title: Label-free optical detection of C-reactive protein by nanoimprint lithography-based 2D-photonic crystal film.
abstract: The development of high-sensitive, and cost-effective novel biosensors have been strongly desired for future medical diagnostics. To develop novel biosensor, the authors focused on the specific optical characteristics of photonic crystal. In this study, a label-free optical biosensor, polymer-based two-dimensional photonic crystal (2D-PhC) film fabricated using nanoimprint lithography (NIL), was developed for detection of C-reactive protein (CRP) in human serum. The nano-hole array constructed NIL-based 2D-PhC (hole diameter: 230 nm, distance: 230, depth: 200 nm) was fabricated on a cyclo-olefin polymer (COP) film (100 µm) using thermal NIL and required surface modifications to reduce nonspecific adsorption of target proteins. Antigen-antibody reactions on the NIL-based 2D-PhC caused changes to the surrounding refractive index, which was monitored as reflection spectrum changes in the visible region. By using surface modified 2D-PhC, the calculated detection limit for CRP was 12.24 pg/mL at an extremely short reaction time (5 min) without the need for additional labeling procedures and secondary antibody. Furthermore, using the dual-functional random copolymer, CRP could be detected in a pooled blood serum diluted 100× with dramatic reduction of nonspecific adsorption. From these results, the NIL-based 2D-PhC film has great potential for development of an on-site, high-sensitivity, cost-effective, label-free biosensor for medical diagnostics applications.
authors.affiliation: Department of Applied Chemistry, Osaka Prefecture University, Osaka, Japan. endo@chem.osakafu-u.ac.jp.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Endo
authors.affiliation: SCIVAX Corporation, Kanagawa, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kajita
authors.affiliation: HORIBA STEC, Kyoto, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kawaguchi
authors.affiliation: HORIBA STEC, Kyoto, Japan.
authors.forename: Terumasa
authors.initials: T
authors.lastname: Kosaka
authors.affiliation: HORIBA STEC, Kyoto, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Himi
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002097:C-Reactive Protein / Q000032:analysis*; D003460:Crystallization; D006801:Humans; D055095:Optics and Photonics / Q000295:instrumentation* / Q000379:methods; D011327:Printing / Q000295:instrumentation / Q000379:methods; D013499:Surface Properties
chemical_list: D055910:Antibodies, Immobilized; D002097:C-Reactive Protein
keywords: Antigen-antibody reaction; Biosensor; Nanoimprint lithography; Photonic crystal; Printable photonics