Patent Application
20250128219
The present invention relates to container systems for mixing and storing fluid compositions used in biopharmaceutical field. It also relates to a method for mixing a biopharmaceutical composition in single-use bioreactor, in which a stirrer is driven from below.
By “biopharmaceutical composition”, it is meant a product coming from biotechnology, culture environments, cell cultures, buffer solutions, artificial nutrition liquids, blood products and derivatives of blood products, or a pharmaceutical product, or more generally, a product intended to be used in the medical field. Such a product/composition is in liquid or paste form after mixing. The invention also applies to the filling of flexible pouches with other products but subjected to similar requirements concerning the packaging thereof.
The mixing and/or suspension of solutions is ubiquitous in many technologies. For example, biotech companies use extensive amounts of culture media, buffers, and reagents. Such materials originally come in powdered form and must be hydrated with purified water prior to use. The hydration process typically comprises combining a precise amount of powdered material and purified water in a closed reservoir. As disclosed for instance in document U.S. Pat. No. 7,153,021 B2, the reservoir is typically a bag of flexible plastic material, which is a disposable/single-use 3D fillable bag. The bag, which may have a polygonal section, is disposed inside a rigid container of cylindrical shape. A special mixer is then used to mix the components into the desired solution. A stir member is provided inside the bag and is driven from below. As disclosed in document US 2011/0158037, bags can be removably placed in a rigid container having same transverse rectangular section as the side wall of the bag, allowing a centering of the stir member. In use, such bag of parallelepiped shape is provided with a spraying and dispersing device at a bag upper wall of rectangular section.
Use of collapsible bags having side panels is of interest for storing the bag before use, in a folded state. When draining, the bag easily collapses. Commercially available bags Flexsafe® Pro Mixer, from Sartorius Stedim, are designed to fit inside a rigid container and are suitable to contain various amounts of products to be mixed since the stirring device is located on the bottom wall of the bag.
In 3-D bags of this type, single-use and configured to receive a biopharmaceutical product, the volume is typically delimited by a lower end wall, an upper end wall and a flexible lateral wall, which could be located in two extreme states—folded-flat and expanded-unfolded. The 3-D bag can be deformed to pass from either of these states or be in a whole intermediate state. The walls of the bag, composed of a single-layer or multilayer film, made of plastic material such as polyethylene or a complex comprising polyethylene, delimit an inner space which, in folded state, is of minimum volume and, in unfolded and expanded state, is maximum. Such a flexible bag, biocompatible, single use, can be of significant volume (1000 L for instance). Such a bag thus offers a significant capacity, while being able to be easily stored. The U.S. Pat. No. 10,232,331 B2 discloses a rigid container receiving such bag, the rigid container being provided with a movable drive unit to drive the stirring device from below.
In large-scale operations, the use of flexible bags supported by an outer stainless-steel support vessel allows single-use operation. A rectangular section of the support vessel may be preferred for controlling the folding and unfolding operations. However, at such large scales, mixing efficiency becomes an issue and accordingly there is a need for large scale single-use systems with improved mixing. Document U.S. Pat. No. 10,857,510 B2 discloses a bioprocess mixer, provided with two magnetic impellers driven from below, making the system relatively complex. Such bioprocess mixer, with aim at overcoming issues for rapid mixing large volumes, requires a driving solution that is relatively complex.
There is thus still room for improving mixing, using bags that are convenient, for instance using a kind of collapsible bag easy to transport in an initially folded state, with a stirring device included in the interior volume of the disposable bag.
Embodiments of the invention provide an apparatus capable of mixing a biopharmaceutical composition including a liquid, comprising:
where p is an inner perimeter at the base to delimit the receiving compartment, r is a curvature radius as measured at any one of the four rounded corners, and V2 is the capacity of the bag.
Thanks to this arrangement, the stirring device 3 may act more efficiently to create a vortex at upper level of the liquid present in the interior volume, despite significant height which may be superior to 900 mm, preferably superior to 1600 mm. The significant rounding at the bag corners RC1, RC2, RC3, RC4 is formed because the bag 2 no longer touches the walls of the tank in the corners and because of enough reduction of the contact area with the tank panels. The radius of curvature can be more than 160 mm when the bag perimeter p delimits at/along the base is in the range [3000−4200] mm. It is understood that the ratio r/p can be greater than 0.05 and lower than 0.10, in some options. When the perimeter p corresponding to tank inner section is about 4000 mm, the radius of curvature r may thus be much larger than 100 mm and possibly lower than 400 mm.
