Tangential flow filter module and method

Abstract

The invention relates to a tangential flow filter module (10) having a first carrier plate (12), a second carrier plate (14) and a permeable membrane (16) arranged between the carrier plates, wherein a plurality of first channels (20) is arranged in the first carrier plate (12) on the side thereof facing the membrane (16), said first channels extending in a flow direction (24) from a first common inlet (26) to a first common outlet (28), wherein a cavity having a second outlet is arranged in the second carrier plate (18) on its side facing the membrane, and wherein the cavity is arranged opposite the plurality of first channels with respect to the membrane. The invention also relates to a tangential flow filter arrangement (100) in which a first such tangential flow filter module (10) and a second such tangential flow filter module (10) are stacked in such a way that the second carrier plate of the first tangential flow filter module and the first carrier plate of the second tangential flow filter module are formed by a common carrier plate.

Description

[0001] Fraunhofer Society for the Advancement of Applied Research eV

[0002] Our reference number: 240738WO

[0003] Tangential flow filter module and method

[0004] DESCRIPTION

[0005] The invention relates to a tangential flow filter module, a tangential flow filter arrangement with at least two such tangential flow filter modules and a method for filtering a colloidal dispersion with at least one fluid phase and objects dispersed therein (particles, molecules, cells, bacteria, viruses, liposomes, vesicles, droplets, etc.) by means of such a tangential flow filter module or such a tangential flow filter arrangement.

[0006] Tangential flow filtration is a fundamental process step in the purification of biomolecules, or more generally, in downstream processing. The method is used, for example, in the purification, concentration, and buffering of nanoliposomes (e.g., liposomal doxorubicin) or in the production of mRNA vaccines and lipid nanoparticles. Furthermore, the method has a long history in the purification of proteins, antibodies, and similar substances.

[0007] A tangential flow filtration module is described, for example, in GB 2594948 A.

[0008] While dialysis or centrifugal filtration are typically used for these process steps in research and laboratory settings, numerous hollow fiber modules and tangential flow filtration modules based on plate stacks are available on the market for production-scale applications. Such modules are either single-use or autoclavable, as required by quality standards (GMP guidelines), for example, in the manufacture of nanopharmaceuticals. For nanoparticle formulation, it is well known that downstream processing has a decisive influence on subsequent product quality attributes. Examples include RNA encapsulation efficiency, stability, size, and size distribution in the production of mRNA vaccines. Therefore, in the case of LNP production for mRNA vaccines, the entire process must be considered, including buffering and concentration.For the approval of new nanopharmaceuticals, attention is therefore paid to Quality by Design (QbD) and Continuous Manufacturing (CM) standards, even at the research and laboratory scale. Consequently, there is a great need for the availability of continuous purification of minute quantities at the research scale.

[0009] On the other hand, a reliable process transfer from research and laboratory scale to production scale is required. It must be taken into account that expensive agents such as research lipids and RNA are only available in small quantities. Therefore, established tangential flow filtration modules for production scale, which have large dead and process volumes, are only conditionally suitable for the downstream processing of colloidal dispersions.

[0010] The object of the invention is therefore to provide a tangential flow filtration module and a method which enables the process-reliable handling of the smallest quantities of a colloidal dispersion and enables comparable downstream processing of colloidal dispersions on a production scale.

[0011] The problem is solved by a tangential flow filter module comprising a first support plate, a second support plate, and a permeable membrane arranged between the support plates. In the first support plate, a plurality of first channels are arranged on its side facing the membrane, extending in a flow direction from a first common inlet to a first common outlet. In the second support plate, a cavity with a second outlet is arranged on its side facing the membrane, and the cavity is positioned opposite the plurality of first channels with respect to the membrane. The first channels are thus functionally connected in parallel. Geometrically, however, the function does not necessitate parallelism of the channels.

[0012] Preferably, the first channels in the first support plate run geometrically parallel to each other for reasons of space requirements, i.e., with regard to the dimensioning of the support plate.

[0013] The majority of the first channels and the cavity are arranged opposite each other with respect to the membrane, meaning that each of the first channels is directly fluidically connected to the cavity through the membrane, thus ensuring unimpeded permeate drainage. The majority of the first channels, the cavity, the inlets, and the outlets are collectively referred to here as the "structure" or "channel structure."

[0014] Furthermore, the first channels in the first support plate preferably exhibit minimal changes in direction (< 30°) and, in particular, run straight. Meandering structures or changes in direction in general, or similar features, cause the formation of dead volumes along the membrane where particles can accumulate, which must be prevented.

[0015] The first support plate, the second support plate, and the membrane positioned between them form a stack. The stack can additionally be sealed by means of a sealing element, such as an O-ring.

[0016] The first channels are preferably microchannels, where microchannels are defined as channels whose dimensions individually lie in the following ranges:

[0017] - Channel length preferably from 20 mm to 500 mm and particularly preferably from 25 mm to 400 mm,

[0018] - Channel volume preferably of 0.02 mm 3 up to 500 mm 3and especially preferably 0.05 mm 3 up to 320 mm 3 and channel cross-sectional area preferably of 0.001 mm² 2 up to 1 mm 2 and especially preferably 0.002 mm 2 up to 0.8 mm 2 .

[0019] The geometry of the first channels preferably provides an aspect ratio (depth to width) of 1:10 to 1:2, and the number of first channels in the first support plate is preferably from 5 to 1000 and particularly preferably from 10 to 500.

[0020] In contrast to the known hollow fiber and tangential flow filtration modules, the tangential flow filter module according to the invention has a very small dead volume due to the microstructuring.

