Patent Application
20200222858
The present disclosure relates to a microporous hollow fiber filter membrane having a large inner diameter and a thin wall. The fiber can be used for sterile filtration of liquids or removal of particles from liquids. The disclosure further relates to a method for producing the membrane and a filter device comprising the membrane.
WO 2004/056459 A1 discloses a permselective asymmetric membrane suitable for hemodialysis, comprising at least one hydrophobic polymer, e.g. polyethersulfone, and at least one hydrophilic polymer, e.g. polyvinylpyrrolidone. The outer surface of the hollow fiber membrane has pore openings in the range of 0.5 to 3 μm and the number of pores in the outer surface is in the range of 10,000 to 150,000 pores per mm2. Pore size of the membrane is in the range of 5 to 20 nm. The internal diameter of the membrane is less than 500 μm and its wall strength is less than 90 μm.
US 2014/0175006 A1 discloses a composite membrane module with hollow fiber membranes comprising a hollow fiber support layer and an active layer on the surface of the support layer. The active layer is formed by interfacial polymerization of an amine and an acyl halide on the support. The support layer may have an inner diameter of about 0.1 to about 3.0 mm and a thickness of about 10 to about 500 μm, e.g., 50 to 200 μm. In the examples, a support layer having an inner diameter of 0.5 to 1.0 mm and a thickness of 0.1 to 0.15 mm was used.
EP 0 998 972 A1 discloses self-supporting capillary membranes which are longitudinally reinforced by continuous reinforcing fibers incorporated in the wall of the capillary membrane. The inner diameter of the capillary membranes generally is from 0.2 to 6 mm and particularly from 0.4 to 3 mm. The wall thickness is generally from 0.1 to 2 mm and particularly from 0.2 to 1 mm. In the comparative examples, membranes without reinforcing fibers are disclosed which have an inner diameter of 1.5 mm and a wall thickness of 0.5 mm; or an inner diameter of 3 mm and a wall thickness of 1 mm, respectively.
The present disclosure provides a porous hollow fiber membrane showing a sponge structure and having a mean flow pore size, determined by capillary flow porometry, which is larger than 0.2 μm; and comprising polyethersulfone, polyvinylpyrrolidone and a polymer bearing ammonium groups. The present disclosure also provides a continuous solvent phase inversion spinning process for making the porous hollow fiber membrane. The present disclosure further provides filter devices comprising the porous hollow fiber membrane. The filter devices can be used for sterile filtration of liquids, removal of bacteria and/or endotoxins from liquids, or removal of particles from liquids.
In one aspect of the present invention, a porous hollow fiber membrane having a sponge-like structure is provided. The membrane has a mean flow pore size, determined by capillary flow porometry, which is larger than 0.2 μm. In one embodiment, the mean flow pore size is in the range of from 0.2 to 0.4 μm. In another embodiment, the mean flow pore size is larger than 0.3 μm, e.g., in the range of from 0.3 to 0.7 μm. In still another embodiment, the mean flow pore size is larger than 1 μm, e.g., in the range of from 1 to 10 μm, or in the range of from 1 to 5 μm.
Capillary flow porometry is a liquid extrusion technique in which at differential gas pressure the flow rates through wet and dry membranes are measured. Before measurement the membrane is immersed in a low surface tension liquid (e.g., a perfluoroether commercially available under the trade name Porefil®) to ensure that all pores including the small ones are filled with the wetting liquid. By measuring the pressure at which the liquid is pressed out of the pores its corresponding diameter can be calculated using the Laplace equation. With this method the pore size distribution is determined of those pores that are active in the mass transport. Dead end and isolated pores are omitted. The hollow fiber membranes are measured inside-out.
Laplace equation:
Dp=4γ cos θ/ΔP
The membrane comprises polyethersulfone (PESU), polyvinylpyrrolidone (PVP), and at least one polymer bearing ammonium groups selected from polyalkyleneoxides bearing ammonium groups, in particular quaternary ammonium groups, and polyvinylpyridines or copolymers of vinylpyridine and styrene bearing ammonium groups, in particular quaternary ammonium groups.
Suitable polymers bearing ammonium groups include polyalkyleneoxides bearing ammonium groups, in particular quaternary ammonium groups, and polyvinylpyridines or copolymers of vinylpyridine and styrene bearing ammonium groups, in particular quaternary ammonium groups, e.g., N-alkylpyridinium groups.
Suitable counter ions for the ammonium groups include chloride, bromide, sulfate, hydrogen sulfate, trifluoromethane sulfonate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, acetate, lactate, and citrate. In one embodiment, the counter ion is chloride. In another embodiment, the counter ion is bromide. In still another embodiment, the counter ion is sulfate.
