METHOD OF MAKING A CROSS-LINKED POLYMER GEL AND DEVICE FOR PERFORMING THE METHOD

Abstract

The present invention relates to a method of making a composition, the composition comprising a cross-linked polymer and water, comprising at least the following steps: a) providing a first mixture, comprising at least one polymer and an aqueous alkaline solution; b) generating a gel by cross-linking the at least one polymer with a cross-linking agent; c) neutralizing the generated gel by using a neutralization solution; d) optionally adding a second mixture, comprising a cross-linked and/or non-cross-linked polymer and water, to the neutralized gel obtained in step c); e) dialyzing the gel obtained in step d) or dialyzing the gel obtained in step c) and optionally subsequent addition of the second mixture, comprising a cross-linked and/or non-cross-linked polymer and water; and f) filling the dialyzed gel obtained in step e) into a container, wherein at least two or three or four or five or all of steps a) to f) are automated.

Claims

1. Method of making a composition, the composition comprising a cross-linked polymer and water, comprising at least a) to f): a) providing a first mixture comprising at least one polymer and an aqueous alkaline solution; b) generating a gel by cross-linking the at least one polymer with a cross-linking agent; c) neutralizing the generated gel by using a neutralization solution; d) optionally adding a second mixture comprising a cross-linked and/or non-cross-linked polymer and water, to the neutralized gel obtained in c); e) dialyzing the gel obtained in d), or dialyzing the gel obtained in c) and optionally subsequently adding the second mixture comprising a cross-linked and/or non-cross-linked polymer and water; and f) filling the dialyzed gel obtained in e) into a container, wherein at least two or three or four or five or all of a) to f) are automated.

2. Method according to claim 1, wherein as polymers of the first and second mixture independently from one another heparosan, hyaluronan, alginic acid, pectin, gellan, chondroitin, keratin, heparin, cellulose, chitosan, carrageenan, xanthan, or salts or derivatives thereof or combinations thereof are used, in particular hyaluronan, optionally hyaluronic acid, and/or that the method comprises the addition of an anesthetic, optionally lidocaine or of an antioxidant, optionally mannitol, or of an anesthetic and an antioxidant.

3. Method according to claim 1, wherein the provision of the first mixture in a) is performed thereby that the at least one polymer, in particular hyaluronic acid, is fed to a first container, and the aqueous alkaline solution is fed from a second container to the first container optionally by reducing a container volume of the second container, or by applying pressure to the second container, wherein a provided amount of the at least one polymer, optionally hyaluronic acid, and/or a fed amount of the aqueous alkaline solution is, optionally, determined by means of weight measurement of the first and/or the second container by means of a weighing means.

4. Method according to claim 3, wherein in a) the aqueous alkaline solution is fed from the second container to the first container via a particle filter.

5. Method according to claim 3, wherein in a) the first mixture is provided in the first container, and in b) the cross-linking agent is fed to the first container, wherein the interior of the first container has a temperature in the range of, optionally, 2? C. to 35? C., and the cross-linking agent, prior to the feeding, has a temperature, which deviates from the temperature in the interior of the first container, optionally, by 2? C. at the most, and/or wherein after the feeding of the cross-linking agent the interior of the first container is, optionally, tempered to a temperature in the range of from 20? C. to 50? C.; or wherein in b) the gel is generated in first container, and in c) the neutralization solution is fed from second container to the first container, wherein the neutralization solution is fed by reducing a container volume of second container, or by means of applying pressure on second container, and/or a fed amount of the neutralization solution is determined by means of weight measurement of the first and/or second container by means of weighing means.

6. Method according to claim 3, wherein a stirrer is operated in container such that prior or simultaneously or subsequently to the feeding of the neutralization solution from the second container to the first container, optionally prior to the feeding, the gel generated in b) in container is cut, wherein for the cutting said stirrer is used.