[0021] The design according to the invention simultaneously enables scalability of the tangential flow filter module itself, for example by dimensioning the channel geometries and / or by increasing the number of microchannels per plate, as well as by increasing the number of parallel-connected tangential flow filter modules of the entire tangential flow filter arrangement. This scalability allows for the purification of minute quantities just as easily as production quantities without any changes to the process.

[0022] The first channels are preferably designed such that the fluid passing through them, e.g., the colloidal dispersion, experiences at least approximately the same flow resistance in all channels. Preferably, the majority of the first channels are designed such that, with an inlet pressure of 10 bar at the common inlet, the pressure drops by at least 1 bar across the majority of first channels up to the first common outlet.

[0023] Key geometric factors influencing pressure loss are small channel cross-sections and channel lengths. This pressure loss, in turn, ensures an even distribution of the flow across the majority of the first channels when fed through the common inlet. This division of the fluid flow into individual, ideally identical, lamellae (multilamination) guarantees uniform filtration conditions for the entire fluid. The cavity in the second support plate preferably comprises a plurality of second channels that open into the second outlet, wherein the second outlet forms a second common outlet for all second channels, and wherein each of the second channels is arranged parallel to exactly one of the first channels and opposite it with respect to the membrane.

[0024] The first channels are referred to here as retentate channels and the second channels as permeate channels. Each of the first channels is thus assigned to exactly one of the second channels in such a way that the first and second channels are directly fluidically connected in pairs through the membrane, thereby ensuring an unimpeded outflow of the permeate.

[0025] Therefore, for reasons of space requirements, i.e., with regard to the dimensioning of the support plate, the second channels in the second support plate also preferably run geometrically parallel to each other.

[0026] The cavity in the second support plate particularly preferentially features a second common inlet for all second channels.

[0027] The second common inlet and outlet allow the second channels to be permeated with a medium in the same direction and, in particular, preferably in the opposite direction to the first channels.

[0028] The first common inlet of the first carrier plate preferably comprises one or more inlet openings (also referred to as ports) and a distributor structure that widens from the inlet opening(s) towards the first channels in at least one plane. If the cavity has a plurality of second channels and a second common inlet, the second common inlet of the second carrier plate also preferably comprises one or more inlet openings and a distributor structure that widens from the inlet opening(s) towards the second channels in at least one plane. Furthermore, the first common outlet of the first carrier plate preferably comprises one or more outlet openings (also referred to as ports) and a collector structure that narrows from the first channels towards the outlet opening in at least one plane.And analogous to the inlets, in the case that the cavity has a plurality of second channels and a second common outlet, the second common outlet of the second support plate also preferably comprises one or more outlet openings and a collecting structure that narrows from the second channels towards the outlet opening(s) at least in one plane.

[0029] The multiple ports of the common inlets allow liquids from various sources to be fed to the filter module simultaneously and without reconnection, with the liquids from each of these ports distributing themselves to the majority of the first channels. Similarly, the common outlets allow different connection modules or containers to be connected to them simultaneously and without reconnection.

[0030] In addition to the high pressure drop within the channels, the design of the inlet also contributes to an even distribution of the flows on the individual microchannel plates.

[0031] Continuous removal of the permeate increases the particle concentration in the retentate, thus changing its viscosity. This slows the flow velocity in the first channels from the common inlet to the common outlet. To counteract this, at least partially, the sum of the cross-sectional areas of all first channels, and particularly preferably the cross-sectional areas of each of the first channels in the flow direction from the first common inlet to the first common outlet, is advantageously reduced.

[0032] The narrowing of the channel increases the flow velocity and thus also the shear force along the channel. This effectively carries away the objects retained at the membrane along with the retentate, preventing the membrane from becoming blocked. For example, reducing the channel width at the inlet from 150 pm to 50 pm at the outlet, while maintaining a constant channel depth of 30 pm in the initial channels, can keep the flow velocity across the membrane constant. Alternatively or additionally, the channel height from inlet to outlet can also be reduced if a change in channel width is not desired or sufficient, or if a specific aspect ratio (ratio of channel width to channel depth) needs to be maintained. "Lateral direction" refers to the direction perpendicular to the flow direction in the initial channels, which runs parallel to the membrane.Accordingly, the direction perpendicular to the flow direction and perpendicular to the membrane defines the "depth direction". The width is the channel's extent in the lateral direction, and the depth is its extent in the vertical direction. The channel constriction is preferably chosen such that the desired pressure drop is simultaneously achieved across the majority of the first channels.

[0033] It is particularly preferred that the channel cross-section be wider than it is deep. Accordingly, the aspect ratio of channel width to channel depth is preferably greater than 1 and particularly preferably greater than 2. This condition increases the wall friction compared to a square channel cross-section, making it possible to adjust the flow resistances within the channels as desired and simultaneously increasing the active membrane area.

[0034] The first support plate or the second support plate or the first and the second support plate are preferably made of stainless steel.

[0035] Stainless steel support plates, in conjunction with the aforementioned microstructuring of the channels, exhibit high pressure stability. In particular, inlet pressures of more than 10 bar are theoretically conceivable, resulting in a very high overall efficiency of the tangential flow filter module. Pressures of more than 10 bar up to 100 bar are practically limited only by the available pump pressures and the mechanical strength of the objects (cells, liposomes, lipid nanoparticles, plasmids, mRNA, and the like) in the dispersion to be filtered. Depending on the membrane selected, individual tangential flow filter modules of this type already enable a split ratio, i.e., a ratio of recovered retentate to recovered permeate, of preferably 1:1 to 1:100, and particularly preferably 1:2 to 1:50.This enables the series connection of several tangential flow filter modules, allowing for a simple modular design of single-pass tangential flow filter arrangements, which enables a continuous process, for example, of buffering or solvent removal, with an improvement in purification from the % range to the ppm range.