Examples of suitable polyalkyleneoxides include polymers of ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, and their copolymers. In one embodiment, the polyalkyleneoxide is a block copolymer of ethylene oxide and epichlorohydrin. In one embodiment, the polyalkylenoxide has a number average molecular weight in the range of from 50 to 2,000 kDa, e.g., 100 to 250 kDa, for instance, 150 to 200 kDa.
The polyalkyleneoxide polymers are functionalized with ammonium groups. In one embodiment, the ammonium groups are quaternary ammonium groups.
In one embodiment, a polymer bearing ammonium groups is obtained by reacting a block copolymer of ethylene oxide and epichlorohydrin with at least one amine to form a polyalkylenoxide polymer featuring ammonium groups. Examples of suitable amines include primary, secondary, and tertiary amines. The amines can be aliphatic, cycloaliphatic, aromatic-aliphatic, or aromatic. In one embodiment, a primary or secondary amine comprising alkyl or benzyl moieties is used. In another embodiment, a tertiary amine comprising alkyl or benzyl moieties is used. In one embodiment, a polymer bearing quaternary ammonium groups is obtained by reacting a block copolymer of ethylene oxide and epichlorohydrin with at least one tertiary amine to form a polyalkylenoxide polymer featuring quaternary ammonium groups. In one embodiment, the block copolymer is reacted with two different tertiary amines. Examples of suitable tertiary amines include aliphatic amines, e.g., trialkylamines like triethylamine, tripropylamine, benzyldimethylamine, tribenzylamine; cycloaliphatic amines, e.g., N-alkylpiperidines, N,N-dialkylpiperazines, N-alkylpyrrolidines, and N,N-dialkylpyrazolines; and aromatic amines, e.g., pyridine, pyrazine, pyrrole, and pyrazole. In a particular embodiment, the tertiary amine is 1,4-diazabicyclo[2.2.2]octane (“DABCO”). In another particular embodiment, the tertiary amine is 1-azabicyclo[2.2.2]octane.
In one embodiment, all the chlorine functions in the copolymer are reacted with the tertiary amine(s). In another embodiment, only a fraction of the chlorine functions in the copolymer are reacted with the tertiary amine(s), for instance, 10 to 90 mol %, or 20 to 70 mol %, or 30 to 50 mol %.
In one embodiment, the polymer bearing ammonium groups corresponds to the formula
wherein
R1, R2, R3 are individually selected from H, alkyl, benzyl;
X− is Cl−;
with
0≤x≤0.9;
0≤y≤0.8;
0≤z≤0.9;
and x+y+z=1.
In another embodiment, a polymer bearing quaternary ammonium groups is obtained by reacting a polyvinylpyridine or a copolymer of vinylpyridine and styrene with an alkylating agent, e.g., an alkyl sulfate like dimethyl sulfate or diethyl sulfate. In one embodiment, 1 to 20 mol %, e.g., 2 to 10 mol %, or 3 to 8 mol % of the pyridine groups in the polyvinylpyridine are N-alkylated. In one embodiment, the counter ion of the N-alkylpyridinium groups is sulfate. In one embodiment, the polymer bearing quaternary ammonium groups has a weight average molecular weight in the range of from 10 to 500 kDa, e.g., 150 to 200 kDa.
In one embodiment, the polymer bearing quaternary ammonium groups corresponds to the formula
wherein
Examples of suitable polyethersulfones include polyethersulfones having a weight average molecular weight of about 70,000 to 100,000 Da. In one embodiment, a polyethersulfone having a weight average molecular weight Mw in the range of from 90 to 95 kDa is used. An example is a polyethersulfone having a weight average molecular weight Mw of 92 kDa and a polydispersity Mw/Mn of 3. In another embodiment, a polyethersulfone having a weight average molecular weight Mw in the range of from 70 to 80 kDa is used. An example is a polyethersulfone having a weight average molecular weight Mw of 75 kDa and a polydispersity Mw/Mn of 3.4.
Suitable polyvinylpyrrolidones include homopolymers of vinylpyrrolidone having a weight average molecular weight in the range of from 50 kDa to 2,000 kDa. These homopolymers generally have a number average molecular weight in the range of from 14 kDa to 375 kDa. Examples of suitable polyvinylpyrrolidones for preparing the membranes of the invention are Luvitec® K30, Luvitec® K85, Luvitec® K90, and Luvitec® K90HM, respectively, all available from BASF SE.
