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.

Angle-Sensitive Photonic Crystals for Simultaneous Detection and Photocatalytic Degradation of Hazardous Diazo Compounds

“…This shift in the wavelength of maximum reflection peak was consistent with Bragg's law and has been reported as a typical feature for photonic crystals in past research [21,22]. Based on the past studies using 2D-PhC based sensors [9,14,23,24], the relationship between the angle of incidence, the angle sensitive iridescent structural color, and the Bragg peaks observed from the TiO 2 coated 2D-PhC were used to detect the target dye molecules using Bragg's law as follows [23,25]:…”

Label-Free Optical Detection of Fibrinogen in Visible Region Using Nanoimprint Lithography-Based Two-Dimensional Photonic Crystal

“…Furthermore, from the previous our study, height and periodicity of pillar will be affected to the diffraction peak intensity [9], [10], [13]. Based on our previous study, height of pillar was approximately 200 nm.…”

“…By these specific reaction, the surrounding refractive index will be increased which depend on the fibrinogen concentrations. These increment of surrounding refractive index due to the antigenantibody reaction, the diffraction peak intensity-based on Bragg's law will be decreased based on Fresnel equations [9], [10], [13]. From these experimental procedure, fibrinogen concentration can be determined as a diffraction peak intensity change.…”

“…To fabricate the polymerbased nanooptical biosensor cost effectively and rapidly, we have been using the nanoimprint lithography (NIL) [9]- [13]. Using NIL, nanooptical biosensor can be fabricated with high reproducibility and cost effectively.…”

Editorial: Translating the advances of biosensors from bench to bedside

“…In ten research articles, two papers focus on the optimization of biosensors for better sensitivity, one explores the graphene interface for DNA analysis and the other studies the electrode interface for electrochemical detection . Endo et al developed printable photonics‐based photonic crystal films for label‐free optical detection of C‐reactive protein using antigen‐antibody reaction . An electrochemical sensing system employing fructosamine 6‐kinase was developed for glycated albumin measurement without relying on proteolytic digestion .…”