Au-Capped Nanopillar Immobilized with a Length-Controlled Glycopolymer for Immune-Related Protein Detection.

A Au-capped nanopillar chip was prepared using nanoimprint lithography (NIL) and Au sputtering onto a cyclo-olefin polymer film. The Au surface of the chip exerting localized surface plasmon resonance (LSPR) phenomena was immobilized with a glycopolymer for the detection of cytokines. The glycopolymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization for controlled polymer chain length, and thiol-terminated glycopolymers with chain lengths of 20-, 100-, and 200-mers were designed. The thickness of the biomolecular layer on the Au surface was controlled by changing the polymer chain length of the immobilized glycopolymer, and the absorption of proteins onto the Au surface was detected by the shift of absorbance peak wavelength. The value of absorbance peak wavelength shift by protein adsorption increased as the glycopolymer layer thickness became thinner. This difference in LSPR signal response was remarkable for cytokine recognition compared to larger proteins. It was shown that controlling the biomolecular layer thickness was effective for the detection of small proteins, and our research suggested the usefulness of the controlled glycopolymer surface as a molecular recognition material for cytokine detection.