Disclosed is a cross-linked poly-e-lysine polymer in particle form. The poly-e-lysine and cross linker are linked by amide bonds and the cross linker has at least two functional groups capable of reacting with an alpha carbon amine of poly-e-lysine. The cross-linked poly-e-lysine polymer is suitably insoluble in water and other solvents and is provided in particulate form. Also disclosed is a particulate support comprising the cross-linked poly-e-lysine polymer and the cross-linked poly-e-lysine polymer may provide the particle itself or be coated on a particle for example silica. The cross-linked poly-e-lysine polymer is useful in a wide range of applications including wound treatment, as a medical diagnostic comprising a particulate support and a functional material bound or retained by the support and solid phase synthesis of peptides, oligonucleotides, oligosaccharides, immobilisation of species, cell culturing and in chromatographic separation.