[0036] In particular, this makes pharmaceutical GMP compliance achievable through manufacturing in pharmaceutical stainless steel, especially in conjunction with a gap- and dead-volume-free design.

[0037] Suitable carrier plates are preferably stainless steel plates with embossed, etched, punched, milled, laser-cut or eroded channels.

[0038] It has also proven advantageous to have a support structure arranged between the second support plate and the membrane, which mechanically stabilizes the membrane.

[0039] Functionally, a support structure is defined as an open-pored substrate with through-holes, which has a higher flexural stiffness than the membrane itself but no additional filtering function, and thus holds the membrane in the plane between the first and second support plates in the event of a pressure gradient between the retentate side on one side of the membrane and the permeate side on the other.

[0040] In this case, the first support plate, the membrane, the support structure and the second support plate form a stack, which can additionally be sealed by means of a sealing element, such as an O-ring.

[0041] If the cavity in the second support plate has multiple second channels, the separating webs between each pair of adjacent second channels can also serve a membrane-supporting function, either as an alternative to or in addition to the support structure. These separating webs are part of the second support plate. The membrane rests on these webs when installed between the first and second support plates. Depending on the width of the channels and the stiffness of the membrane material itself, a support structure may be entirely unnecessary or designed to be less mechanically robust.

[0042] A support structure arranged between the second support plate and the membrane also includes the possibility that it is partially or completely contained within the cavity in the second support plate.

[0043] The support structure is preferably formed by a perforated plate, a textile surface structure, or a sintered structure.

[0044] The perforated panel can be, for example, a honeycomb structure or a perforated sheet made of a plastic or metal material, or a sufficiently stable textile fabric, such as a woven, knitted, braided, woven, nonwoven, or felt, and in particular, made with or from plastic or metal fibers. Another alternative for the supporting structure is a sintered body, for example, made of plastic, glass, or metal granules, or a ceramic material.

[0045] The membrane preferably consists of PES (polyethersulfone), cellulose, in particular regenerated cellulose, cellulose esters or PFDF (polyfluorinated dibenzofurans).

[0046] The membrane preferably has a penetration limit of 1 kDa to 500 kDa.

[0047] The term "pass limit," measured in Da (Da), refers to the molecular weight cut-off (MWCO) or nominal molecular weight cut-off (NMWC) of the membrane. This value describes the smallest average molecular mass of a standard globular molecule that is retained by the membrane at a rate of 90%. For example, a membrane with an MWCO or NMWC of 1 kDa will generally retain objects with a molecular mass of at least 10 kDa. However, the MWCO or NMWC of a membrane is not a precisely defined value. While the diffusion of molecules around and above the MWCO / NMWC is considerably slower and therefore less likely than that of significantly smaller molecules, statistically and practically, molecules above the MWCO / NMWC of the membrane will also diffuse through it and will not be completely retained.

[0048] An alternative classification of the membrane is the nominal pore size, which, according to the invention, is preferably in the range of 0.5 nm to 100 nm. The nominal pore size indicates the maximum in the pore size distribution and therefore cannot provide a precise statement about the retention capacity of the membrane.

[0049] The membrane's permeability limit is the determining factor for the pressure loss when passing through the membrane on the one hand, and for the split ratio on the other.

[0050] The membrane is preferably designed so that it can be cleaned by autoclaving or SIP / CIP processes.

[0051] The first support plate, the membrane, optionally the support structure, optionally the sealing element, and the second support plate are preferably detachably connected to one another. Detachably connected means that the stack can be disassembled and reassembled non-destructively and repeatably. Non-destructive therefore means, in particular, that there is no welded joint or material bond between the elements of the stack.

[0052] The problem is further solved by a tangential flow filter arrangement with at least two tangential flow filter modules as described above, wherein a first of the at least two tangential flow filter modules and a second of the at least two tangential flow filter modules are stacked such that the second support plate of the first tangential flow filter module and the first support plate of the second tangential flow filter module are formed by a common support plate, wherein a plurality of channels are arranged in the common support plate on each of its two sides associated with the first tangential flow filter module and its two sides associated with the second tangential flow filter module. The tangential flow filter arrangement can have any number of tangential flow filter modules of the same type, wherein each pair of adjacent tangential flow filter modules shares a common support plate.This method provides a space-saving, modular tangential flow filter assembly with a small number of different components. Essentially, identical carrier plates and identical membrane support structure layers, optionally with a sealing element, can be stacked in an alternating arrangement between each pair of adjacent carrier plates. Preferably, the first carrier plate of the first tangential flow filter module and the second carrier plate of the last tangential flow filter module in the stack are designed as end plates with a channel structure on only one side, while all other carrier plates are designed as common carrier plates with a channel structure on both sides. The individual tangential flow filter modules within the tangential flow filter assembly can be operated in series or in parallel.

[0053] Accordingly, in one variant, the first common outlet of the first support plate of the first tangential flow filter module is preferably fluidically connected to the first common inlet of the common support plate on its side assigned to the second tangential flow filter module (i.e., the common inlet of the first support plate of the second tangential flow filter module).

[0054] This tangential flow filter arrangement concerns the series connection of two or more tangential flow filter modules in a stack. As with any series connection of functionally identical modules, the retentate concentration increases exponentially with each additional tangential flow filter module in series, unless the retentate is diluted again with an exchange medium for buffering purposes. In the simplest case, the connection is provided by a through-hole through the common support plate, with the flow direction on the permeate side of the first tangential flow filter module and the flow direction on the retentate side of the second tangential flow filter module being opposite. In a parallel connection of two or more tangential flow filter modules in a stack, preferably at least the first common outlets of the first channels of each tangential flow filter module in the stack are fluidically combined.In particular, the first outlet of the first support plate of the first tangential flow filter module and the first outlet of the common support plate are fluidically connected on their side associated with the second tangential flow filter module. Furthermore, the first common inlets of the first channels of each tangential flow filter module are preferably also grouped together in the stack, whereby these are not necessarily supplied from the same source, but preferably under the same physical conditions (pressure, volume flow rate). In this way, the filter capacity and thus the throughput increase linearly with each additional parallel tangential flow filter module. Furthermore, the second (common) outlets of the second channels of each tangential flow filter module can also be grouped together in the stack, and finally, where present, the second (common) inlets of the second channels of each tangential flow filter module can also be grouped together in the stack.

