Surface attachment of horseradish peroxidase to nylon modified by plasma-immersion ion implantation



The surface of polyamide (nylon 6) was modified by plasma-immersion ion implantation (PIII) with nitrogen ions. Structural changes associated with carbonization, oxidation, and depolymerization were observed in the modified surface layer with Fourier transform infrared/attenuated total reflection (FTIR–ATR) spectroscopy, surface energy measurements, and X-ray photoelectron spectroscopy (XPS). The enzyme activity of surface-attached horseradish peroxidase was studied with a tetramethylbenzidine colorimetric activity assay. Compared to untreated controls, the PIII-treated surface showed a higher level of the attached protein with increased longevity of bioactivity. Detection of the immobilized protein layer was made difficult by the presence of amide groups in nylon. Here we demonstrate the potential of combining FTIR–ATR spectroscopy with XPS measurements for this purpose. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120:2891–2903, 2011