mixed solution into the fermentation culture container to immerse the core material, and starting the rollers to rotate in the same direction for dynamic fermentation; after the completion of fermentation, discharging fermentation broth, at which the outer layer of the core material is coated with bacterial cellulose obtained by strain fermentation to form a core material-bacterial cellulose composite; starting the heating guide plates and allowing the heated liquid of thermoplastic polymer to flow down along the heating guide plates at both sides, respectively; with the rotation of the rollers, uniformly coating the surface of the core material-bacterial cellulose composite with the thermoplastic polymer, thereby producing a bacterial cellulose composite having a core-shell structure; alternatively, starting the heating guide plates and allowing the heated liquid of thermoplastic polymer to flow down along the heating guide plates at both sides, respectively; with the rotation of the rollers, uniformly coating the surface of the core material with the thermoplastic polymer, thereby producing a core material-thermal plastic polymer composite; pouring the fermentation mixed solution into the fermentation culture container to immerse the rollers, and starting the rollers to rotate in the same direction for dynamic fermentation; after the completion of fermentation, discharging fermentation broth, at which the outer layer of core material-thermal plastic polymer composite is coated with bacterial cellulose obtained by strain fermentation, thereby producing a bacterial cellulose composite having a core-shell structure.

8. The method according to claim 7, wherein the method also includes repeating coating bacterial cellulose by dynamic fermentation and/or coating thermoplastic polymer to obtain a bacterial cellulose composite having a core-shell structure with more layers.

9. The method according to claim 7, wherein the core material comprises one or a combination of more of inorganic materials, organic polymer materials and metal materials.

10. The method according to claim 7, wherein the shape of the core material is spherical, quasi-spherical, cylindrical, rod-shaped or any irregular body.

11. The method according to claim 7, wherein the thermoplastic polymer comprises one or a combination of more of polyethylene, polypropylene, polystyrene, polymethyl methacrylate, nylon, polyurethane, polyester and polylactic acid.

12. The method according to claim 7, wherein the heating temperature of the heating guide plates is 50-300° C.

13. The method according to claim 7, wherein the strains comprise one or a combination of more of Acetobacter xylinum, Rhizobium, Sporosarcina, Pseudomonas, Achromobacter, Alcaligenes, Aerobacter, and Azotobacter.

14. The method according to claim 7, wherein the added amount of strain seed mash is 1-5 wt % of the fermentation culture solution.

15. The method according to claim 7, wherein the dynamic fermentation is performed at a temperature of 20-30° C. for 3-30 days.

16. The method according to claim 7, wherein when the dynamic fermentation is performed, the rotation speeds of the two rollers are the same, which are both 0.1-60 rpm.

17. The method according to claim 7, wherein when the dynamic fermentation is performed, the rotation speeds of the two rollers are the same, which are both 4-20 rpm.

18. The method according to claim 7, wherein, during the process of dynamic fermentation, adding 0.1-5 wt % soluble additives to the fermentation mixed solution is further included; and the soluble additives comprise one or a combination of more of gelatin, sodium hyaluronate, starch, pectin, chitosan, sodium alginate, and soluble cellulose derivatives.

19. The method according to claim 7, wherein, after the dynamic fermentation is completed, further comprising purifying the bacterial cellulose-coated composite by washing the bacterial cellulose-coated composite in an aqueous NaOH solution with a mass percentage of 4% to 8% at a temperature of 70-100° C. for 4-6 h, and then repeatedly rinsing with distilled water until neutral.

20. A bacterial cellulose composite having a core-shell structure produced by the method according to claim 7, of which the inner core layer is a core material, which is coated with a single layer or multiple layers of bacterial cellulose and/or thermoplastic polymer.

Description

DESCRIPTION OF THE FIGURE

[0044] The FIGURE is a schematic structural diagram of an apparatus for producing a bacterial cellulose composite having a core-shell structure by dynamic fermentation in an embodiment of the present invention.

REFERENCE NUMBERS

[0045] 1. fermentation culture container, [0046] 2. rollers, [0047] 3. fermentation culture solution, [0048] 4. core material to be coated, [0049] 5. heating guide plates, [0050] 6. fasteners.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0051] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention are now described in detail below, but should not be construed as limiting the scope of implementation of the present invention.

