The present invention provides a method of preparation of articles coated with poly(methylmethacrylate-co-methacrylic acid) coating, wherein methyl methacrylate and methacrylic acid monomers are subjected to free-radical polymerization using a radical polymerization catalyst to yield poly(methylmethacrylate-co-methacrylic acid) polymer, and then an article to be coated is subjected to spin-coating with said polymer. The invention further provides coated articles obtainable by such method, in particular substrates for bio- diagnostic devices.