Methods for preparing a substrate for the arraying and immobilizing of biomolecules or cells are described. The methods include providing a solid support and depositing by a chemical plasma-mediated polymerization process a polymeric coating on the surface. The polymeric coating comprises at least one pendant functional group capable of attaching a biomolecule or a cell. A material of the polymeric coating is preferably selected in such a way that its surface properties enhance binding between the pendant group and the biomolecule or cell. A substrate for the immobilization of biomolecules and cells is also provided. The substrate comprises a solid support made of a polymeric material. The solid support has at least one first pendant functional group suitable for attaching a first biomolecule or a first cell on its surface. The substrate further comprises a polymeric coating deposited on the surface of the substrate. The polymeric coating increases the attachment of the first biomolecule or the first cell to the first functional group.