[0052] The experimental methods used in the following examples are conventional methods, unless otherwise specified.

[0053] The materials, reagents, etc. used in the following examples can be obtained from commercial sources, unless otherwise specified.

EXAMPLE 1

[0054] This example provides an apparatus for producing a bacterial cellulose composite having a core-shell structure by dynamic fermentation. As shown in the FIGURE, the apparatus comprises:

[0055] a fermentation culture container 1 and two rollers 2 and two heating guide plates 5 arranged in the fermentation culture container. Both ends of the rotating shafts of the two rollers 2 are respectively movably connected to the inner wall of the fermentation culture container; the two rollers are arranged in parallel in the horizontal direction; there is a gap between the rollers, and the distance between the rotating shafts of the rollers is adjustable; the two heating guide plates 5 are parallel to the rotating shafts of the two rollers 2, wherein one end of one of the heating guide plates 5 is movably connected to the fermentation culture container 1 via a fastener 6, and the other end extends obliquely downward to be above the gap between the two rollers and abuts against one of the rollers; one end of the other heating guide plate is movably connected to the fermentation culture container via the fastener 6, and the other end extends obliquely downward to be above the gap between the two rollers and abuts against the other roller 2. The two rollers are preferably cylindrical rollers of the same shape and size.

[0056] During dynamic fermentation, the core material to be coated 4 is located above the gap between the two rollers 2 and abuts against the rollers; and the fermentation culture solution 3 is loaded in the fermentation culture container 1. The apparatus further comprises a driving member for driving the two rollers to rotate in the same direction. The apparatus further comprises a heating member for heating the two heating guide plates.

[0057] In another aspect, the example also provides a method for producing a bacterial cellulose composite having a core-shell structure by performing dynamic fermentation using the apparatus in the example as described above. The method comprises the following steps:

[0058] (1) Two cylindrical glass rollers of the same shape and size that can rotate clockwise in the same direction at a constant speed were arranged in parallel in a fermentation culture container with an upward opening. A spherical polyurethane material (core material) with a diameter of 30 mm was placed between the two rollers, as shown in the FIGURE, the distance between the two rollers was adjusted to 26 mm, and the rotation speed was 4 rpm. The spherical polyurethane can realize vibration without horizontal displacement according to the rotation of the rollers.

[0059] (2) Two heating guide plates were fixed on top of the fermentation culture container, and each of the two heating guide plates is adjusted to have an angle with the side of the fermentation culture container of 30 degrees, to ensure that one end of the two heating plates is located at the gap where the spherical polyurethane abuts against the roller.

[0060] (3) Acetobacter xylinum that can secrete bacterial cellulose was activated to prepare a seed mash, and the seed mash with a strain concentration of 1 wt % and a fermentation medium were then mixed to obtain a fermentation mixed solution; wherein, the fermentation medium was a high-temperature sterilized medium, and the components of the medium were the commonly used components for bacterial cellulose fermentation in this field.

[0061] (4) The fermentation mixed solution was poured into the fermentation culture container to immerse the core material. The rollers were started to rotate in the same direction for dynamic fermentation, and the fermentation was carried out at 35° C. for 3 days. After the fermentation was completed, the fermentation broth was discharged. At this time, the outer layer of spherical polyurethane was coated with bacterial cellulose obtained by strain fermentation. The product was immersed an aqueous NaOH solution with a mass percentage of 4% and heated at 100° C. for 6 h, and then repeatedly rinsed with distilled water until neutral, to form a spherical polyurethane-bacterial cellulose composite.

[0062] (5) The heating guide plates were started, and the heating temperature was adjusted to 190° C. The heated liquid of thermoplastic polymeric polyethylene flowed down along the heating guide plates at both sides, respectively. With the rotation of the rollers, the thermoplastic polymer was uniformly coated on the surface of the core material-bacterial cellulose composite, thereby producing a core-shell structural composite material in which the surface of the spherical polyurethane material was uniformly covered with polyethylene/bacterial cellulose.