[0055] The problem is further solved by a tangential flow filter arrangement with at least two tangential flow filter modules as described above, wherein a first of the at least two tangential flow filter modules and a second of the at least two tangential flow filter modules are connected in series, wherein the first common outlet of the first carrier plate of the first tangential flow filter module is connected to the first common inlet of the first carrier plate of the second tangential flow filter module by means of a connecting line.

[0056] This tangential flow filter arrangement therefore again involves a series connection of two tangential flow filter modules of the type described above, but in two separate stacks. As with any series connection of identical modules, the concentration of the retentate increases exponentially with each additional tangential flow filter module if the retentate is not diluted again with an exchange medium for buffering purposes. The connecting line of such a series connection preferably has a branch to which a supply line for introducing a medium is connected.

[0057] This arrangement is particularly useful for buffering. After each tangential flow filter module, except for the last one in a series of several tangential flow filter modules of the tangential flow filter arrangement, an exchange medium can be supplied to the retentate via the branch for exchange with the permeate. The viscosity of the dispersion decreases after each exchange step (depending on the viscosity of the exchange medium, possibly returning to the initial value of the colloidal dispersion), and the pressure on the retentate side is maintained at a high level via the tangential flow filter arrangement.

[0058] The tangential flow filter arrangement of the type described above, with two serially connected separate stacks, can advantageously be combined with a parallel connection of two or more tangential flow filter modules in one stack, such that instead of the first of the at least two series-connected tangential flow filter modules, a tangential flow filter arrangement with a parallel connection of two or more tangential flow filter modules is used, wherein the fluidically connected outlets of the parallel tangential flow filter arrangement are connected together with the common inlet of the second tangential flow filter module (in series connection).

[0059] For example, two parallel-connected tangential flow filter modules, with their connected first outlets, can be cascaded in series with the first inlet of the first carrier plate of a single additional tangential flow filter module (identical in terms of its filter capacity). In this case, the reduced volumetric flow rate of the retentives of both parallel-connected tangential flow filter modules is at least partially compensated for by the reduced filter capacity of the single additional tangential flow filter module, thus increasing the flow velocity in the second tangential flow filter module, at least somewhat. The overall goal is to increase the number of parallel-connected tangential flow filter modules in the tangential flow filter arrangement to such an extent that the inlet pressure of the single additional tangential flow filter module is (approximately) equal to the inlet pressure of each of the parallel-connected tangential flow filter modules.

[0060] The problem is further solved by a method for filtering a colloidal dispersion using a tangential flow filter module or in a tangential flow filter arrangement of the type described above, wherein the colloidal dispersion is fed to the first common inlet of the first support plate under an overpressure pi and directed into the majority of the first channels, wherein a permeate is discharged transversely to the channel direction through the membrane into the cavity and from there through the second outlet under an overpressure ps < pi, and wherein a retentate is discharged through the first common outlet of the first support plate under an overpressure p2 < pi.

[0061] The inlet pressure, i.e., the pressure at which the colloidal dispersion is supplied to the common inlet of the first carrier plate, is preferably in the range of 1.2 bar to 25 bar. The pressures are further preferably set such that the pressure difference π - p2, i.e., the pressure difference across the multiple first channels, is from 0.1 bar to 15 bar, and the pressure difference π - ps, i.e., the pressure difference across the membrane, is from 0.01 bar to 10 bar. Particularly preferably, the pressures are set such that the pressure difference across the first channels and across the membrane is equal, or in other words, that p2 = ps.

[0062] In the process according to the invention, the pressures are preferably set such that the total flow rate of the filtrate, i.e., the retentate and the permeate combined, is preferably from 0.1 mL / min to 2.5 L / min and particularly preferably from 0.25 mL / min to 2 L / min. For this purpose, (multiple) piston pumps are used, for example, to ensure gentle filtrate handling.

[0063] In the case of a tangential flow filter module in which the cavity comprises a plurality of second channels extending in the flow direction from a second common inlet to the second outlet, a medium is preferably supplied to the second common inlet of the second support plate at an overpressure p4 and directed into the plurality of second channels and discharged through the common outlet of the first support plate at an overpressure ps < p4, wherein the flow direction in the second channels is parallel and opposite to the flow direction in the first channels.

[0064] This design of the process allows the tangential flow filter module to be used in a type of "reverse osmosis operation." For example, during buffering, the second channels (permeate channels) are flowed through in countercurrent flow to the first channels (retentate channels) to counteract the pressure gradient within the retentate channels from the common first inlet to the common first outlet. The permeate is thus substituted by the medium introduced into the second channels during filtration, allowing the retentate to retain its viscosity. This keeps the flow velocity on the retentate side across the membrane constant, flushes out any particles retained by the membrane with the retentate without adhesion, and prevents the membrane from becoming blocked.

[0065] Advantageously, the inventive method is used at least once for purification, buffer exchange, or concentration in the production of RNA, liposomes, lipid nanoparticles, biomacromolecules, proteins, enzymes, antibodies, exosomes, nucleic acids, polymers and polymer nanoparticles, polymersomes, niosomes, and extracellular vesicles.