In one embodiment of the invention, the polyvinylpyrrolidone comprised in the porous hollow fiber membrane consists of a high (≥100 kDa) and a low (<100 kDa) weight average molecular weight component.
An example of a suitable polyvinylpyrrolidone having a weight average molecular weight <100 kDa is a polyvinylpyrrolidone having a weight average molecular weight of 50 kDa and a number average molecular weight of 14 kDa. Such a product is available from BASF SE under the trade name Luvitec® K30.
Examples of suitable polyvinylpyrrolidones having a weight average molecular weight >100 kDa include poylvinylpyrrolidones having a weight average molecular weight in the range of about 1,000 to 2,000 kDa, e.g., 1,100 to 1,400 kDa, or 1,400 to 1,800 kDa; a number average molecular weight of about 200 to 400 kDa, e.g., 250 to 325 kDa, or 325 to 325 kDa; and a polydispersity Mw/Mn of about 4 to 5, for instance, 4.3 to 4.4, or 4.3 to 4.8.
One embodiment of the invention uses a polyvinylpyrrolidone homopolymer having a weight average molecular weight of about 1,100 kDa; and a number average molecular weight of about 250 kDa.
Another embodiment of the invention uses a polyvinylpyrrolidone homopolymer having a weight average molecular weight of about 1,400 kDa; and a number average molecular weight of about 325 kDa.
Still another embodiment of the invention uses a polyvinylpyrrolidone homopolymer having a weight average molecular weight of about 1,800 kDa; and a number average molecular weight of about 375 kDa.
In one embodiment, the membrane has an inner diameter of from 2,300 to 4,000 μm and a wall strength of from 150 to 500 μm. In one embodiment, the inner diameter is larger than 3,000 μm and smaller than or equal to 3,700 μm and the wall strength is in the range of from 180 to 320 μm.
In another embodiment, the inner diameter is 2,300 to 2,500 μm and the wall strength is 180 to 320 μm. In yet another embodiment, the inner diameter is 2,900 to 3,400 μm and the wall strength is 180 to 320 μm.
The ratio of the inner diameter of the membrane to its wall strength is larger than 10. In one embodiment, the ratio of inner diameter to wall strength is larger than 15. Membranes having a large ratio of inner diameter to wall strength, i.e. thin-walled membranes, are more flexible and easily deformable. These membranes are less prone to form kinks on bending than thick-walled membranes. The ends of the thin-walled hollow fibers also can readily be closed by crimping to produce dead-end filter elements.
In one embodiment, the membrane shows a burst pressure, determined as described in the methods section below, of at least 2.0 bar (g), for instance, at least 2.5 bar (g), or even more than 3 bar (g). In one embodiment, the membrane shows a burst pressure in the range of from 2 to 5 bar (g).
In one embodiment, the membrane has a bacterial log reduction value (LRV) greater than 7. In another embodiment, the membrane has an LRV greater than 8. The LRV is tested with suspensions of Brevundimonas diminuta (BD) ATCC 19146, as described in the methods section below.
In one embodiment, the membrane has an endotoxin log reduction value (LRV) of greater than 3. In another embodiment, the membrane has an LRV of greater than 3.5. In still another embodiment, the membrane has an LRV of at least 4. The LRV is tested with suspensions of Brevundimonas diminuta (BD) ATCC 19146, as described in the methods section below.
The present disclosure also provides a continuous solvent phase inversion spinning process for preparing a porous hollow fiber membrane, comprising the steps of
Suitable polymers bearing ammonium groups include polyalkyleneoxides bearing quaternary ammonium groups and polyvinylpyridines bearing quaternary ammonium groups, e.g., N-alkylpyridinium groups.
Suitable counter ions for the ammonium groups include chloride, bromide, sulfate, hydrogen sulfate, trifluoromethane sulfonate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, acetate, lactate, and citrate. In one embodiment, the counter ion is chloride. In another embodiment, the counter ion is bromide. In still another embodiment, the counter ion is sulfate.
In one embodiment, the polymer solution comprises from 0.03 to 2 wt %, e.g., 0.05 to 1 wt %, or 0.1 to 0.5 wt %, relative to the total weight of the solution, of a polymer bearing ammonium groups. In one embodiment, the ammonium groups are quaternary ammonium groups. In one embodiment, the polymer bearing ammonium groups has a number average molecular weight of 50 to 2,000 kDa, e.g., 100 to 250 kDa, for instance, 150 to 200 kDa. In another embodiment, the polymer bearing ammonium groups has a weight average molecular weight of 10 to 500 kDa, e.g., 150 to 200 kDa.