EXAMPLE 2

[0063] This example provides a method for producing a bacterial cellulose composite having a core-shell structure by performing dynamic fermentation using the apparatus in the Example 1 as described above. The method comprises the following steps:

[0064] (1) Two cylindrical glass rollers of the same shape and size that can rotate clockwise in the same direction at a constant speed were arranged in parallel in a fermentation culture container with an upward opening. A bioceramic (core material) with a diameter of 50 mm and a length of 70 mm was placed between the two rollers, as shown in the FIGURE, the distance between the two rollers was adjusted to 40 mm, and the rotation speed was 8 rpm. The bioceramic can realize vibration without horizontal displacement according to the rotation of the rollers.

[0065] (2) Two heating guide plates were fixed on top of the fermentation culture container, and each of the two heating guide plates is adjusted to have an angle with the side of the fermentation culture container of 45 degrees, to ensure that one end of the two heating plates is located at the gap where the bioceramic abuts against the roller.

[0066] (3) Rhizobium that can secrete bacterial cellulose was activated to prepare a seed mash, and the seed mash with a strain concentration of 2 wt % and a fermentation medium were then mixed to obtain a fermentation mixed solution; wherein, the fermentation medium was a high-temperature sterilized medium, the components of the medium were the commonly used components for bacterial cellulose fermentation in this field, and the fermentation mixed solution further contained 0.1 wt % gelatin.

[0067] (4) The fermentation mixed solution was poured into the fermentation culture container to immerse the core material. The rollers were started to rotate in the same direction for dynamic fermentation, and the fermentation was carried out at 20° C. for 30 days. After the fermentation was completed, the fermentation broth was discharged. At this time, the outer layer of spherical polyurethane was coated with bacterial cellulose obtained by strain fermentation. The product was immersed an aqueous NaOH solution with a mass percentage of 5% and heated at 90° C. for 5 h, and then repeatedly rinsed with distilled water until neutral, to form a bioceramic-bacterial cellulose composite.

[0068] (5) The heating guide plates were started, and the heating temperature was adjusted to 230° C. The heated liquid of thermoplastic polymeric polypropylene flowed down along the heating guide plates at both sides, respectively. With the rotation of the rollers, the thermoplastic polymer was uniformly coated on the surface of the bioceramic-bacterial cellulose composite, thereby producing a core-shell structural composite material in which the surface of the bioceramic was uniformly covered with polypropylene/bacterial cellulose.

EXAMPLE 3

[0069] This example provides a method for producing a bacterial cellulose composite having a core-shell structure by performing dynamic fermentation using the apparatus in the Example 1 as described above. The method comprises the following steps:

[0070] (1) Two cylindrical stainless steel rollers of the same shape and size that can rotate clockwise in the same direction at a constant speed were arranged in parallel in a fermentation culture container with an upward opening. A titanium alloy orthopedic implant screw of 6.5 mm (core material) was placed between the two rollers, as shown in the FIGURE, the distance between the two rollers was adjusted to 5 mm, and the rotation speed was 12 rpm. The screw can realize vibration without horizontal displacement according to the rotation of the rollers.

[0071] (2) Two heating guide plates were fixed on top of the fermentation culture container, and each of the two heating guide plates is adjusted to have an angle with the side of the fermentation culture container of 45 degrees, to ensure that one end of the two heating plates is located at the gap where the screw abuts against the roller.

[0072] (3) Sporosarcina that can secrete bacterial cellulose was activated to prepare a seed mash, and the seed mash with a strain concentration of 3 wt % and a fermentation medium were then mixed to obtain a fermentation mixed solution; wherein, the fermentation medium was a high-temperature sterilized medium, the components of the medium were the commonly used components for bacterial cellulose fermentation in this field, and the fermentation mixed solution further contained 1 wt % sodium hyaluronate and sodium alginate at a mass ratio of 1:1.

[0073] (4) The fermentation mixed solution was poured into the fermentation culture container to immerse the core material. The rollers were started to rotate in the same direction for dynamic fermentation, and the fermentation was carried out at 25° C. for 5 days. After the fermentation was completed, the fermentation broth was discharged. At this time, the outer layer of the screw was coated with bacterial cellulose obtained by strain fermentation. The product was immersed an aqueous NaOH solution with a mass percentage of 6% and heated at 80° C. for 4 h, and then repeatedly rinsed with distilled water until neutral, to form a screw-bacterial cellulose composite.

