described is a process for producing a biomolecular monolayer on a biosensor surface comprising the steps of : reacting a biosensor surface with a solution of heterobifunctional reagent having a first functional group and a second functional group , the first functional group being capable of forming a covalent bond to the biosensor surface groups , the second functional group forming a covalent bond with a homobifunctional polymer to obtain a self - assembled monolayer , and thereafter reacting the monolayer with capture molecules .