Fabrication of flexible and economical plasmonic biosensor using gold nanograting imprinted on hot-melt adhesive film for label-free sensing of immunoglobulin proteins

Abstract

We report here, the fabrication of plasmonic nanograting patterned on hot-melt adhesive (HMA) film via thermal nanoimprint lithography. A soft polymer stamp textured with nanograting pattern was used as a mold to imprint nanograting structure on HMA film overlaid on a flexible polyethylene terephthalate substrate. Thereafter, a 50 nm thickness of gold film was evaporated over surface of the nanograting to prepare a plasmonic sensing layer. The surface plasmon resonance excitation on gold coated nanograting was characterized with the reflectance measurement under the normal incidence of light, which was further verified with theoretical calculations. The bulk refractive index sensitivity of our prepared sensor was obtained 886 ± 55 nm/refractive index unit (RIU). Additionally, a label-free detection of specific target analytes was shown by recording the specific interactions between rabbit immunoglobulin (R-IgG) and anti R-IgG proteins. A surface mass detection limit of 162 pg mm−2 was found in the detection of 100 nM anti R-IgG proteins. Thus, our proposed plasmonic sensor based on low-cost HMA represents another promising thermoplastic material for nanostructure fabrications that have potential applications in the development of affordable, flexible, label-free, and highly sensitive optical/biological sensor.