Abstract: A charged biomaterial including at least one first hydrophilic polymer, and superparamagnetic iron oxide particles complexed with a second hydrophilic polymer substantially identical to or different from the first hydrophilic polymer, wherein the superparamagnetic iron oxide particles complexed with the second hydrophilic polymer are distributed substantially homogeneously and substantially without aggregates in the first hydrophilic polymer. A process for preparing a charged biomaterial including forming an aqueous solution of hydrophilic monomers and superparamagnetic iron oxide particles complexed with a hydrophilic polymer including monomers substantially identical to or different from the hydrophilic monomers, polymerizing the solution and forming a polymer hydrogel in which are distributed substantially homogeneously and substantially without aggregates the superparamagnetic iron oxide particles complexed with the hydrophilic polymer.