A porous matrix, preparation thereof, and methods of using the same. The porous matrix of calcium alginate is prepared using a plurality of particles containing a multivalent cation, admixing the particles with ionic cross-linked polysaccharides and water to form a mixture, introducing a cross linker to solidify the mixture, dissolving the particles of the mixture in an acid to form a porous structure, and neutralizing and cross-linking the porous structure.