[0066] Accordingly, the tangential flow filter module or the tangential flow filter arrangement according to the invention is advantageously used in at least one process step of purification, buffer exchange, or concentration in a process for processing RNA, liposomes, lipid nanoparticles, biomacromolecules, proteins, enzymes, antibodies, exosomes, nucleic acids, polymers and polymer nanoparticles, polymersomes, niosomes, and extracellular vesicles in one of the embodiments described above.

[0067] Further advantages and features of the invention are explained below with reference to the figures. Figure 1 shows a schematic unfolded view of an embodiment of the tangential flow filter module according to the invention;

[0068] Figure 2 shows a schematic exploded view of an embodiment of the tangential flow filter module according to the invention;

[0069] Figure 3 shows an exploded view of a modified embodiment of the tangential flow filter module according to the invention;

[0070] Figures 4A and 4B show two exploded views of an embodiment of the tangential flow filter arrangement according to the invention and

[0071] Figure 5 shows a schematic representation of an embodiment of the tangential flux filter arrangement according to the invention in series connection.

[0072] The tangential flow filter module 10 according to Figure 1 has a first support plate 12 and a second support plate 14, which are shown here unfolded and lying one above the other. The structures in the first support plate 12 and in the second support plate 14 are therefore mirror images and coincide exactly when the two support plates 12 and 14 are assembled to form the tangential flow filter module 10.

[0073] Between the two support plates 12 and 14, a permeable membrane 16 in contact with the first support plate 12 and a support structure 18 in contact with the second support plate 14 are shown.

[0074] In the first support plate 12, a plurality of first channels 20 are arranged on its side facing the membrane, each separated from the other by separating webs 22 transversely to its longitudinal direction. The illustration in Figure 1 is schematic insofar as the channels lie beneath the membrane in this view and would therefore, strictly speaking, not be visible. The first channels 20 extend in the flow direction 24 from a first common inlet 26 to a first common outlet 28. The first common inlet 26 comprises an inlet opening 30 and a distributor structure 32 that widens from the inlet opening 30 towards the plurality of first channels 20 in the plane of the support plate 12. The first common outlet 28 comprises an outlet opening 34 and a collecting structure 36 that narrows from the plurality of first channels 20 towards the outlet opening in the plane of the support plate 12.

[0075] Along the edge of the first support plate 12, a sealing element 50 is arranged, surrounding all structural elements in the support plate 12 (channels, distribution structures, inlet openings). This sealing element rests against the membrane 16 on one side and, in the assembled state, against the support plate 14 on the other. Furthermore, two annular sealing elements (o-rings) 52 are visible, which enclose mounting bores 55 and also rest against the membrane 16 on one side and, in the assembled state, against the second support plate 14 on the other. If the support plates 12 and 14 are pressed against each other after assembly, for example by means of screws through the mounting bores, the membrane 16 rests tightly against the first support plate 12 and allows permeate to diffuse only perpendicular to the channel structure. On the other side, the sealing elements 50, 54, and 55 close the cavity, respectively.The channel structure in the second carrier plate 14 is peripherally fluid-tight, so that no permeate can escape, for example, through the mounting holes 55 or laterally from the stack.

[0076] The structure in the second support plate 14 is a mirror image of that in the first support plate 12. On its side facing the support structure 18 and the membrane 16, it has a plurality of second channels 40, each of which is separated from the other by separating webs 42 transversely to its longitudinal direction. The second channels 40 open into a second common outlet 44, which is divided into two parts and comprises an outlet opening 46 at each of the open ends of the channels 40 and a collecting structure 48 that narrows from the plurality of the second channels 40 towards the respective outlet opening 46 in the plane of the support plate 12. The second channels 40 formed in the second support plate 14 together constitute the cavity.The channels 20, 40, the distributor and the collecting structures 32, 36, 48 each run parallel to each other and each form recesses in the first and the second support plate 12, 14, which are exactly opposite each other in the assembled state of the tangential flow filter module 10.

[0077] Figure 2 shows a similar tangential flow filter module 10 in an exploded view to illustrate the stack structure, in which the channels are omitted for simplification. From top to bottom, the stack comprises the first support plate 12, the membrane 16, below it the support structure 18, and at the bottom the second support plate 14. A sealing element 50 is arranged around the support structure 18 and the membrane 16, functioning somewhat differently than the one described previously. When the support plates 12 and 14 are pressed against each other after assembly, the elastic sealing element 50 is compressed in the direction of the contact pressure until the membrane 16 is tightly in contact with the support plate 12. In doing so, the sealing element 50 seals the space between the plates to the outside and simultaneously expands in the plane of the space between the plates, thereby also sealing the membrane 16 and the support structure 18 peripherally.The sealing element therefore functions here as both an axial seal and a radial seal.

[0078] The inlet opening or port for the colloid dispersion as well as the outlet openings or ports for the retentate and for the permeate are each provided with connection nozzles 53 on the outside of the carrier plates 12 and 14, to which syringes 56 are connected via hoses 54 as pumps to maintain a certain pressure gradient within the channels and across the membrane between the retentate and permeate sides.

[0079] The exploded view in Figure 3 shows a slightly less schematic exploded view of an embodiment of the tangential flow filter module. Here, too, the stack comprises, from top to bottom, the first support plate 12, the membrane 16, below it the support structure 18, and at the bottom the second support plate 14. A sealing element 50 is again arranged around the support structure 18 and the membrane 16, sealing the plate stack to the environment in the same way as previously described in connection with Figure 3. The structures of the channels 20, dividers 22, distributor structures 32, 36, and inlet and outlet openings 30, 34 correspond to those in Figure 1. Connecting pipes or hoses 60 project from the top and bottom, respectively, into the first and second support plates 12, 14, providing a fluidic connection to the inlet and outlet openings 30, 34, and 46.

