Shunt and void reduction device

Abstract

The filter plate device has an inlet and an outlet, and the filter plate is a polymer framework having a filtration zone and a membrane bed of one or more membranes bonded and sealed to the polymer framework in the filtration zone with a thermosetting plastic, and the diverter is disposed within the membrane bed such that fluid flows uniformly through the membrane bed.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 366,933, filed on Jun. 24, 2022, the entire content of which is incorporated herein by reference.

[0002] Generally, the present disclosure relates to a chromatography unit, and more particularly, to a disposable or single-use chromatography device having a diverter that enables reducing the dynamic flow upstream of the device to assist in reducing elution volume and / or elution tailing.

Background Art

[0003] Good manufacturing practices and government regulations are central to many biopharmaceutical manufacturing processes. Such manufacturing processes often have to undergo forced, often long, and costly validation procedures. For example, equipment used for the separation and purification of biopharmaceuticals must, for obvious reasons, meet strict cleanliness requirements. In the case of a single piece of equipment, the costs associated with a single cleaning validation can easily exceed thousands of dollars. To reduce such cleaning validation costs and expenses and / or to reduce the opportunities where cleaning is necessary or required, the pharmaceutical and biotechnology industries are increasingly exploring pre-validated modular disposable solutions.

[0004] From such a perspective, recently, there has been significant interest in the development of disposable solutions for the primary and / or secondary clarification of industrial, experimental, and clinical quantities of raw pharmaceutically synthesized fluids (e.g., cell cultures). The high-volume, high-throughput requirements of such processes generally favor the use of expensive installed stainless-steel equipment, with replaceable cassettes or cartridges (e.g., typically containing a stack of lenticular filter elements) installed within a stainless-steel housing or similar receptacle. At the end of the filtration operation and upon removal of the used cassette or cartridge, the equipment must be cleaned and validated at significant cost and labor before being used again.

[0005] Membrane-based devices designed for use in the biopharmaceutical processing industry are typically constructed of all thermoplastic components. This is desirable because the selected thermoplastic materials (e.g., polypropylene, polyethylene, polyethersulfone, etc.) are stable in the chemicals and environments to which they are exposed. One negative aspect of all thermoplastic devices that utilize secondary molding operations during manufacture is shrinkage. As the thermoplastic material cools, it shrinks, thus distorting the membrane and creating unwanted voids.

[0006] More specifically, thermoplastic filtration devices have conventionally been manufactured using an overmolding step, where a "window frame" of thermoplastic resin (typically polypropylene) is injection molded around a rectangular membrane or media piece, and then an adhesion step (vibration, hot plate, etc.) is used to attach the subassembly, and finally end caps are welded in a similar manner. In flow-through applications where the separation mechanism is size exclusion or charge-based, additional voids inside the device created by the shrinkage of the "window frame" during cooling (and wrinkling the membrane or media) do not adversely affect device performance. However, in binding and elution mode applications for capture in a chromatography train, any additional voids created by the wrinkled membrane degrade the performance of the device. This performance degradation can be seen in the sharpness of the breakthrough curve and the efficiency of elution.

[0007] Furthermore, in order to increase the efficiency of the device and reduce losses in the final product, it is important to minimize the dynamic flow rate of the device and thus reduce the dead volume. This reduction in dead volume in turn reduces the volume of elution material required at the end of the elution cycle of the device, thereby reducing the elution material, volume, cost, and impact on the device and / or process environment.

Summary of the Invention

Problems to be Solved by the Invention

[0008] Therefore, it is desirable to have a binding and elution device that uses a diverter and / or void reduction element to fill the space within the membrane plate subassembly that is less dynamic (has less dead space) within the device compared to a normal binding and elution chromatography device.

Means for Solving the Problems

[0009] To further understand the nature of the present invention and these and other objects, reference should be made to the following description taken in conjunction with the accompanying drawings.

[0010] The problems of the prior art are addressed by the embodiments disclosed herein, which relate to a disposable or single-use integrated chromatography unit that has an inlet and an outlet and includes one or more plates or a pair of filter plates that can be interposed between a pair of end plates having a diverter and / or void reduction elements between the plates on the upstream side of the membrane bed included in the filter plate. In certain embodiments, each of the filter plates comprises a polymeric framework supporting one or more membranes, and the polymeric framework can include a screen or spacer separating the layers of the membrane, and the screen or spacer further comprises a rib structure or screen shape that reduces the amount of dead space included within the membrane bed. The filter plates and the end plates can be assembled to form a substantially fixed and substantially watertight integral stack. Fluid entering the unit through a common inlet passes substantially simultaneously through one or more membranes of each filter plate, including a rib structure or enhanced screen shape, before exiting the unit through a common outlet (see "parallel" flow). The assembly is modular in design because a plurality of pairs of plates can be stacked within a suitable holder to form a single chromatography unit with low dead space.