7. Method according to claim 6, wherein said stirrer comprises at least one stirring tool comprising at least two different working surfaces, wherein a first working surface comprises an edge configured to allow cutting the gel which is generated in b), and a second working surface, which opposes the first working surface, and which is configured to allow mixing the neutralization solution with the gel which has been cut in b) without further cutting it, optionally wherein the second working surface is edgeless or is cylinder-like.

8. Method according to claim 3, wherein in c) the neutralization solution is fed from the second container to the first container via a particle filter.

9. Method according to claim 3, wherein in c) the gel is neutralized in the first container and is transferred in e) from the first container into a dialysis cell, wherein the dialysis cell comprises a buffer solution, which is exchanged during the dialysis, and/or the gel is, for example, transported into the dialysis cell, which is connected to the first container, wherein the exchange of the buffer solution and/or the transportation of the gel into the dialysis cell is preferably automatedly performed; or wherein in e) the dialyzed gel is mixed in a mixing container with the second mixture, optionally by means of a stirrer, wherein the second mixture is fed from further container to the mixing container, and/or that a fed amount of the second mixture is determined by means of weight measurement by using a weighing means of the mixing container and/or the further container, optionally wherein said mixing container is the first container and said further container is the second container, optionally wherein in e) the second mixture is dialyzed prior to the addition to the dialyzed gel.

10. Method according to claim 1, wherein said method is performed in a device, the device at least comprising: a first container; a second container, which is connected to the first container by means of a passage; at least two stirrers; an accommodation in the passage in which a particle filter is arranged; a dialysis cell which is connected to the first container; and a control device for performing said method.

11. Device for making a composition, the composition comprising at least one cross-linked polymer and water, wherein the device comprises: a first container; a second container, which is connected to the first container by means of a passage; at least two stirrers; an accommodation in the passage in which a particle filter is arranged; a dialysis cell which is connected to the first container; and a control device for performing a method according to claim 1, wherein the at least one polymer is, optionally, heparosan, hyaluronan, alginic acid, pectin, gellan, chondroitin, keratin, heparin, cellulose, chitosan, carrageenan, xanthan, salts or derivatives thereof or combinations thereof, optionally hyaluronan, optionally hyaluronic acid.

12. Device according to claim 11, comprising a shiftable piston for reducing a volume of the first and/or second container, which is arranged in the first and/or second container; or comprising a gear comprising at least two different transmissions by means of which stirrer is selectively drivable with different transmissions; and/or characterized by means of a drive comprising at least two motors by means of which stirrer is selectively drivable, and/or comprising means of different working surfaces of a stirring tool of stirrer; and/or comprising means of the rotational direction of the stirrer; or wherein said stirring tool of stirrer comprises at least two different working surfaces, wherein a first working surface comprises an edge configured to allow cutting the gel generated in b), and a second working surface, which opposes the first working surface, which is configured to allow mixing in c) the neutralization solution with the gel which has been cut in b) without further cutting, optionally wherein the second working surface is edgeless or cylinder-like; or comprising a weighing means for weight measurement of the first and/or second container; or comprising a sterilization means for rinsing the first and/or second container and/or the passage with a sterilization fluid; or characterized by a dialysis cell arrangement, wherein the first or the second dialysis cell of the dialysis cell arrangement is connected to the first container.

13. Dialysis cell for dialyzing a gel, comprising: a first wall comprising a dialysis membrane, which is arranged on a perforated plate (111); an opposing second wall comprising a dialysis membrane, which is arranged on a perforated plate; and a frame, which is connected to the first and second wall, and comprises an inlet and outlet opening for filling and discharging the gel; wherein a distance (a) between the first and second wall is 25 mm at the most, optionally 10 mm at the most; optionally wherein the frame comprises at least one shiftable piston for reducing a volume of the dialysis cell, and/or comprising a protection layer, which is arranged on a side of the dialysis membrane opposing inlet and outlet opening.

14. Dialysis cell arrangement comprising a first dialysis cell according to claim 13, and a second dialysis cell according to claim 13, wherein the first and second dialysis cell have the same or different volumes and the same distance (a) between the first and the second wall.