[0080] The first and second support plates 12, 14 and the sealing element each have peripheral mounting holes 55 for receiving mounting screws (not shown here), which press the support plates 12, 14 against each other. The sealing element 50 surrounds each of the mounting holes 55 and also seals the space between the plates against these holes.

[0081] An embodiment of the tangential flow filter arrangement 100 according to the invention, comprising three tangential flow filter modules 110, 111, 112, is shown in Figures 4A and 4B in two exploded views from different perspectives.

[0082] The first tangential flow filter module 110 has a first support plate 113 and a second support plate 114. The second tangential flow filter module 111 has a first support plate 114 and a second support plate 115. The first tangential flow filter module 110 and the second tangential flow filter module 111 are stacked such that the second support plate of the first tangential flow filter module 110 and the first support plate of the second tangential flow filter module are formed by a common support plate 114.The same applies to the third tangential flow filter module 1 12, which in turn has a first support plate 1 15 and a second support plate 116, wherein the second tangential flow filter module 1 11 and the third tangential flow filter module 112 are stacked such that the second support plate of the second tangential flow filter module 111 and the first support plate of the third tangential flow filter module 112 are formed by a common support plate 115.

[0083] Between the first support plate 113 and the second support plate 114 of the first tangential flow filter module 110, as well as between the first support plate 114 and the second support plate 115 of the second tangential flow filter module 111, and between the first support plate 115 and the second support plate 116 of the third tangential flow filter module 112, a permeable membrane 117 is arranged in contact with the respective first support plate 113, 114, 115, and a support structure 118 is arranged in contact with the respective second support plate 114, 115, 116. A sealing element 150 is arranged around each of the support structures 118 and the membranes 116, sealing the stack of plates all around in the assembled state, as described in connection with Figure 3.It should be noted that in Figures 4A and 4B, the membrane, the support structure, and the sealing element are shown separately only in the case of the first tangential flow filter module 110. In the case of the second tangential flow filter module 111, the membrane and the support structure are combined, and in the case of the third first tangential flow filter module 112, the membrane, the support structure, and the sealing element are combined and shown resting on the associated second support plate 116.

[0084] The structures of the first channels 120, and their separating webs 122, of the second channels 140 and their separating webs 142, of the distributor structures 132, 136, 148 of the inlet and outlet openings 130, 134, 146 correspond in each of the three tangential flow filter modules 110, 111, 112 to those in Figure 1 and in Figure 3, wherein in the common support plate 114, 115 a plurality of second channels 140 is arranged on each of its sides associated with the upper tangential flow filter module 110, 111 and a plurality of first channels 120 is arranged on each of its sides associated with the lower tangential flow filter module 111, 112.

[0085] The first common outlets 128 of the first support plates 113, 114, 115 of the first, second, and third tangential flow filter modules 110, 111, 112 are fluidically connected. Likewise, the first common inlets 126 of the first support plates 113, 114, 115 of the first, second, and third tangential flow filter modules 110, 111, 112 are fluidically connected. Finally, the second common outlets 144 of the second channels of the first, second, and third tangential flow filter modules 110, 111, 112 are also connected in the stack. Thus, the three tangential flow filter modules 1 10, 111 , 112 are operated completely in parallel, which triples the filter capacity of the tangential flow filter arrangement compared to that of a single tangential flow filter module.Figure 5 shows a schematic representation of an embodiment of the tangential flow filter arrangement 200 according to the invention, illustrating a buffering process. The arrangement comprises two separate tangential flow filter modules 210 and 211 as described above, connected in series. A colloidal dispersion to be buffered is supplied to the first tangential flow filter module 210 via the first common inlet at 222 by means of a first pump 220 at an overpressure of 8 bar. Within the first tangential flow filter module 210, the dispersion is split into a retentate stream and a permeate stream. The pressure on the permeate side drops to 4 bar across the membrane. A connecting line 224 is connected to the first common outlet of the first tangential flow filter module 210, linking it to the first common inlet of the second tangential flow filter module 211.The connecting line 224 of this series circuit has a branch 226 to which a supply line 228 is connected. A second pump 230 feeds an exchange medium into the connecting line 220 via this supply line 228 at an overpressure of 4 bar. The medium replaces the volume loss of the permeate from the first tangential flow filter module 210 and accordingly maintains the pressure on the retentate side at 4 bar. Similarly, an overpressure of 4 bar is advantageously set on the permeate side at the second outlet of the first tangential flow filter module 210 at 232 by means of an adjustable pressure relief valve 234, which discharges permeate at a higher pressure at the outlet 236 to ambient pressure.

[0086] The already diluted colloidal dispersion is fed to the second tangential flow filter module 211 via its first common inlet at 238, at an overpressure of 4 bar. Within the second tangential flow filter module 211, the dispersion is again divided into a retentate stream and a filtered permeate stream. The pressure across the membrane at the second outlet (permeate side) at 240 and at the first common outlet of the second tangential flow filter module 211 (retentate side) at 242 drops to ambient pressure. Thus, in this example, the pressure drops by 4 bar after each tangential flow filter module. If further dilution stages were to be added, the inlet pressure would have to be increased by another 4 bar for each stage.

[0087] Pressure stability is therefore important for single-pass tangential flow filter arrangements, where several tangential flow filter modules must be connected in series.

[0088] For example, if a solvent concentration of 20% in a dispersion needs to be reduced to below 100 ppm, a cascade of three tangential flow filter modules, each concentrating by a factor of 15, is required. The inlet pressure at the first tangential flow filter module is then, for example, 15 bar, while the retentate outlet pressure is maintained at 10 bar by adding a diluent, and the permeate outlet pressure is maintained at 10 bar by using a differential pressure valve. The dilution of the retentate corresponds to the previous concentration, i.e., a factor of 15. Therefore, the remaining solvent concentration after the first tangential flow filter module is only 1.333%.

