Abstract: A process for covalently bonding biopolymer, such as protein, to an organic polymer surface coated with hydrophilic nonionic polymer having groups reactive with the biopolymer and having a cloud point in the reaction medium that is at least 5.degree. C. above the temperature at which the coated organic polymer surface is to be used, which comprises reacting biopolymer with the surface in an aqueous reaction medium, at a temperature not less than 5.degree. C. below the cloud point; but not above a temperature at which the biopolymer is deleteriously affected, and preferably not above about 100.degree. C., the product comprises a biopolymer immobilized on a hydrophilic solid surface having a nonionic polymer and a hydrophilic layer, coupled thereto via biopolymer-reactive groups of the nonionic polymer, and accordingly has low spontaneous adsorption of proteins and other biopolymers through electrostatic attraction and/or hydrophobic interaction.