In one embodiment, the polymer bearing ammonium groups is a block copolymer of epichlorohydrin and alkylene oxide that has been reacted with a bifunctional amino compound, e.g. DABCO. In one embodiment, 30 to 50% of the chlorine atoms in the block copolymer of epichlorohydrin and alkylene oxide have been substituted by DABCO. In one embodiment, the ion exchange capacity of the polymer bearing ammonium groups is in the range of from 1.5 to 2.5 mmol/g, e.g., 1.7 to 2.1 mmol/g.
In another embodiment, the polymer bearing ammonium groups is a polyvinylpyridine having a weight average molecular weight of 150 to 200 kDa, wherein 3 to 8 mol % of the pyridine groups in the polyvinylpyridine have been transformed into N-alkylpyridinium groups with sulfate as counter ion.
The concentration of polyethersulfone in the polymer solution generally is in the range of from 15 to 20 wt %, for instance, 17 to 19 wt %.
In one embodiment, the polymer solution comprises a polyethersulfone having a weight average molecular weight Mw in the range of from 90 to 95 kDa is used. An example is a polyethersulfone having a weight average molecular weight Mw of 92 kDa and a polydispersity Mw/Mn of 3. In another embodiment, polymer solution comprises a polyethersulfone having a weight average molecular weight Mw in the range of from 70 to 80 kDa is used. An example is a polyethersulfone having a weight average molecular weight Mw of 75 kDa and a polydispersity Mw/Mn of 3.4.
The concentration of polyvinylpyrrolidone in the polymer solution generally is in the range of from 10 to 15 wt %, e.g., from 11 to 12 wt %.
In one embodiment of the process, the polymer solution comprises a high (≥100 kDa) and a low (<100 kDa) molecular weight PVP. In one embodiment, 50-60 wt %, e.g., 50-55 wt %, based on the total weight of PVP in the polymer solution, is high molecular weight component, and 40-60 wt %, e.g., 45-50 wt %, based on the total weight of PVP in the polymer solution, is low molecular weight component.
In one embodiment, the polymer solution comprises 5 to 6 wt % of a polyvinylpyrrolidone having a weight average molecular weight of 50 kDa; and 6 to 7 wt % of a polyvinylpyrrolidone having a weight average molecular weight of 1,100 kDa.
In one embodiment, the polymer solution comprises from 4 to 6 wt %, e.g., 5 wt %, relative to the total weight of the solution, of water.
In one embodiment of the process for preparing the membrane, the center fluid comprises 35 to 50 wt % of water and 50 to 65 wt % of NMP, for instance, 35 to 45 wt % of water and 55 to 65 wt % of NMP, or 40 to 50 wt % of water and 50 to 60 wt % of NMP, e.g., 40 wt % of water and 60 wt % of NMP, relative to the total weight of the center fluid.
In one embodiment of the process, the precipitation bath is comprised of water. In one embodiment of the process, the precipitation bath has a temperature in the range of from 70 to 99° C., for instance, 75 to 95° C., or 85 to 90° C.
In one embodiment of the process for preparing the membrane, the temperature of the spinneret is in the range of from 50 to 60° C., e.g., 52-56° C.
In one embodiment of the process, the distance between the opening of the nozzle and the precipitation bath is in the range of from 10 to 90 cm, e.g., 15 to 60 cm.
In one embodiment of the process, the spinning speed is in the range of 5 to 15 m/min, e.g., 8 to 13 m/min.
The membrane then is washed to remove residual solvent and low molecular weight components. In a particular embodiment of a continuous process for producing the membrane, the membrane is guided through several water baths. In certain embodiments of the process, the individual water baths have different temperatures. For instance, each water bath may have a higher temperature than the preceding water bath.
The membrane then is dried and subsequently sterilized. The sterilization step is important to increase the liquid permeability (Lp) of the hollow fiber membrane. Larger fluid flows can be achieved with a sterilized membrane, compared to a membrane that has not gone through the sterilization step. In one embodiment, the hollow fiber membrane subsequently is sterilized with gamma radiation. In a particular embodiment, radiation dose used is in the range of from 25 to 50 kGy, for instance, 25 kGy. In another embodiment, the hollow fiber membrane subsequently is sterilized with steam at a temperature of at least 121° C. for at least 21 min. After the sterilization step, the hollow fiber membrane shows a greatly increased hydraulic permeability.
The present disclosure also provides a filtration device comprising at least one hollow fiber membrane having the characteristics described above. In one embodiment, the filtration device comprises a single hollow fiber membrane. In one embodiment, the filtration device is a sterilization grade filter which is able to remove microbial contaminants from a liquid.