[0074] (5) The heating guide plates were started, and the heating temperature was adjusted to 200° C. The heated liquid of thermoplastic ethylene propylene copolymer flowed down along the heating guide plates at both sides, respectively. With the rotation of the rollers, the thermoplastic polymer was uniformly coated on the surface of the screw-bacterial cellulose composite, thereby producing a core-shell structural composite material in which the surface of the screw was uniformly covered with ethylene propylene copolymer/bacterial cellulose.

EXAMPLE 4

[0075] This example provides a method for producing a bacterial cellulose composite having a core-shell structure by performing dynamic fermentation using the apparatus in the Example 1 as described above. The method comprises the following steps:

[0076] (1) Two cylindrical polytetrafluoroethylene rollers of the same shape and size that can rotate clockwise in the same direction at a constant speed were arranged in parallel in a fermentation culture container with an upward opening. A rod-like material of nano-hydroxyapatite-filled polymethyl methacrylate with a diameter of 2 mm (core material) was placed between the two rollers, as shown in the FIGURE, the distance between the two rollers was adjusted to 1.5 mm, and the rotation speed was 2 rpm. The rod material can realize vibration without horizontal displacement according to the rotation of the rollers.

[0077] (2) Two heating guide plates were fixed on top of the fermentation culture container, and each of the two heating guide plates is adjusted to have an angle with the side of the fermentation culture container of 60 degrees, to ensure that one end of the two heating plates is located at the gap where the rod material abuts against the roller.

[0078] (3) Pseudomonas that can secrete bacterial cellulose was activated to prepare a seed mash, and the seed mash with a strain concentration of 4 wt % and a fermentation medium were then mixed to obtain a fermentation mixed solution; wherein, the fermentation medium was a high-temperature sterilized medium, the components of the medium were the commonly used components for bacterial cellulose fermentation in this field, and the fermentation mixed solution further contained 2 wt % soluble starch.

[0079] (4) The fermentation mixed solution was poured into the fermentation culture container to immerse the core material. The rollers were started to rotate in the same direction for dynamic fermentation, and the fermentation was carried out at 30° C. for 7 days. After the fermentation was completed, the fermentation broth was discharged. At this time, the outer layer of rod material was coated with bacterial cellulose obtained by strain fermentation. The product was immersed an aqueous NaOH solution with a mass percentage of 7% and heated at 70° C. for 6 h, and then repeatedly rinsed with distilled water until neutral, to form a rod material-bacterial cellulose composite.

[0080] (5) The heating guide plates were started, and the heating temperature was adjusted to 270° C. The heated liquid of thermoplastic polymer nylon flowed down along the heating guide plates at both sides, respectively. With the rotation of the rollers, the thermoplastic polymer was uniformly coated on the surface of the rod material-bacterial cellulose composite, thereby producing a core-shell structural composite material in which the surface of the rod material was uniformly covered with nylon/bacterial cellulose.

EXAMPLE 5

[0081] This example provides a method for producing a bacterial cellulose composite having a core-shell structure by performing dynamic fermentation using the apparatus in the Example 1 as described above. The method comprises the following steps:

[0082] (1) Two cylindrical plastic rollers of the same shape and size that can rotate clockwise in the same direction at a constant speed were arranged in parallel in a fermentation culture container with an upward opening. An irregular silicone rubber (core material) for filling breasts was placed between the two rollers, as shown in the FIGURE, the distance between the two rollers was adjusted to 70 mm, and the rotation speed was 30 rpm. The silicone rubber can realize vibration without horizontal displacement according to the rotation of the rollers.

[0083] (2) Two heating guide plates were fixed on top of the fermentation culture container, and each of the two heating guide plates is adjusted to have an angle with the side of the fermentation culture container of 45 degrees, to ensure that one end of the two heating plates is located at the gap where the silicone rubber abuts against the roller.

[0084] (3) Achromobacter and Alcaligenes that can secrete bacterial cellulose was activated to prepare a seed mash, and the seed mash with a strain concentration of 5 wt % and a fermentation medium were then mixed to obtain a fermentation mixed solution; wherein, the fermentation medium was a high-temperature sterilized medium, the components of the medium were the commonly used components for bacterial cellulose fermentation in this field, and the fermentation mixed solution further contained 3 wt % pectin.