The bag 2 may withstand liquid pressures by having a multilayer film thickness broadly greater than 100 or 200 micrometers, for instance greater than 380 micrometers but less than 700 micrometers. The film material of the bag 2 thus can remain flexible (easy to fold/unfold), facilitating folding when filling the bag 2 and collapsing effect when draining the product. The wide central face portions of the bag may stretch under the liquid pressure to meet the walls of the tank while the corners stretch much less, creating more of a radius in each corner.
The mixing occurs for large volumes, including the case of a capacity greater than 2000 L, without waiting too much time (typically about two minutes or less) after starting the rotation of a lower impeller or any suitable stirring part of the stirring device.
In some options, a lifting and deployment of the mixing bag are performed before any mixing, in order to ensure the top wall of the bag is initially at least 1500 or 2000 mm higher than the bottom wall. This is of interest to prevent undesirable folds in the bag sidewall.
In practice, it is desirable that the flexible bag can be expanded without undesirable folding which limits the actual folding volume. Instead of requiring a human monitoring, because of the expansion defects, a lift system may be fasted to the tank, in order to lift a top end of the bag before any unfolding of the sidewall due to liquid pressure.
Optionally, the bag is a gusseted bag with two opposite gussets.
The two gussets may interconnect two outer sheets of greater surface than the gussets. The gussets are each delimited between a pair of longitudinal seams, so that the bag includes four longitudinal seams, a portion thereof can extend vertically in parallelepiped configuration of the bag, forming corner seams as view in any cross-section.
Typically, with such arrangement, the longitudinal seams, forming corner seams as view in any cross section, can be maintained each at a distance from the rigid walls of the outer tank. The seams may of high strength as compared to plastic material strength for the bag. In such case, the pouch withstands the weight of the content and keep a generally rectangular section due to the very strong seams. Preferably, an overlapping width at the welded regions forming the longitudinal seams is superior or equal to 6 or 7 mm, for instance between, 7 or 8 mm and 15 or 20 mm.
The central faces of the bag stretch under the flowable content pressure (water pressure for instance) to meet the walls of the outer tank while the corners stretch much less, creating more of a radius in each corner.
Using such kind of bag able to stretch for contacting the inner face of the tank selectively in areas away from the tank edges, with a significant rounding in the corners of the cross-section of the bag, facilitates creating proper vortex to quickly (typically less than two minutes) mix the liquids or the liquid and the solid (for instance powder material).
Option with seams of high strength, vertical and stronger that the bag wall may be of interest for having low or no variation of the bag cross-section in the part of the bag filled with liquid.
In some embodiments, the bag is in contact with each of the four panels that are vertical panels. Contact between the bag and each of the four vertical panels may obtained at four respective rectangular contact areas which extend each upwardly from the base. Typically, the rectangular contact area along a given panel is obtained with a contact width representing more than 50%, preferably, at least 60%, of the panel width of the given panel.
In various embodiments of the present invention, one or more of the following arrangements may possibly be employed, separately or in combination:
In some embodiments, the bag has opposite end seals. Either the two end seals are distributed in the bottom wall and the top wall, with the stirring device comprising an impeller that is shifted laterally relative to the end seal provided in the bottom wall, or the two end seals are provided in the tubular side wall, with the stirring device comprising an impeller that is preferably arranged centrally with respect to the bottom wall.
Optionally, the bag comprises:
It is also provided a method for mixing in single-use bioreactors, using a bag specifically designed to contain a biopharmaceutical composition including a liquid, wherein the bag, made of flexible plastic material, is a 3D-bag adapted to have a parallelepiped configuration so that the bag is provided with a bottom wall, a top wall and a tubular sidewall extending from the bottom wall to the top wall, the method comprising unfolding the bag due to liquid pressure of a liquid, without any contact of corners formed at any cross-section thereof below liquid upper level with sides panels of a tank, in which the bag is received, wherein liquid content of the bag is mixed by a stirring device extending in the bag and optionally driven from below a base of the tank.
