Preparation of crosslinked matrices containing covalently immobilized chemical species and unbound releasable chemical species

A method for forming a matrix having a first chemical specie covalently immobilized therein and including free molecules of a second chemical specie different from the first chemical specie whereby the second chemical specie molecules may be gradually released from the matrix, comprising:

• a. bringing together in covalent bonding proximity a first chemical specie and a polymeric coupling compound that is different than the first chemical specie having at least two photochemical latent reactive groups per molecule, each latent reactive group being capable of covalently bonding to another coupling compound or to the chemical specie;
• b. simultaneously activating the latent reactive groups to cause formation via covalent bonding of a three-dimensional molecular network in which molecules of the chemical specie are covalently bonded to molecules of the coupling compound, and molecules of the coupling compound are covalently bonded to each other, and
• c. contacting the three dimensional network with a second chemical specie different from the first chemical specie under conditions favoring incorporation of the second chemical specie in said three dimensional network in unbound form so that the second chemical specie can be gradually released,
• wherein the first and second chemical specie are each, independently, a carbohydrate selected from the group consisting of chitosan, heparin, hyaluronic acid, alginic acid, cellulose, glycogen, pectin and dextran sulfate or a protein selected from the group consisting of antithrombic agents, attachment proteins, extracellular matrix proteins, growth factors and enzymes,
• and the coupling compound is selected from the group consisting of photoderivatized forms of the following polymers:
• polyacrylamide, polyethylene glycol, polyvinyl pyrrolidone, polyvinylpyridine, polyacetylene, and polypyrrole.