[0085] (4) The fermentation mixed solution was poured into the fermentation culture container to immerse the core material. The rollers were started to rotate in the same direction for dynamic fermentation, and the fermentation was carried out at 31° C. for 15 days. After the fermentation was completed, the fermentation broth was discharged. At this time, the outer layer of silicone rubber was coated with bacterial cellulose obtained by strain fermentation. The product was immersed an aqueous NaOH solution with a mass percentage of 8% and heated at 70° C. for 5 h, and then repeatedly rinsed with distilled water until neutral, to form a silicone rubber-bacterial cellulose composite.

[0086] (5) The heating guide plates were started, and the heating temperature was adjusted to 190° C. The heated liquid of thermoplastic polymeric polyethylene flowed down along the heating guide plates at both sides, respectively. With the rotation of the rollers, the thermoplastic polymer was uniformly coated on the surface of the silicone rubber-bacterial cellulose composite, thereby producing a core-shell structural composite material in which the surface of the silicone rubber was uniformly covered with polyethylene/bacterial cellulose.

EXAMPLE 6

[0087] This example provides a method for producing a bacterial cellulose composite having a core-shell structure by performing dynamic fermentation using the apparatus in the Example 1 as described above. The method comprises the following steps:

[0088] (1) Two cylindrical plastic rollers of the same shape and size that can rotate clockwise in the same direction at a constant speed were arranged in parallel in a fermentation culture container with an upward opening. A cobalt-chromium-molybdenum alloy artificial hip joint of irregular shape (core material) was placed between the two rollers, as shown in the FIGURE, the distance between the two rollers was adjusted to 50 mm, and the rotation speed was 15 rpm. The alloy can realize vibration without horizontal displacement according to the rotation of the rollers.

[0089] (2) Two heating guide plates were fixed on top of the fermentation culture container, and each of the two heating guide plates is adjusted to have an angle with the side of the fermentation culture container of 60 degrees, to ensure that one end of the two heating plates is located at the gap where the alloy abuts against the roller.

[0090] (3) Aerobacter and Azotobacter that can secrete bacterial cellulose was activated to prepare a seed mash, and the seed mash with a strain concentration of 3 wt % and a fermentation medium were then mixed to obtain a fermentation mixed solution; wherein, the fermentation medium was a high-temperature sterilized medium, the components of the medium were the commonly used components for bacterial cellulose fermentation in this field, and the fermentation mixed solution further contained 5 wt % chitosan and sodium carboxymethyl cellulose at a mass ratio of 1:3.

[0091] (4) The fermentation mixed solution was poured into the fermentation culture container to immerse the core material. The rollers were started to rotate in the same direction for dynamic fermentation, and the fermentation was carried out at 32° C. for 10 days. After the fermentation was completed, the fermentation broth was discharged. At this time, the outer layer of the alloy was coated with bacterial cellulose obtained by strain fermentation. The product was immersed an aqueous NaOH solution with a mass percentage of 6% and heated at 90° C. for 4 h, and then repeatedly rinsed with distilled water until neutral, to form an alloy-bacterial cellulose composite.

[0092] (5) The heating guide plates were started, and the heating temperature was adjusted to 190° C. The heated liquid of thermoplastic polymeric polyethylene flowed down along the heating guide plates at both sides, respectively. With the rotation of the rollers, the thermoplastic polymer was uniformly coated on the surface of the alloy-bacterial cellulose composite, thereby producing a core-shell structural composite material in which the surface of the alloy was uniformly covered with polyethylene/bacterial cellulose.

Performance Test Experiments:

[0093] The following performance tests were performed on the core-shell structural composite material in which the surface of the spherical polyurethane material was uniformly covered with polyethylene/bacterial cellulose prepared in the Example 1.

[0094] Biocompatibility test: in accordance with GB/T 16886 Biological evaluation of medical apparatuses, the composite material (Example 1) and the polyurethane material (the core material of Example 1) evaluated for cytotoxicity, delayed contact sensitization in guinea pigs, skin irritation, etc.

[0095] The results show that the polyurethane material (the core material of Example 1) had a cytotoxicity of grade 2 and skin sensitization response; the composite material (Example 1) had a cytotoxicity of less than grade 2, no skin sensitization response and no intradermal irritation response, and have good biological safety. This indicated that the use of this patent improves the biocompatibility of the material.