Plasma treatment in air at atmospheric pressure that enables reagent-free covalent immobilization of biomolecules on polytetrafluoroethylene (PTFE)

Abstract

Covalent immobilization of biomolecules to surfaces is desirable in applications in biomedicine and biotechnology, such as biosensors, protein microarrays and implantable biomedical devices. Surface-embedded radicals in polymers, produced by plasma immersion ion implantation, are known to covalently immobilize biomolecules directly from buffer without additional reagents. Here we explore the prospects for creating a surface activated for direct covalent immobilization using a dielectric barrier discharge in air at atmospheric pressure, eliminating the need for vacuum and gas feed systems. We find that a surface activation process at atmospheric pressure in air can activate polytetrafluoroethylene (PTFE) in order to achieve reagent-free covalent immobilization of biomolecules. The presence of surface immobilized protein was verified by X-ray photoelectron spectroscopy (XPS), and its covalent immobilization was demonstrated by resilience to rigorous SDS washing at elevated temperature. Time course immobilization studies show that the covalent coupling capability of the activated surfaces is retained for several days. Proof-of-concept cell assays with immobilized tropoelastin demonstrate the technique’s ability to present functional cell binding molecules for the production of truly bioactive surfaces.