[0011] A method of manufacturing such filter plates and chromatography units is also disclosed.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

[0013] Referring now to FIG. 1, a flow splitter 10 according to a particular embodiment is shown. The flow splitter 10 may have a generally rectangular shape to fit between membranes or membrane stacks. The flow splitter 10 is preferably made of a polymeric material to which a thermosetting resin used to attach one or more membranes adheres well and which is itself thermally weldable, thereby allowing the flow splitter 10 to be bonded to other parts of the chromatographic device. Suitable polymeric materials include resins such as amorphous blends of polyphenylene ether and polystyrene commercially available from SABIC, for example, NORYL resin HNA033, which is an unreinforced blend of polyphenylene ether and impact-resistant polystyrene. Epoxy bonds well to these resins and allows the use of low-shrinkage materials and non-dried membranes.

[0014] a. In a particular embodiment, each flow splitter 10 consists of one or more or a series of ribs 20 substantially parallel to the membrane surface. The ribs 20 have an axial profile 30 shaped in a number of ways including, but not limited to, square, triangular, circular, elliptical, pentagonal, hexagonal, octagonal, decagonal, dodecagonal, or irregular shapes. The fluid flowing through the device is directed by the ribs and enters the device in a way that substantially simultaneously (i.e., "in parallel") before exiting the unit or in a way that reduces the void volume of the chromatographic device and reduces the amount of elution material required to elute the material captured by the chromatographic membrane of the device.

[0015] The shunt 10 can be implemented at a relatively low cost. Specifically, the shunt 10 is a "single-use" item, i.e., upon completion of the desired (or predetermined) operation, the device can be disposed of (e.g., as may be required by law after filtering certain environmentally regulated substances), or can be partially or fully regenerated or recycled (e.g., after filtering non-regulated substances), and can be manufactured as an inexpensive "single-use" component.

[0016] Figures 2 and 3 show cross-sectional views of a chromatographic device 40 cut in half. The chromatographic device can be molded from the same or a similar compatible material as the splitter 10. In Figures 2 and 3, a membrane or membrane stack 50 is disposed in the center of the device 40. The center 60 of the membrane stack 50 is where the flow of chromatographic fluid is introduced into the membrane stack 50. Figure 2 does not include the splitter 10. Figure 3 shows the splitter 10 disposed between the membrane stacks 50 of the center 60. In the embodiment shown in Figure 3, the flow is distributed along the vertical and horizontal lengths of the splitter 10 such that the volume of dead space within the center 60 is minimized and then the liquid is delivered to the membrane stack 50 in a more efficient manner. Suitable membranes include those suitable for binding / elution chromatography and include ligands such as Protein A ligands attached thereto. In certain embodiments, the membrane stack 50 is a non-dryable wet membrane, such as a porous hydrogel. Suitable membranes are disclosed in U.S. Patent No. 7,316,919, U.S. Patent No. 8,206,958, U.S. Patent No. 8,383,782, U.S. Patent No. 8,367,809, U.S. Patent No. 8,206,982, U.S. Patent No. 8,652,849, U.S. Patent No. 8,211,682, U.S. Patent No. 8,192,971, and U.S. Patent No. 8,187,880, the disclosures of which are incorporated herein by reference. Such membranes include a composite material including a support member having a plurality of pores extending therethrough and a macroporous crosslinked gel located within the pores of the support member and substantially filling the pores of the support member. In some embodiments, the macroporous gel used responds to environmental conditions to provide a responsive composite material. In other embodiments, the microporous gel serves to facilitate or support the chemical synthesis or growth of microorganisms or cells.

[0017] In certain embodiments, the binder (or overmold agent) is a polymer that has low shrinkage characteristics (less than 7%) and that readily binds to the polymer and support plate material. In this example, the support plate material is PPO (Poly(p-phenylene oxide)). The membrane stack can be adhered by overmolding with the same material (PPO) or a more easily moldable and low shrinkage component of PPO and impact-resistant polystyrene. The overmolding process encapsulates and seals the membrane stack and binds it to the plate. The selection of the low shrinkage material minimizes shrinkage, thereby minimizing warping and movement of the components and providing the desired high-quality chromatography characteristics.

[0018] In certain embodiments, the membrane or membrane stack 50 is adhesively bonded and sealed to the polymer framework in an overmolding process in order to effectively encapsulate the membrane or membrane stack 50 within the framework around the diverter 10 such that all of the fluid entering the device at the inlet passes through the diverter 10 and then reaches the membrane or membrane stack 50 before reaching the outlet of the device.