The method may comprise the steps essentially consisting in:
where p is an inner perimeter at said base to delimit the interior volume, r is a curvature radius as measured at any one of the four rounded corners, and V2 is the capacity of the bag.
We will now describe several embodiments of the invention with the aid of the drawings, in which:
Below, a detailed description of several embodiments of the invention matched with examples and in reference to the drawings.
In the different figures, identical references indicate identical or similar elements. As illustrated in
Referring to
The stirring device 3 is configured to allow a mixing of a biopharmaceutical composition/product 4 contained in the interior volume V, possibly to quickly disperse powder material or another suitable additional substance. The stirring device 3 may be arranged to have an impeller 13, typically a single impeller located inside the bag 2 and driven from below the bag 2, in the filled state. In other words, the rotor of the stirring device extends inside the bag 2, for instance with the impeller 13 located as close as possible from the bottom wall 2a. The height level of the impeller can be fixed.
As shown in
The tank T may include one or more modules MT of substantially same cross-section, here superimposed, to define a side wall 15 that is rigid. The tank T typically includes a front opening 150 allowing the bag 2, still folded, to be introduced inside the tank T, above the base 5. The front opening 150 is here vertically distant (far below) the upper edge of the tank T. As shown in non-limiting embodiment of
The tank T may be designed, either as a single block, or provided with a main part provided with a base opening O5, in the base 5 of the tank T, and one or more modules MT vertically added on the main part. The base opening O5 is forming an access for driving in rotation the impeller 13. The panels of the tank may be distributed in several parts, in particular when using one or more addition tank modules MT. A drive-bag interface may be formed, using a connector of tubular shape or similar suitable connecting part, entering inside the tank via the base opening O5. Such base opening O5 opens vertically upwards in a receiving compartment delimited by the panels 15a, 15b, 15c, 15d of the tank T.
More generally, a drive-bag interface is present and a coupling with the stirring part is obtained, typically before any filling of the bag 2 resting on the base 5. In some embodiments, a coupling clamp (for a mechanical coupling or a magnetic clamp) is inserted with its aligner, before any bag unfolding for instance. A movable motorized device of a known type, possibly a magnetic mixer drive unit 16, may be placed just below the tank T (in the lower space 10), with a tubular coupling part or similar connector engaging the drive-bag interface that typically protrudes downwardly from the base 5 though the base opening O5. The lower structure 24, extending entirely below the receiving compartment, may be a part of/integral with the tank T, possibly with wheels for transport.
Referring to
The apparatus 1 here comprises a bracket B2, which is typically rigid, and a linking element 6 coupled to the bracket B2. The linking element 6 may be flexible and can be drawn to lift the bag 2. The lift system LS is suitable for:
Besides, the apparatus 1 may include a plate or similar rigid cover (not shown) that supports a powder transfer bag 2′. Such cover includes a passageway for the powder pouring operation which may be disposed above the bag. The powder transfer bag 2′ may contain at least 10 L of powder material, for instance at least 30 L. This powder transfer bag 2′ may be lifted, optionally using same lift system LS as illustrated in
Powder addition can take place only when the bag 2 is positioned in the tank T, below or at the level of the upper opening O, resting in a dedicated frame TC or upper support (the tank upper frame of rectangular shape forming all or part of this frame TC). Such frame can also serve to support/fasten the lifting system. While the frame TC is here designed as a rectangular frame in non-limiting example of
Referring to
The impeller 13 is a plastic part, preferably not containing any metal substance, suitable for contact with biopharmaceutical composition obtained as a mix of a liquid, water for instance, and one or more substances that are initially in a solid, pasty, semi-liquid state or possibly in liquid state (optionally with active substances dissolved in another liquid).
