Protein immobilization to polystyrene via long poly(ethylene lycol) chains

Human albumin has been attached to 24-hole polystyrene plates via branched poly(ethylene lycol) (PEG) spacer arms. A tetraepoxude of PEG of molecular weight (1.4-1.5) x 10(4) g/mol was reacted with the protein in solution allowing approximately one-third of the oxirane rings to react. The protein conjugate was then coupled to the long, cationic polymer poly(ethylene imine) (PEI), and the protein-PEG-PEI adduct was subsequently adsorption to unmodified polystyrene. Since the protein is linked to the surface via long, hydrophilic and nonchargedchains, interactions between the biomolecule and the surface is minimized.