15. Stirrer comprising at least one stirring tool comprising at least two different working surfaces, wherein a first working surface comprises an edge configured to allow cutting, optionally cutting a gel, and a second working surface, which opposes the first working surface, and which is configured to allow mixing without cutting, optionally mixing a gel with water, optionally wherein said second working surface is edgeless or cylinder-like.

Description

[0132] Further features and advantages result from the dependent claims and the examples. The figures, partially schematized, show in

[0133] FIG. 1: a sectional view of a device according to one embodiment of the present invention along the line I-I in FIG. 2;

[0134] FIG. 2: a top view on the device, wherein stirrers are arranged in a working position;

[0135] FIG. 3: a sectional view of the device along the line III-III in FIG. 4;

[0136] FIG. 4: a top view on the device, wherein a second piston is arranged in a working position in place of a second stirrer;

[0137] FIG. 5: a sectional view through a stirrer paddle of a first stirrer of the device along line V in FIG. 3;

[0138] FIG. 6: the device according to the invention corresponding to the sectional view in FIG. 1, FIG. 3 during dialysis;

[0139] FIG. 7: a sectional view of a dialysis cell according to one embodiment of the present invention of the dialysis cell along line VII-VII in FIG. 8; and

[0140] FIG. 8: a top view on the dialysis cell.

[0141] FIG. 1 shows a longitudinal sectional view of a device according to an embodiment of the present invention, FIG. 2 shows a top view on the device of FIG. 1.

[0142] The device comprises a first stainless steel container 10 (first container) having a double jacket, which has, for example, for a scale of 10 kg gel, an inner diameter of approx. 200 mm and a container height of approx. 700 mm, and thus a total volume of approx. 23.5 L, and a useable, respectively useful volume of approx. 10 L. For a scale of 20 kg, the first container 10 has, for example, for the same container height of approx. 700 mm, an internal diameter of approx. 270 mm, and thus a total volume of approx. 40 L, and a useable, respectively useful volume of approx. 20 L, for a scale of 30 kg, for example, for the same height of approx. 700 mm, an inner diameter of approx. 330 mm, and thus a total volume of approx. 60 L, and a useable, respectively useful volume of approx. 30 L. The first container 10 comprises on one side an inspection glass having light, an outlet at the bottom comprising an inlet and outlet valve 11, an inlet for HA powder (not shown), an inlet for BDDE solution (not shown), an outlet at the bottom for transfer of gel from the first container to a dialysis unit 100 (not shown), a sampling tube comprising a valve (not shown), and feed and discharge ports and a water conduit in the double jacket comprising baffle plates for a homogeneous tempering of the container (not shown). The internal side of container 10, i.e. the inner surface, is centrically milled out.

[0143] Further, the device comprises a second stainless steel container 20 (second container) comprising a double jacket, which has, for example, for a scale of 10 kg an inner diameter of approx. 200 mm, and a container height of approx. 700 mm, and thus a total volume of approx. 15 L, and a useable, respectively useful volume of approx. 10 L. For a scale of 20 kg, the second container 20 has, for example, for the same container height of approx. 700 mm, an inner diameter of approx. 270 mm, and thus a total volume of approx. 25 L, and a useable, respectively useful volume of approx. 20 L, for a scale of 30 kg, for example, for the same container height of approx. 700 mm, an inner diameter of approx. 330 mm, and thus a total volume of approx. 35 L, and a useable, respectively useful volume of approx. 30 L. The second container 20 comprises on one side an inspection glass having light, an outlet at the bottom comprising valve 21, an inlet for NaOH pellets or NaOH solution (not shown) as well as feed and discharge ports for a tempering of the container (not shown). The internal side of container 20, i.e. the inner surface, is also centrically milled out.

[0144] The first container 10 and the second container 20 are connected to one another by means of a passage 30, in which a particle filter 31 is arranged, and which are sealedly integrated in a basis 80 against the surroundings. This means that first container 10 and second container 20 are in fluid communication. Particle filter 31 may be arranged or accommodated in an accommodation 32. The dialysis cell 100 is connected to the first container 10 only.