[0089] The inlet pressure at the second tangential flow filter module is therefore 10 bar. The retentate outlet pressure is again maintained at 5 bar by introducing a diluent, and the permeate outlet pressure is maintained at 5 bar by means of a differential pressure valve. The subsequent dilution of the retentate again corresponds to the previously achieved concentration, i.e., a factor of 15. The remaining solvent concentration after the second tangential flow filter module is therefore only 60 ppm.

[0090] The tangential flow filter module or the tangential flow filter arrangement according to the invention can be used, for example, in the RNA production summarized below.

[0091] RNA production is currently carried out predominantly in batch processes. For this, the plasmid (in a circular form) is enzymatically linearized in a stirred tank reactor. The first purification step then involves a diafiltration process with buffer exchange to prepare the linearized plasmid. At this point, the invention enables a continuous process (single-pass) using a tangential flow filter, as described above, instead of the previously used batch process, even for very small quantities. The linearized, purified plasmid is then returned to a batch-operated stirred tank reactor where in vitro transcription takes place, i.e., the enzymatic synthesis and translation of DNA into mRNA. Afterward, the plasmid template is degraded by DNase.This is followed by another diafiltration iteration with buffer change, in which the invention is again advantageously employed, before the mRNA is finely purified by chromatography. The mRNA is then concentrated by another diafiltration with buffer change to adjust the pH and osmolarity. Here, the inventive method is advantageously employed a third time. Subsequent 0.2 pm sterile filtration yields the pharmaceutically active mRNA component, which is then used for product filling.

[0092] Another area of ​​application is the continuous production or downstream processing (purification, rebuffering, concentration) of liposomes or lipid nanoparticles (LNPs). The stability of the liposome dispersion and the lipid nanoparticle dispersions, as well as various critical quality attributes such as particle size or the encapsulation rate of the lipid nanoparticles, are strongly dependent on the residual organic solvent content. This should therefore be significantly reduced from approximately 20–30% after the initial continuous mixing of the nanoparticle formulation or particle formation by means of an initial dilution. A waiting period of seconds to minutes may then be advantageous to allow for reorganization and initial stabilization of the particles. By connecting several of the tangential flow filter modules according to the invention in series, a pH or pH value can be achieved simultaneously with the addition of buffer or salt / sugar solutions.Osmolarity is adjusted and the solvent content is reduced. In the final step, without any further addition of solvent, the dispersion is concentrated.

[0093] Other areas of application of the invention include production processes of biomacromolecules, such as therapeutic viruses, proteins, enzymes, antibodies, exosomes, nucleic acids, polymers and polymer nanoparticles, polymersomes, niosomes or extracellular vesicles.

[0094] Reference symbol list

[0095] 10 Tangential flow filter module

[0096] 12 first support plate

[0097] 14 second support plate

[0098] 16 Membran

[0099] 18 Support structure

[0100] 20 first channel

[0101] 22 dividing bridge

[0102] 24 Flow direction

[0103] 26 first joint entry

[0104] 28 first common outlet

[0105] 30 Entrance opening

[0106] 32 Distribution structure

[0107] 34 Outlet opening

[0108] 36 Collection structure

[0109] 38 mounting holes

[0110] 40 second channel

[0111] 42 dividing bridge

[0112] 44 second common outlet

[0113] 46 Outlet opening

[0114] 48 Collection structure

[0115] 50 sealing elements

[0116] 52 Sealing element, O-ring

[0117] 53 connection spigots

[0118] 54 hose

[0119] 56 syringes

[0120] 60 Connecting pipe, hose 100 Tangential flow filter assembly

[0121] 110 Tangential flow filter module

[0122] 111 Tangential flow filter module

[0123] 112 Tangential flow filter module

[0124] 113 First support plate of the first tangential flow filter module

[0125] 114 common carrier plate

[0126] 115 common carrier plate

[0127] 116 second support plate of the third tangential flow filter module

[0128] 117 Membran

[0129] 118 Support structure

[0130] 120 first channel

[0131] 122 Dividing Bridge

[0132] 126 first joint admission

[0133] 128 first common outlet

[0134] 130 Entrance opening

[0135] 132 Distribution structure

[0136] 134 Outlet opening

[0137] 136 Distribution structure

[0138] 140 second channel

[0139] 142 dividing bridge

[0140] 144 second common outlet

[0141] 146 Outlet opening

[0142] 148 Distribution structure

[0143] 150 sealing elements

[0144] 200 tangential flow filter arrangement

[0145] 210 first tangential flow filter module

[0146] 211 second tangential flow filter module

[0147] 220 first pump

[0148] 222 first inlet of the first tangential flow filter module

[0149] 224 Connecting cable

[0150] 226 Branch

[0151] 228 Supply line second pump second outlet of the first tangential flow filter module pressure relief valve outlet of the pressure relief valve first inlet of the second tangential flow filter module second outlet of the second tangential flow filter module first outlet of the second tangential flow filter module

Claims

Patent claims 1. Tangential flow filter module (10) comprising a first support plate (12), a second support plate (14) and a permeable membrane (16) arranged between the support plates, wherein in the first support plate (12) a plurality of first channels (20) are arranged on its side facing the membrane (16), which extend in a flow direction (24) from a first common inlet (26) to a first common outlet (28), wherein in the second support plate (18) a cavity with a second outlet (44) is arranged on its side facing the membrane, and wherein the cavity is arranged opposite the plurality of first channels (20) with respect to the membrane (16).

2. Tangential flow filter module (10) according to claim 1, characterized in that the cavity comprises a plurality of second channels (40) opening into the second outlet (44), wherein the second outlet (44) forms a second common outlet of all second channels (40) and wherein each of the second channels (40) is arranged parallel to exactly one of the first channels (20) and opposite the membrane (16).