The filtration device comprises a tubular housing, the ends of the tubular housing defining an inlet and an outlet, respectively, of the device; at least one hollow fiber membrane disposed within the tubular housing, one end of the at least one hollow fiber membrane being connected to the inlet of the device, and the other end of the at least one hollow fiber membrane being sealed, e.g., by crimping. In one embodiment, the filtration device comprises a single hollow fiber membrane. In another embodiment, the filtration device comprises a plurality of hollow fiber membranes. In one embodiment, the number of hollow fiber membranes is in the range of from 3 to 20, for instance, from 5 to 10.
In one embodiment within the scope of the present disclosure, the outlet 7 is fluidly connected to a sterile fluid container. A solution may enter the inlet 4 of the device and pass through the connector 3 into the hollow fiber membrane 2. The solution then filters through the hollow fiber membrane 2 out a filter outlet 7 into the sterile container fluidly connected to the outlet 7. The device provides an isolated fluid connection between the inlet 4 and the container, such that once the solution is filtered through the membrane, the filtered solution passes directly into the sterilized environment of the container. The part of the housing 1 between the outlet 7 of the filter and an inlet of the container may be configured as a cut and seal area. Once the solution has been filtered into the container, the connection between the outlet 7 of the filter and an inlet of the container may be sealed and the filter device cut off upstream of the sealed area.
In one version of the filter device shown in
In an alternative embodiment, the hollow fiber membrane 2 is inserted into a mold, and a thermoplastic polymer is injection-molded around it to form the hollow connector 3. In one embodiment, both the connector 3 and the housing 1 are formed by injection-molding a thermoplastic polymer around the hollow fiber membrane 2.
The hollow connector 3 further includes a fluid inlet 4. A fluid can be fed via a connected fluid supply line, for example, into the fluid inlet 4 of the hollow connector 3. In some versions, the fluid inlet 4 can include a Luer lock type fitting or other standard medical fitting. The housing 1 is attached to a sealing surface of the hollow connector 3. The sealing surface in this version is cylindrical and has a diameter larger than a diameter of the fitting 5, and is disposed generally concentric with the fitting 5. In fact, in this version, the diameter of the sealing surface is generally identical to or slightly smaller than an inner diameter of the housing 1. So configured, the housing 1 receives the sealing surface and extends therefrom to surround and protect the hollow fiber membrane 2 without contacting the surface of the hollow fiber membrane 2. The housing 1 can be fixed to the sealing surface with adhesive, epoxy, welding, bonding, etc. The housing 1 receives the fluid after it passes through the pores of the hollow fiber membrane 2. From there, the now filtered fluid passes into the container.
In one version of the foregoing assembly of
Suitable materials for the housing 1 include PVC; polyesters like PET or PETG; poly(meth)acrylates like PMMA; polycarbonates (PC); polyolefins like PE, PP, or cycloolefin copolymers (COC); polystyrene (PS); silicone polymers, etc.
The membrane and the filtration device of the present disclosure may advantageously be used to remove particles from a liquid. Examples of particles that may be removed include microorganisms like bacteria; solids like undissolved constituents of a solution (e.g., salt crystals or agglomerates of active ingredients), dust particles, or plastic particles generated during manufacture by abrasion, welding etc. When the filtration device incorporates a membrane bearing cationic charges, it is also able to remove endotoxins and bacterial DNA from a liquid.
In one embodiment intended to be covered by the scope of the present disclosure, the device of the present disclosure forms part of an infusion line for injecting fluid into a patient, e.g., into the bloodstream or the peritoneum of the patient. Examples of such fluids include sterile medical fluids like saline, drug solutions, glucose solutions, parenteral nutrition solutions, substitution fluids supplied to the patient in the course of hemodiafiltration or hemofiltration treatments, or dialysis fluids supplied to the patient in the course of peritoneal dialysis (PD) treatments. The device of the present disclosure forms a final sterile barrier for the fluid entering the bloodstream or the peritoneum, respectively, of the patient.
A further aspect of the present disclosure is a method of removing particles from a liquid, comprising filtration of the liquid through the filtration device of the present disclosure. The filtration is normal-flow filtration (NFF), which is also called dead-end or direct flow filtration. As the membrane of the present disclosure does not have a skin, it is possible to perform both inside-out and outside-in filtration with it.
Examples of suitable liquids that can be filtered with the device of the present disclosure include medical liquids like sterile water, saline, drug solutions, dialysis fluid, substitution fluid, parenteral nutrition fluids etc.