[0145] Further, the device may comprise a mobile storage container for storing dialyzed gel (not shown) made from stainless steel, the dimensions of which correspond to those of the first and second container 10, 20, and which comprises an outlet at the bottom comprising a valve.

[0146] Furthermore, the device comprises a first and a second parking container 41, 42 for stirrers, and a first and second parking container 51, 52 for pistons 91, 92 made from stainless steel comprising a bottom outlet comprising a valve, which are arranged in a cover positioning unit 60 (vertical in FIG. 2) on both sides adjacent to the first container 10, respectively second container 20. The parking containers 41, 42 have, for example, for a scale of 10 kg, an inner diameter of approx. 240 mm, and a container height of approx. 700 mm, for a scale of 20 kg, for example, at the same container height of approx. 700 mm, an inner diameter of approx. 290 mm, and for a scale of 30 kg, for example, for the same container height of approx. 700 mm, an inner diameter of approx. 350 mm.

[0147] The device further comprises a first stirrer 71 in the form of a single or double planetary mixer for the first container 10 comprising a mixing motor (not shown), whose driving direction is reversible, and which is connected to a container cover, and is capsuled or is arranged at the exterior, and two stirring paddles 71A, 71B, which are arranged in the first container 10 in a working position, which is shown in FIG. 1, with a distance from the bottom and the wall of maximally approx. 1 to 3 mm.

[0148] The first stirring paddle 71A may be rotated with up to 150 revolutions per minute. The other stirring paddle 71B is coupled to the mixing motor via a gear, which selectively may have a single or a double transmission, respectively selectively may represent a transmission ratio of 1:1 and 2:1 such that said second stirring paddle also may be rotated with up to 150 revolutions per minute, when the gear is operated in the single transmission, and may be rotated with up to 300 revolutions per minute at the same motor rotation speed, when the gear is operated in the double transmission. The first stirrer 71 may be put down into the first container 10 or the first parking container 41 via a telescopic device of the cover positioning unit 60, and may be positioned between said working position and parking position by means of said cover positioning unit 60.

[0149] The blades at the backside of the paddles are sharply edged, which facilitates the cutting of cross-linked gel, however are curved at the front side.

[0150] FIG. 5 shows for this a sectional view through stirring paddle 71A along line V in FIG. 3. As is recognizable, stirring paddle 71A preferably has a knife-like first working surface 73A, and an opposing curved second working surface 73B, which is cylinder-like and different therefrom. By means of a reversal of the rotating direction of stirring paddle 71A around its rotational axis (perpendicular to the plane of projection of FIG. 5), which is indicated in FIG. 5 by means of a double-pointed arrow, the first working surface 73A or the second working surface 73B may be selectively inserted into the medium. Accordingly, the stirring paddle 71A has different working surfaces 73A, 73B depending on the rotational direction.

[0151] The device further comprises a second stirrer 72 in the form of a single mixer for the second container 20 having a mixing motor (not shown), which is connected to the cover of the container 20 and is capsuled or is positioned at the exterior. Stirrer 72 has a stirring paddle 72A having a large area, which is arranged in a working position in the second container 20, which is shown in FIG. 1, with a distance from the bottom and wall of approx. 1 to 3 mm. The stirring paddle 72A may be rotated with up to 150 revolutions per minute and may be put down into the second container 20 or the second parking container 42 via a telescopic device of the cover positioning unit 60, and may be positioned between said working position and parking position by means of the cover positioning unit 60.

[0152] The device further comprises cooling elements and/or heating elements for tempering the first and second container 10, 20 as well as a vacuum system for degassing gels ready to be filled up in the first container 10 and/or the mobile storage container (not shown).

