Protein A-silica immunoadsorbent and process for its production

An immunoadsorbent material useful for removing IgG and IgG-complexes from biological fluids, said material comprising purified protein A covalently coupled to a silica matrix prepared by the method comprising:

• introducing free amino or carboxyl groups onto a silica matrix;
• reacting the silica matrix with purified protein A in the presence of a carbodiimide at a pH in the range from 3.3 to 3.7 to covalently link the protein A to the matrix through the amino or carboxyl groups;
• and
• washing the silica matrix at a pH in the range from 2.0 to 2.5 to remove loosely bound protein A from the matrix.

A method for preparing an immunoadsorbent material useful for removing IgG and IgG-complexes from biological fluids, said method comprising:

• introducing free hydroxyl groups onto a silica matrix;
• activating the silica matrix in the presence of cyanogen bromide at a pH in the range from 11.0 to 11.5, and covalently linking the protein A to the matrix at a pH in the range from 8.5 to 9.0;
• and
• washing the silica matrix at a pH in the range from 2.0 to 2.5 to remove loosely bound protein A from the matrix.

An immunoadsorbent material useful for removing IgG and IgG-complexes from biological fluids, said material comprising purified protein A covalently coupled to a silica matrix prepared by the method comprising:

• introducing free hydroxyl groups onto a silica matrix;
• activating the silica matrix in the presence of cyanogen bromide at a pH in the range from 11.0 to 11.5, and covalently linking the protein A at a pH in the range from 8.5 to 9.0;
• and
• washing the silica matrix at a pH in the range from 2.0 to 2.5 to remove loosely bound protein A from the matrix.