A POROLUX™ 1000 (POROMETER N.V., 9810 Eke, Belgium) is used for these measurements; Porefil® wetting fluid is used as low surface tension liquid.
The POROLUX™ 1000 series uses a pressure step/stability method to measure pore diameters. The inlet valve for the gas is a large, specially designed needle valve that is opened with very accurate and precise movements. To increase pressure, the valve opens to a precise point and then stops its movement. The pressure and flow sensors will only take a data point when the used defined stability algorithms are met for both pressure and flow. In this way, the POROLUX™ 1000 detects the opening of a pore at a certain pressure and waits until all pores of the same diameter are completely opened before accepting a data point. This results in very accurate measurement of pore sizes and allows a calculation of the real pore size distribution. The POROLUX™ 1000 measures mean flow pore size. Measurable pore size ranges from ca. 13 nm to 500 μm equivalent diameter (depending on the wetting liquid).
The hollow fiber samples were cut into pieces of 8 cm; and one end of each piece was sealed by crimping. These were glued into a module with epoxy resin and measured with the POROLUX™ 1000. The effective fiber length after potting was about 5 cm.
At differential gas pressure the flow rates through wet and dry membranes were measured. Before measurement the membrane was immersed in a low surface tension liquid (Porefil®, 16 dyne/cm) to ensure that all pores including the small ones are filled with the wetting liquid. By measuring the pressure at which the liquid is pressed out of the pores, its corresponding diameter can be calculated using the Laplace equation.
Laplace equation:
Dp=4γ cos θ/ΔP
Dp=diameter pores [m]
γ=surface tension [N/m]; for Porefil® 0.016 [N/m]
ΔP=pressure [Pa]
Cos θ=contact angle; by complete wetting cos θ=1
The flow rate was measured at a certain pressure over the wet and over the dry membrane, resulting in a wet curve, a dry curve, and a half dry curve in between. The point where the half dry curve crosses the wet curve is the mean flow pore size. The pore size is calculated via the first derivative from the flow pressure. All measurements were carried out in two independent, different modules, duplicate measurements were made.
Mini-modules [=fiber in a housing] are prepared by cutting the fiber to a length of 20 cm, drying the fiber for 1 h at 40° C. and <100 mbar and subsequently transferring the fiber into the housing. The ends of the fiber are closed using a UV-curable adhesive. The mini-module is dried in a vacuum drying oven at 60° C. over night, and then the ends of the fiber are potted with polyurethane. After the polyurethane has hardened, the ends of the potted membrane bundle are cut to reopen the fibers. The mini-module ensures protection of the fiber.
The hydraulic permeability of a mini-module is determined by pressing a defined volume of water under pressure through the mini-module, which has been sealed on one side, and measuring the required time. The hydraulic permeability is calculated from the determined time t, the effective membrane surface area A, the applied pressure p and the volume of water pressed through the membrane V, according to equation (1):
Lp=V/[p·A·t] (1)
The effective membrane surface area A is calculated from the fiber length and the inner diameter of the fiber according to equation (2)
A=π·d
i
·l·[cm2] (2)
The mini-module is wetted thirty minutes before the Lp-test is performed. For this purpose, the mini-module is put in a box containing 500 mL of ultrapure water. After 30 minutes, the mini-module is transferred into the testing system. The testing system consists of a water bath that is maintained at 37° C. and a device where the mini-module can be mounted. The filling height of the water bath has to ensure that the mini-module is located underneath the water surface in the designated device.
In order to avoid that a leakage of the membrane leads to a wrong test result, an integrity test of the mini-module and the test system is carried out in advance. The integrity test is performed by pressing air through the mini-module that is closed on one side. Air bubbles indicate a leakage of the mini-module or the test device. It has to be checked if the leakage is due to an incorrect mounting of the mini-module in the test device or if the membrane leaks. The mini-module has to be discarded if a leakage of the membrane is detected. The pressure applied in the integrity test has to be at least the same value as the pressure applied during the determination of the hydraulic permeability in order to ensure that no leakage can occur during the measurement of the hydraulic permeability because the pressure applied is too high.
LRV of the membranes was tested with suspensions of Brevundimonas diminuta (BD) ATCC 19146 according to the following procedure:
It is important that the method for production of BD pass the criteria set forth in ASTM F838-05 (reapproved 2013) and that the challenge suspension reach a challenge of ≥107 CFU/cm2 membrane area.
To determine if the colonies are monodispersed, the BD challenge organism will be tested with membrane filtration on filters with pore size 0.45 μm and microscopically.