[0153] The first container 10 (reaction container) and the second container 20 (supply container) are exchangeably fixed on basis 80, both respectively flanked on both sides by the respective parking containers 41, 42, respectively piston parking containers 51, 52 for placing and optionally cleaning the stirrers 71, 72 and pistons 91, 92, when said pistons 91, 92 are not needed. The additional devices for tempering and degassing as well as a control may be integrated in the basis 80 or may be provided.

[0154] In the following, in one embodiment, by means of FIGS. 1 to 5, the making of a cross-linked hyaluronic acid-containing gel, which is ready to be filled up, is explained in more detail. In one embodiment, this process is partially or fully automatedly controlled by means of a control device (not shown). For this, the control device, in particular the cover positioning unit 60, may control the motors of the stirrers 71, 72, the actuators of the pistons 91, 92, and the valves of the containers 10, 20 which are sealed against the surroundings, in particular the bottom valves 11, 21 and/or the inlet valves at the inlets for HA powder, for BDDE solution, and/or NaOH solution, and may receive data from temperature measuring devices, weighing cells, and the like.

[0155] NaOH solution is provided in the second container 20, in which the second stirrer 72 is in its working position, and is subsequently transferred via bottom valve 21 of this container 20, the passage 30 and the bottom valve 11 in the first container 10 into the first container 10. In the passage 30, a filter is arranged in the form of a sterilized candle filter 31 having 0.2 ?m pore size. Particle filter 31 may be arranged in an accommodation 32.

[0156] Hyaluronic acid (HA) is fed into the first container 10 via a cover opening. The first stirrer 71, which is in its working position in the first container 10, is operated for a short period in order to remove HA from the stirring paddles 72A, 72B. In one embodiment, the addition of the HA amount is controlled by means of weighing cells 81 of basis 80 for weighing the first container 10.

[0157] The addition of NaOH solution is controlled via weighing cell 81 of the first container 10. For this, at first the second stirrer 72 is telescoped out from its first working position by means of cover positioning unit 60 in the second container 20, and is positioned via the second parking container 42, and is telescoped in its parking position in said container. Subsequently, by means of cover positioning unit 60, the second piston 92 is analogously telescoped out from its parking position in the second piston parking container 52, is positioned via the second container 20 and is telescoped in its working position in said second container 20. Subsequently, it transfers by insertion into the second container 20 the NaOH solution into the first container 10. This is shown in FIG. 3, 4. Alternatively, the transfer may also be provided by means of pressure application.

[0158] In another embodiment, NaOH solution is transferred from the second container 20 into the first container 10 as described above. Subsequently, HA is directly fed to container 10.

[0159] By means of high speed stirring, the second stirring tool 71B of the first stirrer 71, HA is mixed with the NaOH solution in the first container. Hereby, the gear is operated in the double transmission. As soon as HA is homogeneously dissolved, BDDE is added under stirring at the same speed of the first stirrer 71. In one embodiment, as soon as this cross-linker is homogeneously distributed in the first solution of hyaluronic acid and NaOH solution, the stirrer is stopped and the first container 10 is heated up to a pre-determined temperature.

[0160] Subsequently, the cross-linking occurs without stirring at a pre-determined temperature over a pre-determined time of period.

[0161] In parallel, in the second container 20, neutralization solution, respectively buffer, is provided. Hereby, at first, the second container 20 is cleaned and is dried, and the particle filter 31, e.g. in the form of a candle filter, is rinsed. Subsequently, phosphate buffer and HCl are added into second container 20, and this neutralization solution is stirred by means of the second stirrer 72 until homogeneity is achieved. The temperature in second container 20 is in the range of from 10 to 35? C. such as 21? C.

[0162] Prior to the neutralization, the first container 10 is tempered to room temperature, for example, approx. 21? C., and the gel is cut with the sharp-edged working surface of the first stirrer 71 at low stirring speed. For this, the gear is operated in the simple transmission at low speed.