3. Tangential flow filter module (10) according to claim 1 or 2, characterized in that the first common inlet (26) of the first carrier plate (12) comprises one or more inlet openings (30) and a distributor structure (32) widening from the inlet opening(s) (30) towards the first channels (20) at least in one plane, and / or that a second common inlet is provided in the second carrier plate (14) comprising one or more inlet openings and a distributor structure (32) widening from the or comprising a distributor structure that widens at least in one plane towards the inlet openings towards the second channels (40).

4. Tangential flow filter module (10) according to one of the preceding claims, characterized in that the first common outlet (28) of the first support plate (12) comprises one or more outlet openings (34) and a collecting structure (36) narrowing from the first channels (20) towards the outlet opening (34) at least in one plane and / or that the second common outlet (44) of the second support plate (14) comprises one or more outlet openings (46) and a collecting structure (48) narrowing from the second channels (40) towards the outlet opening (46) at least in one plane.

5. Tangential flow filter module (10) according to one of the preceding claims, characterized in that the first channels (20) run parallel to each other and / or that the second channels (40) run parallel to each other.

6. Tangential flow filter module (10) according to one of the preceding claims, characterized in that the plurality of the first channels (20) is designed such that, with an inlet pressure of 10 bar applied to the first common inlet (26), the pressure drops by at least 1 bar across the plurality of first channels (20) to the first common outlet (28).

7. Tangential flow filter module (10) according to one of the preceding claims, characterized in that the sum of the cross-sectional areas of all first channels (20) and preferably the cross-sectional area of ​​each of the first channels (20) is oriented in the flow direction narrowed from the first common inlet (26) to the first common outlet (28).

8. Tangential flow filter module (10) according to one of the preceding claims, characterized in that the first support plate (12) or the second support plate (14) or the first and the second support plate are made of stainless steel.

9. Tangential flow filter module (10) according to one of the preceding claims, characterized in that a support structure (18) is arranged between the second support plate (14) and the membrane (16), which mechanically stabilizes the membrane (16).

10. Tangential flow filter module (10) according to one of the preceding claims, characterized in that the membrane (16) consists of PES (polyethersulfone), cellulose, cellulose esters or PFDF (polyfluorinated dibenzofurans).

11. Tangential flow filter arrangement (100) with at least two tangential flow filter modules (110, 111, 112) according to one of the preceding claims, characterized in that a first of the at least two tangential flow filter modules (110, 111, 112) and a second of the at least two tangential flow filter modules (110, 111, 112) are stacked in such a way that the second support plate of the first tangential flow filter module and the first support plate of the second tangential flow filter module are formed by a common support plate (114, 115), wherein in the common support plate (114, 115) on its two surfaces assigned to the first tangential flow filter module (110, 111) and the second Each of the sides associated with the tangential flow filter module (111 , 112) has a plurality of channels (120) arranged.

12. Tangential flow filter arrangement (100) according to claim 1 1 , characterized in that the first common outlet of the first support plate (113) of the first tangential flow filter module (110) is fluidically connected to the first common inlet of the common support plate (1 14) on its side associated with the second tangential flow filter module (111).

13. Tangential flow filter arrangement (100) according to claim 1 1 , characterized in that the first common outlet (128) of the first support plate (113) of the first tangential flow filter module (110) and the first common outlet (128) of the common support plate (114) are fluidically connected on their side associated with the second tangential flow filter module (111).

14. Tangential flow filter arrangement (100) with at least two tangential flow filter modules (10) according to one of claims 1 to 10, characterized in that a first of the at least two tangential flow filter modules (10, 210, 211 ) and a second of the at least two tangential flow filter modules (10, 210, 211 ) are connected in series, wherein the first common outlet (28) of the first carrier plate (12) of the first tangential flow filter module (10, 210) is connected to the first common inlet (26, 238) of the first carrier plate (12) of the second tangential flow filter module (10, 211) by means of a connecting line (224).

15. Tangential flow filter arrangement (100) according to claim 14, characterized in that the connecting line (224) has a branch (226) to which a supply line (228) for supplying a medium is connected.

16. Tangential flow filter arrangement (100) according to claim 14 or claim 15, characterized in that instead of the first of the at least two tangential flow filter modules (10) a tangential flow filter arrangement (100) according to claim 13 is used, wherein the fluidically connected outlets of the tangential flow filter arrangement (100) according to claim 13 are connected together with the first common inlet (26, 238) of the second tangential flow filter module (10) according to claim 14 or 15.

17. Method for filtering a colloidal dispersion using a tangential flow filter module (10) or in a tangential flow filter arrangement (100) according to one of the preceding claims, wherein the colloidal dispersion is fed to the first common inlet of the first support plate under an overpressure pi and directed into the plurality of the first channels, wherein a permeate is directed transversely to the channel direction through the membrane into the cavity and from there is discharged through the second outlet under an overpressure ps < pi and wherein a retentate is discharged through the first common outlet of the first support plate under an overpressure p2 < pi.

18. Method according to claim 17, characterized in that a medium is supplied to the second common inlet of the second carrier plate under an overpressure ps and directed into the plurality of the second channels and discharged through the second common outlet of the first carrier plate under an overpressure p4 < p3, wherein the flow direction in the second channels is parallel and opposite to the flow direction in the first channels.

19. Method according to one of claims 17 or 18, characterized in that it is used at least once for purification, buffer exchange, or concentration in the production of RNA, liposomes, lipid nanoparticles, biomacromolecules, proteins, enzymes, antibodies, exosomes, nucleic acids, polymers and polymer nanoparticles, polymersomes, niosomes, extracellular vesicles.

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