[0019] In certain embodiments, the adhesive within the device 40 is a thermosetting resin or thermosetting plastic. Thermosetting resins strengthen during heating, as opposed to thermoplastic resins which soften when heated and harden and strengthen after cooling. Thermosetting resins also, unlike thermoplastic resins, retain their strength and shape when heated and exhibit excellent strength characteristics even at high temperatures. One suitable thermosetting resin is the commercially available TW062601 by EpoxySet Inc. This thermosetting resin cures to a hard, elastic polymer and, when cured, is a two-component encapsulant material that adheres well to the polymer framework capable of fabricating the diverter 10.

[0020] Examples Materials and Methods Chromatographic devices made as described in the present disclosure with various membrane volumes (MV) in the range of 1 mL to 112 mL were evaluated for dynamic binding and elution chromatographic performance. The chromatographic performance of the devices was run at a flow rate of 10 MV / min on either an AKTA(TM) Avant 150 (GE Healthcare, Uppsala, Sweden) or a K-Prime(R) 40-III (EMD Millipore, Billerica, MA, USA) chromatographic system.

[0021] The equilibration buffer used in this study was 20 mM phosphate, pH 7.0. Lyophilized human gamma globulin (IgG) powder (SeraCare Life Sciences, Milford, MA, USA, catalog number 1860-0048) was mixed with 20 mM phosphate, 50 mM sodium chloride, pH 7.0 buffer to prepare an IgG solution with an IgG concentration of 2.7 - 3.0 g / l. The IgG concentration was verified by UV absorbance at 280 nm using a UV-vis spectrophotometer. The elution buffer used in this study was 100 mM citrate, pH 2.5.

[0022] Phosphate (monohydrate and disodium phosphate), sodium chloride and citrate were procured from Sigma Aldrich (St. Louis, MO, USA). All solutions were filtered through a 0.22 μm polyethersulfone hydrophilic filter unit (EMD Millipore, Billerica, MA, USA) prior to use.

[0023] The device was equilibrated with 20 mM phosphate (pH 7.0). Then, the IgG solution was filled onto the device until at least 10% breakthrough. As the IgG solution flowed through the device, IgG specifically bound to the membrane contained in the device, while other contaminants either flowed through the membrane or bound non-specifically to the membrane. Next, washing steps were sequentially performed to wash away non-specifically bound species in the device with 20 mM phosphate buffer. After the washing steps, the specifically bound IgG of interest was recovered from the device using 100 mM citrate elution buffer. A final washing step using the equilibration buffer was performed to re-equilibrate the device.

[0024] Figure 4 shows the chromatographic performance in devices with volumes ranging from 1 ml (407A) to 10 ml (10 ml-H) and 112 ml (XL-04, XL-05) with and without a diverter (labeled as screen). The breakthrough curves show that the tailing for devices with a diverter was significantly reduced compared to that for devices without a diverter. For devices with higher tailing, a higher elution volume, typically sodium hydroxide (NaOH), is then required at the end of the elution cycle. Thus, elution devices with a diverter use less NaOH per elution cycle and are therefore more environmentally friendly and less expensive to operate.

Claims

**Claim 1** A filter plate device having an inlet and an outlet, wherein the filter plate is a polymer framework, and comprising a polymer framework having a filtration zone and a membrane bed of one or more membranes bonded and sealed to the polymer framework in the filtration zone with a thermosetting plastic, and a diverter disposed within the membrane bed such that fluid flows uniformly through the membrane bed. **Claim 2** The filter plate device according to claim 1, wherein the polymer framework comprises a polyphenylene ether / polystyrene blend. **Claim 3** The filter plate device according to claim 1, wherein the diverter has a plurality of shapes along a vertical axis of the diverter to assist in the dispersion of fluid into the filtration zone. **Claim 4** The filter plate according to claim 3, wherein the shape can be square, triangular, circular, oval, pentagonal, hexagonal, octagonal, decagonal, dodecagonal, or irregular. **Claim 5** A chromatography unit having an inlet and an outlet and comprising at least a pair of filter plates interposed between a pair of end plates, wherein each of the filter plates of the at least a pair of filter plates is a polymer framework, and comprising a polymer framework having a filtration zone and a membrane bed having one or more membranes bonded to the polymer framework in the filtration zone with a thermosetting plastic, and a diverter disposed within the membrane bed such that fluid flows uniformly through the membrane bed, and the filter plates of the at least a pair of filter plates are arranged back-to-back, thereby creating a channel between one or more membranes in the first plate of the pair and one or more membranes in the second plate of the pair, and fluid flows uniformly from the inlet, passes through one or more membranes of each of the first and second plates, and exits through the outlet. **Claim 6** The chromatography unit according to claim 5, wherein the polymer framework comprises a polyphenylene ether / polystyrene blend.

Images