Use of a colloidal suspension of a cationic polymer to treat a support for medical use

A composite support comprising a base support for the treatment of a biological fluid, in which:

• the base support is essentially constituted by a first polymer carrying anionic or anionizable groups;
• at least a part of the surface of the base support is coated with a second polymer ionically bonded to the first polymer, the second polymer carrying cationic or cationizable groups which are capable of forming an ionic bond with the anionic or anionizable groups of the first polymer;
• characterized in that the second polymer is in the colloidal form, allowing the composite membrane to adsorb at least one entity containing anionic or anionizable groups by bonding with cationic or cationizable groups of the second polymer, the second polymer being in association with an organic polyacid;
• wherein the composite support has an endotoxin adsorption capacity in aqueous medium of 500 UE/m2 or more.

A method for manufacturing a composite support for the treatment of biological fluid, said method comprising the following steps:

• a) providing a base support essentially constituted by a first polymer carrying anionic or anionizable groups;
• b) providing a suspension in an acidic medium comprising a second polymer carrying cationic or cationizable groups which are capable of forming an ionic bond with the anionic or anionizable groups of the first polymer, the second polymer being in the colloidal form;
• c) bringing the suspension into contact with at least a portion of the surface of the base support, wherein
• the anionic or anionizable groups of the first polymer are selected from sulphonic, phosphonic, carboxylic, sulphuric, and phosphoric groups and salts of said groups, and wherein
• the second polymer is a cationic polymer selected from polyamines and polyimines, and
• the second polymer is obtained in the colloidal form by a step for mixing a first solution comprising the second polymer with a second solution comprising at least one organic polyacid.

A method for manufacturing an exchanger for the treatment of a biological liquid, the exchanger comprising a housing defining a first compartment and a second compartment, the first compartment being provided with an inlet and an outlet and being intended for the circulation of biological liquid to be treated, the second compartment being intended for the circulation of dialysate or filtrate and being provided with an outlet and optionally with an inlet, the two compartments being separated by a base support, the method comprising the following steps:

• a1) providing the base support essentially constituted from a first polymer carrying anionic or anionizable groups;
• a2) assembling the various components of the exchanger, including mounting the base support in the housing;
• b1) providing a suspension in an acidic medium containing a second polymer carrying cationic or cationizable groups which can form an ionic bond with the anionic or anionizable groups of the first polymer, the second polymer being in the colloidal form;
• b2) bringing the suspension into contact with at least a first portion of the surface of the base support intended to be brought into contact with the liquid to be treated;
• b3) in the case in which steps (b1-b2) are carried out after step a2), rinsing and/or purging the exchanger of the solution containing the second polymer;
• c1) optionally, sterilizing the exchanger thus obtained, wherein
• the anionic or anionizable groups of the first polymer are selected from sulphonic, phosphonic, carboxylic, sulphuric, and phosphoric groups and salts of said groups, and wherein the second polymer is a cationic polymer selected from polyamines and polyimines.