Now referring to
The bag 2 may be produced by assembling four pieces, namely four films or sheets of plastic material. Two sheets are initially outer sheets 21, 22 and the two other sheets are gussets 11, 12, as apparent in
The gussets 11 and 12 can have a similar material and a similar thickness (preferably identical) to what is provided for the two outer sheets 21, 22. It is understood the gussets 11 and 12 are constituted by respective films, for instance cut from one part. The cut could occur before, during or after the step of connection with the sheets 21, 22. Advantageously for a filling with a biopharmaceutical fluid, the inner layer of each of the films which compose the flexible bag 2 is made of hot-weldable plastic material, which is biocompatible with the mediums transported. In a preferred embodiment, each film has a multilayer structure with layers which are typically non-metal, plastic layers. As a non-limiting example, the film can be transparent or translucid. The sheets may be of same plastic material.
According to some embodiments, the end seals W1, W2 and the longitudinal seams W are forming junctions by a local heating for a sufficiently long exposure period to heat, using a weld head. Heating technique by a low-voltage electrical impulse can be used such that the appearance of the visible face is unchanged, while guaranteeing a good weld quality: indeed, it does not require any high pressure at the time of the weld.
Impulse weld, thermal or laser weld techniques can make it possible to obtain resistant welding seals and seams W1, W2, W. In the case of a thermal weld, it is preferable to simultaneously weld the four films by applying a pressure of between 4 and 8 bars between weld blades or bars, using the configuration shown in
Referring to
Referring to
While
In a preferred embodiment, the gussets each have an inner, hot-weldable layer, made of a material selected from among polyethylene (preferably linear low density) and ethylene vinyl acetate copolymer; and an outer weldable layer, made of a material selected among polyethylene (preferably linear low density, or possibly linear high density), polyamide, ethylene vinyl acetate copolymer, polyamide and polyethylene terephthalate.
An intermediate layer, for example having a barrier effect (for example EVOH-based or equivalent material), can be provided in the multilayer structure of the elements 11, 12, 21, 22 delimiting the interior volume of the flexible bag 2.
Now referring to
In some options, the bag 2 is provided with one or more non-containing parts NCP (not delimiting the interior volume V), which may serve for fixation with the linking element 6 of the lift system LS and/or for handling the bag 2. Possibly, four parts NCP are connected to a cross bracket or similar lifter beam. In some options a handle may be formed at a top of the bag 2. At the bottom wall 2a, the opening 20 may be associated with/covered with a rigid cup or with any suitable fitting that is part of a connecting interface allowing a central region of the bottom wall 2a to be centered relative to the base 5. Optionally, such connecting interface retains the bottom wall 2a, which is of interest when displacing the top of the bag 2 upwardly, so that centering of the bottom wall 2a is ensured.
In some options, as illustrated in
More generally, the apparatus may have a lift system LS for controlling unfolding of the bag 2. Once the bracket is fastened and the linking element or cross bracket centered relative to the upper opening O, the sidewall 2C of the bag 2 may be unfolded progressively, by a lifting displacement of a top end of the bag 2. The bottom wall 2a may be retained by a fastening element of the connecting interface (for the coupling with a drive unit 16) and/or by weight of a part of the liquid already present at the bottom of the bag 2.
In some embodiments, the bag 2 is provided with a stiffening part at the top end with a through hole arranged in and/or surrounded by the stiffening part. The linking element 6 can pass through the through hole in a hold configuration of the bag 2, with the top of the bag 2 maintained in a top region of the receiving compartment, using the bracket and the linking element 6.
Near the bottom side, the bag 2 comprises a first opening 20, for instance provided in the plastic outer sheet 21 in
When the stirring device 3 is magnetically driven, the first opening 20 is not apparent from outside the bag 2, due to coverage by the receiving cup. This cup is typically fastened (in tight manner), at an annular junction, to the sheet 21 and entirely covering the first opening 20.
The bag 2, housing the stirring device 13 at the cup, can be associated with the drive unit 16 for levitating and/or rotating the stirring device 13. The drive unit may have a receiving coupler of cylindrical shape, adapted to house the protruding cup.
Referring to
The opening O2 is here suitable for introduction of such powder material. In some variants, another kind of additional substance may be supplied via a hose, using a suitable opening of the bag 2.
