Covalent Attachment and Bioactivity of Horseradish Peroxidase on Plasma-Polymerized Hexane Coatings

A plasma polymer coating from a hexane/argon mixture is deposited on PE. Protein attachment is investigated after incubation in a HRP-containing buffer solution. Covalent bonding of the attached HRP is demonstrated by means of ATR FT-IR, which shows that the protein peaks persist after washing in heated SDS solution. An enzyme activity assay demonstrates high levels of bioactivity of the attached protein over several days after washing. The retention of the protein's bioactivity depends on the coating's structure, which in turn depends on the potential between the plasma and the surface during deposition. Covalent coupling is less sensitive to polymerization parameters and occurred on polymer layers deposited both on grounded and negatively self-biased electrodes.