[0163] The provided neutralization solution is transferred via passage 30 comprising the candle filter 31 into the first container 10. The control of the addition of neutralization buffer is gravimetrically performed by means of weighing cells 81 of the first container 10. Thereby, for stirring the neutralization solution and for the subsequent transfer into the first container 10, as already explained above, at first the second stirrer 72 and, subsequently in place of said second stirrer 72, the second piston 92 is positioned in the second container 20. In order to reduce the volume of the second container 20 for transferring the neutralization solution in the first container 10, the second piston 92 is inserted into the second container 92. Alternatively, the transfer may be provided by pressure application.

[0164] The gel is stirred at low speed until the neutralization and the pre-determined swelling degree are achieved.

[0165] For carrying out dialysis, the remaining neutralization solution in the second container 20 is discharged, and container 20 is rinsed with filtered water. Dialysis buffer having a volume, which is 10 to 50 times of the gel volume, is provided in a supply unit (not shown), which is in fluid communication with dialysis cell 100 via a sterile candle filter (not shown) having 0.2 p pore size for the sterile filtration of the buffer.

[0166] The dialysis cell 100 is connected to the first container 10, i.e. in fluid communication with container 10. Optionally, first of all, dialysis cell 100 is assembled from perforated plates, membranes and frames, as described in the following with reference to FIG. 7.

[0167] Additionally, stirrer 71 from the first container 10 is positioned by means of cover positioning unit 60 in its parking position in its first parking container 41. Subsequently the first piston 91 may be positioned analogously by means of the cover positioning unit 60 from its parking position in the first piston parking container 51 in its working position in the first container 10, wherein the space between piston and gel, respectively container bottom, is ventilated.

[0168] Now, as presented in FIG. 6, when the ventilation valve is closed (not shown), the first piston 91 is put down to the bottom of the first container 10, and thus the gel is inserted from said container 10 into the dialysis cell 100.

[0169] From a supply unit (not shown) comprising dialysis solution, respectively buffer, the buffer containment of dialysis cell 100 is filled, preferably is filled while avoiding bubbles, and a flow from the supply unit to a storage unit for discarded dialysis solution (not shown) is effected while dialysis solution is e.g. flowing around dialysis cell 100. The buffer solution may be changed during the dialysis; in particular continuously and/or discardingly until the desired extent of dialysis has taken place.

[0170] After dialysis, the gel is in the dialysis cell 100. Subsequent to dialysis, said dialyzed gel is transferred to the first container 10. In one embodiment, the dialyzed gel is transferred to a mobile storage container (not shown).

[0171] In another embodiment, a further viscoelastic gel is added to the dialyzed gel contained in container 10. For this, in the second container 20, a further non-crosslinked viscoelastic gel is provided with or without admixtures. The further viscoelastic gel is controlledly slowly transferred to the first container 10 by means of inserting the second piston 92 into container 20. The quantity control is performed by means of weighing cells 81, respectively 82 of the first container 10, respectively the second container 20. The double-phased gel mixture in the first container 10 is re-stirred. Hereby, as already described above, in turn the first stirrer 71 is positioned in place of the first piston 91 in the first container 10.

[0172] Prior to the filling into a syringe, the gel is either degassed in the first container 10, or is transferred to an additional mobile storage container (not shown), and is degassed therein. The filling in sterile syringes is correspondingly performed from the first container 10 or from the mobile storage container.

[0173] The device shown in FIG. 6 further comprises a control device (not shown) for performing the method defined in the first aspect.

[0174] In one embodiment, thus the method is characterized in that in step a) the hyaluronic acid is fed to the first container 10, and the diluted alkaline solution is fed from a second container 20 to the first container 10, in particular via a filter 31, wherein: [0175] the interior of the first and second container 10, 20 have a temperature in the range of from 3? C. to 50? C., and/or [0176] the diluted alkaline solution is made in the second container 20; and/or [0177] the diluted alkaline solution, prior to the feeding to the first container 10, has a temperature, which deviates from the temperature of the cooling medium in the jacket of the container by 2? C. at the most; and/or [0178] the diluted alkaline solution is fed by means of reducing a container volume of the second container 20, or by means of applying pressure; and/or [0179] the diluted alkaline solution is passed through a particle filter 31; and/or [0180] a fed amount of the diluted alkaline solution is determined by means of weighing means 81 of the first and/or second container 10, 20, and [0181] a provided amount of the hyaluronic acid is fed directly into container 10; and/or [0182] after feeding the hyaluronic acid into the first container 10, a stirrer 71 is operated, in particular time- and/or process-depending and/or with high speed until the hyaluronic acid is completely dissolved, preferably homogeneously dissolved.