Referring to
In other words, the length L10 is typically a width of the bag 2 since the gussets 11, 12 have fold lines 112 that remain mutually distant in folded configuration. Accordingly, the outer sheets 21, 22 define a greater face. In some embodiments of interest, the following relationship is satisfied:
In
Referring to
The seams are formed with a relatively great overlapping width at the welded regions, which may be about 12 mm, for instance superior or equal to 7 mm and inferior to 15 mm.
The bag 2 is sized to stretch within limits of a rectangular section that is smaller than rectangular section delimited by the inner face of the tank side wall 15. Referring to
where p is an inner perimeter at the base 5 to delimit the interior volume V (delimitation of a lower part thereof) and r is a curvature radius (see
The bag 2 is here provided with a rectangular cross section including four rounded corners that are each spaced from the side wall 15 of the tank T, due to the short sizes L10 and L20. The following table shows experiments performed to analyse impact of the bag footprint on a good mixing with powder material that cannot easily dissolve into the liquid if a significant vortex is not present at the top surface of the liquid.
Referring to
However, the lack of mixing for high bag capacities is an issue. The table below reflects gain in mixing operations due to special rounding at the four vertically elongated corner regions of the bag 2, using sizes L10 and L20 that are surprisingly highly efficient to obtain a vortex 100 despite a height superior or equal to 3000 mm (i.e. with a challenge to propagate the impeller rotation action to the top surface of the liquid).
The experiments as reflected below were performed at same rotational speed of 500 rpm, using same tank T and sale kind of impeller 13, here a Rushton impeller. Filling level was 2400 L with water forming the liquid before pouring a same amount (30 liters) of powder 40. At this point, addition of powder is started to mix and fill up to a total volume of 3000 L once all powder 40 is added.
The test A reflects the case illustrated in
In contrast with the tests C1, C2, C3, it can be seen that bag height is still increased despite this size is already about three times greater than the two other sizes (length and width), here becoming superior to 3000 mm without being over 3250 mm, in order to have a sufficient interior volume V despite reduction for width L10 (only 788, 800 or 812 mm) and length L20 (988, 1000 or 1012 mml). Referring to
Referring to
When the curvature radius is of an order of magnitude much smaller than a width of the bag cross section (in unfolded configuration), for instance lower than 90 or 100 mm when the width is about 900 mm, there is no possibility for the powder 40 or any other additional substance be adequately mixed:there is a lack of downward attraction, reflected by absence of suitable vortex.
Here, height dimension of the bag 2 may vary. For instance, the bag 2 is at least 1600 mm tall in unfolded configuration, the height being for instance about 2100 or 3000 mm for a capacity V2 higher than 1500 L. In some options, bag cross-section is specifically chosen to have a circumference significantly lower than the inner perimeter p of the tank cross-section, while properly allowing contact, typically flat contact, onto the respective four panel inner faces of the tank T.
It is to be noted that the positive effect for the mixing is encountered for both cases illustrated in
Here, width of the bag 2 equals twice the width of a gusset 11 or 12 in the folded state (as shown in
Capacity V2 of the bag 2 may be substantially identical to the interior volume V delimited by the bag sidewall 2c. Practically, the bag 2 has no undesirable fold and the footprint of the impeller 13 (or other part/instrument possibly disposed inside the bag 2) has a low impact so that capacity V2 as verified with the bag 2 unfolded inside the tank T is close or almost equal to the bag interior volume V delimited by the sidewall 2c in fully stretched parallelepiped configuration of the bag 2.
Once received in the receiving compartment, the bag 2 resting on the base 5 is unfolded, using the lift system LS and is filled with liquid, possibly water. Before starting a stirring operation, the bag 2 (in the filled state) has a parallelepiped configuration and is maintained upright thanks to the four panels 15a, 15b, 15c, 15d. Practically, the bag 2 is in contact with each of the four panels 15a, 15b, 15c, 15d that are vertical panels. Contact between the bag 2 and each of the four vertical panels 15a, 15b, 15c, 15d may be obtained at four respective substantially rectangular contact areas which extend each upwardly from the base 5. Typically, the rectangular contact area RA along a given panel is obtained with a contact width representing more than 50%, preferably, at least 60%, of the panel width of the given panel.
