Support matrices of the type given above are typically in form of porous monolithic beds or porous or non-porous particles. The support particles may be used in fluidised beds or packed beds. In order to reach a sufficient rigidity, the matrices often have to be cross-linked.
Typical problems associated with support matrices for the above-mentioned uses are:                (a) high flow velocities may lead to an increased back pressure which ultimately causes collapse of the matrix;        (b) when in particle form, the matrices may have a tendency not to withstand mechanical forces during packing in columns and other reaction vessels;        (c) tricky to manufacture; and        (d) the matrices may need a separate sterilization.        
One previous way of manufacturing support matrices that have an improved rigidity is to start from a polymer carrying nucleophilic groups and groups that have a masked electrophilic reactivity activating the masked groups and permitting the electrophilic and nucleophilic groups to react with each other. The polymer is typically a polysaccharide. See WO 9738018 (Amersham Pharmacia Biotech AB).
Another recent method is to heat a polymeric support matrix carrying residual unsaturated groups. This method is in particular adapted to support matrices obtained by polymerisation of mixtures comprising vinyl aryl monomers, aryl or methacryl monomers or other unsaturated monomers. See International Patent Application PCT/SE99/0126 (Amersham Pharmacia Biotech AB).
WO 9726071 (Amersham Pharmacia Biotech AB) and WO 9700255 (Amersham Pharmacia Biotech AB) include electron beam irradiation and gamma-ray irradiation as two out of many examples for initiating polymerisation of unsaturated groups in order to manufacture support matrices for various uses.
EP 534016 (W.R. Grace & Co) describes chromatographic matrices with thermoresponsive properties. The publication suggests that one could cross-link beads consisting of linear polymers by irradiation with light, electron rays and gamma rays. It is also suggested that linear polymer after adsorption to a base matrix could be crosslinked in the same way.
WO 9603147 (Fidia Advanced Biopolymers) suggests production of gels and biocompatible substrates by electron beam irradiation of a polymer funtionalized with a plurality of unsaturations. The uses are as carriers in drug administration, as biocompatible substrates for cell culture in three-dimensional systems etc.
EP 159694 (E.I. Du Pont de Nemours) suggests electron beam irradiation for the production of gels from monomers with one and two polymerisable unsaturations.
There are no demands on withstanding liquid flow on the monolithic or packed bed formats of the matrices described in WO 9603147 and EP 159694.