a method of coating an spr biosensor specific for an analyte to reduce protein fouling , the method has the steps of providing an spr biosensor , providing a solution of 11 - mercaptoundecanol ; incubating the spr biosensor in the 11 - mercaptoundecanol solution to form a self - assembling monolayer ; incubating the spr with sam in a solution of epichlorohydrin and diglyme ; next incubating the spr in ethanolamine ; preparing a solution of edcnhs and a biocompatible polymer ; incubating the spr from ethanolamine in the edc / nhs / polymer solution ; providing a ligand specific for the analyte in a solution ; incubating the polymer - coated spr in the ligand solution to permit the ligand to react with the polymer - coated spr ; washing the ligand - coated spr to remove unreacted ligand , thereby providing an spr capable of reacting with the analyte . another method replaces the solution for the sam layer with a solution of mha or nhs - mha with ht , and attaches the ligand to the resulting sam layer .