[0183] In a further embodiment, the method is characterized in that in step a) the first mixture is provided in a first container 10, and in step b) the cross-linker is fed to said first container 10, wherein [0184] the interior of the first container 10 is tempered to a temperature in the range of from 4? C. to 50? C., in particular corresponding to a pre-determined profile; [0185] the cross-linker, prior to the feeding, has a temperature, which deviates from the temperature in the interior of the first container 10 by 2? C. at the most; and/or [0186] after feeding the cross-linker into the first container 10, a stirrer 71 is operated, in particular process-depending and/or with different speeds until cross-linker is homogeneous distributed.

[0187] In a further embodiment, the method is characterized in that in step b) the cross-linked gel is made in a first container 10, and in step c) the neutralization solution is fed from a second container 20, in particular via a particle filter 31, wherein [0188] in the first and/or second container 10, 20 a stirrer 71, 72 is/are operated, in particular process-depending; and/or [0189] the interior of the first container 10 has a temperature in the range of from 25? C. to 35? C.; and/or [0190] a sample is taken for performing a puncture test; [0191] the neutralization solution is made in the second container 20; and/or [0192] the neutralization solution is fed by means of reducing a container volume of the second container 20; and/or [0193] the neutralization solution is passed through a particle filter 31; and/or [0194] a fed amount of the neutralization solution is determined by means of weight measurement 81 of the first and/or second container 10, 20; [0195] a sample is taken for pH measurement.

[0196] In a further embodiment, the method is characterized in that in step c) the gel is neutralized in first container 10, and is transferred in step e) from said first container 10 into a dialysis cell 100, wherein [0197] the dialysis cell 100 is a dialysis cell as defined in the third aspect, and/or [0198] the dialysis cell 100 comprises a buffer solution, which is changed during dialysis, in particular continuously and/or discardingly; and/or [0199] dialysis time is from 2 to 4 days at a temperature of from 15 to 35? C. [0200] dialyzed gel is transferred back to container 10, which serves as mixing container, where further gel and/or an anesthetic and/or an antioxidant may be added, wherein the formed product may be transferred to a mobile storage container.

[0201] In a further embodiment, the method is characterized in that in step e) the dialyzed gel is mixed in a mixing container with further cross-linked hyaluronic acid and/or non-cross-linked hyaluronic acid, wherein [0202] in the mixing container a stirrer is operated at lower speed, in particular process-depending; and/or [0203] from a further container cross-linked hyaluronic acid and/or the non-cross-linked hyaluronic acid gel is fed to the mixing container, in particular by reducing a container volume of the further container; [0204] a fed amount of the non-cross-linked hyaluronic acid and/or of the further gel is determined by weight measurement of the mixing container and/or further container; and/or [0205] the mixture is degassed prior to the filling in the mixing container or a storage container, in particular a mobile storage container.

[0206] In one embodiment, the mixing container is the first container 10, and the further container is the second container 20.

[0207] In the following, with reference to FIG. 7, dialysis cell 100 is described in more detail.

[0208] Dialysis cell 100 comprises a flat square basis material having a first and a second wall 110, 120 comprising dialysis membranes 112, 122 and stabilizing perforated plates 111, 121. Perforated plates 111, 121 and membranes 112, 122 are secured with a frame-like cover 130 in a form-fit and frictionally engaged manner. This assembly is further secured by a frame in the form of a non-perforated plate. An internal gel compartment 150 of the dialysis cell has a volume of approx. 1 to 4 L and is sealed with a frame 140, which has openings 141 for filling and discharging dialysis cell 100.