The challenge of the filter shall be performed at 19-24° C. The set-up for the test is shown in
A solution of 19% w/w polyethersulfone having a weight average molecular weight of about 75 kDa (Ultrason® 6020, BASF SE); 6.5% w/w PVP having a weight average molecular weight of about 1,100 kDa (Luvitec® K85, BASF SE); 6% w/w PVP having a weight average molecular weight of about 50 kDa (Luvitec® K30, BASF SE); and 0.1% w/w of Additive 1; in 5% w/w water and 63.4% w/w NMP was thermostatted at 75° C. and extruded through the outer ring slit of a spinneret with two concentric openings, the outer opening having an outer diameter of 2,700 μm and an inner diameter of 1,900 μm; the inner opening having a diameter of 1,700 μm; into a coagulation bath containing water. A solution containing 40% w/w water and 60% w/w NMP was used as the center fluid and extruded through the inner opening of the spinneret. The temperature of the spinneret was 53° C.; the temperature of the coagulation bath was 89° C. and the air gap 52.5 cm. The fibers were spun at a speed of 9.5 m/min.
The fibers subsequently were washed with demineralized water at 70° C. and dried for 150 min at 50° C. under a constant flow of dry air. The fiber obtained had an inner diameter of 3,385 μm and a wall thickness of 196 μm. A portion of the fibers was sterilized with steam at 121° C. for 21 min, another portion of the fibers was sterilized with gamma radiation at a dose of >25 kGy. Mean flow pore size was determined to be 478 nm for the steam-sterilized fibers, and 485 nm for the gamma-sterilized fibers.
Mini-modules were prepared as described above and hydraulic permeability of the fibers and burst pressure was tested as described above.
The mini-module comprising a non-sterilized fiber showed an Lp of 81·10−4 cm3/(cm2·bar·sec).
The mini-module comprising a steam-sterilized fiber showed an Lp of 1038·10−4 cm3/(cm2·bar·sec).
The mini-module comprising a gamma-sterilized fiber showed an Lp of 1,372·10−4 cm3/(cm2·bar·sec).
Burst pressure was determined to be 2.5 bar (g) for the steam-sterilized fibers; and 2.3 bar (g) for the gamma-sterilized fibers.
Endotoxin LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >3.9. Endotoxin LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >3.9.
Bacterial LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >9. Bacterial LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >9.
A solution of 19% w/w polyethersulfone having a weight average molecular weight of about 75 kDa (Ultrason® 6020, BASF SE); 6.5% w/w PVP having a weight average molecular weight of about 1,100 kDa (Luvitec® K85, BASF SE); 6% w/w PVP having a weight average molecular weight of about 50 kDa (Luvitec® K30, BASF SE); and 0.3% w/w of Additive 1; in 5% w/w water and 63.2% w/w NMP was thermostatted at 75° C. and extruded through the outer ring slit of a spinneret with two concentric openings, the outer opening having an outer diameter of 2,700 μm and an inner diameter of 1,900 μm; the inner opening having a diameter of 1,700 μm; into a coagulation bath containing water. A solution containing 40% w/w water and 60% w/w NMP was used as the center fluid and extruded through the inner opening of the spinneret. The temperature of the spinneret was 53° C.; the temperature of the coagulation bath was 89° C. and the air gap 52.5 cm. The fibers were spun at a speed of 9.5 m/min.
The fibers subsequently were washed with demineralized water at 70° C. and dried for 150 min at 50° C. under a constant flow of dry air. The fiber obtained had an inner diameter of 3,373 μm and a wall thickness of 193 μm. A portion of the fibers was sterilized with steam at 121° C. for 21 min, another portion of the fibers was sterilized with gamma radiation at a dose of >25 kGy. Mean flow pore size was determined to be 577 nm for the steam-sterilized fibers, and 575 nm for the gamma-sterilized fibers.
Mini-modules were prepared as described above and hydraulic permeability of the fibers and burst pressure was tested as described above.
The mini-module comprising a non-sterilized fiber showed an Lp of 176·10−4 cm3/(cm2·bar·sec).
The mini-module comprising a steam-sterilized fiber showed an Lp of 1,721·10−4 cm3/(cm2·bar·sec).
The mini-module comprising a gamma-sterilized fiber showed an Lp of 3,208·10−4 cm3/(cm2 bar·sec).
Burst pressure was determined to be 2.3 bar (g) for the gamma-sterilized fibers.
Endotoxin LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >3.8. Endotoxin LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >3.8.
Bacterial LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >9. Bacterial LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >9.
