Surface initiated polymerization from substrates of low initiator density and its applications in biosensors.

Surface initiated polymerization (SIP) has become an attractive method for tailoring physical and chemical properties of surfaces for a broad range of applications. Most of those applications relied on the merit of high density coating. In this study, we explored a long overlooked field of SIP: SIP from substrates of low initiator density. We combined ellipsometry with AFM to investigate the effect of initiator density and polymerization time on the morphology of polymer coatings. In addition, we carefully adjusted the nanoscale separation of polymer chains to achieve a balance between nonfouling and immobilization capacities. We further tested the performance of those coatings on various biosensors, such as quartz crystal microbalance, surface plasmon resonance, and protein microarrays. The optimized matrices enhanced the performance of those biosensors. This report shall encourage researchers to explore new frontiers in SIP that go beyond polymer brushes.