Once the bag is stretched under liquid pressure but with a containment effect due to the side panels 15a, 15b, 15c, 15d, it becomes parallelepiped with a sidewall 2c in contact against the four side panels 15a, 15b, 15c, 1, with a rectangular cross section including four rounded corners RC1, RC2, RC3, RC4 each spaced from the side wall 15, with the following relationship satisfied:
where p is an inner perimeter at said base, r is a curvature radius d at the four rounded corners.
Accordingly, a significant fraction of the bag circumference is not in contact with the side panels 15a, 15b, 15c, 15d. Typically, more than 15% of the bag circumference (bag outer perimeter in filled state) is spaced from the tank delimitation, each rounded corner being included in a vertically elongated corner portion where liquid pressure is not counterbalanced by reaction of a tank side panel.
After mixing, a connection port connected to a suitable flexible pipe allows emptying the bag. Such flexible pipe may extend downwardly from the bag 2 which is received above the lower space 10. More generally, the flexible bag 2 includes one or more connectors forming connection ports, optionally provided on a same outer sheet 21 or 22, to make it possible to fill the flexible bag 2 (with typically several inlet or supply openings). Here, the flexible pipes connected to the connectors (see
Of course, the position of the connection port(s) can vary, preferably by making openings on one (preferably only one) of the outer sheets 21, 22. These connection ports are placed at a distance from the connection zones (seams W, end seals W1, W2) between the two outer sheets 21, 22, and they do not interfere with the unfolding of the gussets 11 and 12 of the flexible bag 2, of 3-D type. The ports can be closed sealed in a manner known per se (the ports are connected sealed to a tube length or pipe itself blocked, sealed, by a clip generally called “clamp” by a person skilled in the art, a aseptic connector, or could include one-way dampers or valves or other similar sealed closing systems).
Examples of functional, multilayer films making it possible to constitute the wall elements, i.e. the gussets 11, 12 and the outer sheets 21, 22 of the flexible bag 2 may be films of great flexibility coupled with a satisfactory resistance, which facilitates the unfolding of the gussets 11, 12 without risk that a swelling (during filling) in any bag end or in the sidewall 2c generates a breaking of the film.
The folding lines 112 for each gusset 11, 12 are thus straight-lined and parallel to the side edges 8, 18 and 9, 19 defined by the wall elements. It can be seen that the folding lines 112 extend on either side of a longitudinal axis (in this case, a central axis, as can be seen in
Referring to
The first gusset 11 and the second gusset 12 can each be folded along the folding line 112 thereof, towards the inside. In this example, the folding is done in two equal halves for each gusset 11, 12, at least in the flat configuration of the flexible bag 2. Each folding line 112 extends between two opposite ends of the flexible bag 1 where the gussets 11, 12 are joined with the outer sheet axial ends.
Embodiments with a bag 2 having specific rounded corners RC1, RC2, RC3, RC4 forming a significant radius of curvature r are of interest to facilitate mixing. Effective mixing, which is a challenge at high volume, is repeatably obtained. The relatively high radius r, combined with efficient containment in a tank T of rectangular shape, cumulatively facilitates:
While the stirring device 3 has been shown with a symmetrical impeller 13, for instance Rushton impeller, typically with a shaft 30 extending downwardly, any suitable stirring part may be used. Besides, magnetic coupling may be provided to allow rotation of such stirring part. A short shaft 30 for guiding rotation may be provided.
Also, the stirring device 3 may comprise any suitable configuration for agitation, with one or more impellers 13 driven for initiating agitation adjacent to a tank base 5. Embodiments are not limited, neither with respect to the specific design of the one or more impellers, or regarding rotational speed involved. Many options with enough agitation, in order to allow liquid movement to propagate upwardly (from the bag region adjacent to the base 5), are available. Rotation speed of 500 rpm has been only indicated as a non-limiting example. In other options, rotational speed may be lower, for instance about 400 rpm or less. Such lower speed may be used with a bag height h lower than 2500 or 3000 mm. Higher rotations speed can also provide efficient results, for instance a speed of 700 or 900 rpm may be involved.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21181542.8 | Jun 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/066637 | 6/17/2022 | WO |