A solution of 19% w/w polyethersulfone having a weight average molecular weight of about 75 kDa (Ultrason® 6020, BASF SE); 6% w/w PVP having a weight average molecular weight of about 1,100 kDa (Luvitec® K85, BASF SE); 6% w/w PVP having a weight average molecular weight of about 50 kDa (Luvitec® K30, BASF SE); and 0.3% w/w of Additive 2 in 5% w/w water and 63.7% w/w NMP was thermostatted at 75° C. and extruded through the outer ring slit of a spinneret with two concentric openings, the outer opening having an outer diameter of 2,700 μm and an inner diameter of 1,900 μm; the inner opening having a diameter of 1,700 μm; into a coagulation bath containing water. A solution containing 40% w/w water and 60% w/w NMP was used as the center fluid and extruded through the inner opening of the spinneret. The temperature of the spinneret was 53° C.; the temperature of the coagulation bath was 90° C. and the air gap 52.5 cm. The fibers were spun at a speed of 9.5 m/min.
The fibers subsequently were washed with demineralized water at 70° C. and dried for 150 min at 50° C. under a constant flow of dry air. The fiber obtained had an inner diameter of 3,366 μm and a wall thickness of 189 μm. A portion of the fibers was sterilized with steam at 121° C. for 21 min, another portion of the fibers was sterilized with gamma radiation at a dose of >25 kGy. Mean flow pore size was determined to be 577 nm for the steam-sterilized fibers, and 576 nm for the gamma-sterilized fibers.
Mini-modules were prepared as described above and hydraulic permeability of the fibers and burst pressure was tested as described above.
The mini-module comprising a non-sterilized fiber showed an Lp of 296·10−4 cm3/(cm2·bar·sec).
The mini-module comprising a steam-sterilized fiber showed an Lp of 2,796·10−4 cm3/(cm2 bar·sec).
The mini-module comprising a gamma-sterilized fiber showed an Lp of 3,233·10−4 cm3/(cm2 bar·sec).
Burst pressure was determined to be 2.8 bar (g) for the steam-sterilized fibers; and 2.5 bar (g) for the gamma-sterilized fibers.
Endotoxin LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >3.6. Endotoxin LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >3.6.
Bacterial LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >9. Bacterial LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >9.
A solution of 19% w/w polyethersulfone having a weight average molecular weight of about 75 kDa (Ultrason® 6020, BASF SE); 6.5% w/w PVP having a weight average molecular weight of about 1,100 kDa (Luvitec® K85, BASF SE); 6% w/w PVP having a weight average molecular weight of about 50 kDa (Luvitec® K30, BASF SE); and 0.2% w/w of Additive 2; in 5% w/w water and 63.3% w/w NMP was thermostatted at 75° C. and extruded through the outer ring slit of a spinneret with two concentric openings, the outer opening having an outer diameter of 2,700 μm and an inner diameter of 1,900 μm; the inner opening having a diameter of 1,700 μm; into a coagulation bath containing water. A solution containing 40% w/w water and 60% w/w NMP was used as the center fluid and extruded through the inner opening of the spinneret. The temperature of the spinneret was 53° C.; the temperature of the coagulation bath was 89° C. and the air gap 52.5 cm. The fibers were spun at a speed of 9.5 m/min.
The fibers subsequently were washed with demineralized water at 70° C. and dried for 150 min at 50° C. under a constant flow of dry air. The fiber obtained had an inner diameter of 3,347 μm and a wall thickness of 199 μm. A portion of the fibers was sterilized with steam at 121° C. for 21 min, another portion of the fibers was sterilized with gamma radiation at a dose of >25 kGy. Mean flow pore size was determined to be 519 nm for the steam-sterilized fibers, and 520 nm for the gamma-sterilized fibers.
Mini-modules were prepared as described above and hydraulic permeability of the fibers and burst pressure was tested as described above.
The mini-module comprising a non-sterilized fiber showed an Lp of 164·10−4 cm3/(cm2·bar·sec).
The mini-module comprising a steam-sterilized fiber showed an Lp of 1,453·10−4 cm3/(cm2·bar·sec).
The mini-module comprising a gamma-sterilized fiber showed an Lp of 3,856·10−4 cm3/(cm2·bar·sec).
Burst pressure was determined to be 2.5 bar (g) for the gamma-sterilized fiber.
Endotoxin LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >3.6. Endotoxin LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >3.6.
Bacterial LRV for the mini-modules comprising a steam-sterilized fiber was determined to be >9. Bacterial LRV for the mini-modules comprising a gamma-sterilized fiber was determined to be >9.
| Number | Date | Country | Kind |
|---|---|---|---|
| 17182171.3 | Jul 2017 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/069458 | 7/18/2018 | WO | 00 |
