A method for preparing a polymeric material doped with a first metal element, which is gold and at least one second metal element, said first metal element and said, at least one second metal element being identical or different from each other, said method comprising: a) a step for copolymerization of at least one first monomer comprising at least one chelating group of said first metal element and of at least one second monomer comprising at least one chelating group, of at least a second metal element, in return for which a polymeric material is obtained comprising recurrent units stemming from the polymerization of said first monomer, which recurrent units comprise at least one chelating group of said first metal element and comprising recurrent units stemming from the polymerization of said second monomer, which recurrent units comprise at least one chelating group of said at least one second metal element, said second monomer being selected from among: - aromatic monomers comprising at least one aromatic ring, which ring comprises at least one ethylenic group, at least one hydroxide group -OH, at least one oxime group and the optional salts thereof; and - the monomers comprising an alicyclic amine group; and said first monomer being a cyclic monomer comprising at least one nitrogen-containing group; b) when the first metal element, and said at least one second metal element are identical (i.e. they both correspond to the gold element), a step for putting the material obtained in a) in contact with an aqueous solution comprising gold, in return for which the gold is complexed to the aforementioned chelating groups; and b') when the first metal element and said at least one second metal element are different, a first step for putting the material obtained in a) in contact with an alcoholic solution comprising gold followed by a second step for putting the material in contact with an aqueous solution comprising said at least one second metal element. a) a step for copolymerization of at least one first monomer comprising at least one chelating group of said first metal element and of at least one second monomer comprising at least one chelating group, of at least a second metal element, in return for which a polymeric material is obtained comprising recurrent units stemming from the polymerization of said first monomer, which recurrent units comprise at least one chelating group of said first metal element and comprising recurrent units stemming from the polymerization of said second monomer, which recurrent units comprise at least one chelating group of said at least one second metal element, said second monomer being selected from among: - aromatic monomers comprising at least one aromatic ring, which ring comprises at least one ethylenic group, at least one hydroxide group -OH, at least one oxime group and the optional salts thereof; and - the monomers comprising an alicyclic amine group; and said first monomer being a cyclic monomer comprising at least one nitrogen-containing group; - aromatic monomers comprising at least one aromatic ring, which ring comprises at least one ethylenic group, at least one hydroxide group -OH, at least one oxime group and the optional salts thereof; and - the monomers comprising an alicyclic amine group; and b) when the first metal element, and said at least one second metal element are identical (i.e. they both correspond to the gold element), a step for putting the material obtained in a) in contact with an aqueous solution comprising gold, in return for which the gold is complexed to the aforementioned chelating groups; and b') when the first metal element and said at least one second metal element are different, a first step for putting the material obtained in a) in contact with an alcoholic solution comprising gold followed by a second step for putting the material in contact with an aqueous solution comprising said at least one second metal element.