# US 8,771,516 B2 · Membranes having improved performance

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- Number: US 8,771,516 B2
- Document ID: US8771516B2
- Status: Granted
- Kind: B2
- Application number: 13/320,699
- Filed: 2010-05-19
- Published: 2012-03-29
- Granted: 2014-07-08
- Earliest claimed: 2009-05-20
- Assignees: Gambro Lundia AB
- Applicants: Bernd Krause; Carina Zweigart; Heinrich Behr
- Inventors: Bernd Krause; Carina Zweigart; Heinrich Behr
- Web page: https://patentgrep.com/patent/US8771516B2

## CPC

- B01D 69/088: {Co-extrusion; Co-spinning}
- A61M 1/16: with membranes
- A61M 1/34: Filtering material out of the blood by passing it through a membrane, i.e. hemofiltration or diafiltration
- A61M 1/3403: {Regulation parameters}
- A61M 1/341: {by measuring the filtrate rate or volume}
- A61M 1/3413: {Diafiltration}
- A61M 1/3496: {Plasmapheresis; Leucopheresis; Lymphopheresis (A61M1/3472 takes precedence)}
- B01D 71/56: Polyamides, e.g. polyester-amides
- B01D 71/68: Polysulfones; Polyethersulfones
- A61M 2205/15: Detection of leaks
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## Abstract

Permselective asymmetric membranes suitable e.g. for hemodialysis, hemodiafiltration and hemofiltration of blood, and having improved performance, including improved sieving characteristics, providing enhanced removal of middle molecular weight substances, e.g. inflammatory mediators having a molecular weight between 20 and 40 kDa. The improved sieving characteristics are due to a narrow pore size distribution of the membranes created in the production process. Processes for the preparation of these membranes, devices comprising these membranes, and the use of these membranes in hemodialysis, hemodiafiltration and hemofiltration of blood, as well as in bioprocessing, plasma fractionation and the preparation of protein solutions.

## Claims

### Claim 1

A permselective asymmetric hollow fiber membrane having a difference in sieving coefficient of the membrane for ovalbumin in aqueous solution and sieving coefficient of the membrane for albumin in aqueous solution of at least 50%, the membrane made by
a) dissolving at least one hydrophobic polymer selected from the group consisting of polysulfones, polyethersulfones, polyamides and polyacrylonitriles, and at least one hydrophilic polymer in at least one solvent to form a polymer solution;
b) extruding said polymer solution through an outer ring slit of a nozzle with two concentric openings;
c) extruding a center fluid through the inner opening of the nozzle; and thereafter
d) washing the membrane obtained;
e) treating said membrane with a salt solution containing from 0.5 wt.-% to 12 wt.-% of a physiologically tolerable salt and no physiologically intolerable salts subsequently to washing; and thereafter
f) drying said membrane and, optionally, sterilizing said membrane by steam treatment.

### Claim 2 (depends on 1)

The membrane of claim 1, wherein the hydrophilic polymer comprises polyvinylpyrrolidone.

### Claim 3

A process for preparing a permselective asymmetric hollow fiber membrane, comprising
a) dissolving at least one hydrophobic polymer selected from the group consisting of polysulfones, polyethersulfones, polyamides and polyacrylonitriles; and at least one hydrophilic polymer in at least one solvent to form a polymer solution;
b) extruding said polymer solution through an outer ring slit of a nozzle with two concentric openings;
c) extruding a center fluid through the inner opening of the nozzle; and thereafter
d) washing the membrane obtained;
e) treating said membrane with a salt solution containing from 0.5 wt.-% to 12 wt.-% of a physiologically tolerable salt and no physiologically intolerable salts subsequently to washing; and thereafter
f) drying said membrane and, optionally, sterilizing said membrane by steam treatment.

### Claim 4 (depends on 3)

The process of claim 3 wherein the salt is sodium chloride.

### Claim 5 (depends on 3)

The process of claim 3, wherein the hydrophilic polymer comprises polyvinylpyrrolidone.

### Claim 6

A diffusion and/or filtration device comprising a membrane prepared by
a) dissolving at least one hydrophobic polymer selected from the group consisting of polysulfones, polyethersulfones, polyamides and polyacrylonitriles; and at least one hydrophilic polymer in at least one solvent to form a polymer solution;
b) extruding said polymer solution through an outer ring slit of a nozzle with two concentric openings;
c) extruding a center fluid through the inner opening of the nozzle; and thereafter
d) washing the membrane obtained;
e) treating said membrane with a salt solution containing from 0.5 wt.-% to 12 wt.-% of a physiologically tolerable salt and no physiologically intolerable salts subsequently to washing; and thereafter
f) drying said membrane and, optionally, sterilizing said membrane by steam treatment.

### Claim 7

A method for at least one of hemodialysis, hemodiafiltration, and hemofiltration of blood, the method comprising preparing a membrane by
a) dissolving at least one hydrophobic polymer selected from the group consisting of polysulfones, polyethersulfones, polyamides and polyacrylonitriles; and at least one hydrophilic polymer in at least one solvent to form a polymer solution;
b) extruding said polymer solution through an outer ring slit of a nozzle with two concentric openings;
c) extruding a center fluid through the inner opening of the nozzle; and thereafter
d) washing the membrane obtained;
e) treating said membrane with a salt solution containing from 0.5 wt.-% to 12 wt.-% of a physiologically tolerable salt and no physiologically intolerable salts subsequently to washing; and thereafter
f) drying said membrane and, optionally, sterilizing said membrane by steam treatment, and
performing the at least one of hemodialysis, hemofiltration and hemodiafiltration of blood using said membrane.

### Claim 8

A method for at least one of bioprocessing; plasma fractionation; and the preparation of protein solutions, the method comprising preparing a membrane by
a) dissolving at least one hydrophobic polymer selected from the group consisting of polysulfones, polyethersulfones, polyamides and polyacrylonitriles; and at least one hydrophilic polymer in at least one solvent to form a polymer solution;
b) extruding said polymer solution through an outer ring slit of a nozzle with two concentric openings;
c) extruding a center fluid through the inner opening of the nozzle; and thereafter
d) washing the membrane obtained;
e) treating said membrane with a salt solution containing from 0.5 wt.-% to 12 wt.-% of a physiologically tolerable salt and no physiologically intolerable salts subsequently to washing; and thereafter
f) drying said membrane and, optionally, sterilizing said membrane by steam treatment, and
at least one of treating a substance to be bioprocessed, fractionated and prepared into a protein solution using said membrane.

### Claim 9 (depends on 6)

The device of claim 6 wherein the salt is sodium chloride.

### Claim 10 (depends on 1)

The membrane of claim 1 wherein the salt is sodium chloride.

### Claim 11 (depends on 7)

The method of claim 7 wherein the salt is sodium chloride.

### Claim 12 (depends on 8)

The method of claim 8 wherein the salt is sodium chloride.

### Claim 13 (depends on 6)

The device of claim 6, wherein the hydrophilic polymer comprises polyvinylpyrrolidone.

### Claim 14 (depends on 7)

The method of claim 7, wherein the hydrophilic polymer comprises polyvinylpyrrolidone.

### Claim 15 (depends on 8)

The method of claim 8, wherein the hydrophilic polymer comprises polyvinylpyrrolidone.