Plasmonic Metasurface as Surface Enhanced InfraRed Absorption Spectroscopy Platform for Biosensing Applications

Abstract

An innovative pixeled plasmonic metasurface (MS) has been developed for surface-enhanced infrared absorption (SEIRA) spectroscopy. The MS is comprised of different pixels, each designed to monitor a specific region of the electromagnetic spectrum. These pixels are engineered with plasmonic resonances that match the Amide I and Amide II vibrational bands in the range of 1500-2000 cm-1. The proposed MS allowed a label-free spectroscopic characterization of a solution of biofibers isolated from cultured fibroblasts treated with an oligothiophene based oligomer. The reflection spectra acquired on areas containing a biofiber show the presence of the typical Amide I and Amide II vibrational bands, while reflection spectra acquired outside the fibers show no signal. Additionally, the evaluated enhancement factor (up to 1.4·103) enables the detection of very small amounts of material bound on the proposed platform, as in the case of a biofiber placed on the nanoantennas composing the MS pixels.