[0209] The maximal diffusion paths over days in the gel are not more than 5 to 7 mm depending of the viscosity of gel. The distance (a) between the first and second wall 110, 120 of dialysis cell 100 thus amounts to 10 mm. The dialysis is performed by means of membranes 112, 122, which preferably are construed from a cellulose acetate membrane, or a net made from nylon, PE, PP, or stainless steel. The membranes have a pore size of 10,000 Da at the most, and the net has a pore size of preferably from 10 ?m to 25 ?m, which are permeable for the component to be separated off, however are impermeable for the cross-linked gel.

[0210] Frame 140, perforated plates 111, 121, membranes 112, 122, and cover 130 of dialysis cell 100 are made from plastics, preferably nylon PA12, or stainless steel.

[0211] Dialysis cell 100 in the sectional view of FIG. 7 has from the bottom up to the top the following assembly: The first frame-like cover plate 130A of cover 130 is followed by a first perforated plate 111, a first dialysis membrane 112, which is arranged on said first perforated plate 111 on the inner side, and a protection layer in form of a further plate 113 with recess, which is arranged on said membrane on the inner side, which form the first wall 110, which borders gel compartment 150. On the opposing side thereof, a protection layer in the form of a plate 123 with a recess, a second dialysis membrane 122, which is arranged on second perforated plate 121 on the external side which form the second wall 120, followed by a second frame-like cover plate 130B of cover 130, which is arranged on the second wall 120 on the external side. Dialysis cell, respectively frame 140, further comprises at least one shiftable piston 160 for reducing the volume of dialysis cell 100.

[0212] One of the short sides (right in FIG. 7) of frame 141 serves for filling gel to be dialyzed and discharging the dialyzed gel. On the insert of the other short side a piston 160 is arranged. The filling insert serves by means of its opening for the filling of the gel to be dialyzed into dialysis cell 100, i.e. it serves as inlet opening. The same opening serves for the discharging of the dialyzed gel from dialysis cell 100, i.e. it serves as outlet opening. After terminating the dialysis, the gel may be extruded using the inserted piston.

[0213] In a not shown embodiment of the dialysis, the total gel is filled into dialysis cell 100 (see e.g. FIG. 6). The buffer containment of the dialysis cell is filled with buffer solution with an approx. 10 to 15 fold excess of buffer.

[0214] The dialysis cell can also be provided as a dialysis cell arrangement. In one embodiment, said dialysis arrangement comprises a first dialysis cell (100) and a second dialysis cell (100) as defined above with respect to FIG. 7, wherein said first and second dialysis cell (100) have the same or different volumes, but the same distance (a) between the first and the second wall (110,120).

REFERENCE NUMERALS

[0215] 10 first container [0216] 11 bottom valve [0217] 20 second container [0218] 21 bottom valve [0219] 30 passage [0220] 31 particle filter [0221] 32 accommodation for particle filter 31 [0222] 41 first parking container for first stirrer 71 [0223] 42 second parking container for second stirrer 72 [0224] 51 first piston parking container for first piston 91 [0225] 52 second piston parking container for second piston 92 [0226] 60 cover positioning unit comprising a telescopic unit [0227] 71 first stirrer [0228] 71A, 71B stirring tools in the form of paddles [0229] 72 second stirrer [0230] 72A stirring tool in the form of a paddle [0231] 80 basis [0232] 81, 82 weighing cell (weighing means) [0233] 91 first piston [0234] 92 second piston [0235] 100 dialysis cell [0236] 110 first wall [0237] 111 perforated plate [0238] 112 dialysis membrane [0239] 113 protection layer [0240] 120 second wall [0241] 121 perforated plate [0242] 122 dialysis membrane [0243] 123 protection layer [0244] 130 cover [0245] 130A, 130B cover plate [0246] 140 frame [0247] 141 inlet opening/outlet opening [0248] 150 gel compartment [0249] 160 piston